Phenol → 3,5-Dichloroaniline

Participants

Reaction Steps

131 parts of a mixture of 2,3,4,5- and 2,3,5,6-tetrachloroaniline and pentachloroaniline in the ratio of 38:60:2 percent by weight and 200 parts of phenol are reacted with hydrogen over 20 parts of a 1% strength palladium/charcoal catalyst and a maximum pressure of 50 bar and at 170° C. in a tantalum autoclave, in the course of 10 hours, while stirring. After the autoclave has been cooled and the pressure released, the reaction mixture is diluted with 500 parts of water and separated off from the catalyst, and after the addition of toluene, the mixture is rendered alkaline with sodium hydroxide solution. The solution of 3,5-dichloroaniline in toluene, obtained by separation of the layers, is distilled. Yield: 90 g (=98%) of a 99% strength 3,5-dichloroaniline. The phenol can be recovered from the aqueous phase by acidifying the latter and extracting it by shaking with toluene. It was possible to re-use the catalyst 20 times without it losing any of its activity.

Provenance & Evidence