Thionyl Chloride → 5-Chloro-2-methoxy-4-methylbenzoyl chloride
Reaction equation
S(Cl)([Cl:3])=O.[CH3:5][O:6][C:7]1[CH:15]=[C:14]([CH3:16])[C:13]([Cl:17])=[CH:12][C:8]=1[C:9](O)=[O:10]>>[CH3:5][O:6][C:7]1[CH:15]=[C:14]([CH3:16])[C:13]([Cl:17])=[CH:12][C:8]=1[C:9]([Cl:3])=[O:10]Participants
3
Conditions
- Temperature
- 30 °C
Procedure
In a 500 ml flask equipped with a refrigerant, there are introduced 87 g of thionyl chloride and about 31 g of 2-methoxy-4-methyl-5-chlorobenzoic acid and the mixture is heated on a water bath at 30° C. Dissolution occurs almost immediately, followed by reprecipitation. Then 31 g of acid is added. There is obtained a very thick, rose-colored precipitate. 41 g of thionyl chloride are added and the mixture is heated at 50°-55° C. At the end of 3/4 of an hour at this temperature, if dissolution is not complete, heating is continued to dissolution (70°-75° C). The excess thionyl chloride is removed under vacuum. There are obtained 79 g (yield 99%) of 2-methoxy-4-methyl-5-chlorobenzoyl chloride (m.p. 106°-107° C).