Problem 708

Problem # 708

The overall mechanism for Fischer esterification is shown below. This isn't a real mechanism, just an outline.

Methanol (the nucleophile) attacks the carbonyl carbon, forming a tetrahedral intermediate, which then loses a water to reform the carbonyl. This mechanism is called nucleophilic acyl substitution.

Use curved arrows to draw a full mechanism for this reaction. I've included structures for you to use as a guide.

This reaction takes place under acidic conditions, so the mechanism you draw will be similar to those in problem 706.

Solution

Acidic mechanisms only appear complicated because they contain several proton transfer steps.

Nucleophilic acyl substitution mechanisms have only three real steps- the "up, down, and kick."

First, the nucleophile attacks the carbonyl carbon, forming a tetrahedral intermediate (the "up").

Then the carbonyl reforms (the "down") and a leaving group leaves (the "kick").

Problem Details

MendelSet practice problem # 708 submitted by Matt on July 22, 2011.

Subject: Organic Chemistry

Subject Topic(s): Carboxylic Acids (Inductive Effects, Esterification), Nucleophilic Acyl Substitution (Carboxylic Acid Derivatives)

Question Type: Mechanism (show a mechanism using curved arrows..)

Keyword(s): nucleophilic acyl substitution, Fischer esterification, up-down-kick carbonyl mechanism

Problem 708

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