E1CB Mechanism

Q. The rate determining step during a $E1$ reaction is:

1. Formation of carbocation
2. Elimination of hydrogen atom
3. Both (a) and (b) are rate determining step
4. Cannot be predicted

Q. The correct statement regarding a unimolecular elimination reaction is

1. Rearrangement of carbon skeleton won't occur during elimination reaction
2. More substituted alkenes are major product
3. Step II is the rate determining step
4. Alkyl fluorides favours E1 reaction

Q. Consider the following reaction and predict the number of possible product:

1. 2
2. 4
3. 6
4. 3

Q. Which of the following statements regarding the E1 mechanism is wrong?

1. Reactions by the E1 mechanism are unimolecular
2. Reactions by the E1 mechanism are generally first order.
3. Reactions by the E1 mechanism usually occur in one step.
4. Reactions by the E1 mechanism are multi-step reactions.

Q. Alcohols can be prepared by haloalkanes using hydroxide ion in aqueous media through $S_{N}1$ and $S_{N}2$.
The $S_{N}1$ reaction is a two-step reaction. In the first step, the carbon-halogen bond breaks to generate a stable carbocation. In the second step, the nucleophile reacts rapidly with the carbocation. This reaction follows first order kinetics.
The $S_{N}2$ is a concerted reaction in which transition state is achieved where bond making and bond breaking occur simultaneously. This reaction follows second order kinetics.
Consider the following reaction sequence.

Which of the following statement is correct about regarding the reaction?

1. Molecularity of the reaction is two
2. Polar protic solvents drive this reaction
3. Polar aprotic solvents are preferred
4. None of these

Q. Select whether the following combinations of reactants will react by substitution ($S_{N}1,S_{N}2$ or elimination ($E_1,E_2$ mechanism).

1. $S_{N}1$
2. $S_{N}2$
3. $E1$
4. $E2$

Q. Which of the following step is not involved during acidic hydrolysis of acyl chloride to form carboxylic acid?

1. Attack of the nucleophile $H_{2}O$
2. Removal of the leaving group $H_3{O}^{+}$
3. Removal of the leaving group $C{l}^{-}$
4. None of the above

Q. What are the products (A) and (B) formed in above reaction?

Q. Assertion: $1^o$ allylic halides are more reactive than $1^{o}RX$ in $S_{N}1$ reaction
Reason: Allylic carbocation intermediate is stabilised by resonance

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
3. Assertion is correct but Reason is incorrect
4. Both Assertion and Reason are incorrect
5. Assertion is incorrect but Reason is correct

Q. Reaction of trans-2-Phenyl-1-bromocyclopentane on reaction with alcoholic $KOH$ produces

1. 4-phenylcyclopentene
2. 2-phenylcyclopentene
3. 1-phenylcyclopentene
4. 3-phenylcyclopentene

Q. The reaction is slowest when X is:

1. $-N_2^{+}$
2. $-I$
3. $-OC{H}_3$
4. Triflate

Q. In the following reactions, if the rate of reaction of (I) and (II) are different, then, both reactions proceed by which mechanism?

1. $E1$
2. $E2$
3. None of the above
4. Anti-elimination

Q. The carbonyl compound producing an optically active product by reaction with $LiAl{H}_4$ is

1. propnone
2. 3- pentanone
3. butanone
4. benzophenone

Q. Predict the major product.

1. 
2. 
3. 
4. 

Q. Arrange the following carbocation in the increasing order of stability.

1. $II<III<I$
2. $I<II<III$
3. $III<II<I$
4. $III<I<II$

Q. Which of the following options is correct about the following reaction?

1. Reaction goes though anti elimination so it is highly stereo specific.
2. Reaction is bimolecular with respect to RDS step.
3. Over all order of the reaction is 2.
4. Reaction is goes through $E_2$ Mechanism.

Q. Which of the following compound will give $S_{N}2$ mechanism?

1. $C{H}_3-C{H}_2-C{H}_2-Br$
2. $C_6{H}_5-C{H}_2-Br$
3. All of these
4. $C{H}_3-Br$

Q. Which of the following step is not involved during acidic hydrolysis of acyl chloride to form carboxylic acid?

1. Attack of the nucleophile​ $H_{2}O$
2. Removal of the leaving group​ $H_3{O}^{+}$
3. Removal of the leaving group​ $C{l}^{-}$
4. None of the above

Q. Hydrogenation of the above compound in the presence of poisoned Pd catalyst gives :

1. an optically active compound
2. an optically inactive compound
3. a racemic mixture
4. a diastereomeric mixture

Q. Stability of alkyl carbocation can be explained by ?

1. hyperconjugation effect
2. both inductive and hyperconjugation efffect
3. inductive effect
4. electromeric effect only.

Q. The decreasing stability order for the following anions is :

1. $I>II>III>IV$
2. $IV>III>II>I$
3. $III>IV>II>I$
4. $IV>II>III>I$

Q. Which of the following options is correct about the following reaction?

1. Reaction is goes through $E_2$ Mechanism.
2. Reaction goes though anti elimination so it is highly stereo specific.
3. Reaction is bimolecular with respect to RDS step.
4. Over all order of the reaction is 2.

Q. The $K_{eq.}$ values in HCN addition to following aldehydes are in the order.

1. I $>$ II $>$ III
2. II $>$ III $>$ I
3. III $>$ I $>$ II
4. II $>$ I $>$ III

Q. In the $\alpha$ halogenation of aliphatic acids (HVZ reaction), the catalyst used is :

1. $Zn$
2. $P$
3. $AlC{l}_3$
4. $FeC{l}_3$

Q. Compare the given compounds for their reactivity in $S_{N}1$ reaction.

1. $III<II<I$
2. $I<II<III$
3. $III<I<II$
4. None of these

Q. The intermediate formed in $E1cB$ reaction is a

1. carbanion
2. carbocation
3. free radicle
4. benzyne

Q.
The elimination takes place by which mechanism?

1. $E_1$
2. $E_2$
3. $E_i$
4. $E_{1}cB$

Q. $E1cB$ reaction is given by those compounds which have poor leaving group, otherwise carbanion will not be formed.

1. True
2. False

Q. Match the compounds/reactions in List 1 with their mechanism in List 2. Matching can be one or more than one.