Die Gewinnung von Naphthalin aus dem Steinkohlenteer

Abstract

The extraction of naphthalene from coal-tar takes place in two stages. The first stage is combined with the crude distillation of the tar and results in an oil containing up to 75% of naphthalene. In the second stage this oil is cooled so that the naphthalene crystallizes and may be separated by means of centrifugation or hot pressing. The extracted product is of a purity of minimum 96% and serves as a raw product for the fabrication of phthalic anhydride. For other purposes a purity higher than 99% is required. This degree of purity may be obtained by treating the product with concentrated sulphuric acid and subsequent distillation, as well as by reaction with hydrogen under pressure or with metallic natrium.