Test: E2 Reaction Basics


25 Questions MCQ Test Chemistry Class 12 | Test: E2 Reaction Basics


Description
This mock test of Test: E2 Reaction Basics for Class 12 helps you for every Class 12 entrance exam. This contains 25 Multiple Choice Questions for Class 12 Test: E2 Reaction Basics (mcq) to study with solutions a complete question bank. The solved questions answers in this Test: E2 Reaction Basics quiz give you a good mix of easy questions and tough questions. Class 12 students definitely take this Test: E2 Reaction Basics exercise for a better result in the exam. You can find other Test: E2 Reaction Basics extra questions, long questions & short questions for Class 12 on EduRev as well by searching above.
QUESTION: 1

Only One Option Correct Type

Direction (Q. Nos. 1-15) This section contains 15 multiple choice questions. Each question has four choices (a), (b), (c) and (d), out of which ONLY ONE is correct.

Q. 

Provide the structure of the major organic product which results in the following reaction.

Solution:


β - H anti to leaving halide is taken by base.

QUESTION: 2

Provide the structure of the major organic product which results in the following reaction.

Solution:


β-H, anti to Br at more substituted β-carbon is lost to give more stable alkene.

QUESTION: 3

Provide the structure of the major organic product which results in the following reaction.

Solution:

β-H at the bridging carbon is anti to leaving group,lost in E2 reaction.

QUESTION: 4

Provide the structure of the major organic product which results in the following reaction.

Solution:

QUESTION: 5

How many distinct alkene products are possible when the alkyl iodide given below undergoes E2 elimination?

Solution:


QUESTION: 6

Provide the structure of the major organic product given in the following reaction.

Solution:



In the above reaction, appropriate conformer of the given compound is drawn first which has ‘Br’ and ‘H‘ an anti position (I).

QUESTION: 7

Which of the following alkyl halides can produce only a single alkene product when treated with sodium methoxide?

Solution:


In the above reaction, all β-H are equivalent. Hence, a single alkene is formed in E2 reaction

QUESTION: 8

Which of the alkyl chlorides listed below undergoes dehydrohaiogenation in the presence of a strong base to give 2-pentene as the only alkene product?

Solution:

QUESTION: 9

Which of the following statements is true concerning the E2 reactions of alkyl fluorides?

Solution:

FI uorine is most electronegative, increases acidity of β-H to the most.

QUESTION: 10

What is the increasing order of reactivity of the following in an E2 reaction with ethanolic KOH solution?

Solution:

(III) is most reactive as it has most acidic β-H as well as it gives resonance stabilised alkene.Next to (III) is (IV) as it is tertiary. (I) is less reactive than (II) because (I) gives less substituted alkene.

*Multiple options can be correct
QUESTION: 11

Consider the following reaction,

Q. 

The correct statement regarding the above reaction is

Solution:

Reaction proceed by E2 mechanism, hence there would be only one transition state in the activation energy diagram. Moreover, since very bulky base (tertiary butoxide) is being used, least substituted alkene, 1-butene in the present case, would be formed as the major product.

*Multiple options can be correct
QUESTION: 12

Consider the following reaction,

Q. 

The correct statement concerning the above reaction is

Solution:



C—H bond is weaker than C—D bond hence, hydrogen is taken preferably by base. If diastereomers of the given substrate is taken, cis-alkene would be formed.

*Multiple options can be correct
QUESTION: 13

Consider the following reaction,

Q. 

The correct statement concerning the above reaction is

Solution:

The reagent C2h5ONa C2H5OH does elimination.

HBr is removed and a double bond is formed. For maximum stability of current compound Trans isomer is formed.

If the current compound gives trnas isomer then its diastereomer would give cis isomer.

Hence B and C are correct.

*Multiple options can be correct
QUESTION: 14

In the reaction the given below, 

Q. 

The correct statement(s) concerning the above reaction is/are

Solution:

With ethoxide base, most substituted alkene (I) is formed as the major product. In the formation of (ll),C2H5O- takes proton from less hindered β-carbon, hence less activation energy and greater rate of reaction although stability of product determines it content at equilibrium. Also,since E2 reaction is an elementary reaction in which halogen leaves in the rate determining step, iodide leaves most easily and fluoride with maximum difficulty.

*Multiple options can be correct
QUESTION: 15

Consider the following two reactions, 


Q. 

The correct statement concerning the above reaction is

Solution:

(I) Iodide ion attacks as nucleophile at α-carbon, brings about SN2 reaction.

QUESTION: 16

Comprehension Type

Direction (Q. Nos. 16-21) This section contains 2 paragraphs, each describing theory, experiments, data, etc. Six questions related to the paragraphs have been given. Each question has only one correct answer among the four given options (a), (b), (c) and (d).

Passage I

An alkyl halide X shows diastereomerism but cannot be resolved into enantiomers. X when treated with KOH solution gives alkene as well as alcohol in comparable amounts by E2 and SN2 reactions respectively. Also, E2 reaction above gives alkene Y as single structural isomer which exists as stereoisomers. The SN2 reaction above produced alcohol Z which show stereoisomerism but cannot be resolved into enantiomers.

Q. 

The structure of X is

Solution:

Both option (a) and option (b) can be resolved into enantiomers. Option (c) and option (d) are non-enantiomeric, but show geometrical isomerism. However, option (d) is a 3° halide, it is almost inert in SN2 reaction but highly reactive in E2 reaction.

QUESTION: 17

Passage I

An alkyl halide X shows diastereomerism but cannot be resolved into enantiomers. X when treated with KOH solution gives alkene as well as alcohol in comparable amounts by E2 and SN2 reactions respectively. Also, E2 reaction above gives alkene Y as single structural isomer which exists as stereoisomers. The SN2 reaction above produced alcohol Z which show stereoisomerism but cannot be resolved into enantiomers.

Q. 

The correct statement concerning Y is

Solution:

QUESTION: 18

Passage I

An alkyl halide X shows diastereomerism but cannot be resolved into enantiomers. X when treated with KOH solution gives alkene as well as alcohol in comparable amounts by E2 and SN2 reactions respectively. Also, E2 reaction above gives alkene Y as single structural isomer which exists as stereoisomers. The SN2 reaction above produced alcohol Z which show stereoisomerism but cannot be resolved into enantiomers.

Q. 

The correct statement concerning alcohol (Z) is

Solution:

QUESTION: 19

Passage II

In an E2 reaction, following one step mechanism is involved.

As shown in the above mechanism, a β-proton anti to leaving group is abstracted by the alkoxide base. If a less bulky base is used, β-proton is eliminated giving most substituted, most stable product as the major product. On the otherhand if a bulky base is used, β-proton is abstracted from β-carbon where there is least steric hindrance and this gives least substituted, although least stable, alkene as the major product.

Q. 

What is the major product in the following elimination reaction?

Solution:

Only deuterium is present at anti position of a β-carbon, it is abstracted by base, although giving less substituted alkene as the major product. On tertiary β-carbon, hydrogen is not available in anti position to leaving group.

QUESTION: 20

Passage II

In an E2 reaction, following one step mechanism is involved.

As shown in the above mechanism, a β-proton anti to leaving group is abstracted by the alkoxide base. If a less bulky base is used, β-proton is eliminated giving most substituted, most stable product as the major product. On the otherhand if a bulky base is used, β-proton is abstracted from β-carbon where there is least steric hindrance and this gives least substituted, although least stable, alkene as the major product.

Q. 

In the following reaction, how many elimination products would be formed in principle by E2 mechanism?

Solution:


QUESTION: 21

Passage II

In an E2 reaction, following one step mechanism is involved.

As shown in the above mechanism, a β-proton anti to leaving group is abstracted by the alkoxide base. If a less bulky base is used, β-proton is eliminated giving most substituted, most stable product as the major product. On the otherhand if a bulky base is used, β-proton is abstracted from β-carbon where there is least steric hindrance and this gives least substituted, although least stable, alkene as the major product.

Q. 

What is the major elimination product in the following reaction?

Solution:

Bulky base takes β-H from least hindered β-carbon, giving least substituted alkene as the major product.

*Answer can only contain numeric values
QUESTION: 22

One Integer Value Correct Type

Direction (Q. Nos. 22-25) This section contains 4 questions. When worked out will result in an integer from Ot oQ (both inclusive).

Q. 

If trans-3-methylchlorocyclopentane is treated with KOH solution, both SN2 and E2 occur simultaneously. How many total substitution and elimination products are formed in principle?


Solution:


*Answer can only contain numeric values
QUESTION: 23

How many different alkenes would be formed in the following reaction?


Solution:

*Answer can only contain numeric values
QUESTION: 24

How many different isomers of an alkyl bromide, upon treatment with C2H5ONa in C2H5OH can give 3-methyl-2-hexene as one of the elimination product by E2 mechanism?


Solution:

*Answer can only contain numeric values
QUESTION: 25

An alkene X has molecular formula C11H24. X on free radical chlorination gives three monochloro alkanes derivatives P, Q and R as positional isomers. Only Q is resolvable into enantiomers. P does not undergo E2 elimination reaction with ethanolic KOH solution while Q and R both give the same alkene with ethanolic KOH which is capable of showing geometrical isomerism. How many carbon atoms are present in the parent chain of X?


Solution:

Related tests