Evidence for the similarity recognition hypothesis. Structure dependence of the selectivity in oxidation of a pair of associating thiols each having an alkyl group.

In base-catalyzed oxidation of a pair of associating thiols [HSCH2–CONHCONH–R1 and HSCH2CH2–NHCONHCO–R2] (R1=n-C4H9, R2=n-CnH2n+1) with oxygen, the selectivity (a measure of molecular recognition) at 35.0°C reached a maximum for R1=R2 (=n-C4H9) both in aqueous acetonitrile (n=2 to 6) and in aqueous ethanol (n=3 to 5).