The Synthesis and Properties of 11, 11, 12, 12-Tetracyanoanthraquinodimethan and Its Derivatives

Abstract

11, 11, 12, 12-Tetracyanoanthraquinodimethan (TCNAQ) has been prepared in high yield by direct condensation of anthraquinone and malononitrile using dry pyridine and molecular sieves. The intermediate in the formation reaction was found to be 10-(dicyanomethylene)anthrone. TCNAQ was readily hydrolyzed to 10-(dicyanomethylene) anthrone and anthraquinone under basic conditions. Although TCNAQ was stable against dilute H₂SO₄, treatment whith conc. H₂SO₄ gave a diamide [4], a partially hydrolyzed product. Reaction of TCNAQ with mercaptoacetic acid gave no reduction product, but reaction with NaBH₄ gave tetrahydro-TCNAQ [5]. The different reactivity of TCNAQ with reducing reagents from that of TCNQ can be explained in terms of nonplanar structure of TCNAQ as well as the difference of aromaticity between the benzene and anthracene units. In order to investigate the substituent effects on the properties, several TCNAQ derivatives substituted at the 1-or 2-position were prepared. A linear correlation between the reduction potentials and (σm+σp)/ 2 was observed. The reduction potentials show that TCNAQs are weaker acceptors than TCNQ.