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Watanabe et al. (J. Chem. Soc., Chem. Commun. (1990) 1497) reported a synthesis of N,N'-diphenylurea in 92% yield by dehydrogenating formanilide in the presence of aniline and a ruthenium catalyst: ##STR2## Watanabe et al. prepared numerous symmetric N,N'-diarylureas in this manner. In contrast, N-phenyl-N'-p-tolylurea was not obtained selectively from the reaction of formanilide and p-toluidine. Instead, a mixture of three ureas -- N,N'-diphenylurea (19%), N,N'-di-p-tolylurea (21%), and the unsymmetric product, N-phenyl-N'-p-tolylurea (38%) -- was obtained: