Hydrocarbons - Class 11 Medical Chemistry - Extra Questions

IUPAC names for the following:
(i) $$(CH_3)_3 C \,CH_2 C (CH_3)_3$$
(ii) $$(CH_3)_2 C (C_2H_6)_2$$
(iii) tetra-tert butylmethane

(i)$$\overset{1}{C}H_3 - \overset{\,\,\,\,\,\,CH_3}{\overset{2|}{\underset{\,\,\,CH_3}{\underset{|}{C}}}} - \overset{3}{C}H_2 - \overset{\,\,\,\,\,\,CH_3}{\overset{4|}{\underset{\,\,\,\,CH_3}{\underset{|}{C}}}}  - C\overset{5}{H}_3$$
IUPAC Name - $$2, 2, 4, 4$$- Tetramethyl-pentane


(ii) $$CH_3 - \overset{\,\,\,\,CH_3}{\overset{|}{\underset{\,\,\,CH_3}{\underset{|}{C}}}} - C_2H_5 \equiv CH_3 - \overset{\,\,\,\,\,\,CH_3}{\overset{\!3|}{\underset{\,\,5 \,CH_3}{\underset{|}{\underset{\,\,4 \,CH_2}{\underset{|}{C}}}}}} - C\overset{2}{H}_2 - C\overset{1}{H}_3$$
IUPAC Name - $$3, 3$$ Dimethyl pentane


(iii) Ref. Image
IUPAC Name $$3, 3$$D-butyl -$$2, 2, 4$$- tetramethy pentane

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Give the IUPAC name of $$CH_2=C(CH_3)-CH_2-Br$$.

The parent chain has 3 carbons. The parent chain is numbered so that the double bond has the lowest number. The substitutions are $$methyl$$ group at 2nd carbon and $$bromo$$ at 3rd carbon. Priority functional group is alkene thus the suffix would be $$-ene$$.  The IUPAC name of compound is $$3-Bromo-2-methylprop-1-ene$$.


$${ CH }_{ 3 }-CH=CH-C\equiv CH$$
What is the IUPAC name of the given compound?

$$C{ H }_{ 3 }-CH=CH-C\equiv CH$$ is Pent-3-ene-1-yne by following the IUPAC nomenclature.


Give the IUPAC names  Image result for Oct-3-ene or 3-octene?

IUPAC name is
$$Oct-3-ene$$ or $$3-octene$$


Write the IUPAC names of all the alkanes in Table 6.2.
1835425_f3e442fe56ac454a988f4684b758fec6.png

$$CH_4$$ - Methane
$$C_2H_6$$ - Ethane
$$C_3H_8$$ - Propane
$$C_4H_{10}$$ - Butane
$$C_5H_{12}$$ - Pentane


Write the $$IUPAC$$ name of the following

1287055_b88163e7fd2543c88df2985e5f15d466.png

Refer image. 1
IUPACX Name-3- chloro-proponal
1) Select the longest carbon chain i.e $$3$$ in this case
2) Identical the functional group which is aldehyde in this
3) Numbering of the chain occurs in such way that functional group gets the least number, according to the priority of the functional group.

1356158_1287055_ans_0db7d6135073428782fd2dd9d867224d.png


Write the IUPAC name of the compound given above.
$$CH_3 - \underset{CH_3}{\underset{\!\!\!\!\!|}{CH}} - \underset{CH_3}{\underset{\!\!\!\!\!|}{CH}} - CH_2 - CH_2 - \underset{CH_3}{\underset{\!\!\!\!\!|}{CH}} - CH_3$$

$$2, 3, 6$$- trimethylheptane


 
Write the IUPAC name of the given chemical compound.

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1. At first find the number of carbon in the longest chain. Here we have only  5 carbon in one chain.
2. Counting of carbon will be started from functional grouped carbon as the lowest possible number.
3. Since one $$C=C$$ is present in the chain so -ene will be added with the name.

So the answer is$$\text{ pent-3-en-2-ol}$$.


Carbide of calcium yields ethyne on reaction with $$H_2O$$. 
If true enter 1, else 0.

Hence, the given statement is correct.


Assuming that cation stability governs the barrier for protonation in H -X additions, predict which compound in each of the pairs parts (I) & (II) will be more rapidly hydrochlorinated in a polar solvent.
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$$II \text{ will be hydrochlorinated fastly because of less more stability of intermediate carbocation.}$$

$$\text{Compound II will form 2 degree carbocation whereas compound I will form 1 degree carbocation in intermediate.}$$


"$$Be_2C$$ and $$Al_4C_3$$ are called ethanides because they react with $$H_2O$$ yielding ethane."
Answer whether the above statement is true or false.
If true enter 1, else enter 0.

$$Be_2C$$ and $$Al_4C_3$$ are called methanides because they react with $$H_2O$$ yielding methane.
Hence, the statement is false.


 SN1 reaction undergoes through a carbocation intermediate as follows:
organic-chemistry-questions-answers-nucleophilic-substitution-reaction-q3
[R = t-Bu, iso-Pr, Et, Me] $$(X = Cl, Br, I)$$
The correct statements are:
I. The decreasing order of rate of SN1reaction is $$t-BuX > iso-PrX > EtX > MeX$$
II. The decreasing order of ionization energy is $$MeX > EtX > iso-PrX > t-BuX$$
III. The decreasing order of energy of activation is $$t-BuX > iso-PrX > EtX > MeX$$

I and II are correct.
Explanation:
(1) Formation of the carbocation is Rate determining step, more stable the cation more easily it will form. Hence rate order is $$t-BuX > iso-PrX > EtX > MeX$$
(2) Formation of carbocation $$CH_3$$ is most difficult hence ionization energy is highest. Similarly, $$EtX$$ has lesser ionization energy than $$MeX$$ and so on.
(3) Order of energy of activation is $$MeX > EtX > iso-PrX > t-BuX$$


Which among the following is the simplest example for polycyclic arenes?

a) Benzacephenanthrylene
b) Naphthalene
c) Pyrene
d) Dibenzo-anthracene

Explanation: Naphthalene has a fused ring of aromaticity and has the simplest structure as compared with other polycyclic aromatic hydrocarbons.

So, the correct answer is  naphthalene ( option-b )


When $$Mg_2C_3$$ undergoes hydrolysis, how many carbon atoms is/are present in product?

When $$Mg_2C_3$$ undergoes hydrolysis, allylene is formed as the product which contains 3 C atoms.

$$Mg_2C_3+ 4H-OH\rightarrow 2Mg(OH)_2 + CH_{2}=C=CH_{2}$$


"Of the alkaline earth metals, only magnesium carbide gives $$CH_4$$ on reaction with $$H_2O$$."
Answer whether the above statement is true or false.
If true enter 1, else enter 0.

Of the alkaline earth metals, only beryllium carbide gives $$CH_4$$ on reaction with $$H_2O$$. 
While others like magnesium carbide gives propyne on reaction with $$H_2O$$.
$$Be_2C +4H_2O \longrightarrow 2Be(OH)_2 + CH_4$$
$$Mg_2C_3 +4H_2O \longrightarrow 2Mg(OH)_2 + C_3H_6$$


Bring about the following conversion 
1-pentene $$ \rightarrow 1-$$ pentyne

A molecule of bromine is added to the carbon carbon double bond in 1-pentene to obtain 1,2-dibromopentane. This is followed by dehydro bromination in presence of soda amide to form 1-pentyne.

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Suggest a sequence of reactions suitable for preparing following compound from the indicated starting material. You may use any necessary organic or inorganic reagents.
Cyclopentyl iodide from cyclopentane occurs through the following reactions:
$$\xrightarrow[HgO]{I_{2}/Heat}$$

When cyclopentane is heated with iodine in presence of HgO, cyclopentyl iodide is obtained. In this reaction, H atom is replaced with iodine atom.

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The IUPAC name of the following compound is: 

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The IUPAC name of the given compound is $$2,2-Dimethylpentane$$.
There are two methyl groups substituted at the $$2^{nd}$$ carbon atom in the longest carbon chain of 5 carbons.

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Give the correct IUPAC name:
423646_50f33268499946c8b37c71a605109984.png

The correct IUPAC name is 2,2-dimethyl pentane as the numbering is required for both the methyl groups.


Write the IUPAC name of $$CH_3-CH(Cl)-CH_2-CH=CH_2$$.

Alkene is functional group chlorine is substituents. Hence Double bond is given more importance.

IUPAC Name: 4 chloropent –1 –ene


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An aromatic compound 'A' of molecular formula $$C_{7}H_{7}ON$$ undergoes a series of reaction as shown below. Write the structures of A, B, C, D and E in the following reactions.

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Why are certain compounds called hydrocarbons? Write the general formula for homologous series of alkanes, alkenes and alkynes and also draw the structure of the first member of each series. Write the name of the reaction that converts alkenes into alkanes and also write a chemical equation to show the necessary conditions for the reaction to occur. 

Hydrocarbons are a group of compounds made up of carbon and hydrogen. 

The general formula of homologous series of alkanes is $$C_nH_{2n+2} $$, of alkenes is $$C_nH_{2n} $$ and of alkynes is $$C_nH_{2n-2} $$.

The reaction that converts alkenes to alkanes is an addition reaction. It is as follows: 

$$ CH_2 = CH_2 + H_2 \xrightarrow[Heat]{Ni\: catalyst} CH_3 - CH_3 $$

For this rection catalysts like Raney Ni, Pt and Pd can be used.

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Give the following reaction:
$$Propan - 1 - ol \rightarrow Propoxy\ propane$$.


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Consider the following alkane and answer the following questions.
$${ \left( { CH }_{ 3 } \right)  }_{ 2 }CH{ CH }_{ 2 }CH\left( { C }_{ 2 }{ H }_{ 5 } \right) CH\left( { CH }_{ 3 } \right) { CH }_{ 3 }\quad $$
(a) Write the complete structural formula of the alkane.
(b) What is its molecular formula?
(c) Write its bond line formula and give IUPAC name.
(d) How many methyl, methylene and methine groups are present in this alkane?
(e) How many ethyl and isopropyl groups are present in this alkane?
(f) How many carbon atoms are $${ 1 }^{ o },{ 2 }^{ o },{ 3 }^{ o },{ 4 }^{ o }$$?

(a) $$CH_3-\underset{CH_3}{\underset{|}{CH}}-CH_2-\overset{C_2H_5}{\overset{|}{CH}}-\underset{CH_3}{\underset{|}{CH}}-CH_3$$
(b)  Molecular formula $$=C_{20}H_{22}$$
(c) ( Refer image ) IUPAC name $$\equiv 3-ethyl-2,5-dimethyl\,hexane$$
(d) methyl $$=5$$, methylene $$=2$$, methine $$=2 (-CH_2)$$
(e) Ethyl $$=1$$, Iso-propyl $$=2$$
(f) $$1^o-$$ carbon $$=5,2^o-$$ carbon $$=2,3^o-$$ carbon $$=3,4^o-$$ carbon $$=0$$

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Consider the alkane- $${ \left( { CH }_{ 3 } \right)  }_{ 2 }CH{ CH }_{ 2 }CH\left( { C }_{ 2 }{ H }_{ 5 } \right) CH\left( { CH }_{ 3 } \right) { CH }_{ 3 }$$
(i) What is its molecular formula?
(ii) How many $${ 1 }^{ o },{ 2 }^{ o },{ 3 }^{ o },{ 4 }^{ o }$$ carbon atom are present.
(iii) State the number of methyl, methylene and methane group in the alkane.

$$\underset{1^0}{CH_3}-\overset{3^0-}{\underset{\underset{1^0-}{CH_3}}{\underset{|}{CH}}}-\underset{2^0-}{CH_2}-\overset{\overset{1^0-}{2^0CH_5}}{\overset{|}{\underset{3^0-}{CH}}}-\underset{1^0-}{\underset{CH_3}{\underset{|}{\overset{3^0-}{CH}}}}-\underset{1^0-}{CH_3}$$

Molecular formula $$\equiv C_{10}H_{22}$$
$$\left.\begin{matrix}3^o-carbon=\sqrt{2}\\2^o-carbon=2\\1^o-carbon=0\end{matrix}\right|\begin{matrix}-CH_3\Rightarrow methyl(\sqrt{2})\\-CH_2\Rightarrow Methylene(2)\\Methane\Rightarrow zero\end{matrix}$$


$$CS_{2} + H_{2}S\xrightarrow {Cu} (A) \underset {473K/ 100\ atm}{\xrightarrow {[O]Cu\ tube}} (B)$$.

The reaction is:
$$C{ S }_{ 2 }+H_{ 2 }S\overset { Cu }{ \longrightarrow  } \underset { A }{ CH_{ 4 } } +C{ u }_{ 2 }S\overset { [O]\\ Cu\ tube }{ \underset { 473\quad K,\\ \ 100\ atm }{ \longrightarrow  }  } \underset { B }{ CH_{ 3 }OH } $$
Therefore A is methane and B is methanol.


Butylated hydroxy toluene is antioxidant why?

Since, it is soluble in fat , and insoluble in water, and are volatile. So it is useful for adding to pack material.


Match the column :

$$(A)$$ $$CH_3-Cl\overset {Na}{\underset {Dery\quad ether}{\longrightarrow}}$$ $$CH_3-CH_3$$
$$(B)$$ $$CH_3-Cl+CH_3-CH_2-Cl\overset {Na}{\underset {Ether}{\longrightarrow}} C_2H_6+C_4H_{10}+C_3H_8$$
$$(C)$$ $$CH_3Cl+C_2H_5Cl+C_3H_7Cl\overset {Na}{\underset {Ether}{\longrightarrow}} C_2H_6+C_4H_{10}+C_6H_{14}+C_3H_8+C_5H_{12}$$
$$(D)$$ $$H_2C=CH-CH=CH-CH_2-Cl+C_2H_5Cl\overset {Na}{\underset {Ether}{\longrightarrow}}C_4H_{10}+R-C_2H_5+R_2$$
where we take $$H_2C=CH-CH=CH-CH_2$$ as $$R$$
In these type of reactions all possible reactions occurs between $$R$$ and $$R^{\prime}$$.


Give the IUPAC name of the following:
996649_9dc53b0c2dcd447e9ad608b968a408ce.PNG

This is a bicyclo compound.

2 - methylbicyclo [3.1.1] heptane


Give the IUPAC name of the following:
996639_79903f33a7f54f33877f3a25b81a5492.PNG

Two methyl groups are attached to octane at 2nd position.
Propyl group is attached to 4th position.
2, 7 - dimethyl - 4 - propyloctane


Give the IUPAC name of the following.
996656_d360e0490712472e8c9b1f99c348a659.PNG

The numbering is done for the longest carbon chain with another carbon chain attached to it having another numbering.
The IUPAC name of the compound which is shown above is-
$$5-[\{1^{\prime}-ethyl,(1^{\prime\prime}-methyl-ethyl),2^{\prime}-methyl\}propyl-nonane]$$

1071448_996656_ans_e8efbc89251649f1b545a726874664ae.PNG


Give the IUPAC name of the following.
996653_0da5a62afa0c4ecd942d73a0e84707e7.PNG

The numbering is done with the longest carbon chain. any carbon chain attached to it is given alternate another numbering. The numbering for this starts from the carbon attached to the longest chain.
The IUPAC name of the above compound is-
$$2,3,5-trimethyl-4-(1^{\prime}-methyl)-propyl-nonane$$

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Find the final product of the reaction.

1003365_75fa242706bd4ea68cad69d9e1cad6a0.jpg

($$C_3H_8$$) propane when reacts with $$Br_2$$, it follows free radical mechanism to form secondary free radical which gives 2-bromopropane as a product.
When 2-bromopropane reacts with $$Na/ether$$. it undergoes Wurtz synthesis to form 2,3-dimethylbutane as a product.

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Why oxidizing agents like $$HNO_3$$ and $$HIO_3$$ are used in the iodination of alkane?

Since above reaction is reversible in nature, so to destroy $$HI$$, we use oxidising agent like $${ HNO }_{ 3 }$$ or $${ HIO }_{ 3 }$$ which oxidises$$HI$$ to $${ I }_{ 2 }$$ and makes reaction irreversible.
1036012_1055046_ans_2787e35b5a9c4e52bf0c97b61c7f81bd.PNG


Convert Ethanol to But-1-yne.

$$\underset{ethanol}{CH_{3}CH_{2}OH}\overset{Al_{2}O_{3}}{\longrightarrow}CH_{2}=CH_{2}\overset{HBr}{\longrightarrow}CH_{3}CH_{2}Br$$
$$CH\equiv CH+CH_{3}CH_{2}Br\overset{NaNH_{2}}{\longrightarrow}\underset{but-1-yne}{CH\equiv CH-CH_{2}CH_{3}}$$

Note: NaNH2 acts as base takes up acidic H of alkyne which is terminal alkyne.


What is the role of sigma and pie bond in aromatic electrophylic substitution?


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Explain Kolbe's electrolytic method.

Kolbe's electrolysis method uses sodium salt of fatty acid to form the corresponding alkane as a product.
In this reaction, the decarboxylation of the sodium salt of fatty acid takes place.

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$$C_6H_6+CH_{3}CH_{2}CH_{2}Cl\xrightarrow  { Anhydrous \ AlCl_ 3 } P$$
Identify $$P$$.

Benzene undergo reaction at room temperature with a chloroalkane (for example, chloromethane or chloroethane) in the presence of aluminium chloride as a catalyst.
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Alkyl halides (except fluorides) on reduction with zinc dilute hydrochloric acid give alkanes.
Write the reaction involved for chloromethane to methane

This is reduction of alkyl halide to alkane on zinc surface.
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How will you synthesize
(i) cumene from benzene?
(ii) benzene to n-propyl benzene

$$(i)$$ cumene from benzene
$$(ii)$$ benzene to n - propyl benzene.

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Preparetion of Butane from ethene?

Preparation of butane from ethene-
$$\underset{\text{Ethene}}{2 C{H}_{2}=C{H}_{2}} \xrightarrow{2 HCl} 2 C{H}_{3}-C{H}_{3} \xrightarrow{Na/\text{ether}} \underset{\text{Butane}}{C{H}_{3}-C{H}_{2}-C{H}_{2}-C{H}_{3}}$$


Trans-but-$$2$$-ene is treated with $$Br_{2}$$ in $$CCl_{4}$$ solvent. Write the product formed.


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Given name for the following substituted alkanes:
1068167_15a45943467a4499be3b147a26f0fb5a.png

$$1-ehlero-2,4-demethyl$$ $$cyclohexane $$

$$or$$ $$2,4-dimethyl$$ $$cyclohexylchloride.$$ 

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$$HC \equiv CH \dfrac{Hg^{+2}}{CH_3COOH}$$
Complete the reaction.


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(i) Give the hydration of 1-butyne.
(ii) Convert propyne to propyn-2-ol.


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Predict the alkanes  obtained by (i) the action of sodium metal on n-propyl chloride (ii)catalytic hydrogenation of isobutylene.


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How will you prepare ethane from:
Ethyl Chloride


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Comment on alkynes preparation and chemical properties of alkyne.

$$i.$$ An alkyne may be prepared by heating a dehaloalkane with alcoholic $$KOH$$.
$${ R }-\underset { X }{ \underset { | }{ { \overset { X }{ \overset { | }{ CH }  }  } }  } -\underset { X }{ \underset { | }{ { CH_{ 2 } } }  } +2KOH\longrightarrow R-C\equiv CH+2KX+2H_2O$$
$$ii.$$ Vicinal tetrahaloalkanes can be dehalogenatedwith $$Zn$$ metal in an organometallic reaction to form alkynes.
$${ R }-\underset { X }{ \underset { | }{ { \overset { X }{ \overset { | }{ C }  }  } }  } -\underset { X }{ \underset { | }{ { \overset { X }{ \overset { | }{ C }  }  } }  } -R+Zn\longrightarrow R-C\equiv C-R+ZnX_2$$
$$\underline {Chemical\quad properties}$$ 
$$1.$$ The $$H$$ atoms attached to triply bonded carbon atoms are acidic in nature.
$$2.$$ Alkynes undergo electrophilic addition reactions.
See the given structure.
$$3.$$ Alkynes undergo polymerisation under suitable conditions.

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How will you prepare ethane from:
Ethanol


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Predict the alkanes obtained by 
(i) the action of sodium metal on n-propyl chloride  
(ii) catalytic hydrogenation of isobutylene.


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Consider the following alkane and answer the following question
$${({CH}_{3})}_{2}CH{CH}_{3}CH({C}_{2}{H}_{5})CH({CH}_{3}){CH}_{3}$$
(a) How many methyl, methylene and methine groups are present in this alkane?
(b) How many ethyl and isopropyl groups are present in this alkane?
(c) How many carbon atoms are $${1}^{o},{2}^{o},{3}^{o}$$ and $${4}^{o}$$?


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Identify 'A' and 'B' in the following reactions? 


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What will be the product of the given reaction?
1163854_8549a74a4270421cb4b2d16c474c9195.png

At high temperature in presence of sunlight, the chlorine follow free radical mechanism.

In this reaction, the chlorination of methyl group present on benzene ring takes place to form Benzyl chloride.

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Name the carbon compound which heating with an excess of concentrated sulphuric acid at 3 k gives ethane.


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Why are alkali metals normally kept under kerosene ?

Alkali metals are highly reactive because they have only one electron in their valence shell which can easily be lost and metal get oxidized. In presence of water, they react to form highly flammable gas Hydrogen, so they are kept in kerosene.


How will you prepare propane from sodium salt of fatty acid?


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What is the action of the following reagents on propyne?
i) Chlorine gas
ii) hydrogen iodide

Reaction of propyne with chlorine gas:
$$CH_3C≡CH+Cl_2\rightarrow HC≡C-CH_2Cl+HCl$$
Reaction of propyne with Hydrogen iodide:
$$CH_3C≡CH+HI\rightarrow  CH_3CI=CH_2$$


Complete and balance the following equation:
$$CH_4+ Cl_2 \xrightarrow{Sunlight}$$


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What happens when methane reacts with chlorine?

When methane reacts with chlorine in presence of sunlight, it undergoes chlorination to form methyl chloride.
$$CH_4+Cl_2\xrightarrow{hv} CH_3Cl+HCl$$
This reaction go on further to produce polyhalogen derivative of alkane until all the hydrogen atom on methane is replaced by the corresponding number of the chlorine atom.
$$CH_3Cl+Cl_2\xrightarrow{hv} CH_2Cl_2+HCl$$
$$CH_2Cl_2+Cl_2\xrightarrow{Hv} CHCl_3+HCl$$
$$CH_3Cl+Cl_2\xrightarrow{hv} CCl_4+HCl$$


Name two catalysts that can be used in the hydrogenation of unsaturated compounds.

Nickel or palladium can be used as catalyst in the hydrogenation of unsaturated compounds.


Propane from n- propyl alcohol


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How will you prepare acetylene from:- (Give Balanced chemical equation)
Ethlidence dichlioride?


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What effect does branching of an alkane chain has on its boiling point?

As branching increases, the surface area of the molecule decreases which results in a small area of contact. As a result, the Van der Waals force also decreases which can be overcome at a relatively lower temperature. Hence, the boiling point of an alkane chain decreases with an increase in branching


Carry out the following resonance:
Ethyl alcohol to ethane.


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How will you convert ethene to ethane.

Ethene on catalytic hydrogenation in presence of Nickel catalyst gives ethane.
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Why trans-isomers of alkene has higher melting point than its Cis-isomer?


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Write the IUPAC names of the given compounds:
1717118_52b28aa28f6e45f3975b713d15a5731e.PNG

3,3,4-Trimethyl octane


Fill in the blanks:
The carbon atoms of ethyne are ______ hybridized.

$$\overset{sp}CH\equiv \overset{sp}CH$$

2 $$\sigma$$ + 2$$\pi$$ bond for each carbon atom is present in ethene both the carbon are $$sp$$ hybridized.


Write the IUPAC names of the given compounds:
1717149_b650300c96e848be9c022cb4a497b9e1.PNG

1-Chloro-3-ethyl-2-pentanone


Write the IUPAC names of the given compounds:
1717116_a8404834f4bc4f94a90b5f48e64ebb7f.PNG

3-Methyl hexane


Fill in the blanks:
Carbon atoms in $$Ag_{2}C_{2}$$ (silver acetylide) are ________ hybridized.


$$Ag^+C^{-}\equiv C{^-}Ag^+$$

Each carbon has 2 $$\sigma$$ and 2 $$\pi$$ bond. Hence both are $$sp$$ hybridized.

Ans-$$sp$$


Write the IUPAC names of the given compounds:
1717133_ad40712efadd427c92cb57d50035e7c4.PNG

3-Methyl-1-cyclohexyne


Write the IUPAC names of the given compounds:
1717135_17f8f7a3af394e62a309be61026e3c99.PNG

Trans-1,2-dimethyl cyclohexane


Write the IUPAC name of the given compounds:
1717150_df35229eb9b6499c8edcbefe031ff9cf.PNG

3,7--Dimethyl octa-1,3,6-triene


Complete the following equations :

$$(CH_{3})_{3} C - CH = CH_{2} + HCl \rightarrow (A)$$.


1638108_1717596_ans_addc8238814a4f7da73e95037f37540c.jpg


Complete the following equations :

$$H_{2}C = CH - CH_{3} + HCl\rightarrow (A)$$.


1638106_1717588_ans_1a634893f8d249e78ec408aa450039cb.jpg


Complete the following equations:

$$H_{2}C = CH_{2} + CH_{2}N_{2} \rightarrow (A)$$.


1645780_1717619_ans_7e7455630b0948c090da1fcdb7f79cb5.jpg


Give the IUPAC names for the given compound.
1717965_10d56fdcad5241f8b70f1568e062f495.PNG

1,1',3',1''-Tercyclobutane
1550762_1717965_ans_a4a9c42804c44684a1f230ac1c80cedd.png


Give the IUPAC names for the given compound.
1717961_9a70a669db294d61af1209cce4b2dce8.PNG

1,3,5-Trisdecylcyclohexane


Complete the following equations :
$$C_{6}H_{5}C \equiv CH (A) \underset {(ii) CH_{3}I}{\xrightarrow {(i) NaNH_{2} (3.0 equiv.)}} (B)$$.


1645788_1717627_ans_435ad6c3d4cf43718cff62a51e66f56c.jpg


Give the IUPAC names for the given compound.
1717950_3e06995467ef4e73b0b8248a91a0300f.PNG

3-Chloro-2-ethyl-1,8-dimethylbicyclo[3.2.1]octane


Write the various types of isomerism shown by alkenes. Give one example of each.

Position isomerism
Example: $$but-1-ene$$ and $$but-2-ene$$

Chain isomerism
Example: $$but-1-ene$$ and $$2-methylPropene$$

Geometrical isomerism
Example : cis- or trans-$$but-2-ene$$

Ring chain isomerism
Example: propene and cyclopropane.


Give the IUPAC names of the given compounds:
1717971_dcebe1a694f84dcea9d611ddde049c0e.PNG

2-(3'-Oxobutyl) cyclohexan-1-one


Give the IUPAC names of the given compounds:
1717978_2519efa859e4453aa7fc6316c7a88f48.PNG


1550338_1717978_ans_cafe7c8ae2e841a793906637bcb6f1ff.jpeg



Give the IUPAC names of the given compound.
1718021_056427413db9447580ea5ec18ba40ec8.PNG


1551471_1718021_ans_e9636cdb6e9c43c6886ac9595e46aca3.jpg


Give the IUPAC names of the given compounds:
1717994_7cc49dacfec3483b9ec59ee1f3fba177.PNG

2,3,3,7,7-Pentamethyloctane


Give the IUPAC names of the given compounds:
1717975_da75372fc86a420eb0faf4d2224ae07f.PNG


1550252_1717975_ans_e757bb7b00f64dfb961fe6ca87ea88b5.jpeg


Give the IUPAC names of the given compounds:
1718014_f4012f2ab13041038f1fb839c43cd4e7.PNG

7,7-Dimethyl bicyclo [2.2.1] heptane


Give the IUPAC names of the given compounds:
1718015_9dae8368610546dea94d8a1e0e25252f.PNG

2-Chlorospiro [4.5] decane


Give the IUPAC names of the given compounds:
1718000_01d3ff2b88c84a1ba2d4131a0c46b081.PNG

1,4-Dioxacyclohexane


Fill in the blanks in the following: 
All alkanes are ...... than water. 

All alkanes are lighter than water. 


What happens when: 
Water is added to aluminium carbide?

Aluminum carbide is a solid that reacts with water to form aluminum hydroxide and methane gas. The reaction can be represented by the following chemical equation.
$$Al_4C_3+12H_2O\rightarrow 3CH_4+4Al(OH)_3$$


Fill in the blanks in the following: 
Halogenation of alkanes does not occur in ......

Halogenation of alkanes does not occur in dark because for halogenation, sunlight act as reaction initiator.


Fill in the blanks in the following: 
When ...... is strongly heated with sodalime $$ C_{2}H_{6}$$ is obtained.

When sodium propanonate is strongly heated with sodalime $$ C_{2}H_{6}$$ is obtained.


Calculate the total moles of major products are obtained when dry sodium propionate is heated with soda-lime.


1556142_1718469_ans_4dacdd19f3a14f85b0b4da5aca88b4c8.jpg


Complete the following reaction:

$$CH_{3}Br\xrightarrow[ether]{Na}(A)\xrightarrow[Br_{2}]{hv}(B)\xrightarrow[ether]{Na}(C)$$

$$2CH_3Br\overset{Na/Ether}{\longrightarrow}2CH_3-CH_3 (A)\overset{hv/Br_2}{\longrightarrow}2CH_3CH_2Br (B)\overset{Na/ether}{\longrightarrow}CH_3CH_2CH_2CH_3 (C)$$

Wurtz reaction is a method of synthesis of higher alkanes by treating alkyl halides with sodium metal in dry ether. Formation of A and C occurs by Wurtz reaction.

Alkane reacts with bromine in the presence of UV light to form bromoalkane. The formation of B occurs by this method.


What happens when: 
Ethyl iodide dissolved in dry ether is treated with sodium metal?

 The reaction of an alkyl halide with sodium metal in the presence of the dry ether results in the formation of higher alkanes. 

$$2C_2H_5I+2Na\rightarrow C_4H_{10}+2NaI$$




How will you prepare the following? 

Ethane from ethanol in one step.

Chemical equation for the preparation of ethane from ethanol is 

$$\underset{Ethanol}{C_2H_5OH}+2HI\overset{Pt}{\rightarrow}\underset{Ethane}{C_2H_6+I_2}+H_2O$$


Complete the following reactions:

$$(CH_{3})_{3} C - Cl \underset {\triangle}{\xrightarrow {CH_{3}COO^{-}}}$$   ?

$$(CH_{3})_{2}C = CH_{2}$$


How will you synthesise?
$$But-1-yne$$ from acetylene.

$$HC\equiv CH \xrightarrow {NaNH_{2}} HC \equiv CNa \xrightarrow {CH_{3}CH_{2}Br} HC \equiv C - CH_{2}CH_{3}$$.


How will you synthesize propane from isopropyl alcohol?

-
1543171_1720118_ans_53286f65357a48d888381b1c2e296d16.jpg


Identify the (A), (B), (C) and (D) in the following reactions sequence:

$$ CH_3COCH_3 \xrightarrow {LiAIH_4 } (A) \xrightarrow {HBr} (B) \xrightarrow { Alc.KOH } (C) $$

$$ (A) CH_3CHOHCH_3 (B) CH_3CHBrCH_3 (C) CH_3-CH=CH_2  $$


Fill in the blanks:
The ring structure of benzene was proposed by ______.

Kekule proposed the benzene ring structure.

Ans-Kekule


How will you synthesize cyclohexene from cyclohexane?

The most common method of making cyclohexene is by taking cyclohexanol (cyclohexane with an $$-OH$$ group attached to it) and treating it with an acid of some sort. When cyclohexanol is reacted with an acid it undergoes a reaction called a dehydration reaction, which means it loses a water molecule. The product of this dehydration process is actually cyclohexene itself!
1644259_1720127_ans_5c712b5e061b44b2b0dcf4ccbf681704.png


How will you obtain the following from propene?

$$1,2-$$Dichloropropane

Treat with $$Cl_{2}$$ in $$CCl_{4}$$.


How would you bring the following conversions?

Acetaldehyde to ethylene


1565426_1720905_ans_299f0363cc9e4388a4c17b151d0d5327.jpg


How will you synthesise?
$$n-Hexane$$ from propene.

$$CH_{3}CH = CH_{2} \underset {Peroxide}{\xrightarrow {HBr}}CH_{3}CH_{2}CH_{2}Br \underset {Wurtz\ reaction}{\xrightarrow {Na/ether}} CH_{3}(CH_{2})_{4}CH_{3}$$.


Write the IUPAC names of the following:
1721313_9256db5626e94a469ee803017849dad2.jpg

$$2-Phenyl \ nitro \ ethane$$.


Answer the following:
Prove that benzene molecule has three double bonds.

Benzene contains 3 carbon with three double bonds.

And it is aromatic and most stable due to resonance for 4n + 2 electrons.

And by the resonance structure itself U can show that it has 3 pi bonds obvious.




Complete the following equations:
1721535_08aced0df7d143a1b329fd3ade16bc4b.jpg

-
1544568_1721535_ans_45ad3085dc3541aba8249d0a81241d57.jpg


Name the final product of the following reaction:
Benzene is catalytically hydrogenated.

When benzene is catalytically hydrogenated, all the double bonds dissolve and a hydrogen atom attached to each carbon and hence formed cyclohexane.
1610242_1721615_ans_b48598ff50ea4e0d840ee849030dc46f.PNG


Name the final product of the following reaction:
Benzene is treated with methyl chloride in the presence of anhydrous aluminium chloride.

This is Friedel-craft  alkylation reaction. Acylation of benzene with methyl chloride gives toluene.
1610308_1721609_ans_2f48a8aed0174915bfd6ddbb5a9b019e.PNG


How will you obtain $$o-$$ chlorotoluene from toluene?

The major products formed in the reaction of toluene with chlorine in the presence of ferric chloride are o-chlorotoluene and p-chlorotoluene.
1657133_1722329_ans_3b06f8764ea64da3b8f47aa2346ec473.png


Complete the following, giving the structures of the principal organic products:
1722469_afd9881e49b14466be9e47127a79d3ca.jpg


1661866_1722469_ans_5cfa2570542d437cbfc3454bf2360031.jpg


Number of possible fractions of $$B$$ are:

1749093_10c61b6456174367b165a3d21ad71fca.png


1596200_1749093_ans_b491a03a109f4d0c8632c8c8e201fe3a.png


Identify the following compounds:

1767445_9ae05065f0c84fbfbe985be7a7a63ff8.png

The compounds are: 


Convert $$but-1-yne$$ to $$but-2-yne$$ and $$vice\ versa$$.


1694117_1768099_ans_8fad687418894c219240f6c78157f8b2.png


Identity the products:
1768077_a65d7fff82d6413dbef6ab53982387c7.png


1692622_1768077_ans_24d27d4d249d4a90bebe32836cb16ad2.png


Complete the above reactions:
1767756_f4d0406ac4f141c3a56218f9383f7262.png


1692770_1767756_ans_d945aaaa68714f54abc1f5924dfdbf58.png


Convert the above
1768074_aff249e9f724478c848f14e6667ca504.png


1692618_1768074_ans_72aa6c269c474449a52128c4372cb272.png


Give an example example branched chain compund.

Branched chain compounds (isobutane)
1648833_1784698_ans_8efd59be0c4b485f9a0ed923a6f3e6f6.png


 What are the sources for alkynes ? Give the general formula of alkynes.

Natural gas and Petroleum are sources for alkynes.

The general formula of alkynes are:
$$C_{n}H_{2n-2}$$


Outline the reaction sequence for the conversion of ethene to ethyne ( the number of steps should not be more than two).


1693186_1768355_ans_32310120f2d14e29b5c69db90c1d4256.png


Convert $$(cis- or\ trans)\ pent-2-ene$$ to $$pent-2-yne$$ and $$vice\ versa$$.


1693076_1768101_ans_b8e4e29636b04fedb1eacc79da1a9d30.png


 Which alkane having a molecular weight of 86, will form only two monobromo alkanes?

Alkane is $$C_nH_{2n+2}$$ Molecular weight=86

$$\therefore 12n+2n+2=86 \Rightarrow n=6$$

Therefore, alkane is $$C_6H_{14}$$

1781280_1769028_ans_9db07e80c7e3435cabdadadd89ff323e.png


Give the IUPAC names of the following compounds
1797101_559afb9279d7450e93e8b7e7624eee2b.png

the IUPAC names of the given compounds is $$ 3-phenylprop-2-ene-1-al$$


Give the trivial (common) names and the $$IUPAC$$ names of the following:
$$C_{2}H_{2}$$

  Common Name- Acetylene 

IUPAC Name - Ethyne


Give the trivial (common) names and the $$IUPAC$$ names of the following:
$$C_{2}H_{4}$$


Common Name - Ethylene

$$IUPAC$$ Name - Ethene



Name the compound prepared from:
"sodium propionate"
Write a balanced equation for the same

Ethane is prepared from sodium propionate.

$$C_2H_5COONa+NaOH\  \xrightarrow {CaO, 300^oC}\ Na_2CO_3+C_2H_6$$


How ethane is prepared in the laboratory?

Laboratory preparation of ethane:

When the mixture of sodium propionate and soda lime in the boiling tube and heated the ethane gas is evolved. It is also collected by downward displacement of water.

$$C_2H_5COONa+NaOH  \xrightarrow {CaO, 300^oC}\ Na_2CO_3+C_2H_6$$


Name a compound of each type and draw the figure.

Cyclic compound with a single bond



Cyclic compound with single bond: cyclopentane

Structure: As shown

1702216_1807420_ans_eac75f03d6804f34bc8b80a940ab5fe7.png


What will be the formula and structure of benzene?


Formula of benzene: $$C_{6}H_{6}$$

Structure of benzene as shown 

1702555_1807494_ans_45c46db346dd42f78643875471bf7468.png


Write: molecular formula of ethene ( ethylene)

The molecular formula of ethene is $$C_2H_4$$


Give the trivial (common) names and the $$IUPAC$$ names of the following:
$$C_{3}H_{6}$$

Common name - Propylene 

IUPAC name - Propene


Write IUPAC name of isobutane.

the IUPAC name of isobutane is 2-methylpropane


Write the:
Molecular formula of methane and ethane

For methane:
Molecular formula is $$CH_4$$
For ethane:
Molecular formula is $$C_2H_6$$


How will you bring about the following conversions?
Propene to propyne


1738961_1828548_ans_1730ebe39d33427d9cf5d53bac9de4f4.png


Write the rules of nomenclature of alkane.

Following are the rules of nomenclature of alkane:

  • The longest chain is selected. The Group out of the main chain is called substituent.
  • When two or more chains of the same length are present then the chain with greater number of substituents is selected.
  • Name of substituent is first to be written and prefixes are written in alphabetical order.
  • If more than one but the same substituent are present then mono, di, tri, tetra, Penta, etc. are written as per the number of substituents.
  • Two numbers are separated by comma and hyphen is used between a number and a name.


Write the general formula for each of the following hydrocarbons and give one example for each.
Alkyne

The general formula of alkynes is$$C_nH_{2n-2}$$ where n is the number of carbon atoms in one molecule of the alkyne. 
$$C_2H_2$$ is the molecular formula of ethyne.


Name the second member of the alkyne series.

propyne
The second member of alkyne family is propyne


Write the name of the following compounds?
(i)$$CH_{3}-CH_{2}-Br$$

(ii)$$H-\overset{H}{\overset{|}{C}}=O$$

(iii)$$H-\overset{H}{\overset{|}{\underset{H}{\underset{|}{C}}}}-\overset{H}{\overset{|}{\underset{H}{\underset{|}{C}}}}-\overset{H}{\overset{|}{\underset{H}{\underset{|}{C}}}}-\overset{H}{\overset{|}{\underset{H}{\underset{|}{C}}}}-CH=CH_2$$

Names of the given compounds are:
(i) Bromoethane.
(ii) Methanol
(iii) Hexane.


Write IUPAC names of following:
Iso-octane

$$2,2,4$$-trimethyl pentane
1724188_1822357_ans_40af34c46feb42b08fd63dea2341f72c.jpg


Name the following compound.
1822484_2f4ad44e09854e569af53c67036575f4.png

Benzene, $$C_6H_6$$.


Write the formula of inorganic benzene.

Borazine is inorganic benzene with formula $$B_3N_3H_6$$.


Write down the IUPAC name of the given compound.

1835568_922c02dfa9094500ba617c9d90d3a4e4.png

The IUPAC name of the given compound is $$2$$- Methyl Pentane.


Write the IUPAC name of $$\mathrm{CH_3-CH_2-CH_2-OH}$$.

The IUPAC Name of the above compound is Propanol.


 CompoundIUPAC name 
 $$CH_3 - \underset{CH_3}{\underset{\!\!\!\!\!\!|}{CH}} - CH_2 - \underset{CH_3}{\underset{\!\!\!\!\!\!|}{CH}} - CH_2 - CH_3$$.............. 
 ............. 2, 3, 3-Trimethylpentane
 .............. 3, 3-Diethylpentane
Complete the table given above.


1753424_1835464_ans_40d6a0edbd1f4ba088126eba7da8ba59.png


Write general formula of alkenes and explain general method for its preparation.

The general formula of alkenes is $$C_{n}H_{2n}$$. 
General method of preparation of alkene : 
Alkenes are generally prepared by dehydration of alcohols, These are prepared by passing the vapours of an alcohol over heated alumina at $$623 K$$.
$$\underset{alcohol}{RCH_{2}CH_{2}OH}\xrightarrow [623K]{Al_{2}O_{3}}\underset{alkene}{RCH=CH_{2}}+H_{2}O$$


Write the name and structure of two aromatic hetrocyclic compounds.


1744824_1830770_ans_e5dc481613d441b9af085aa3347df791.png


Number the carbon atoms in the main chain of the above compound given above. Put a tick mark against the correct position numbers of the branches.
$$CH_3 - CH_2 - \overset{CH_3}{\overset{\!\!\!\!\!|}{CH}} - CH_2 - \underset{CH_3}{\underset{\!\!\!\!\!|}{CH}} - CH_3$$
a. What is the IUPAC name?
b. Which is the second branch?

$$\cdot$$ Number of carbon atoms in the main chain: $$5$$
$$\cdot$$ Number of branch/branches: $$2$$
$$\cdot$$ Position of the first branch while numbering from left to right: $$2$$
$$\cdot$$ Position of the first branch while numbering from right to left: $$2$$

So, the IUPAC name: $$2,4$$ dimethyl pentane

Both branches are of methyl group.

Hence,
a. $$2, 4$$- Dimethyl hexane.
b. $$CH_3$$


Complete the table given above.
1835427_2040c7f680aa49798c11ac7519941994.png


1752900_1835427_ans_92a1d63536d142caa888b65236b02cc8.png


Name the given compound.
$$CH_3 - \overset{CH_3}{\overset{|}{CH}} - CH_2 - C \underset{CH_3}{\underset{|}{H - }}  CH_3$$

$$\cdot$$ Number of carbon atoms in the main chain: $$5$$
$$\cdot$$ Number of branch/branches: $$2$$
$$\cdot$$ Position of the first branch while numbering from left to right: $$2$$
$$\cdot$$ Position of the first branch while numbering from right to left: $$2$$

So, the IUPAC name: $$2,4$$ dimethyl pentane


$$CH_3 - CH - CH_3$$
              $$|$$
             $$CH_3$$
a. Write the IUPAC name of this compound.
b. Write the molecular formula.
c. Write the structural formula of its isomer
d. Identify the type of isomerism in the above.

a. $$2$$ - Methyl propane
b. $$C_4 - H_{10}$$
c. $$CH_3 - CH_2 - CH_2 - CH_3$$
d. Chain isomerism


Write down the IUPAC name of the given compound.
1835588_d2d4ea9ba20f4ca39ef4a30f89f1e371.png

The IUPAC name of the given compound is $$2,2,4$$-Trimethylpentane.


Match the above.
1835825_19f64b82ada74eb1994e665b504e95e2.png


1756324_1835825_ans_d43e794f8ff848a6898748b491678b56.png


Write down the IUPAC name of the given compound.

1835581_66bf0b4e5a21441c86b37a3fe05dd187.png

The IUPAC name of the given compound is Hexane.


Write down the IUPAC name of the given compound.
1835585_270871dea5b144fd80b4da29c5cd841d.png

The IUPAC name of the given compound is $$2,3$$-Dimethylpentane.


Write down the IUPAC name of the given compound.
1835570_9678555fea6044f9b5d25697b9863bc5.png

The IUPAC name of the given compound is $$3$$- Methyl Hexane


Write down the IUPAC name of the compound given above:
1835609_d2412a1a8e2b4c7b97c7af30a9faf4de.png

The IUPAC name of the given compound is $$3, 5$$- diethylheptane.


Write down the IUPAC name of the compound given above:
1835610_fc1f263552fd4428a146b6963f188b0f.png

The IUPAC name of the given compound is $$2, 4$$- dimethyl hexane.


Write down the IUPAC name of the compound:
$$\mathrm{CH_3-CH(CH_3)-CH_2-CH_3}$$

The IUPAC name of the compound is 22- Methyl Butane.


A hydrocarbon chain with molecular $$C_{7}H_{16}$$ is numbered in four different ways.
a. Which of the above is numbered correctly ?
b. What is the name of alkyl radical found as the branch ?
c. Write the IUPAC name of the compound.
1835763_ba9b7de8cf7b4457820cfbe9cf385620.png

a. The chain number correctly is C
b. The name of alkyl radical attached as the branch is Methyl
c. IUPAC name of compound is $$3$$- methyl hexane


Give equations for the following :

Formation of acetylene.

The chemical formula for acetylene or ethyne is $$C_2H_2$$. Acetylene can be produced by the following methods :

  • By reaction of water with calcium carbide.

  •  By heating methane in absence of air or oxygen.

The chemical equation for each process is as follows :

$$(1)$$ Reaction of water with calcium carbide $$(CaC_2)$$ :

$$CaC_2+2H_2O\ \rightarrow\ C_2H_2+Ca(OH)_2$$

$$2)$$ By heating methane $$(CH_4)$$ in absence of air or oxygen :

$$2CH_4\ \xrightarrow{1500^{\circ}C}\ C_2H_2 + 3H_2$$ 



Write the IUPAC name of the following organic compound:
$$CH_3 - CH - CH_2 - CH_2 - CH_2 - CH_3$$
              $$|$$
             $$CH_3$$

Steps for IUPAC naming
  • Identification of the longest carbon chain. This chain is called the parent chain.
  • Identification of all of the substituents (groups appending from the parent chain).
  • Identification of parental functional group.
  • Identification of other remaining functional group.
 ex:- double bond, triple bond
  • Identification of side chain
  • The numbering of chain, side chain, various substituent, and bond with their locant.
  • assigning primary and secondary prefixes, suffixes, and root words in order to complete IUPAC naming.

The IUPAC name of the given compound is $$2-methyl-hexane.$$ It contains 6 carbon atoms in a long chain, and the prefix is hex-, and the -ane postfix is due to the all single bond present. It is $$2-methyl -hexane.$$ Since it contains the $$methyl $$ group is present at 2nd carbon.


How can the following reactions be used to prepared alkanes?

Kolbe's electrolytic method

Kolbe's electrolysis method uses sodium salt of fatty acid to form the corresponding alkane as a product.
In this reaction, the decarboxylation of the sodium salt of fatty acid takes place.

$$ 2R-COO^{-}Na^{+} + H_{2}O \rightarrow R-R + 2CO_{2} + H_{2} + 2NaOH $$



Write the name of the group: $$-CH_2 - CH_3$$

The name of the given group is Ethyl.


Write the IUPAC name of the following organic compound:
$$CH_3 - CH_2 - CH_2 - C \equiv C - CH_3$$

Steps for IUPAC naming
  • Identification of the longest carbon chain. This chain is called the parent chain.
  • Identification of all of the substituents (groups appending from the parent chain).
  • Identification of parental functional group.
  • Identification of other remaining functional group.
 ex:- double bond, triple bond
  • Identification of side chain
  • The numbering of chain, side chain, various substituent, and bond with their locant.
  • assigning primary and secondary prefixes, suffixes, and root words in order to complete IUPAC naming.

$$\text{The IUPAC name of the given compound is }hex-2-yne.\text{ It contains 6 carbon atoms in a long chain, hence}$$ $$\text{the prefix is hex-, and the -yne postfix is due to the triple bond (alkyne). It is hex-2-yne since it contains the }$$$$\text{triple bond at 2nd carbon.}$$


How can alkanes be prepared from an alkane?

Alkane can be prepared from alkene and alkyne through the process of hydrogenation. In this process, dihydrogen gas is added to alkynes and alkenes in the present catalyst. This catalysts which are finely divided is like nickel, palladium or platinum to form alkanes.


Organic compounds which contain at least one benzene ring are called ....compounds.

Aromatic hydrocarbons or arenes are hydrocarbons with sigma bonds and delocalized pi electrons between carbon atoms forming a ring. 

Aromatic hydrocarbons can be monocyclic or polycyclic. The configuration of six carbons atoms in aromatic compounds is known as a benzene ring.
some non-benzene based compounds called heteroarenes which follow Huckle's rule are also known as aromatic compounds.

Usually, hydrocarbons which contain at least one benzene ring in their molecules are called aromatic hydrocarbons.


Discuss the orbital structure of benzene


We know that benzene has a planar hexagonal structure in which all the carbon atoms are $$sp^{2}$$ hybridized, and all the carbon-carbon bonds are equal in length. As shown below, the remaining cyclic array of six p-orbitals ( one on each carbon) overlap to generate six molecular orbitals, three bonding and three antibonding.
1929797_1875234_ans_0da13e80ad4a4e098c9c65dce13bbb84.png


Comment upon acidic character of terminal alkynes.

The acidity of a terminal alkyne is due to the high level of s character in the sp hybrid orbital, which bonds with the s orbital of the hydrogen atom to form a single covalent bond. The high level of s character in an sp‐hybridized carbon causes the overlap region of the σ bond to shift much closer to the carbon atom. This polarizes the bond, causing the hydrogen atom to become slightly positive. This slight positive charge makes the hydrogen atom a weak proton, which can be removed by a strong base.




A ....chain alkane has usually a lower boiling point than corresponding ....chain alkane.

Branched alkanes normally exhibit lower boiling points than unbranched alkanes of the same carbon content. This occurs because of the greater van der Waals forces that exist between molecules of the unbranched alkanes. These forces can be dipole‐dipole, dipole‐induced dipole, or induced dipole‐induced dipole in nature.

Hence , A branched chain alkane has usually a lower boiling point than corresponding straight chain alkane.

Hence , correct answer is branched and straight .


Coal is the chief source of..... hydrocarbons.

Simple aromatic hydrocarbons come from two main sources: Coal and petroleum. Coal is a complex mixture of a large number of compounds, most of which are long-chain compounds. If coal is heated to about $$1000^{0} C $$ in the absence of air (oxygen), volatile components, the so-called tar oil, are stripped out.

Hence , correct answer is aromatic .


How will you distinguish between buta$$-1,3-$$diene and but$$-1-$$yne? 

But-1-yne is a terminal alkyne and hence can be distinguished from buta-1,3-diene by Tollens' regent which forms white ppt. with but-1-yne and but not with buta-1,3-diene.

$$CH_3CH_2-C\equiv CH+[Ag(NH_3)_2]^+ OH^- \to CH_3CH_2-C\equiv C\ Ag+2NH_3 +H_2O$$
But-1-yne                            Tollens' reagent                       Silver but-1-ynide

$$CH_2-CH-CH =CH_2 +[Ag (NH_3)_2]^+ OH^- \to $$ No reaction.


Give the $$IUPAC$$ name of the lowest molecular weight alkane that contains a quaternary carbon.

The lowest molecular weight alkane that contains a quaternary carbon is $$2,2$$-Dimethylpropane.
1829863_1875173_ans_a27e3cd539c04badb96e0a37ac871543.jpg


How can the following reactions be used to prepared alkanes?

Sabatier and Senderen's reaction

Sabatier and Senderens established nickel‐based hydrogenation and converted the unsaturated organic molecules into corresponding saturated compounds by passing the vapor of organic molecules and hydrogen over hot, finely divided nickel and is know as Sabatier–Senderens reduction .

Sabatier senderens reaction: $$ C_{n}H_{2n} + H_{2} \rightarrow C_{n}H_{2n+2} + heat $$ 


Give reasons for the following:
The  boiling points alkanes decrease with branching.

With increase in the branching, the surface area of the molecule decreases and vander waals forces of attraction decreases which can be overcome at a relatively lower temperature. Hence, the boiling point of an alkane chain decreased with an increase in branching.


Out of isopentane and neopentane,......has a higher boiling point because of the larger surface area.

If the number of carbons are the same then the boiling point depends on the surface area of the molecule and hence if, it is a straight chain molecule it will have more surface area than a branched one. 
n pentane has higher surface area , thus the van der waals force between the molecules increases and thus the boiling point increases.

Hence , Out of isopentane and neopentane, isopentane has higher boiling point because of larger surface area.

Hence , The correct answer is isopentane 



Why is that the carbon-carbon bond distance in benzene is intermediate between carbon-carbon single bond and a carbon-carbon double bond.

Due to delocalisation of pi electrons of double bond, all C-C bond length of benzene are equal and this delocalisation process is called resonance. 
This is because Benzene molecule exhibits resonance.


What are alkynes? How are they prepared in the laboratory?

Alkynes

Alkynes are unsaturated hydrocarbons containing a triple bond between two carbon atoms. The least number of hydrogen atoms is present in alkynes among alkanes, alkenes, and alkynes. The general formula of this class of organic compound is $$C_nH_{2n-2}$$The first stable of an alkyne is ethyne or acetylene.

Preparation of Alkynes

Alkynes from Calcium Carbide

This is the industrial method for the preparation of ethyne. In this method, calcium carbide undergoes treatment with water to form ethyne. Preparation of calcium carbide is possible by heating quicklime and coke. We can obtain quicklime by heating limestone.

alkynes

Alkynes from Vicinal Dihalides

Treatment of vicinal dihalides with potassium hydroxide (alcoholic) results in the dehydrohalogenation reaction. In this reaction, removal of a hydrogen halide molecule takes place thereby forming alkenyl halide. Furthermore, treatment of Alkenyl halide with sodamide produces alkyne.

alkynes



How will you demonstrate is that double bonds of benzene are somewhat different from that of olefins?

The double bonds of olefins decolourize bromine water and discharge the pink colour of Baeyer’s reagent while those of benzene do not. This is beacuse bromine gets added across olefinic double bond but not across the benzene double bond. It happens beacuse benzene double bonds are not 100% double bonds.


Discuss briefly the various physical properties and chemical reaction of alkanes.

Solution:

Physical Properties of Alkanes:

·         Alkanes are colourless.

·         Alkanes are less dense than water (alkanes float on top of water).

·         Alkanes are non-polar molecules so they are more soluble in non-polar solvents than they are in polar solvents.

Chemical Properties of Alkanes:

1) Alkanes are relatively unreactive. 

2) Alkanes combust (react rapidly with oxygen) releasing energy, which makes alkanes useful as fuels.

3) Alkanes will react with halogens such chlorine gas and bromine water in the presence of ultraviolet light.



Devise a scheme for the synthesis of n-butane using $$CH_3I$$ as the only carbon source. Can you employ the reactions in your scheme to synthesis propane in fairly pure state? Explain.

Propane cannot be synthesized by the above scheme in fairly pure state because Wurtz reaction between $$CH_3 I$$ and $$C_2H_4 Cl$$ will give three products, i.e., ethane, propane and butane.
1832425_1875734_ans_a724af59d4b44ab1b23c37c5591c7e16.png


Lithium di(3-pentyl) cuperate on reaction with an alkyl bromide produced (X) $$\mathrm C_{7}H_
{16}$$. The mixture of a total number of monochloro isomers formed from (X) is subjected to fractional distillation. The number of fractions obtained is :


111744_74957_ans_bd201eb4e78c44748e24552a9f0628b4.png


Calculate the number of $$3^{\circ}$$-free radical formed by homolysis of C-H bonds of alkanes having molecular formula $$\mathrm C_{6}H_{14}$$ .

$$CH_3-CH_2-\!\!\underset{\,\,CH_3}{\underset{\!\!|}{\overset{\,\,CH_3}{\overset{\!\!|}{C^{\bullet}}}}}$$      $$CH_3-CH_2-CH_2-\!\!\underset{\,\,CH_3}{\underset{\!\!|}{\overset{\,\,CH_3}{\overset{\!\!|}{C^{\bullet}}}}}$$

$$CH_3-\overset{CH}{\overset{|}{C}H}-\!\!\underset{\,\,CH_3}{\underset{\!\!|}{\overset{\,\,CH_3}{\overset{\!\!|}{C^{\bullet}}}}}$$


Number of alkenes (be sure to consider the stereochemistry of the alkene) which can be hydrogenated to form methyl cyclohexane are_________.


Total 6 alkenes are possible (including stereoisomers) which can be hydrogenated to form methyl cyclohexane.
111760_76803_ans.png


The number of alkenes (consider stereochemistry of the alkene too) that can be hydrogenated to form methyl cyclohexane is :

There are 4 alkene structures are possible which on hydrogenation gives methyl cyclohexane. 

Out of this 4 alkenes, 2 have one optically active carbon. 

Thus there are total 6 alkenes possible for hydrogenation to form methyl cyclohexane.

111758_76499_ans.png


Free-radical chlorination of $$CH_{4}$$ is nearly 11 times faster than $$CD_{4}\,$$. What is the reason behind it?

Chemically $$H$$ and $$D$$ are identical but (CD) bonds are slightly stronger than $$(CH)$$ bonds; therefore, the energy of activation of D is greater than thar of H. Since abstraction is a slow step, removal of H will be faster.
Relative abstraction of $$H : D = 2.7 : 1$$
Relative abstraction of 4H : $$D\, \approx\, 10.8 : 1$$
$$\approx\, 11 : 1$$


$$CH_3 - \underset{H}{\underset{|}{\overset{H}{\overset{|}{C}}}} - D + Cl_2 \rightarrow CH_3C\overset{D}{\overset{|}{H}} - Cl + HCl ] \, 93\% \, + \, CH_3 - CH_2 - Cl + DCl ] \, 7\%$$
What is the relative abstraction of H and D?

i. A number of H atoms abstracted by D = 5 and the percentage of the compound formed = 93%.
Therefore, reactivity factor for replacement of H atoms = $$93/5$$ = $$18.6$$
ii. Number of D abstracted by Cl = 1 and percentage of compound formed = 7%.
Therefore, reactivity factor for D replacement = $$7/1$$ = 7
iii. Relative reactivity of H : D abstration = $$18.6/7$$ = $$2.7 : 1$$, i.e., 
each H is abstrated 2.7 times faster than D.


Which factors determine the reactivity of halogens in the substitution reaction?

Reactivity order of halogens in the substitution reaction of alkane is 
$$F_{2}\, > Cl_{2}\, Br_{2}\, > I_{1}$$
Two factors that the responsible ;
a. Low energy of activation for the chain-propagating steps.
b. More negative heat of reaction $$(\Delta H_{\varsigma}^{\circ})$$ of the overall reaction.
$$E_{activation}$$ for the chain-propagating steps $$(X\, +\, CH_{4}\, \rightarrow\, HX + CH_{3}) for F_{2},\, Cl_{2},\, Br_{2},\, and I_{2}$$ is +5.1, +15.9, +77.8, and +140.2 kj $$mol^{-1}$$ respectively, and $$(\Delta H_{\varsigma}^{\circ})$$ of overall reaction for fluorination, chlorination, bromination and iodination is 426.8, 102.5, 31.4, and +60.0 kJ $$mol_{1},$$ respectively. THerefore, it is clear that the chain-initiatig step is not responsible for the observed order of reactivities, but the two factors discussed above are responsible.
AS $$E_{activation}$$ for the chain-propagating step increases from F to I, the fraction of collisions with energies greater than $$E_{activation}$$ decreases and, consequently, the reactivity decreases as shown below in the plot of $$E_{activation}$$ versus fraction of the collision with the given energy.


Calculate the percentage of compounds obtained by monobromination of isobutane. The relative reactivity of $$1, 2, 3$$ H atoms to bromination is $$1 : 82 : 1600.$$

Reactivity order of bromination = $$3 : 2 : 1 = 1600 : 82 : 1$$

(A) is obtained from the reaction of nine equivalent 1 H atoms.

(B) is obtained from the reaction of one 3 H atom.

Percentage of (A) (isobutyl bromide) = $$\displaystyle\frac{9\, \, 100}{1609}$$ = $$0.56\%$$

Percentage of (B) (tert-butyl bromide) = $$\displaystyle\frac{1600\, \, 100}{1609}$$ = $$99.4%$$
Ratio = $$177.7 : 1$$

Formation of $$t-butyl$$ bromide is $$177.7$$ times to that of Isobutyl bromide.

Relative amount

$$9 1 = 9.0$$

$$1600 1 = 1600.0$$

Total = 1609.0


If pure $$(+)-2-$$ chlorobutane is heated with chlorine gas, how many different dichlorobutanes would be formed?

If pure $$(+)-2-$$ chlorobutane is heated with chlorine gas, five different dichlorobutanes would be formed.

252290_230478_ans.png


How many positional isomers would result on dichlorination of $$2,4-$$ dimethylpentane?

Nine positional isomers would result on dichlorination of $$2,4-$$ dimethylpentane.

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Alkanes are monochlorinated with t-butyl hypochlorite $$((Me)_3C-O-Cl)$$ as a radical initiator. Give the mechanism of the reaction.



Alkanes are monochlorinated with t-butyl hypochlorite $$((Me)_3C-O-Cl)$$ as a radical initiator. The mechanism is shown:


The t-butoxy radical ($$(CH3)3C-O^.$$) that forms in the initiation step (Step 1), abstracts an H from the alkane ($$R-H$$) to give $$R^.$$ (Step 2). 

The alkyl radical then abstracts a halogen atom (Cl) from the t-butyl hypohalite (Step 3) to give the haloalkane product and another t-butoxy radical.

The t-butoxy radical is the "chain carrying radical" since it reacts by abstracting an H from $$R-H$$ in Step 2 and is reformed in Step 3. 

417364_248209_ans_aec9f094ae1e4fbd982d7676c0fcf7d3.png


Match column.

Reaction (A) and (C) are Swart reactions which are carried out by $$SbF_{3}\, or\, Hg_{2}F_{2}\, or\, AsF,\, AgF,\, CoF_{3}$$, etc.
So, the answer is both (2) and (3).

Reaction (B) is Finkelstein reaction and is carried out by Nal + Acetone, So, the answer is (4).

Reaction (D) is iodination that is carried by $$I_{2}$$ in the presence of an oxidising agent, such as $$HNO_{3},\, HgO$$ or $$HIO_{3}.$$
So the answer is (1) and (5).


Halogenation takes place by free-radical mechanism. The values of $$E$$ for chain initiation and chain propagation steps and enthalpy of overall reaction of halogens with alkane are given. Match the values with the type of halogens.

(A) The halogenation reaction is as given below.
Chain-initiation step - $$F_{2}\, \rightarrow\, 2\overset{.}F$$
Chain propagation step - 
i. $$\overset{.}F + CH_{4}\, \rightarrow\, CH_{3} + HF$$
ii. $$CH_{3}\, +\, F_{2}\, \rightarrow\, CH_{3}F\, +\, \overset{.}F$$
The values of E for chain initiation and chain propagation steps and enthalpy of overall reaction of halogens with alkane are 1591, 5.1 and 426.8 respectively.
(B) The halogenation reaction is as given below.
Chain-initiation step - $$Cl_{2}\, \rightarrow\, 2 \overset{.}Cl$$
Chain propagation step - 
i. $$ \overset {.}{Cl} + CH_{4}\, \rightarrow\, HCl\, =\,CH_{3}$$ 
 ii. $$CH_{3}\, +\, Cl_{2}\, \rightarrow\, CH_{3}Cl\, +\, \overset{.}{Cl}$$
The values of E for chain initiation and chain propagation steps and enthalpy of overall reaction of halogens with alkane are 242.7, 15.9 and 102.5 respectively.
(C) The halogenation reaction is as given below.
Chain-initiation step - $$Br_{2}\, \rightarrow\, 2Br$$
Chain propagation step - i. $$Br + CH_{4}\, \rightarrow\, CH_{3}\, =\, HBr$$ ii. $$CH_{3}\, +\, Br_{2}\, \rightarrow\,

CH_{3}Br\, +\, Br$$
The values of E for chain initiation and chain propagation steps and enthalpy of overall reaction of halogens with alkane are 192.5, 77.8 and 31.4 respectively.
(D) The halogenation reaction is as given below.
Chain-initiation step - $$I_{2}\, \rightarrow\, 2\overset{.}I$$
Chain propagation step - i. $$I + CH_{4}\, \rightarrow\, CH_{3}\,+  HI$$
                                      ii. $$CH_{3}\, +\, I_{2}\,\rightarrow\, CH_{3}I\, +\, \overset {.}I$$
The values of $$E$$ for chain initiation and chain propagation steps and enthalpy of overall reaction of halogens with alkane are 150.7, 140.2 and +46.0 respectively.


Complete the following reaction
What is major product?

248358_ae5235f12fb24290a6f74b862e90995e.png

The major product is exo.
$$Br_2$$ approaches the intermediate radical from the exo side rather than endo side. Which is hindered by the transannular H atoms.

417421_248358_ans_be32fcc821c747aaac179099beb5480a.png


Synthesis the following:
Propane to 1-fluoropropane


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An experiment is conducted in the laboratory by heating the mixture of sodium acetate and sodalime. With respect to the above experiment answer the following.
(a) Name the gas evolved and write its molecular formula.
(b) Write the balanced chemical equation for the above reaction.
(c) How the gas evolved is collected?
(d) The gas liberated does not react with nitric acid. Give reason.

(a) Methane gas is evolved having the molecular formula $$CH_4$$.
(b) $$ CH_3COONa +NaOH \overset{CaO}{\rightarrow} Na_2CO_3 +CH_4 $$
(c) The methane gas is collected by the downward disacement of water.
(d) We know that methane is a saturated hydrocarbon. Thus, being saturated it does not react with nitric acid.


Identify reactant.
879776_50aed145e3b342b2b7726c6e714ed17b.png


Sodium salts of carboxylic acids on heating with soda lime (mixture of sodium hydroxide and calcium oxide) gives alkanes which contain one carbon atom less than the carboxylic acid.
This is decarboxylation i.e elimination of $${ CO }_{ 2 }$$ from carboxylic acid.

1071068_879776_ans_c1a798f51eab4d3799070829faf8f575.png


Give the IUPAC name of the following compounds.
996575_2a9842a3cefc4c6fa357db2c536da45a.PNG

Functional group:-Acid
Substituent Groups: $$OH$$ at $$C_6$$ , $$CH_3$$ at $$C_5$$ , $$C_6H_{11}$$ at $$C_5$$
Name:- 5-Cyclohexyl-6-hydroxy-5-methylhex-3-en-carboxylic acid


What is the major product B?
1112769_9aac9c57ecdf458ea835a23227256e1c.png


1127725_1112769_ans_1791a81568af432489cf9e71fe74bfb4.png


How will you convert benzene into N,N-dimethylaniline?

Benzene is nitrated to nitrobenzen followed by reduction to get Aniline. Aniline is further treated with methyl chloride to get N.N-dimethylaniline.
1175642_1103185_ans_4abef8f042e24791aab4667612208b43.png


A hydrocarbon $$C_5H_{12}$$ gives only one monochlorination product. Identify the hydrocarbon.

$$C_{5}H_{12} $$ gives only one monochloroderivative, i.e., all the hydrogen are equivalent. It must be neopentane.
1825712_1187813_ans_e7f3fb1d47974a6f91369cacdd402deb.png


Find the number of delocalized electrons in naphthalene molecule.

Generally pi electrons are delocalised electrons.In Naphthalene 5 pi bonds are there each pi bond holds 2 electrons,so naphthalene has 10 pi electrons.

1210146_1373636_ans_5476062e80f24e7face67a47df38447d.png


IUPAC name of the above structure is ............
1465533_0a43199b56054bb0bc6bc1bb7b62f474.PNG


2048543_1465533_ans_c2ae071ba85641a1a138b3f97d9c3e4a.jpg


Fill in the blanks:
A compound of carbon and hydrogen used for welding purposes is ______.

Ans- $$\text {Acetylene}$$

Fuel gases such as acetylene, propane, butane are used for welding purposes.


Match List I with List II and select the correct answer from the given codes: 

Reagent for Wurtz's reaction is Sodium.
The catalyst for Sabatier Senderen's reaction is Nickel.
Reagent of Frankland's reaction is Zinc.
Reagent of Corey House synthesis reaction is Lithium.

Hence, 
A matches with 4.
B matches with 1.
C matches with 2.
D matches with 3.



Write short notes on: Sabatier and Senderen reduction

Sabatier-Sender's reaction is the reaction in which preparation of ethane is done by the catalytic hydrogenation of ethene. This reduction is carried out in presence of catalyst like Nickel.

$$CH_2=CH_2+H_2\overset{Ni}{\rightarrow}C_2H_6$$



What happens when: 

Electrolysis of an aqueous solution of potassium acetate is done?

An aqueous solution of Potassium acetate gives Ethane on the electrolysis. Ethane is an organic compound. The molecular of Ethane is $$C_2H_6$$. Ethane is obtained when potassium acetate is electrolyzed. This process is an example of a Kolbe electrolysis. 

$$2CH_3COOK+2H_2O\rightarrow C_2H_6+2CO_2+2KOH+H_2$$


Complete the following equations :

$$CH_{3}CH = CH_{2} + CH_{2}I_{2} \rightarrow (A)$$.


1645781_1717620_ans_512f6f744d434a71a76c6c48ec5f48ba.jpg


What happens when lithium dimethyl cuprate is treated with ethyl bromide?

Reaction of Lithium dimethyl cuprate with ethyl bromide:

$$\mathrm{Li(CH_{3})_{2}Cu+C_{2}H_{5}Br\rightarrow C_{3}H_{8}+CH_{3}Cu+LiBr}$$



Sodium salt of which acid will be needed for the preparation of propane? 

Sodium salt of butanoic acid will be needed for the preparation of propane and the reaction is:

$$ \underset{Sodium\,butanoate}{CH_{3}CH_{2}CH_{2}COO^{-}Na^{+}}+NaOH\xrightarrow[\Delta ]{CaO}\underset{Propane}{CH_{3}CH_{2}CH_{3}}+Na_{2}CO_{3}$$



Formation of naphthalence takes place in following step.What are (A),(B),(C),(D),(E),(F) and (G) formed in between 
1720449_754d922a39dd42039dc86dfaff8b69d6.PNG

$$\xrightarrow{AlCl_3}(A)$$ Friedel craft reaction(Acylation)

$$(A)\xrightarrow{Zn/Hg}(B)\Rightarrow $$ Reduction of $$-CO-$$ group

$$(B)\xrightarrow{SOCl_2}(C)\Rightarrow $$ Acylation take place $$(-OH\rightarrow Cl)$$

$$(C)\xrightarrow{AlCl_3}(D)\Rightarrow $$ acylation $$(\text{removal of -Cl and ring formation} )$$

$$(D)\xrightarrow{H_2/Pt}(E)\Rightarrow $$ Reduction of $$-CO-$$ group into $$-OH$$


$$(E)\xrightarrow{Conc.\ H_2SO_4}(F)\Rightarrow $$ removal of water molecule

$$(F)\xrightarrow{NBS}(G)\Rightarrow $$ broination

$$(G)\xrightarrow{alc. \ KOH}(product)\Rightarrow $$ removal of $$HBr$$

1795047_1720449_ans_3dd37113e22a45ed881cc9db126abc32.PNG


Write the structure of alkene that can be hydrogenated to form propane.

Structure of alkene which on hydrogenation form propane is $$\mathrm{CH_2=CH-CH_3}$$.



Which of the following reactions would provide a better synthesis of $$2-pentene$$?
1720239_1c27c3ecc137446c883794248639a863.jpg


1645832_1720239_ans_a738a353498a4b30bc1ff03302428c78.jpg


In a monochlorination experiment, some of the monochloro products obtained have been mentioned (a to j). Find the total number of alkane reactants which can give these products.
1749091_934da2187e5e437682e1296a58373cc7.png


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What is the action of water on the following?
Calcium carbide

Acetylene is evolved.

$$CaC_2 + 2H_2O \rightarrow Ca(OH)_2 + C_2H_2$$


A liquid aromatic organic compound (A) containing carbon $$(92.3 \%)$$ and hydrogen $$(7.7 \%)$$ decolourised $$KMnO_4$$, and on ozonolysis gave methanal and another compound (B). The molecular mass of (A) is $$104$$. On treatment with a suitable catalyst, (A) gave high molecular mass solid product (C) having  the same empirical formula as that of compound (A). Compound (C) is used in making toys and household goods. Identify (A), (B), and (C), and explain the reactions

Given that compound (A) is an aromatic compound with $$92.3$$ % C and $$7.7$ % H
Let the empirical formula of the compound (A) be $$CH_x$$ 
$$\therefore \dfrac {12}{12+x} = 92.3 $$
$$\therefore x= 1 $$
Empirical formula of the compound (A) is $$CH$$
Also it is given that the molecular mass of the compound is  104 
$$\therefore Molecular \ formula = \dfrac{104}{12+1} = 8 = C_8H_8$$

Also the compound decolourised $$KMnO_4$$ and on ozonolysis it gives methanal and another compound (B)

Thus the possible compound that (A) is Styrene and compound (B) is Benzaldehyde which is formed with methanal during ozonolysis.

Now if compound (A) is treated with suitable catalyst it forms a high molecular mass solid with the same empirical formula.
Thus it is a polymer used for making toys and household items, known as Polystyrene = compound(C)




1669441_1768603_ans_2a43480577fb49d98661c0ead8cc7a69.png


How will you bring about the following conversions in not more than two steps?
Toluene to benzyl alcohol


1820456_1768511_ans_c943d56dabb842b8956fefc9ed213200.png


An alkane (A) $$C_5H_{12}$$on chlorination at $$300^0C$$ gives a mixture of four different monochlorinated derivatives, (B),(C),(D) and (E).Two of these derivatives give the same stable alkene (F) on dehydrohalogination. On oxidation with hot alkaline $$KMnO_4$$ followed by acidification,(F) gives two product (G) and (H).Give the structures of (A) to (H) with proper readoning.

Alkane (A)$$C_5H_{12}$$ on chlorination gives four monochloro products and thus (A) is isopentane.
1785139_1769025_ans_2a882ac9d7be41f78319615aac2dfb6a.png


Name the organic compound prepared by each of the following reactions:
$$C_2H_5COONa+NaOH\to$$

$$C_2H_5COONa+NaOH\xrightarrow [300^oC]{CaO}Na_2CO_3+C_2H_6$$

Ethane is prepared by decarboxylation reaction of sodium propionate using soda lime.


Molecular formula of some compounds are given in the box.
$$C_{2}H_{4}$$  , $$C_{6}H_{14}$$, $$CH_{3}-CH_{2}-Cl$$ , $$CH_{3}-COOH$$,  $$ C_{6}H_{6}$$

Which is an aromatic compound?

$$C_{6}H_{6}$$ known as benzene which aromatic compound.


How will you prepared $$3-$$methylbut$$-1-$$yne by starting with ethyne?


1829833_1875104_ans_2b842ea235f54fef83b2281b9bd1d1cf.png


Give reasons for the following:
Normally benzene gives electrophilic substitution reaction rather than electrophilic addition reaction although it has a double bond.

In the typical reaction of benzene the $$\pi -$$ electron of the benzene ring server as a source of electrons for electrophile reagents.

Benzene does not show addition reactions as in the case of alkenes but undergoes a substitution reaction in which a hydrogen atom attached to the $$C$$ atom is replaced by another atom or group of atoms in the form of $$H^+$$ i.e., it gives electrophilic substitution reaction.

Benzene is a stable aromatic compound, so it does not undergoes an addition reaction.


What are paraffins and olefins? Give one example of each and write chemical reaction to differentiate them.

Paraffins : Paraffins is a Latin word which means $$(Parum = little + affinis = reactivity)$$. These are saturated hydrocarbons, which are also called alkanes. They contain carbon-carbon single bonds. There general formula is $$C_{n}H_{2n+2}$$. Example : Methane ($$CH_{4}$$) 
Olefins : Olefins means oil forming. These are unsaturated hydrocarbons containing atleast one double bond. These are also called alkenes. Their general formula is $$C_{n}H_{2n}$$ Example : Ethylene $$(C_{2}H_{4})$$
REACTION :
$$\underset{Methane}{CH_{4}}+Cl_{2}\xrightarrow {hv} CH_{3}Cl+HCl$$

$$\underset{Ethylene}{CH_{2}=CH_{2}}+Cl_{2}\rightarrow \underset{CH_{2}-Cl}{\underset{|}{CH_{2}-Cl}}$$


Write the equations for the following preparations:

Preparations: Ethane from sodium propionate Solution

Ethane from sodium propionate

$$C_2H_5COONa +NaOH\xrightarrow [300^oC]{CaO}Na_2CO_3+C_2H_6$$


What are alkanes? Discuss briefly the various methods used for the preparation of alkenes. Describe with a labelled diagram the laboratory preparation of ethene from ethanol.

Preparation of Alkenes
Preparation Of Alkenes

(1) Preparation of alkene by dehydra-tion of alcohol:

When an alcohol is heated at $$430-440$$ K with excess of concentrated sulphuric acid, a molecule of water from alcohol is removed and an alkene is formed. This reaction is called elimination reaction.


Ethene can also be prepared in laboratory by catalytic dehydration of alcohol.



What are arenes? How are they classified? Discuss briefly the isomerism and nomenclaure of arenes.  

An arene or aromatic hydrocarbon is a hydrocarbon with alternating double and single bonds between carbon atoms forming rings.

Example of Arene are benzene, toluene,phenol etc.

They are classified on the basis of number of fused ring present in molecule. Their general formula is $$C_nH_{2n-6m}$$ where n=number of carbon and m=number of rings.

Monocyclic arene-$$1$$ ring is present, example toluene, benzene.

Polycyclic arene- when more than $$1$$ rings are present Example –Napthalene, anthracene

Isomerism of Aromatic Hydrocarbons

If we consider any “disubstituted benzene”, there is a possibility of the formation of three different position isomers on the basis of substituent’s position in relation to the other. Thus, we use ortho-position to indicate the position of two substituents $$(1,2)$$

Similarly, meta-position will represent the relative position $$(1,3)$$ and para-position will represent the relative position $$(1,4)$$. Let’s take the example of xylene. Refer to the diagram below to observe the different isomers of xylene (dimethylbenzene) depending on the position.

Nomenclature of Aromatic Hydrocarbons

IUPAC System

  • Rule 1: As per IUPAC nomenclature system, it is important to place the substituent’s name before the name of the compound as a prefix in any substituted aromatic hydrocarbon. For example, nitrobenzene where the benzene ring is present along with a nitro group.
  • Rule 2: You have to attach Greek numerical prefixes such as di, tri, and tetra to indicate similar substituents group in case of compounds with more than one substituent group present in the benzene ring. For instance, a benzene ring with two bromo groups present on the adjacent carbon atoms of the benzene ring refers to as $$1,2-di-bromobenzene$$.
  • Rule 3: If different substituent groups are present in the aromatic compounds, it is important to assign number one position to the substituent of the base. Furthermore, the numbering direction for the rest of the compound is chosen in such a manner that the next substituent will have the lowest numbering position. Moreover, we have to use alphabetical order for the naming of the substituent. For example, if a benzene consists of chloro group as well as a nitro group, then we start with the chloro group and then the nitro groups on the basis of the alphabetical order.
  • Rule 4: In case of aromatic compounds with more than one substituents, it is necessary to use terms such as ortho, meta, and para as prefixes to represent the relative positions like $$1,2$$-; $$1,3$$-; $$1,4$$-. For instance, we can rewrite $$1,2$$ di-bromo-benzene as $$o-di-bromo-benzene$$.
  • Rule 5: If an organic compound consists of an alkane with a functional group and aromatic compound, then the aromatic compound will act as a substituent instead of the parent group. For instance, when there is a benzene ring joined with an alkane and a functional group, then the aromatic group is known as phenyl (Ph-).


How will you prepared (i) cis$$-$$pent$$-2-$$ene and trans$$-$$pent$$-2-$$ene by starting with ethane.


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Give reason for the following:
The melting point of $$cis-2-butane$$ is lower than that of $$trans-2-butane.$$

Thus, trans alkenes, which are less polar and more symmetrical, have lower boiling points and higher melting points, and cis alkenes, which are generally more polar and less symmetrical, have higher boiling points and lower melting points. 

Hence , The melting point of cis−2−butane is lower than that of trans−2−butane. 


Explain the directive influence of various substituents and their effect on reactivity of arenes.

Substituents can be of two types: Electron-donating substituents $$(+I$$ effect$$)$$ and electron-withdrawing substituents $$(-I$$ effect$$)$$.

The electron releasing groups $$(+I$$ effect$$)$$ direct the incoming group to ortho and para positions, and are called ortho and para directing groups, as the electron density is more on $$o$$-and $$p$$-positions. Hence, the electrophilic substitution takes place mainly at these positions on the benzene ring. As a result, the aromatic ring becomes reactive at these positions.

On the other hand, at the meta position, the electron density is less. Hence, it is less reactive. So, the electron-withdrawing $$(-I$$ effect$$)$$ groups are meta directing. The electron-withdrawing groups pull electrons towards themselves and reduce the electron density at the meta position. 

$$-CH_3, -OCH_3, -NH_2, -NR_2$$, etc. are some of the examples of ortho and para directing groups as they are electron-donating in nature $$(+I$$ effect$$)$$. Thus, these are activating groups.

An atom or a group that makes the benzene molecule less reactive by removing electron density from the ring acts as a deactivating group. Deactivating groups direct incoming electrophiles to the meta position. 

$$-NO_2, -X\ (halogens), -CN, -OH$$, etc. are a few examples of  meta directing groups $$(-I$$ effect$$)$$. These are, therefore, deactivating groups.

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Give reason for the following:
Addition of $$Br_2$$ to cyclohexane gives only trans-addition product.

The bromines add to opposite faces of the double bond (“anti addition”). Sometimes the solvent is mentioned in this reaction – a common solvent is carbon tetrachloride $$(CCl_{4}). CCl_{4}$$ actually has no effect on the reaction, it’s just to distinguish this from the reaction where the solvent is $$H_{2}O$$, in which case a bromohydrin is formed .




The real structure of benzene is a ....of two.....structures.


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How will you bring about the following conversion in not more than two steps?

propene to propyne


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Class 11 Medical Chemistry Extra Questions