A. Rank the following esters from most reactive to least...

Name: Problem 67, Chapter 18: Organic Chemistry
Uploaded: 2020-10-31T01:34:59-08:00
Duration: 9 min 28 s
Channel: Zubair Abdulla
Description: a. Rank the following esters from most reactive to least reactive in the first slow step of a nucleophilic acyl substitution reaction (formation of the tetrahedral intermediate): A B C D b. Rank the same esters from most reactive to least reactive in the second slow step of a nucleophilic acyl substitution reaction (collapse of the tetrahedral intermediate).

a. Rank the following esters from most reactive to least reactive in the first slow step of a nucleophilic acyl substitution reaction (formation of the tetrahedral intermediate): A B C D b. Rank the same esters from most reactive to least reactive in the second slow step of a nucleophilic acyl substitution reaction (collapse of the tetrahedral intermediate).

a. Rank the following esters from most reactive to least reactive in the first slow step of a nucleophilic acyl substitution reaction (formation of the tetrahedral intermediate):
A
B
C
D
b. Rank the same esters from most reactive to least reactive in the second slow step of a nucleophilic acyl substitution reaction (collapse of the tetrahedral intermediate).

Key Concepts

Nucleophilic Acyl Substitution Mechanism

This reaction mechanism involves a nucleophile attacking a carbonyl compound to yield a tetrahedral intermediate, which then collapses to form the final product with the expulsion of a leaving group. The process typically comprises two key steps: formation of the tetrahedral intermediate and its subsequent collapse.

Tetrahedral Intermediate Formation

The first slow step is the formation of a tetrahedral intermediate when a nucleophile adds to the electrophilic carbonyl carbon. The rate of this step is influenced by the electrophilicity of the carbonyl carbon and the ability of substituents to stabilize the developing negative charge during the addition.

Leaving Group Ability

In the nucleophilic acyl substitution reaction, the ability of a substituent to leave from the tetrahedral intermediate is crucial, particularly in the second slow step. A good leaving group stabilizes the negative charge upon departure, thereby making the collapse of the intermediate more favorable and speeding up the reaction.

Electronic Effects

Substituents bound to or near the carbonyl group can either withdraw or donate electron density. Electron-withdrawing groups enhance the electrophilicity of the carbonyl carbon, increasing the rate of nucleophilic attack, whereas electron-donating groups have the opposite effect. These electronic factors play a significant role in determining the reactivity in both steps of the reaction.

Steric Effects

The steric environment around the reactive center affects how easily the nucleophile can approach the carbonyl carbon and form the intermediate. Bulky substituents can hinder nucleophilic attack and may also affect the collapse of the tetrahedral intermediate, thereby altering the overall reaction rate.

Transcript

Please give Ace some feedback