Metabolism of azulene in rats

1. Azulene was rapidly metabolized in the rat and excreted in the urine as the sulphate conjugate of 1-hydroxyazulene; 45% of the dose was recovered as pure metabolite from the 0-24 h urine. 2. [1,3(-2)H2]Azulene was converted in vivo to 1-hydroxyazulene sulphate which was shown by 1H-n.m.r. spectroscopy to contain one deuterium at C-3 and essentially no detectable deuterium at C-2. This result suggests that, if a 1,2-oxide of azulene was an intermediate in the 1-hydroxylation, it rearranged with direct loss of deuterium from C-1 rather than an NIH shift to C-2.