Question 1

Which of the following substrate types is most likely to undergo nucleophilic addition rather than substitution or elimination?

Accepted Answer

CH3CHO (carbonyl)

Question 2

A reaction is performed with a 2° alkyl halide and a strong base (e.g., $$HO^-) at $$high temperature. Which mechanism and product are most favored?

Accepted Answer

E2, E/Z alkene formation

Question 3

Which solvent type most strongly favors SN2 and E2 mechanisms by enhancing nucleophilicity?

Accepted Answer

Polar aprotic (e.g., DMSO, acetone)

Question 4

Which of the following is NOT a key feature of the E1 mechanism?

Accepted Answer

Concerted bond breaking and forming

Question 5

A tertiary alkyl halide reacts with $$H_2O as $$the solvent. Which mechanism is most likely and why?

Accepted Answer

SN1, because tertiary carbocations are stabilized and $$H_2O is $$polar protic

Question 6

Which factor most strongly increases the rate of E1 reactions?

Accepted Answer

Increasing the number of alkyl groups on the carbon with the leaving group

Question 7

What is the effect of increasing temperature on the competition between substitution and elimination reactions?

Accepted Answer

It favors elimination due to greater entropy ($$\Delta S)$$

Question 8

Which of the following is a strong nucleophile but a weak base, and thus favors SN2 reactions?

Accepted Answer

$$CN^-$$

Question 9

Why are SN1 and E1 reactions never observed for 1° alkyl halides?

Accepted Answer

1° alkyl halides cannot form stable carbocations

Question 10

Which of the following leaving groups is considered 'good' for E1, SN1, SN2, and E2 reactions?

Accepted Answer

$$Br^-$$

Question 11

A reaction of 1-bromopropane with $$NaOEt in $$ethanol at 25°C will most likely proceed via which mechanism?

Accepted Answer

SN2

Question 12

Which mechanistic pathway is characterized by anti stereochemistry in its products?

Accepted Answer

E2

Question 13

Which reagent type is most likely to initiate radical chain reactions?

Accepted Answer

Radical initiator (e.g., $$ROOR$$, $$hv)$$

Question 14

What is the expected stereochemical outcome of an SN2 reaction?

Accepted Answer

Inversion of configuration

Question 15

Which of the following statements about polar protic solvents is TRUE?

Accepted Answer

They stabilize ions and favor SN1 and E1 reactions

Question 16

Which of the following best explains why E2 reactions are favored with strong bulky bases like t-butoxide?

Accepted Answer

Bulky bases are poor nucleophiles and cannot attack the carbon directly

Question 17

Which mechanistic pathway involves a concerted, single-step process with simultaneous bond breaking and forming?

Accepted Answer

SN2

Question 18

What is the effect of using a polar aprotic solvent in a reaction with a strong nucleophile and a primary alkyl halide?

Accepted Answer

It enhances the nucleophilicity and favors SN2 mechanism

Question 19

Which of the following is a key factor in optimizing the rate of SN2 reactions?

Accepted Answer

Using a strong, small nucleophile

Question 20

Which of the following statements about the E1 rate law is correct?

Accepted Answer

The rate is unimolecular and depends only on the substrate concentration

Predicting Organic Reaction Mechanisms: Substitution and Elimination Pathways

Study Guide - Practice Questions