文档介绍：Preparation of Acetanilide
(乙酰苯胺的合成)
1. Purpose
Study the principle and method of preparing acetanilide by acetic anhydride (乙酸酐)and glacial acetic acid(冰乙酸) as the acetylating(酰基化) reagent.
Master the experimental technique of recrystallization.
2. Principle
Reactions 1
Reaction mechanism(反应机理):
Reactions 2
The procedure with glacial acetic is mercial interest since it is economical, but it requires long heating.
Acetanilide can be prepared from aniline in several ways, using acetyl chloride(乙酰氯), acetic anhydride(乙酸酐) or glacial acetic acid(冰乙酸) as starting materials.
Acetyl chloride reacts very vigorously.
Acetic anhydride is preferred for a lab synthesis because its rate of hydrolysis(水解) is low enough to allow the acetylation of amine to be carried out in aqueous solution. It gives a product of high purity and in goodd yield.
Acetylation is often used to “protect” a primary or a secondary amine functional group. The amine group can be regenerated readily by hydrolysis in acid or base.
NH
2
+
CH
3
COX
NHCOCH
3
HX
+
X:—Cl、—OCOCH3、—OH
酰化试剂特点:
项目
试剂
冰醋酸
醋酸酐
乙酰氯
反应活性
价格
来源
较慢
较快
激烈
便宜
便宜
较贵
易得
受限
易得
1
11
2
3
4
5
6
7
8
9
1
10
2
3
4
5
6
7
8
9
1
10
Zn
105 ℃ at this temperature, the water formed duiring the reaction can be removed and the glacial acetic acid will remain in the reaction flask.
3. Apparatus and