登录

The benzylic position describes the position of a carbon atom attached directly to a benzene ring. Benzene by itself does not undergo oxidation. In contrast, the benzylic carbon is quite reactive in the presence of strong oxidizing agents such as KMnO4 or H2CrO4. Therefore, alkylbenzenes are readily oxidized to benzoic acid, irrespective of the type of alkyl groups.

Figure1

Halogen and nitro substituents on a benzene ring remain unaffected by these oxidizing agents.

Figure2

When more than one alkyl side chain is attached to the benzene ring, each gets oxidized to carboxyl groups.

Figure3

The only condition required for benzylic oxidation is to have at least one hydrogen at the benzylic position. This means that tert-butylbenzene, which lacks benzylic hydrogen, does not undergo oxidation.

Figure4

Benzene is also unreactive towards catalytic hydrogenation. A typical alkene double bond attached to a benzene ring can be selectively reduced under specific conditions without affecting the other functional groups. For example, in the selective reduction of 4-phenyl-3-buten-2-one to 4-phenyl-2-butanone, the benzene ring and ketone group remain unaffected.

Figure5

Tags

Benzylic PositionOxidationReductionAlkylbenzenesBenzoic AcidHalogenNitro SubstituentsCatalytic HydrogenationAlkene Double Bond4 phenyl 3 buten 2 one4 phenyl 2 butanone

来自章节 18:

article

Now Playing

18.2 : Reactions at the Benzylic Position: Oxidation and Reduction

Reactions of Aromatic Compounds

3.2K Views

article

18.1 : 苯衍生物的 NMR 波谱

Reactions of Aromatic Compounds

7.2K Views

article

18.3 : 苄基位置的反应:卤化

Reactions of Aromatic Compounds

2.3K Views

article

18.4 : 亲电芳烃取代:概述

Reactions of Aromatic Compounds

9.8K Views

article

18.5 : 亲电芳烃取代:苯的氯化和溴化

Reactions of Aromatic Compounds

6.9K Views

article

18.6 : 亲电芳烃取代:苯的氟化和碘化

Reactions of Aromatic Compounds

5.5K Views

article

18.7 : 亲电芳烃取代:苯的硝化

Reactions of Aromatic Compounds

5.0K Views

article

18.8 : 亲电芳烃取代:苯磺化

Reactions of Aromatic Compounds

5.0K Views

article

18.9 : 亲电芳烃取代:苯的 Friedel-Crafts 烷基化反应

Reactions of Aromatic Compounds

6.1K Views

article

18.10 : 亲电芳烃取代:苯的 Friedel-Crafts 酰化

Reactions of Aromatic Compounds

6.3K Views

article

18.11 : Friedel-Crafts 反应的局限性

Reactions of Aromatic Compounds

5.1K Views

article

18.12 : 取代基的定向效应:邻位-对位定向群

Reactions of Aromatic Compounds

5.7K Views

article

18.13 : 取代基的定向效应:元定向群

Reactions of Aromatic Compounds

4.0K Views

article

18.14 : 邻位对位定向激活剂: –CH3, –OH, –⁠NH2, –OCH3

Reactions of Aromatic Compounds

5.3K Views

article

18.15 : 邻位对位钝化剂:卤素

Reactions of Aromatic Compounds

4.9K Views

See More

JoVE Logo

政策

使用条款

隐私

科研

教育

关于 JoVE

版权所属 © 2025 MyJoVE 公司版权所有,本公司不涉及任何医疗业务和医疗服务。