Fluorinated acetylenes. Part II. Certain ionic and radical additions to NN-bistrifluoromethylethynylamine

Abstract

NN-Bistrifluoromethylethynylamine reacts with hydrogen bromide or with bromine in the dark to give 1-bromo-NN-Bistrifluoromethylvinylamine or trans-1,2-dibromo-NN-bistrifluoromethylvinylamine, respectively. Under photolytic conditions the products are cis- and trans-2-bromo-NN-bistrifluoromethylvinylamine (ratio 34 : 66) and cis- and trans-1,2-dibromo-NN-bistrifluoromethylvinylamine (ratio 64 : 36), respectively. trans-1,2-dibromo-NN-bistrifluoromethylvinylamine on photolysis alone partially isomerises to give a mixture of the cis- and trans-olefins in the ratio 64 : 36. The dehydrobromination of a mixture of the 1,2-dibromo-NN-bistrifluoromethylvinylamine isomers gives bromo-NN-bistrifluoromethylethynylamine in good yield and this acetylene is also formed by the reaction of NN-bistrifluoromethylethynylamine with alkaline hypobromite. Bromo-NN-bistrifluoromethylethynylamine reacts with hydrogen bromide in the dark to give only cis-1,2-dibromo-NN-bistrifluoromethylvinyl-amine. The acid-catalysed hydration of NN-bistrifluoromethylethynylamine gives NN-bistrifluoromethylacetamide and hydrogenation yields NN-bistrifluoromethylvinylamine. NN-Bistrifluoromethylethynylamine does not react with methanol under neutral or acid-catalysed conditions at room temperature, but it reacts under basic conditions at 100° to give mainly 1-methoxy-NN-bistrifluoromethylvinylamine and cis-2-methoxy-NN-bistrifluoromethylvinylamine (ratio 64 : 32).