The chemical composition of high‐boiling fractions of coal tar. I. A steam distillate from a vertical‐retort soft pitch

Abstract

Abstract A neutral oil boiling above 380°/760 mm., obtained from a soft vertical‐retort coal‐tar pitch, has been separated by chromatography into paraffin waxes, fluorescent oils, solids and brown residual oils. The fluorescent oils, which cannot be induced to crystallize, consist mainly of non‐picrate‐forming components, which have average molecular weights of about 250 and average hydrogen: carbon ratios of about 1·1:1. These oils are resistant to dehydrogenation. The chief components of the solids are: fluoranthene, pyrene, brazan, 2:3‐benzofluorene, 5:12‐dihydronaphthacene, chrysene and 1:2‐benzanthracene. Minor components that have been identified are: 4‐methylpyrene, 1:2:8‐trimethylphenanthrene, triphenylene, 2:3‐benzocarbazole, 1:2‐benzofluorene, an alkylbrazan and an unidentified compound, C 16 H 10 OS. 1:2‐Benzocarbazole has been separated from the brown residual oils. Of these substances, 5:12‐dihydronaphthacene, 4‐methylpyrene and 1:2:8‐trimethylphenanthrene have not previously been isolated from coal tar.