Keywords: Urocanic acid.svg Skeletal formula of urocanic acid Created using http //www acdlabs com/download/chemsk html ACD/ChemSketch 8 0 and http //www inkscape org Inkscape Own 2007-05-13 Fvasconcellos 17 22 13 May 2007 UTC Carboxylic acids Imidazoles Intermediates |