Structures and pesticidal activities of derivatives of dinitrophenols. Part V. Reactions of certain dinitro-aryl thiocarbamates with potassium hydroxide in methanol and with various nucleophiles

Abstract

NN-Dialkylthiocarbamoyl chloride and potassium 2,4-dinitrophenoxide, 2-chloro- or 2-methyl-4,6-dinitrophenoxide, or 2,4-dinitro-1-naphthoxide, on heating in acetone, give S-aryl thiocarbamates, whereas potassium nitrophenoxide gives an O-arylthiocarbamate. On treatment with potassium hydroxide in methanol at room temperature the 6-substituted-2,4-dinitrophenyl and 2,4-dinitro-1-naphthyl thiocarbamates and iminothiocarbonates yield highly coloured p-quinonoid potassium 1,1-gem-dimethoxy-aci-nitro-salts of different stabilities, in which the two methoxy-groups are equivalent. The aci-salts decompose in solution to the methyl ethers or potassium phenoxides, or both, depending on conditions. 2,4-Dinitrophenyl thiocarbamate does not yield the aci-salt, but hydrolyses with potassium hydroxide in methanol to the benzenethiolate. However, it produces an intense violet colour with acetone in the presence of alkali. Thiocarbamates, carbamates, and iminothiocarbonates give intense colours in the presence of alkali with various nucleophiles capable of producing the ion RCHX- where X is an electron-withdrawing group; carbonates, thio-, or dithio-carbonates do not give colours.