Reactions of 5-Amino-2, 3-dicyano-1, 4-naphthoquinone with Anilines

Abstract

2, 3-Dicyano-1, 4-naphthoquinone [1], which is expected to be a strong electron acceptor, is an interesting compound. For the synthesis of coloring matters, 5-amino-2, 3-dicyano-1, 4naphthoquinone [5] was prepared from 2, 3-dichloro-5-nitro-1, 4-naphthoquinone [3] by cyanation, reduction and oxidation. The reactions of [5] with anilines (aniline [9], p-toluidine [10], p-anisidine [11], p-chloroaniline [12], N, N-dimethyl-p-phenylenediamine [13]) were carried out. Anilines [9]∼[13] gave [9a]∼[13a] (8-substitution) as major products, in which the 8-position of [5] reacted with amino group of anilines, and [9b]∼[12b](CN-substitution)as minor products, in which the cyano group is substituted by amino group.
The structure of [9b] was determined as the 2-substituted by the synthesis from a known compound. The 8-position substitution in [5] is rather unusual and interesting, therefore more detailed investigation of the reaction was carried out under various conditions.
The mechanism for the formation of [9a] and [9b] were discussed from the se results.5-Nitro-[4], 6-nitro-[7] and 6-amino-2, 3-dicyano-1, 4-naphthoquinones [8] were synth esized and the CN-substituted products were obtained by the reaction with aniline, but 8-substitution could not be observed. According to the visible absorption measurements of the obtained compounds, the bathochromic shift were shown more 300 nm by the 8-substituted [9a]∼[12a] than the CN-substituted [9b]∼[12b].