Class 11 Engineering Chemistry - Hydrocarbons

What effect the branching of an alkane has on it melting point?

In general, as the branching increase, the packing of the molecules in the lattice becomes less close and hence the

$m.p$ decreases accordingly. However, if the branching makes the molecule symmetrical the packing of the molecules in the crystal lattic becomes close and hence the

$m.p$ .

For example, the

$m.p$ of isopentane

$(113\ K)$ lower than of

$n-$ pentane

$(143\ K)$ but the

$m.p$ of neopentane

$(256\ K)$ is much higher than that of isopentane and

$n-$ pentane.

The direct iodination of alkane fail to product an alkyl iodid. If true enter 1, else 0.

The direct iodination of alkane fail to product an alkyl iodide.
This is because the by-product HI reduces iodoalkane back to alkane.
Hence, strong oxidizing agents like iodic aicd, nitric acid or HgO are used which destroys the HI and prevent the reversibility of the reaction.
Iodo compounds can be obtained by halogen exchange reaction in which chloro or bromo alkanes are treated with NaI in acetone.

$C_2H_5Br + NaI \rightarrow C_2H_5I + NaBr$

2-butyne is less reactive than butene towards electrophilic addition reaction. If true press 1 else 0.

So the transition state of alkyl cation will be more stable than that of Vinyl cation. Therefore, alkynes are less reactive than alkene towards electrophilic addition reaction.

When $1-$ pentene is treated with an acid, $trans-2-$ pentene is produced. Propose mechanism of this isomerization reaction and justify.

In the first step, the electrons of pi bond are donated to the hydrogen ion to form more stable secondary carbocation. This is followed by the loss of a proton to form trans-2-pentene. thus it is a rearrangement reaction and involves migration of double bond.

How do you account for the formation of ethane during chlorination of methane?

During chlorination of methane, ethane is formed due to side reaction in termination step by the combination of two methyl free radicals.

For the following compounds, write structural formulas and IUPAC names for all possible isomers having the number of the double or triple bond as indicated :
(a) $C_4H_8$ (one double bond)
(b) $C_5H_8$ (one triple bond)

Three isomers are possible. Their IUPAC names are

(I)

$pent-1-yne$ ,

(II)

$pent-2-yne$ and

(III)

$3-methylbut-1-ene$ .
The structural formulas are as shown.

Write $IUPAC$ names of the following compound:
$CH_3CH = C(CH_3)_2$

The correct IUPAC name of the compound

$\displaystyle CH_3CH = C(CH_3)_2$ is 2-methyl-but-2-ene. The parent hydrocarbon contains

$4 C$ atoms and a double bond. Hence, it is but-2-ene. A methyl group is present at a second carbon atom.

Let us consider the following reaction
$CH_2=CH-CH=CH_2 + HBr \overset{-80^oC}{\longrightarrow} \underset{(Major)}{A} + \underset{(Minor)}{B}$ .
At which carbon (follow IUPAC nomenclature) bromine is present in the major product?

At low tempt, kinetic control product dominates the image above.

According to

$IUPAC$ ,

$Br$ is present at third position.

1034910_698172_ans_ecb5cb0e2d954ed385be34e2f897ae09.PNG

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

1372774_1151737_ans_42562143f701400e9efc74230f733e3f.jpg

How is chloroform converted into Methane?

$CHC{l_3} + LiAl{H_4} \to C{H_4}$

Note

$:-$ This reaction may require extreme conditions of temperature and pressure

$CHC{l_3} + {H_2}/Ni \to C{H_4}$

The reaction $CH_2=CH_2+CH_3COCl \xrightarrow{AlCl_3}$ gives the product:

As refer to the reaction in IMAGE

$01$ the mechanism is shown in IMAGE

$02$

1158486_1218314_ans_ba31cb1d4f594f0db499fef7f7c9035d.PNG

Convert Propene into Propan $-1-ol$

1316066_1298327_ans_985e745297b847cf8dab483c619b85d5.PNG

Heat of Hydrogenation of $C_6H_6$ & Cyclohexene is K & Y. Find Resonance energy.

1359910_1584890_ans_39c9ceb8ab0f4ba48f04816d3d233408.jpeg

Write the name and formula of the product formed in each case below:
$H_2C=CH_2+HBr \to ........$

$H_2C=CH_2+HBr \to CH_3-CH_2-Br$

Bromoethane

Bring out the following conversions:
Acetaldehyde to Ethane

$\underset{Acetaldehyde}{CH_{3}CHO}+4[H]\xrightarrow [ conc. HCl ]{ Zn-Hg } \underset{Ethane}{CH_{3}-CH_{3}}+H_{2}O$

Write the name and formula of the product formed in each case below:
$C_2H_4+Cl_2 \to .................$

$C_2H_4+Cl_2 \to CH_2(Cl)-CH_2(Cl)$

$1, 2-$ dichloro ethane

Complete and balanced the following equations. State the conditions wherever necessary.
$C_{2}H_{4}+HCl\rightarrow ............$

$C_{2}H_{4}+HCl\rightarrow CH_{3}-CH_{2}-Cl$

The addition reaction between hydrochloric acid (

$HCl$ ) and ethene (

$C_2H_4$ ) yields chloroethane.

Give reaction : What happens when :
Passing ethene in cold aqueous solution of alkaline potassium permanganate.

On passing ethene in cold aqueous solution of alkaline potassium permanganate,

$KMnO_{4}$ gets decolourized and

$ethane-1,2-diol$ is formed.

$\overset{CH_{2}}{\overset{\parallel}{CH_{2}}}+ H_{2}O + [O]\xrightarrow [Cold]{Alkaline\,KMnO_{4}}\underset{Ethane-1,2-diol}{\overset{CH_{2}OH}{\overset{|}{CH_{2}OH}}}$

Complete and balanced the following equations. State the conditions wherever necessary.
$C_{2}H_{2}+Br_{2}\rightarrow ...........$

$HC\equiv CH+Br_{2}\xrightarrow{CCl_4} H(Br)C=C(Br)H$

Explain with chemical equation what happens when:
Acetylene reacts with bromine water ?

When acetylene.reacts with bromine water, it gets decolourized and form dibromo derivative.

$\underset{Acetylene}{\overset{CH}{\overset{|||}{CH}}}+Br_{2}\rightarrow \underset{dibromomethane}{\overset{CHBr}{\overset{||}{CHBr}}}$

Complete the reaction :

Major product is endo. Exo approach is more hindered by gem-dimethyl groups than the endo approach is hindered by the transannular H atoms .
1652842_1767880_ans_92c462c14ffc4a19bcebac2cfd455bb5.png

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Identify the products in the following reactions:

1819716_1768548_ans_e282f7c72957466bb8a3a0b79f79f378.png

Complete the reaction:

Major product is exo.

$Br_2$ approaches the intermediate norbornyl radical from the exo side rather than endo side , which is hindered by the transannular H atoms.
1652841_1767878_ans_f169cb95e77e4d21b30f9935601be416.png

1652841_1767878_ans_f169cb95e77e4d21b30f9935601be416.png

Identify the product when $(A)$ reacts with:
$Br_2/ CCl_4$

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Among the isomers of pentane $(C_{5}H_{12})$ , Write the one which on photochemical chlorination yields a singe monochloride.

Neopentane, as all the hydrogen atoms are equivalent and replacement of any hydrogen will give the same product.

1642228_1779374_ans_66a0d55012204d5c9b2276917fecda05.png

1642228_1779374_ans_66a0d55012204d5c9b2276917fecda05.png

Complete the following, giving the structures of the principal organic products:

1822653_1769232_ans_cf92493661104911971065be4e79efd2.png

Write the name and formula of the product formed in each case below:
$CH_2=CH_2 \xrightarrow {alk.\ KMnO_4}...........$

$H_2C=CH_2 \xrightarrow {cold\ dilute\ alkaline\ KMnO_4}\ CH_2(OH)-CH_2(OH)$

$1, 2-$ Ethanediol

Ethanol can be converted into ethene which can be changed into ethane. choose the correct word or phrase from the brackets to complete the following sentences.
The conversion of ethene into ethane is an example of _________

The conversion of ethene into ethane is an example of hydrogenation.

Consider the three types of replacement of group X by group Y as shown here.
This can result in giving compound (A) or (B) or both. What is the process called if
(A) is the only compound obtained

The process is called Retention.

Write the chemical equations for the following conversions ( not more than $2$ steps):
Acetone to propene

1650157_1780834_ans_77728532de604065b623e6a03faeb374.png

Name the alkene which will yield 1-chloro-1-methylclohexane by the reaction with HCl. Write the reactions involved.

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Consider the three types of replacement of group X by group Y as shown here.
This can result in giving compound (A) or (B) or both. what is the process called if
(A) and (B) are formed in equal proportions.

The Proess is called Racemisation.

Consider the tree types of replacement of group X by group Y as shown here.
This can result in giving compound (A) or (B) or both. what is the process called if
(B) is the only compound obtained.

The Process is called Inversion.

What do you observe when ethylene is passed through alkaline $KMnO_4$ solution?

When ethylene is passed through alkaline

$KMnO_4$ solution

$1, 2-$ Ethanediol is formed. The purple colour of

$KMnO_4$ decolourizes.

$CH_2=CH_2+H-O-H+[O] \xrightarrow {cold\ alkaline\ KMnO_4 \ solution} CH_2(OH)-CH_2(OH)$

Chlorination of ethane to ethy1 chloride is more practicable than the chlorination of n-pentane to 1-chloropentane.

The statement is true, because chlorination of n-pentane gives various isomers of C5H11Cl but chlorination of ethane gives only ethyl chloride.

"n-pentane has lesser boiling point than neopentane"

n-Pentane have a higher boiling point than neopentane. The shape of n-pentane, a straight chain, fits well together with other n-pentane molecules, forming tight, well-compacted layers, which are harder to separate. In neopentane, which is 2,2-dimethylpropane, trying to fit neopentane molecules together is difficult because of the substituents. Because of this uneven "packing" it becomes easier to separate and boiling point is lower.

Alkynes are more reactive than alkene towards catalytic hydrogenation. State whether the statement is True or False

Alkynes suffer less steric hindrance during adsorption on the surface of metal catalyst.
Hence, alkynes are more reactive than alkene towards catalytic hydrogenation.

" $Mg_2C_3$ on reaction with water forms propane."
Answer whether the above statement is true or false.
If true enter 1, else enter 0.

$Mg_2C_3$ on reaction with water forms propyne.

$Mg_2C_3 +4H_2O \longrightarrow 2Mg(OH)_2 + C_3H_4$

Free radical chlorination is a highly reactive process but very less selective, however, free radical bromination is less reactive, require a greater amount of energy very highly selective.
State whether the statement is True or False

Reactivity and selectivity have inverse relationship. Higher reactivity results in lower selectivity and lower reactivity results in higher selectivity.
Free radical chlorination is highly reactive process but very less selective. Hence, the substitution is governed by the probabiity factor.
However free radical bromination is less reactive, require greater amount of energy (and occurs at higher temperature) very highly selective. Hence, substitution is governed by relative reactivity of H atom.

Complete the following reaction :
HC $\equiv$ CH $\overset{Hg^{2+}}{\underset{H_2SO_4}{\rightarrow}}(A) \overset{O}{\rightarrow} (B)$ .

$\underset { \displaystyle \text { Acetylene } }{ HC \equiv C-H} \overset{Hg^{2+}}{\underset{H_2SO_4}{\rightarrow}} \underset { \displaystyle \text {Acetaldehdye (A) } }{ CH_3- \underset { \displaystyle { \underset { \displaystyle \text { O } }{ || } } }{C }-H} \xrightarrow [\text {oxidation}]{[O]}\underset { \displaystyle \text { Acetic acid (B) } }{ CH_3- \underset { \displaystyle { \underset { \displaystyle \text { O } }{ || } } }{C }-OH}$ .

Hydration of acetylene (followed by keto enol tautomerism) gives acetaldehdye. This is followed by oxidation to form acetic acid.

Isopropyl chloride and ethyl chloride both react with $Na$ in presence of dry ether. How many products are obtained?

When any alkyl halide reacts with

$Na$ in presence of dry ether, then free radical alkyl formed along with halide ion because

$Na$ is a metal and provide a free electron.

$R-X+Na \xrightarrow [ether]{dry} R^\cdot+Cl^-$

Thus when isopropyl chloride & ethyl chloride both react with sodium the free radical formed are

(Refer to Image 1)

Maximum product which can form are

(Refer to Image 2)

$B\overset { Liadlar }{ \longleftarrow } R-C\equiv C-R\overset { { Na }/{ { NH }_{ 3 } } }{ \longrightarrow } A$
What is A and B in the given raction repectivley?

$R-C\equiv C-R \overset { { Na }/{ { NH }_{ 3 } } }{ \longrightarrow } R-C=C-R (A)$ trans alkene

$R-C\equiv C-R \xrightarrow[BaSO_{4}]{H_{2}-Pd} R-C=C-R (B)$ is alkene

1132096_864959_ans_227e1bfe3020481fb628d3a8585885a3.png

Explain the free radical mechanism of chlorination of methane.

Image result for chlorination method of methane

What is the number of stereo isomers possbile for the given compound?

This compound can exist in two isomeric forms that are cis and trans. In cis type of configuration, same type of substituents are attached at similar positions & in trans they are attached at diagonally opposite positions.

Product all the alkenes that would be formed by dehydrohalogenation of the following halides with sodium ethoxide in ethanol and identify the major alkene:
(i) $1$ -Bromo- $1$ -methylcyclohexane
(ii) $2$ -Chloro- $2$ -methylbutane
(iii) $2, 2, 3$ -Trimethyl- $3$ -bromopentane.

1431939_1029366_ans_5309e8a6f383439488b2dcf7b3ac7e70.png

Alkanes are called paraffin's. They undergo substitution reactions with chlorine in present of sunlight. Prove this with suitable example.

Alkanes are saturated hydrocarbons. They are paraffin. They undergo substitution reactions with

$Cl_2$ in presence of sunlight.

$CH_3-CH_3 \rightarrow ^{Cl_2}_{hv}$

$CH_3-CH_2-Cl+HCl$

$CH_4 \rightarrow^{Cl_2}_{hv} CH_3-Cl+HCl$

Identify $B$ .

Alkylic position will undergo bromination in hv.
1156923_1087612_ans_bbfda72ae0d842ad862ee212e6388bc4.png

A and B are:

$3°$ alcohol do not undergo oxidation.
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${ C }_{ 6 }{ H }_{ 6 }\overset { { HNO }_{ 3 } }{ \underset { { H }_{ 2 }{ SO }_{ 4 } }{ \longrightarrow } } A\overset { { Br }_{ 2 } }{ \underset { { FeBr }_{ 3 } }{ \longrightarrow } } B$ , Find the final product B.

$-NO_2$ is meta directing group.
1155761_1100459_ans_ac2e933bbbe4484797a676ffeecc3593.png

How is propyne prepared from an :
$(i)$ alkylene dihalide
$(ii)$ alkylidene dihalide and
$(iii)$ Tetrahaloalkane

(i) & (ii) Preparation of propyne from alkylene or alkylidene dihalide:-

$Br$

$H_3C-\overset {|}{\underset {|}C}-\overset {|}{\underset {|}C}-H \xrightarrow [(2 equi)]{NaNH_2} \underset {\text{Propyne}}{CH_3-C\equiv CH}+2NaBr$

$H$

$\text{Propylene Dibromide}$

(iii) Preparation of propyne from Tetrahaloalkane:-

$Br$

$H_3C-\overset {|}{\underset {|}C}-\overset {|}{\underset {|}H} \xrightarrow [Zn]{Heat}\underset {Propyne}{H_3C-C\equiv C-H} +2ZnBr_2$

$Br$

What is the producy 'P'.

Ref. image I

Deuterium exchange destroys the resonance of the benzene by replacing all the

$H^-$ atoms by D.

Thus, the product P is :-

$C_6D_6$

Ref. image II

If Deuterium oxide is present in limited amount it will only replace 1 Hydrogen by deuterium.

Ref. image III

1344337_1133067_ans_a7a714aabaed46cdbae3c366d3c9cdc1.png

Complete the reaction.

1127593_1105203_ans_181bb59dffbd4d4fb46ed96b7f8292a8.png

1,1-Dihalides undergo dehydrohalogenation when treated with $NaN{H_2}$ to give alkynes .
$C{H_3}C{H_2}CHC{l_2} \to C{H_3}C \equiv CH$

1348612_1145992_ans_1494cdfa35b0404fb108398f0eae6e44.jpg

Nitrosyl chloride, $NOCl$ , is a reactive gas that is sometimes formed when $NO$ reacts with $Cl_{2}$ . $NOCl$ is a strong electrophile and readily undergoes an addition reaction with alkenes. Complete the diagram to show the mechanism of the electrophilic addition reaction of $NOCl$ with ethene.
Include all necessary charges, lone pairs and curly arrows, and the structure of the organic intermediate.

Step 1: Curly arrow from

$C = C$ to

$N^{\delta +}$

And curly arrow from

$N - Cl$ to

$Cl^{\delta -}$

Step 2: intermediate

And curly arrow from lone pair on

$Cl^{-}$ to

$C(+)$ .

1315747_1642273_ans_8b6c9bd922224dcfac6c4ec3891750e3.png

Complete the following table:

Straight chain of Carbon compound Structural formula Molecular formula Name
$C$ $H - \underset{H}{\underset{|}{\overset{H}{\overset{|}{C}}}} - H$ $CH_4$ Methane
$C - C$ - - Ethane
$C-C-C$ - $C_3H_8$ -
$C-C-C-C$ $H- \underset{H}{\underset{|}{\overset{H}{\overset{|}{C}}}} - \underset{H}{\underset{|}{\overset{H}{\overset{|}{C}}}} - \underset{H}{\underset{|}{\overset{H}{\overset{|}{C}}}} - \underset{H}{\underset{|}{\overset{H}{\overset{|}{C}}}} - H$ - -

Straight chain of Carbon compound	Structural formula	Molecular formula	Name
$C$	$H - \underset{H}{\underset{\|}{\overset{H}{\overset{\|}{C}}}} - H$	$CH_4$	Methane
$C - C$	$H - \underset{H}{\underset{\|}{\overset{H}{\overset{\|}{C}}}} - \underset{H}{\underset{\|}{\overset{H}{\overset{\|}{C}}}} - H$	$C_2H_6$	Ethane
$C-C-C$	$H - \underset{H}{\underset{\|}{\overset{H}{\overset{\|}{C}}}} - \underset{H}{\underset{\|}{\overset{H}{\overset{\|}{C}}}} - \underset{H}{\underset{\|}{\overset{H}{\overset{\|}{C}}}} - H$	$C_3H_8$	Propane
$C-C-C-C$	$H- \underset{H}{\underset{\|}{\overset{H}{\overset{\|}{C}}}} - \underset{H}{\underset{\|}{\overset{H}{\overset{\|}{C}}}} - \underset{H}{\underset{\|}{\overset{H}{\overset{\|}{C}}}} - \underset{H}{\underset{\|}{\overset{H}{\overset{\|}{C}}}} - H$	$C_4H_{10}$	Butane

$HC \equiv CH \xrightarrow {NaNH_{2}}$ _______ $\xrightarrow {CH_{3}Br}$ ________.

$HC \equiv CH \xrightarrow {NaNH_{2}}$

$CH \equiv CNa$

$\xrightarrow {CH_{3}Br}$

$CH_{3}- C \equiv CH$ .

Fill in the blanks :
$H_{2}C = CH_{2}\underset {CCl_{4}}{\xrightarrow {Br_{2}}}$ $\underset {KOH}{\xrightarrow {Alc.}}$ .

$CH_{2}Br - CH_{2}Br, CH\equiv CH$ .

Trialkylborane on deomposition by $CH_{3}COOH$ forms ______.

alkane

1644961_1716841_ans_67e15d5014304e30904c040abd2c3954.png

Complete the following equations :

$C_{6}H_{5}CH = CHCH_{3}\underset {H_{2}O}{\xrightarrow {Br_{2}}} (A)$ .

1645798_1717646_ans_00546ac2fabe4b36882dab282a9825a1.jpg

Complete the following equations:
$(CH_{3})_{2}C = CH_{2} + isobutane \underset {273\ K}{\xrightarrow {HF}} (A)$ .

1645794_1717642_ans_4637d8b74eb348d8a019241a893ddb50.jpg

What happens when :
Acetylene is passed through ammonical cuprous chloride solution?

Reaction of acetylene with ammonical cuprous chloride solution gives copper acetylide of red precipitate and it is very dangerous explosive.

What type of reactions usually occur in alkenes?

Electrophilic addition reactions usually occur in alkenes.

What happens when :
Acetylene is passed through ammoniacal solution of silver nitrate?

When acetylene gas is passed over ammoniacal silver nitrate soln gives white ppt of disilveracetylide is formed. - When acetylene is passed over ammoniacal silver nitrate solution, white ppt of disilveracetylide is formed

What happens when ethyl bromide is heated with zinc? Give equations only:

$2C_2H_5Br +2Zn \longrightarrow (C_2H_5)_2Zn +ZnBr_2$

Fill in the blanks:
Electrolysis of an aqueous solution of sodium propionate will form ____

Butane

How will you synthesise?
$But-2-yne$ from propyne.

$CH_{3}C \equiv CH \xrightarrow {NaNH_{2}} CH_{3} C \equiv CNa \xrightarrow {BrCH_{3}} CH_{3}C\equiv CCH_{3}$ .

How will you synthesise $2,3-$ Dimethylbutane from propene?

1543174_1720120_ans_9d20042867804b9abb877844721731a3.jpg

Provide the structures of compounds A, B, C, and D in the above questions.

1824388_1767857_ans_a088b6ee74674ec49951031efb70ed8c.png

How will you bring about the following conversions in not more than two steps?
But $-1-$ ene to but $-2-$ ene

1822769_1773794_ans_0a7919df4c0a423186671edc7b3df24d.png

What are addition reactions? Which category of compounds undergoes addition reactions? Explain.

Addition reactions are reactions in which two or more molecules combine to form a larger molecule, with no other products. No atoms or molecules get eliminated in this reaction. An example of addition reaction is the hydrogenation of alkenes to form alkanes.

Unsaturated compounds i.e. compounds containing double or triple bond (s) undergo addition reactions very easily. To accommodate the new incoming atoms (s) (in the case of hydrogenation, the incoming atoms are hydrogen), the double/triple bond (s) gets cleaved and converted into single bonds such that all elements present in the compound get a stable electronic configuration.

1623288_1772537_ans_72211020f187477bb1187654ddf8c528.png

What is the function of conc. $H_{2}SO_{4}$ in the formation of ethane from ethanol?

Concentrated sulphuric acid (conc.

$H_{2}SO_{4}$ acts as a dehydrating agent in the conversion from ethanol to ethane . It helps in removing water molecule (more specifically , the -OH group from one carbon and -H from the other carbon) in the following reaction:

$CH_{3}CH_{2}OH \xrightarrow[443 k]{conc.H_{2}SO_{4}}CH_{2}= CH_{2}$

What are alkanes? Write general formula of alkanes and four general methods for preparation of alkanes.

Alkanes : Alkanes are saturated open chain hydrocarbons containing carbon-carbon single bonds. These are also known as paraffins.
The general formula of alkanes in

$C_{n}H_{2n+2}$ where n stands for number of carbon atoms and

$2n + 2$ for number of hydrogen atoms in the molecule. Example :

$CH_{4}(methane)$ ,

$C_{2}H_{6}(ethane)$ etc.
General methods for preparation of alkanes :
(1) From unsaturated hydrocarbons :The unsaturated hydrocarbons are converted into alkanes by catalytic hydrogenation in the persence of catalyst such as

$Ni, Pt$ or

$Pd$ at

$150^{o}-200^{o}$ C.
$$\underset{Ethene}{CH_{2}=CH_{2}}
+H_{2}\xrightarrow[\Delta]{Ni}\underset{Ethane}{CH_{3}-CH_{3}}$$
(2) From alkyl halides : When an alkyl halide is treated with sodium in the presence of dry ether, alkane is obtained. This reaction is called wurtz reaction.

$Example :$

$\underset{methyl\,bromide}{2CH_{3}Br}+2Na\rightarrow \underset{Ethane}{CH_{3}-CH_{3}}+2NaBr$
(3) By the use of Grignard reagent: Alkyl halide on treating with magnesium in the presence of dry ether forms alkyl magnesium halide. It is called Grignard reagent. It undergoes hydrolysis to from alkane.
(Refer image)

(4) By Cleinmensen reduction : When an aldehyde or ketone is refluxed with

$40\%$ aqueous hydrochloric acid, amalgamated zinc and an organic solvent like, toluene, it undergoes reduction to form alkane.
(Refer image)
1783608_1831653_ans_8d208754342c44f3b7ac4bb444cfc740.png

1783608_1831653_ans_8d208754342c44f3b7ac4bb444cfc740.png

Explain with chemical equation what happens when:
Hydrogen bromide is added to acetylene.

When hydrogen bromide is added to acetylene, it forms ethylidene dibromide.

$\underset{Acetylene}{\overset{CH}{\overset{|||}{CH}}}+HBr\rightarrow \underset{Vinyl\,bromide}{\overset{CH_{2}}{\overset{||}{CHBr}}}\xrightarrow{HBr}\underset{Ethylidene\,dibromide}{\overset{CH_{3}}{\overset{|}{CHBr_{2}}}}$

The boiling point of re-pentane is higher than neopentane. Explain the reason.

The boiling point of re-pentane is higher than neo pentane because with the increase in number of branched chain, the molecule attains spherical shape. This results in smaller area of contact and so weak intermolecular forces between spherical molecules, which decreases the boiling point of neopentane.

Why alkanes are chemically inert? Explain general reaction of alkanes.

Alkanes are chemically inert due to presence of

$C-H$ and

$H-H$ bond and polar nature. They do not react with acid, base, oxidation, reduction etc. in normal conditions.
General reaction of alkanes :
(i) Combustion : Alkanes burn readily with non-luminous flame in the presence of air or oxygen to form

$CO_{2}$ and water with the evolution of heat.
e.g.

$CH_{4}+2O_2\rightarrow CO_2+2H_2O, \Delta H=-ve$
(ii) Halogenation: When alkanes react with halogen such chlorine, the replacement of H- atom of alkane by halogen takes place and it forms alkyl halide.
e.g.

$CH_4+Cl_2\xrightarrow{hv}CH_3Cl+HCl$

(iii) Isomerization : n-alkanes on heating in the presence of anhydrous aluminium chloride and

$HCl$ gas isomerise to branched chain alkanes.
Example:

$CH_3-\underset{n-butane}{CH_2}-CH_2-CH_3\xrightarrow[573 \,K]{AlCl_3/HCl}CH_3-\underset{Isobutane}{\underset{CH_3}{\underset{|}{CH}}}-CH_3$

(iv) Pyrolysis : Higher alkanes on heating to higher temperature decompose into lower alkanes, alkene etc.
(Refer iamge)
1783612_1831662_ans_d169235efe634258abe105b5f327eb94.png

1783612_1831662_ans_d169235efe634258abe105b5f327eb94.png

Write the common name,IUPAC name and formula of isomers of butane, pentane and hexane.

Compound	Isomers	IUPAC name
Butane	(i)n-butane (ii)n-pentane	Butane 2-methyl propane
Pentane	(i)n-pentane (ii)Isopentane (iii)Neopentane	2 methyl butane 2,2-dimethyl propane
Hexane	(i)n-Hexane (ii)Isohexane (iii) (iv) (v)	Hexane 2-methyl pentane 3-methyl pentane 2,2-dimethyl butane 2,3-dimethyl butane

Give reasons for the following:
The melting points alkanes with odd number of carbon atoms are lower than those with even number of carbon atoms

Alkanes with even carbon atoms have higher melting points than alkanes with an odd number of carbon atoms. Explain. This is because alkane chains with an even number of the carbon atoms (more symmetrical) pack more closely than those with an odd number of carbon atoms (less symmetrical) in the crystalline state.

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Pick out the suitable compounds from the box for the following reactions
$CH_4,\ C_2H_4,\ C_3H_8,\ CH_3Cl$

A) Addition Reaction

Unsaturated compounds (alkene,alkyne) generally undergoes addition reaction.

$C_2H_4$ is alkene, so undergoes addition reaction.

How can alkanes be prepared from alcohol

Direct reduction of alcohols to alkanes is generally difficult. The conversion usually requires a two-step sequence involving the conversion of alcohols into leaving groups (such as halides and sulfonate esters) followed by reduction with metal hydrides (such as

$LiAlH_{4}, LiHBEt_{3}, Bu_{3}SnH$ + radical initiator).

There are also other classical methods for reductive removal of halides such as heterogeneous hydrogenation and the Birch reduction.

The reagents such as

$PX_{3}, PX_{5}, SOCl_{2},$ and

$(COCl_{2})$ provide easy ways for the halogenation step. The Appel conditions are suited when one needs to do the halogenation under neutral conditions. For the sulfonation,

$MsCl-Et_{3}N$ and

$TsCl-Py(-DMAP)$ are the typical conditions used.

The mechanism can be regarded as nucleophilic displacement by the hydride (for the reactions using metal hydrides).

What effect does branching of an alkane have on its melting point?

The melting point of alkanes with even number of carbon atoms is higher than that of the odd numbered from the immediate next lower alkanes.

For example,

$C_{3}H_{8}$ is 85.9 K while that of

$C_{6}H_{14}$ is 179 K. Since the packing is symmetrical in even numbered alkanes, they have higher melting point.

Therefore, neopentane with a spherical molecule has the highest melting point out of the three isomers due to more compact packing.

The melting point order is

(i) > (ii) > (iii)

(256.4 K > 143.3 K > 113.1 K)

The boiling point order is

(ii) > (iii) > (i)

(309 K > 300.9 K > 282.5 K)

Hence , increases the melting point .

Which of the following has the highest boiling point?
$2-$ methylpentane
$2,3-$ dimethylbutane
$2,2-$ dimethylbutane.

As the branching increases, the surface area decreases. As a result, the magnitude of van der Waal's forces of attraction decreases and hence the boiling decreases.

Now,

$2-$ methylpentane has the largest surface area and hence has the highest boiling point. Further because of two branches on the same carbon,

$2,2$ dimethylbutane has lower surface area and hence lower boiling point that

$2,3-$ dimethylbutane. Thus, the overall order of decreasing boiling points is:

$2-$ methylbutane

$(333\ K)> 2,3-$ dimethylbutane

$(331\ K)> 2,2-$ dimethylbutane

$(323\ K)$ .

Discuss briefly the mechanism of halogenation of methane.

Halogenation mechanism.

In the methane molecule, the carbon‐hydrogen bonds are low‐polarity covalent bonds. The halogen molecule has a nonpolar covalent bond. The fracture of the chlorine molecule leads to the formation of two highly reactive chlorine free radicals (chlorine atoms).

The reaction of a halogen with an alkane in the presence of ultraviolet (UV) light or heat leads to the formation of a haloalkane (alkyl halide). An example is the chlorination of methane.

Experiments have shown that when the alkane and halogen reactants are not exposed to UV light or heat, the reaction does not occur. However, once a reaction is started, the light or heat source can be removed and the reaction will continue. The mechanism of the reaction explains this phenomenon.

Halogenation mechanism. In the methane molecule, the carbon‐hydrogen bonds are low‐polarity covalent bonds. The halogen molecule has a nonpolar covalent bond. UV light contains sufficient energy to break the weaker nonpolar chlorine‐chlorine bond (∼58 kcal/mole), but it has insufficient energy to break the stronger carbon‐hydrogen bond (104 kcal/mole). The fracture of the chlorine molecule leads to the formation of two highly reactive chlorine free radicals (chlorine atoms). A free radical is an atom or group that has a single unshared electron.

Arrange the following in order of increasing volatility : gasoline, kerosene and diesel.

Increasing order of volatility: Diesel < kerosene < gasoline.

Consider the electrophilic addition reaction of List 1 and match them with the properties of product from List 2

(A) When HCl is added to 3-methyl-1-butene, major product is achiral The raction forms at least one pair of enatiomer.
The reaction involve rearrangement of reactive intermediate .
(B) When HCl is added to 2-methyl-2-butene, the reaction do not involve rearrangement of reaction intermediate.
Major product is achiral
(C) When 3,3-dimethyl-1-butene is heated with dil sulphuric acid, major product is achiral.
The reaction forms at least one pair of enantiomer. The reaction involve rearrangement of reactive intermediate.
(D) When HBr is added to 2,4-dimethyl 2-pentene, major product is achiral. The reaction do not involve rearrangement of reaction intermediate

$CH_3CH_2CH_2CH_2CH_2CHCl_2 +NaNH_2/NH_3 \rightarrow$

How many $sp$ hybridized carbon atoms are present in the product.

When 1,1-dichlorohexane is treated with soda amide in the presence of ammonia, it undergoes dehydrochlorination to form 1-hexyne.

$CH_3CH_2CH_2CH_2CH_2CHCl_2 +NaNH_2/NH_3 \xrightarrow {dehydrochlorination} CH_3CH_2CH_2CH_2\underset {sp}C \equiv \underset {sp}CH$

Hence, the no. of sp-hybridized carbon present in the product is 2.

For $C_4H_8$ (one double bond), write the structural formula and IUPAC name for all possible isomers.

Three isomers are possible. Their IUPAC names are (I) but-1-ene, (II) but-2-ene and (III) 2-methylprop-1-ene.
The structural formulas are as shown.

Explain the mechanism of the following reaction:
$CH_{3} - CH_{2} - OH\underset {443K}{\xrightarrow {H^{+}}} CH_{2} = CH_{2} + H_{2}^{-}O$

The –OH group in the alcohol donates two electrons to

$H^+$ from the acid reagent, forming an alkyloxonium ion. This ion acts as a very good leaving group which leaves to form a carbocation. The deprotonated acid (the nucleophile) then attacks the hydrogen adjacent to the carbocation and form a double bond.Primary alcohols undergo bimolecular elimination

$(E^2$ mechanism) while secondary and tertiary alcohols undergo unimolecular elimination (

$E^1$ mechanism). Oxygen donates two electrons to a proton from sulfuric acid

$H_2SO_4$ , forming an alkyloxonium ion. Then the nucleophile

$HSO_4^–$ back-side attacks one adjacent hydrogen and the alkyloxonium ion leaves in a concerted process, making a double bond.

(i) $CH\equiv CH\xrightarrow {(A)} (B) \xrightarrow {(O)}CH_{3}COOH \xrightarrow {(C)}CH_{2}ClCOOH$

Complete the given reactions:

(i)

$HC\equiv CH+H_2O \xrightarrow {\underset { \displaystyle \text {(A) } }{ 40\%H_2SO_4/1\%HgSO_4}} \underset { \displaystyle \text { (B) } }{ CH_3-CHO } \xrightarrow {(O)}CH_{3}COOH \xrightarrow {\underset { \displaystyle \text { (C), Hell Vohlard Zelinsky reaction } }{ red \: P/ Cl_2}}CH_{2}ClCOOH$

Hydration of acetylene followed by keto enol tautomerism gives acetaldehdye. Oxidation of acetaldehyde gives acetic acid. Alpha H atom of acetic acid is then replaced with Cl atom.

Give reasons for the following:
Straight chain alkanes posses higher boiling points than the corresponding branched chain isomers.

Branched-chain compounds have weaker van der Waals forces because of the smaller area of contact between the molecules.

So less energy is needed to overcome the intermolecular force.

Linear chain compounds can line up more closely and therefore have stronger van der Waals forces than unbranched compounds.

Alkenes like ethene dissolve in conc. ${ H }_{ 2 }{ SO }_{ 4 }$ but alkynes like ethyne do not dissolve in conc. ${ H }_{ 2 }{ SO }_{ 4 }$ , whereas but-2-yne dissolves. Explain.

Ethyne (acetylene) readily undergoes hydration reaction when reacted with dilute $H_2SO_4$ , in the presence of a mercuric sulfate ( $HgSO_4$ ) catalyst. However, in order for this reaction to be facilitated, the reaction medium must contain water ( $H_2O$ ).

In conc. $H_2SO_4$ , there is very little water available. Since acetylene is a non-polar gas, it readily passes through conc. $H_2SO_4$ , and remains unreactive. In fact, conc. $H_2SO_4$ is a preferred drying medium for obtaining very dry acetylene stream.

The reason acetylene does not react with conc. $H_2SO_4$ is because it does not have anything to react with, no nucleophiles available. Especially in the absence of $HgSO_4$ catalyst, the triple bond is not activated sufficiently to undergo any nucleophilic attack. Whereas but-2-yne dissolves.

What is the product of the given reaction?

1442141_880858_ans_0ff1add77ba3423caa424663e92d5650.png

Propene $(CH_3-CH=CH_2)$ can be transformed to compound (a to j) listed in the left-hand column.
Write letter designating the reagent, you believe will achieve desired transformation. In the case of a multi step sequence, write the reagent in the order they are to be used.

Desired product No. of Steps Write options
Reagent List
a. $CH_3CHBrCH_2Br$ one
A. $Hg(OAc)_2$ in $H_2O$
b. $(CH_3)_2CHOH$ two
B. $B_2H_6$ in THF
c. $CH_3CH_2CH_2OH$ two
C. $NaBH_4$ in alcohol
d. $CH_3COCH_3$ three
D. $Br_2$ in $CH_2Cl_2$
e. $CH_3CH_2CHO$ three
E. $H_2O_2$ in aqueous base
f. $CH_3CH(OH)CH_2Br$ one
F. HOBr(NBS in aqueous acetone)
g. $(CH_3)_2CHBr$ one
G. HBr in $CH_2Cl_2$
h. $CH_3CH(OH)CH_2OH$ two
H. $OsO_4$ in ether
i. $CH_3-CH_2-CH_2-Cl$ three
I. Thionyl chloride $(SOCl_2)$
j. $CH_3-C\equiv CH$ two
J. $NaHSO_3$ in aqueous acetone
K. NaOH in alcohol and reflux
L. $NaNH_2$ (strong base)

Solution:-

	Desired product	No. of Steps	Write options		Reagent
a.	$C{H}_{3}\overset{\underset{\|}{Br}}{CH}C{H}_{2}Br$	one	$D$	A.	$Hg {\left( OAc \right)}_{2}$ in ${H}_{2}O$
b.	${\left( C{H}_{3} \right)}_{2}CHOH$	two	$A \rightarrow C$	B.	${B}_{2}{H}_{6}$ in THF
c.	$C{H}_{3}C{H}_{2}C{H}_{2}OH$	two	$B \rightarrow E$	C.	$NaB{H}_{4}$ in alcohol
d.	$C{H}_{3}COC{H}_{3}$	three	$A \rightarrow C \rightarrow F$	D.	${Br}_{2}$ in $C{H}_{2}{Cl}_{2}$
e.	$C{H}_{3}C{H}_{2}CHO$	three	$B \rightarrow E \rightarrow F$	E.	${H}_{2}{O}_{2}$ in aqueous base
f.	$C{H}_{3}\overset{\underset{\|}{OH}}{CH}C{H}_{2}Br$	one	$F$	F.	$HOBr$ ( $NBS$ in aqueous state)
g.	${\left( C{H}_{3} \right)}_{2} CH Br$	one	$G$	G.	$HBr$ in $C{H}_{2}{Cl}_{2}$
h.	$C{H}_{3} \overset{\underset{\|}{OH}}{CH}C{H}_{2}OH$	two	$H \rightarrow J$	H.	$Os{O}_{4}$ in ether
i.	$C{H}_{3}C{H}_{2}C{H}_{2}Cl$	three	$B \rightarrow E \rightarrow I$	I.	Thionyl chloride
j.	$C{H}_{3}-C \equiv CH$	two	$D \rightarrow L$	J.	$NaHS{O}_{3}$ in aqueous acetone
				K.	$NaOH$ in alcohol and reflux
				L.	$NaN{H}_{2}$ (Strong base)

Among the given reaction which is faster & why?

(i) $Me - \underset{Cl}{\underset{|}{C}}H - Me \xrightarrow{alc. KOH} CH_3-CH = CH_2$

(ii) $CH_3-CH_2-CH_2-Cl \xrightarrow{alc. KOH} CH_3-CH = CH_2$

These reactions are the type of elimination reaction

Here reaction (i) is faster than reaction (ii).

$Me - \underset{Cl}{\underset{|}{C}}H - Me \xrightarrow{alc. KOH} CH_3-CH = CH_2$

In this reaction, the tertiary carbocation is formed.

The formed carbocation is most stable in the first case as two

$-CH_3$ groups are stabilizing it

SO (i) is fast.

Complete the reaction.

(Refer to Image)

In the (I)

$3^o$ - carbocation forms is most stable. In (II) carbocation at the carbon attached to

$-NO_2$ group does not forms as it destabilizes the positive charge formed.

1094645_1177382_ans_a51a7c588a534df7a83f8e07e149a5dc.png

$C{H_3} - C{H_2} - C{H_3}\,\xrightarrow[{{h \nu}}]{{c{l_2}}}$

2041276_1361276_ans_0d2d41fb09d548d5a854fcdecb79eecf.jpg

Fill in the blanks :
$HC \equiv CH \underset {CCl_{4}}{\xrightarrow {Br_{2}}}$ _ $\xrightarrow {Zn}$ .

1645756_1716872_ans_b983724d372f4c04b049ad6292d53592.jpg

Fill in the blank:
Acetylene and formaldehyde interact in the presence of copper acetylide as a catalyst to form the organic compound _____.

Acetylene and formaldehyde interact in the presence of copper acetylide as a catalyst to form 2-butyne-1,4-diol.

1750973_1716824_ans_f14aa315139a413580dd82cddb46706f.png

1750973_1716824_ans_f14aa315139a413580dd82cddb46706f.png

Fill in the blanks :
$HC \equiv CH + CH_{3}OCH_{2} Cl\xrightarrow {AlCl_{3}}$ _______.

1645763_1716889_ans_2a282a826ea14f7b9b6679e55970ee89.jpg

Why toluene reacts with bromine in presence of light gives benzyl bromide while in presence of $FeBr_3$ it gives p-bromotoluene?

In the presence of light, the side chain bromination reaction takes place through the formation of free radical.

On the other hand, in presence of Lewis acid, the benzene nucleus undergoes electrophilic substitution, resulting in the formation of mainly p-bromo toluene, since

$CH_3$ , group is o- and p-directing.

1601712_1718428_ans_00f7724265654bf7a28fba6dea1216ae.JPG

Molecules whose Lewis structures can be drawn as a ring with alternate single and double bonds is termed as a.....

$Annulenes$

Molecules whose Lewis structures can be drawn as a ring with alternating single and double bonds are known as annulenes.

1791615_1718129_ans_e70eabae539f488a8b2f5299480a1841.gif

How many alkenes can be hydrogenated to give an alkane with molecular formula $C_{4}H_{10}$ which give three monochloro derivative on monochlorination.

The alkane is n-butane

$CH_{3}-CH_{2}-CH_{2}-CH_{3}$ and total 3 alkenes can be hydrogenated

$CH_{3}-CH_{2}-CH=CH_{2}$

$CH_{3}-CH=CH-CH_{3}$ (cis and trans)

Synthesis the following:
Propene to 2, 3-dimethyl butane

1986820_1768369_ans_3c8d5fddb62a4f98823976668d3a5094.jpg

Why conjugated dienes undergo $1,4-additions$ ? Explain.

In addition to being more stable than unconjugated dienes, conjugated dienes react differently with electrophilic reagents. Dienes, like all alkenes, can undergo electrophilic addition. Electrophilic addition is a reaction of a double (or triple) bond with an electrophile to give a carbocation (or another cationic intermediate) that then reacts with a nucleophile. The reaction breaks a

$\pi$ bond and a

$\sigma$ bond in the nucleophile while simultaneously creating two

$\sigma$ bonds. In electrophilic addition reactions, however, conjugated dienes undergo either 1,2 additions or 1,4 additions. The predominant product obtained from these electrophilic addition reactions is determined by the temperature at which the reaction is conducted.

If the reaction mixture is allowed to warm or if the original reaction is conducted at a warmer temperature

$(40^{0}C)$ , the reaction mixture will consist primarily of the 1,4-addition product. At this temperature, the reaction is under thermodynamic control. Thermodynamic control is a situation in which the reaction to form products is reversible and the product ratio is determined by relative thermodynamic stabilities. The 1,2 addition product is the kinetic product and forms at cold temperatures, while the 1,4-addition product is the thermodynamic product and forms at higher temperatures.

1929793_1875223_ans_be02cf27a8a242698f269269d1992201.png

Complete the following reactions with appropriate structure of products?

Thus,

$[A]$ is

$1,2-$ dibromo

$-1-$ phenylethane and

$[B]$ is

$1-$ phenylpropyne.
1831033_1875717_ans_2b33e46d46954617b09280adbafcfd83.jpg

Total number of hydroxyl groups present in a molecular of the major product P is______.

[6]

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Hydrocarbons - Class 11 Engineering Chemistry - Extra Questions

What effect the branching of an alkane has on it melting point?

The direct iodination of alkane fail to product an alkyl iodid. If true enter 1, else 0.

2-butyne is less reactive than butene towards electrophilic addition reaction. If true press 1 else 0.

When 1−1-pentene is treated with an acid, trans−2−trans-2-pentene is produced. Propose mechanism of this isomerization reaction and justify.

How do you account for the formation of ethane during chlorination of methane?

For the following compounds, write structural formulas and IUPAC names for all possible isomers having the number of the double or triple bond as indicated : (a) C4H8C_4H_8(one double bond) (b)C5H8C_5H_8 (one triple bond)

Write IUPACIUPAC names of the following compound:CH3CH=C(CH3)2CH_3CH = C(CH_3)_2

Let us consider the following reactionCH2=CH−CH=CH2+HBr−80oC⟶A(Major)+B(Minor)CH_2=CH-CH=CH_2 + HBr \overset{-80^oC}{\longrightarrow} \underset{(Major)}{A} + \underset{(Minor)}{B}.At which carbon (follow IUPAC nomenclature) bromine is present in the major product?

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

How is chloroform converted into Methane?

The reaction CH2=CH2+CH3COClAlCl3→CH_2=CH_2+CH_3COCl \xrightarrow{AlCl_3} gives the product:

Convert Propene into Propan−1−ol-1-ol

Heat of Hydrogenation of C6H6C_6H_6 & Cyclohexene is K & Y. Find Resonance energy.

Write the name and formula of the product formed in each case below:H2C=CH2+HBr→........H_2C=CH_2+HBr \to ........

Bring out the following conversions:Acetaldehyde to Ethane

Write the name and formula of the product formed in each case below:C2H4+Cl2→.................C_2H_4+Cl_2 \to .................

Complete and balanced the following equations. State the conditions wherever necessary. C2H4+HCl→............C_{2}H_{4}+HCl\rightarrow ............

Give reaction : What happens when :Passing ethene in cold aqueous solution of alkaline potassium permanganate.

Complete and balanced the following equations. State the conditions wherever necessary. C2H2+Br2→...........C_{2}H_{2}+Br_{2}\rightarrow ...........

Explain with chemical equation what happens when:Acetylene reacts with bromine water ?

Complete the reaction :

Identify the products in the following reactions:

Complete the reaction:

Identify the product when (A)(A) reacts with:Br2/CCl4Br_2/ CCl_4

Among the isomers of pentane (C5H12) (C_{5}H_{12}) , Write the one which on photochemical chlorination yields a singe monochloride.

Complete the following, giving the structures of the principal organic products:

Write the name and formula of the product formed in each case below:CH2=CH2alk. KMnO4→...........CH_2=CH_2 \xrightarrow {alk.\ KMnO_4}...........

Ethanol can be converted into ethene which can be changed into ethane. choose the correct word or phrase from the brackets to complete the following sentences.The conversion of ethene into ethane is an example of _________

Consider the three types of replacement of group X by group Y as shown here.This can result in giving compound (A) or (B) or both. What is the process called if (A) is the only compound obtained

Write the chemical equations for the following conversions ( not more than 22 steps):Acetone to propene

Name the alkene which will yield 1-chloro-1-methylclohexane by the reaction with HCl. Write the reactions involved.

Consider the three types of replacement of group X by group Y as shown here.This can result in giving compound (A) or (B) or both. what is the process called if(A) and (B) are formed in equal proportions.

Consider the tree types of replacement of group X by group Y as shown here.This can result in giving compound (A) or (B) or both. what is the process called if (B) is the only compound obtained.

What do you observe when ethylene is passed through alkaline KMnO4KMnO_4 solution?

Chlorination of ethane to ethy1 chloride is more practicable than the chlorination of n-pentane to 1-chloropentane.

"n-pentane has lesser boiling point than neopentane"

Alkynes are more reactive than alkene towards catalytic hydrogenation. State whether the statement is True or False

"Mg2C3Mg_2C_3 on reaction with water forms propane."Answer whether the above statement is true or false.If true enter 1, else enter 0.

Free radical chlorination is a highly reactive process but very less selective, however, free radical bromination is less reactive, require a greater amount of energy very highly selective.State whether the statement is True or False

Complete the following reaction :HC ≡\equiv CH Hg2+→H2SO4(A)O→(B)\overset{Hg^{2+}}{\underset{H_2SO_4}{\rightarrow}}(A) \overset{O}{\rightarrow} (B).

Isopropyl chloride and ethyl chloride both react with NaNa in presence of dry ether. How many products are obtained?

BLiadlar⟵R−C≡C−RNa/NH3⟶AB\overset { Liadlar }{ \longleftarrow } R-C\equiv C-R\overset { { Na }/{ { NH }_{ 3 } } }{ \longrightarrow } AWhat is A and B in the given raction repectivley?

Explain the free radical mechanism of chlorination of methane.

What is the number of stereo isomers possbile for the given compound?

Product all the alkenes that would be formed by dehydrohalogenation of the following halides with sodium ethoxide in ethanol and identify the major alkene:(i) 11-Bromo-11-methylcyclohexane(ii) 22-Chloro-22-methylbutane(iii) 2,2,32, 2, 3-Trimethyl-33-bromopentane.

Alkanes are called paraffin's. They undergo substitution reactions with chlorine in present of sunlight. Prove this with suitable example.

Identify BB.

A and B are:

C6H6HNO3⟶H2SO4ABr2⟶FeBr3B{ C }_{ 6 }{ H }_{ 6 }\overset { { HNO }_{ 3 } }{ \underset { { H }_{ 2 }{ SO }_{ 4 } }{ \longrightarrow } } A\overset { { Br }_{ 2 } }{ \underset { { FeBr }_{ 3 } }{ \longrightarrow } } B, Find the final product B.

How is propyne prepared from an :(i)(i) alkylene dihalide(ii)(ii) alkylidene dihalide and(iii)(iii) Tetrahaloalkane

What is the producy 'P'.

Complete the reaction.

1,1-Dihalides undergo dehydrohalogenation when treated with NaNH2NaN{H_2} to give alkynes .CH3CH2CHCl2→CH3C≡CHC{H_3}C{H_2}CHC{l_2} \to C{H_3}C \equiv CH

HC≡CHNaNH2→HC \equiv CH \xrightarrow {NaNH_{2}} _______ CH3Br→\xrightarrow {CH_{3}Br} ________.

Fill in the blanks :H2C=CH2Br2→CCl4H_{2}C = CH_{2}\underset {CCl_{4}}{\xrightarrow {Br_{2}}} ______ Alc.→KOH\underset {KOH}{\xrightarrow {Alc.}} ______.

Trialkylborane on deomposition by CH3COOHCH_{3}COOH forms ______.

Complete the following equations :C6H5CH=CHCH3Br2→H2O(A)C_{6}H_{5}CH = CHCH_{3}\underset {H_{2}O}{\xrightarrow {Br_{2}}} (A).

Complete the following equations:(CH3)2C=CH2+isobutaneHF→273 K(A)(CH_{3})_{2}C = CH_{2} + isobutane \underset {273\ K}{\xrightarrow {HF}} (A).

What happens when :Acetylene is passed through ammonical cuprous chloride solution?

What type of reactions usually occur in alkenes?

What happens when :Acetylene is passed through ammoniacal solution of silver nitrate?

What happens when ethyl bromide is heated with zinc? Give equations only:

Fill in the blanks:Electrolysis of an aqueous solution of sodium propionate will form ____

How will you synthesise?But−2−yneBut-2-yne from propyne.

How will you synthesise 2,3−2,3-Dimethylbutane from propene?

Provide the structures of compounds A, B, C, and D in the above questions.

How will you bring about the following conversions in not more than two steps?But−1−-1-ene to but−2−-2-ene

What are addition reactions? Which category of compounds undergoes addition reactions? Explain.

What is the function of conc. H2SO4 H_{2}SO_{4} in the formation of ethane from ethanol?

What are alkanes? Write general formula of alkanes and four general methods for preparation of alkanes.

Explain with chemical equation what happens when: Hydrogen bromide is added to acetylene.

The boiling point of re-pentane is higher than neopentane. Explain the reason.

Why alkanes are chemically inert? Explain general reaction of alkanes.

Write the common name,IUPAC name and formula of isomers of butane, pentane and hexane.

Give reasons for the following:The melting points alkanes with odd number of carbon atoms are lower than those with even number of carbon atoms

Pick out the suitable compounds from the box for the following reactionsCH4, C2H4, C3H8, CH3ClCH_4,\ C_2H_4,\ C_3H_8,\ CH_3ClA) Addition Reaction

How can alkanes be prepared from alcohol

What effect does branching of an alkane have on its melting point?

Which of the following has the highest boiling point?2−2- methylpentane2,3−2,3- dimethylbutane2,2−2,2- dimethylbutane.

When $1-$ pentene is treated with an acid, $trans-2-$ pentene is produced. Propose mechanism of this isomerization reaction and justify.

For the following compounds, write structural formulas and IUPAC names for all possible isomers having the number of the double or triple bond as indicated :
(a) $C_4H_8$ (one double bond)
(b) $C_5H_8$ (one triple bond)

Write $IUPAC$ names of the following compound:
$CH_3CH = C(CH_3)_2$

Let us consider the following reaction
$CH_2=CH-CH=CH_2 + HBr \overset{-80^oC}{\longrightarrow} \underset{(Major)}{A} + \underset{(Minor)}{B}$ .
At which carbon (follow IUPAC nomenclature) bromine is present in the major product?

The reaction $CH_2=CH_2+CH_3COCl \xrightarrow{AlCl_3}$ gives the product:

Convert Propene into Propan $-1-ol$

Heat of Hydrogenation of $C_6H_6$ & Cyclohexene is K & Y. Find Resonance energy.

Write the name and formula of the product formed in each case below:
$H_2C=CH_2+HBr \to ........$

Bring out the following conversions:
Acetaldehyde to Ethane

Write the name and formula of the product formed in each case below:
$C_2H_4+Cl_2 \to .................$

Complete and balanced the following equations. State the conditions wherever necessary.
$C_{2}H_{4}+HCl\rightarrow ............$

Give reaction : What happens when :
Passing ethene in cold aqueous solution of alkaline potassium permanganate.

Complete and balanced the following equations. State the conditions wherever necessary.
$C_{2}H_{2}+Br_{2}\rightarrow ...........$

Explain with chemical equation what happens when:
Acetylene reacts with bromine water ?

Identify the product when $(A)$ reacts with:
$Br_2/ CCl_4$

Among the isomers of pentane $(C_{5}H_{12})$ , Write the one which on photochemical chlorination yields a singe monochloride.

Write the name and formula of the product formed in each case below:
$CH_2=CH_2 \xrightarrow {alk.\ KMnO_4}...........$

Ethanol can be converted into ethene which can be changed into ethane. choose the correct word or phrase from the brackets to complete the following sentences.
The conversion of ethene into ethane is an example of _________

Consider the three types of replacement of group X by group Y as shown here.
This can result in giving compound (A) or (B) or both. What is the process called if
(A) is the only compound obtained

Write the chemical equations for the following conversions ( not more than $2$ steps):
Acetone to propene

Consider the three types of replacement of group X by group Y as shown here.
This can result in giving compound (A) or (B) or both. what is the process called if
(A) and (B) are formed in equal proportions.

Consider the tree types of replacement of group X by group Y as shown here.
This can result in giving compound (A) or (B) or both. what is the process called if
(B) is the only compound obtained.

What do you observe when ethylene is passed through alkaline $KMnO_4$ solution?

" $Mg_2C_3$ on reaction with water forms propane."
Answer whether the above statement is true or false.
If true enter 1, else enter 0.

Free radical chlorination is a highly reactive process but very less selective, however, free radical bromination is less reactive, require a greater amount of energy very highly selective.
State whether the statement is True or False

Complete the following reaction :
HC $\equiv$ CH $\overset{Hg^{2+}}{\underset{H_2SO_4}{\rightarrow}}(A) \overset{O}{\rightarrow} (B)$ .

Isopropyl chloride and ethyl chloride both react with $Na$ in presence of dry ether. How many products are obtained?

$B\overset { Liadlar }{ \longleftarrow } R-C\equiv C-R\overset { { Na }/{ { NH }_{ 3 } } }{ \longrightarrow } A$
What is A and B in the given raction repectivley?

Product all the alkenes that would be formed by dehydrohalogenation of the following halides with sodium ethoxide in ethanol and identify the major alkene:
(i) $1$ -Bromo- $1$ -methylcyclohexane
(ii) $2$ -Chloro- $2$ -methylbutane
(iii) $2, 2, 3$ -Trimethyl- $3$ -bromopentane.

Identify $B$ .

${ C }_{ 6 }{ H }_{ 6 }\overset { { HNO }_{ 3 } }{ \underset { { H }_{ 2 }{ SO }_{ 4 } }{ \longrightarrow } } A\overset { { Br }_{ 2 } }{ \underset { { FeBr }_{ 3 } }{ \longrightarrow } } B$ , Find the final product B.

How is propyne prepared from an :
$(i)$ alkylene dihalide
$(ii)$ alkylidene dihalide and
$(iii)$ Tetrahaloalkane

1,1-Dihalides undergo dehydrohalogenation when treated with $NaN{H_2}$ to give alkynes .
$C{H_3}C{H_2}CHC{l_2} \to C{H_3}C \equiv CH$

$HC \equiv CH \xrightarrow {NaNH_{2}}$ _______ $\xrightarrow {CH_{3}Br}$ ________.

Fill in the blanks :
$H_{2}C = CH_{2}\underset {CCl_{4}}{\xrightarrow {Br_{2}}}$ $\underset {KOH}{\xrightarrow {Alc.}}$ .

Trialkylborane on deomposition by $CH_{3}COOH$ forms ______.

Complete the following equations :

$C_{6}H_{5}CH = CHCH_{3}\underset {H_{2}O}{\xrightarrow {Br_{2}}} (A)$ .

Complete the following equations:
$(CH_{3})_{2}C = CH_{2} + isobutane \underset {273\ K}{\xrightarrow {HF}} (A)$ .

What happens when :
Acetylene is passed through ammonical cuprous chloride solution?

What happens when :
Acetylene is passed through ammoniacal solution of silver nitrate?

Fill in the blanks:
Electrolysis of an aqueous solution of sodium propionate will form ____

How will you synthesise?
$But-2-yne$ from propyne.

How will you synthesise $2,3-$ Dimethylbutane from propene?

How will you bring about the following conversions in not more than two steps?
But $-1-$ ene to but $-2-$ ene

What is the function of conc. $H_{2}SO_{4}$ in the formation of ethane from ethanol?

Explain with chemical equation what happens when:
Hydrogen bromide is added to acetylene.

Give reasons for the following:
The melting points alkanes with odd number of carbon atoms are lower than those with even number of carbon atoms

Pick out the suitable compounds from the box for the following reactions
$CH_4,\ C_2H_4,\ C_3H_8,\ CH_3Cl$

A) Addition Reaction

Which of the following has the highest boiling point?
$2-$ methylpentane
$2,3-$ dimethylbutane
$2,2-$ dimethylbutane.

$CH_3CH_2CH_2CH_2CH_2CHCl_2 +NaNH_2/NH_3 \rightarrow$

How many $sp$ hybridized carbon atoms are present in the product.

For $C_4H_8$ (one double bond), write the structural formula and IUPAC name for all possible isomers.

Explain the mechanism of the following reaction:
$CH_{3} - CH_{2} - OH\underset {443K}{\xrightarrow {H^{+}}} CH_{2} = CH_{2} + H_{2}^{-}O$

(i) $CH\equiv CH\xrightarrow {(A)} (B) \xrightarrow {(O)}CH_{3}COOH \xrightarrow {(C)}CH_{2}ClCOOH$

Complete the given reactions:

Give reasons for the following:
Straight chain alkanes posses higher boiling points than the corresponding branched chain isomers.

Alkenes like ethene dissolve in conc. ${ H }_{ 2 }{ SO }_{ 4 }$ but alkynes like ethyne do not dissolve in conc. ${ H }_{ 2 }{ SO }_{ 4 }$ , whereas but-2-yne dissolves. Explain.

$C{H_3} - C{H_2} - C{H_3}\,\xrightarrow[{{h \nu}}]{{c{l_2}}}$

Fill in the blanks :
$HC \equiv CH \underset {CCl_{4}}{\xrightarrow {Br_{2}}}$ _ $\xrightarrow {Zn}$ .

Fill in the blank:
Acetylene and formaldehyde interact in the presence of copper acetylide as a catalyst to form the organic compound _____.

Fill in the blanks :
$HC \equiv CH + CH_{3}OCH_{2} Cl\xrightarrow {AlCl_{3}}$ _______.

Why toluene reacts with bromine in presence of light gives benzyl bromide while in presence of $FeBr_3$ it gives p-bromotoluene?

How many alkenes can be hydrogenated to give an alkane with molecular formula $C_{4}H_{10}$ which give three monochloro derivative on monochlorination.

Synthesis the following:
Propene to 2, 3-dimethyl butane

Why conjugated dienes undergo $1,4-additions$ ? Explain.