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 $$1-$$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)
(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.
The structural formulas are as shown.
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?
At low tempt, kinetic control product dominates the image above.
According to$$ IUPAC$$, $$Br$$ is present at third position.
Identify 'A' and 'B' in the following reactions?
How is chloroform converted into Methane?
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 $$02$$
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 ?
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 .
Identify the products in the following reactions:
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.
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.
Neopentane, as all the hydrogen atoms are equivalent and replacement of any hydrogen will give the same product.
Complete the following, giving the structures of the principal organic products:
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
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 $$KMnO_4$$ 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
"$$Mg_2C_3$$ 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?
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
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) $$1$$-Bromo-$$1$$-methylcyclohexane
(ii) $$2$$-Chloro-$$2$$-methylbutane
(iii) $$2, 2, 3$$-Trimethyl-$$3$$-bromopentane.
Alkanes are called paraffin's. They undergo substitution reactions with chlorine in present of sunlight. Prove this with suitable example.
Identify $$B$$.
Alkylic position will undergo bromination in hv.
A and B are:
$$3°$$ alcohol do not undergo oxidation.
$${ C }_{ 6 }{ H }_{ 6 }\overset { { HNO }_{ 3 } }{ \underset { { H }_{ 2 }{ SO }_{ 4 } }{ \longrightarrow } } A\overset { { Br }_{ 2 } }{ \underset { { FeBr }_{ 3 } }{ \longrightarrow } } B$$, Find the final product B.
$$-NO_2$$ is meta directing group.
How is propyne prepared from an :
$$(i)$$ alkylene dihalide
$$(ii)$$ alkylidene dihalide and
$$(iii)$$ Tetrahaloalkane
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
Complete the reaction.
1,1-Dihalides undergo dehydrohalogenation when treated with $$NaN{H_2}$$ to give alkynes .
$$C{H_3}C{H_2}CHC{l_2} \to C{H_3}C \equiv CH$$
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 $$C(+)$$.
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 |
| $$C-C-C$$ | - | $$ C_3H_8$$ | - |
| $$C-C-C-C$$ | $$H- \underset{H}{\underset{|}{\overset{H}{\overset{|}{C}}}} - \underset{H}{\underset{|}{\overset{H}{\overset{|}{C}}}} - \underset{H}{\underset{|}{\overset{H}{\overset{|}{C}}}} - \underset{H}{\underset{|}{\overset{H}{\overset{|}{C}}}} - H$$ | - | - |
$$HC \equiv CH \xrightarrow {NaNH_{2}}$$ _______ $$\xrightarrow {CH_{3}Br}$$ ________.
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 ______.
alkane
Complete the following equations :
$$C_{6}H_{5}CH = CHCH_{3}\underset {H_{2}O}{\xrightarrow {Br_{2}}} (A)$$.
$$C_{6}H_{5}CH = CHCH_{3}\underset {H_{2}O}{\xrightarrow {Br_{2}}} (A)$$.
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 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?
$$But-2-yne$$ from propyne.
How will you synthesise $$2,3-$$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$$-1-$$ene to but$$-2-$$ene
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.
What is the function of conc. $$ H_{2}SO_{4} $$ in the formation of ethane from ethanol?
What are alkanes? Write general formula of alkanes and four general methods for preparation of alkanes.
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)
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)
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.
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)
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)
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
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.
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
A) 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?
Which of the following has the highest boiling point?
$$2-$$ methylpentane
$$2,3-$$ dimethylbutane
$$2,2-$$ dimethylbutane.
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.
Consider the electrophilic addition reaction of List 1 and match them with the properties of product from List 2
$$CH_3CH_2CH_2CH_2CH_2CHCl_2 +NaNH_2/NH_3 \rightarrow $$
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.
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.
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.
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.
What is the product of the given reaction?
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) |
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) $$CH_3-CH_2-CH_2-Cl \xrightarrow{alc. KOH} CH_3-CH = CH_2$$
(i) $$Me - \underset{Cl}{\underset{|}{C}}H - Me \xrightarrow{alc. KOH} CH_3-CH = CH_2$$
(ii) $$CH_3-CH_2-CH_2-Cl \xrightarrow{alc. KOH} CH_3-CH = CH_2$$
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.
$$C{H_3} - C{H_2} - C{H_3}\,\xrightarrow[{{h \nu}}]{{c{l_2}}}$$
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 _____.
Acetylene and formaldehyde interact in the presence of copper acetylide as a catalyst to form 2-butyne-1,4-diol.
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?
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.
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.
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.
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.
Complete the following reactions with appropriate structure of products?
Thus, $$[A]$$ is $$1,2-$$dibromo $$-1-$$phenylethane and $$[B]$$ is $$1-$$phenylpropyne.
Total number of hydroxyl groups present in a molecular of the major product P is______.
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