PROCESS FOR REMOVING NAPTHOQUINONE FROM PHTHALIC ANHYDRIDEPRODUCED THROUGH AIR OXIDATION OF NAPHTHALENE

摘要

Removal of naphthaquinone from drude phthalic anhydride comprises contacting with a polymerised diene oil of mol. wt. 8005000 and which is polybutadiene, polydimethylbutadiene, poly-1,3pentadiene, polyisoprene, polypiperylene or mixts. of these, pref. at 180-280 deg.C for 4-20 hrs. Opt. alkali ions are present to decompose any maleic anhydride present. Pref. 1-40 ppm of alkali ions and 0.005-1.0 (0.1-0.2) wt.% of polymerised oil are used. Polybutadiene of mol. wt. 1000-3000 is suitable. Content of naphthaquione is reduced to less than 5 ppm and the refined phthalic anhydride may be distilled to reduce the naphthaquione to 1 ppm or less. Crude phthalic anhydride for treatment is that obtd. by oxidn. of nahthalene.