The reactions occur in an autoclave. The autoclave is charged with 200 g (1.28 moles) of 2,3-dimethylnaphthalene, 940 g (3.14 moles, 23% excess) of sodium dichromate dihydrate, and 1.8 L of water. The autoclave is closed, heated to 250 °C, and shaken continuously at this temperature for 18 hours. The autoclave is cooled with continued agitation, the pressure is released, and the autoclave is opened. The contents are transferred to a large vessel. To effect complete transfer, the autoclave is rinsed with several 500ml. portions of hot water. Green hydrated chromium oxide in the reaction mixture is separated on a large Büchner funnel and washed with warm water until the filtrate is colorless. The combined filtrates (7–8 L) are acidified with 1.3L of 6N hydrochloric acid. The acidified mixture is allowed to cool to room temperature overnight. The 2,3-naphthalenedicarboxylic acid that has precipitated is collected on a large Büchner funnel, washed with water until the filtrate is colorless, and dried to constant weight in a vacuum oven at 50°C/20 mm. or by long standing in air. The 2,3-naphthalenedicarboxylic acid is a white powder; m.p. 239–241°C; weight 240–256 g. (87–93%). The synthetic route is as follows:

This procedure illustrates a general method for the preparation of aromatic carboxylic acids by oxidation of the corresponding alkylarenes.