Acenaphthene is a polycyclic aromatic hydrocarbon (PAH) consisting of naphthalene with an ethylene bridge connecting positions 1 and 8. It is a colourless solid. Coal tar consists of about 0.3% of this compound.

Production and reactions

Acenaphthene was prepared for the first time in 1866 by Marcellin Berthelot by reacting hot napthalene vapours with acetylene, and a year later he reproduced a similar reaction with ethylene as well as discovered acenaphthene in coal tar. Later Berthelot and Bardy synthesized the compound by cyclization of α-ethylnaphthalene. Industrially, it is still obtained from coal tar together with its derivative acenaphthylene (and many other compounds). Like other arenes, acenaphthene forms complexes with low valent metal centers. One example is (η6-acenaphthene)Mn(CO)3]+.

Uses

It is used on a large scale to prepare naphthalene dicarboxylic anhydride, which is a precursor to dyes and optical brighteners (such as 1,4-bis(2-benzoxazolyl)naphthalene). Besides that, the anhydride is also the precursor to perylenetetracarboxylic dianhydride, precursor to several commercial pigments and dyes.