acyl chlorides and acid anhydrides

Question 1

What is the functional group and general formula of an acyl chloride?

Answer 1

-COCL
CnH(2n-1)OCL

Question 2

What is produced in all reactions of acyl chlorides?

Answer 2

Misty fumes of hydrogen chloride are given off

Question 3

How do acyl chlorides react with water?

Answer 3

React vigorously with cold water, producing a carboxylic acid and HCl

Question 4

How do acyl chlorides react with alcohols?

Answer 4

React vigorously with alcohols at room temp, producing an ester and HCl
This is a much simpler and quicker way to produce an ester than esterification

Question 5

How do acyl chlorides react with ammonia?

Answer 5

React vigorously with ammonia at room temperature, producing an amide and HCl

Question 6

How do acyl chlorides react with primary amines?

Answer 6

React vigorously with primary amines at room temperature, producing an N substituted amide

Question 7

What is the mechanism for acyl chlorides to react called?

Answer 7

Nucelophilic addition-elimination

Question 8

Outline nucleophilic addition-elimination with an acyl chloride:

Answer 8

1. The nucleophile attacks the ∂+ carbon on the acyl chloride
2. A pair of electrons is transferred from the C=O bond onto the oxygen (breaking the double bond).
3. The pair of electrons on the oxygen reform the double bond, and the chlorine is removed
4. This leaves a positively charged ion and a negatively charged chloride ion
5. A pair of electrons is transferred onto the nucleophile from the H-nucleophile bond
6. This leaves an acyl chloride derivative and a hydrogen ion

Question 9

What is an acid anyhydride?

Answer 9

Made from two identical carboxylic acid molecules, which are joined together via an oxygen with the carbonyl groups on either side

Question 10

How do acid anhydrides react with water?

Answer 10

Produce a carboxylic acid (+ another carboxylic acid)

Question 11

How do acid anhydrides react with alcohols?

Answer 11

Produce an ester + carboxylic acid

Question 12

How do acid anhydrides react with ammonia?

Answer 12

Produce an amide + carboxylic acid

Question 13

How do acid anhydrides react with amines?

Answer 13

Produce an N-substituted amide + carboxylic acid

Question 14

How is aspirin made?

Answer 14

By reacting salicylic acid (which has an alcohol group) with either ethanoic anhydride or ethanoyl chloride

Question 15

Why is ethanoic anhydride used in industry instead of ethanoyl chloride?

Answer 15

Cheaper and also safer than ethanoyl chlroide as it is less corrosive, reacts more slowly with water and doesn’t produce HCl fumes