| abstract |
The prodn. of a 1,8-naphthalene-dicarboxylic acid cpd. (I) or anhydride comprises oxidn. of an acenaphthene (II), opt. with a substd. naphthalene ring, in a lower aliphatic monocarboxylic acid (III), pref. HOAc, with O2 in the presence of a heavy metal cpd. oxidn. catalyst (IV), pref. a mixt of a Co and Mn cpd., with a Br cpd. (V) under sufficient pressure to keep (III) in the liquid stage, whilst the concn. of (II) in the mixt. is kept below 0.3 M, pref. below 0.1 M. (II) can have halogen, sulpho, CN, NO2, COOH lower alkyl and/or acetyl substit(s). The process is suitable for (semi) continuous operation. (I) are valuable intermediates for certain dyes and pigments. Provided that the (II) concn. is kept low, little or no black material forms and (I) is obtained in high yield. |