| 词条 | Carbylamine reaction |
| 释义 |
The carbylamine reaction (also known as the Hofmann isocyanide synthesis) is the synthesis of an isocyanide by the reaction of a primary amine, chloroform, and base. The conversion involves the intermediacy of dichlorocarbene. Illustrative is the synthesis of tert-butyl isocyanide from tert-butylamine in the presence of catalytic amount of the phase transfer catalyst benzyltriethylammonium chloride.[1] Me3CNH2 + CHCl3 + 3 NaOH → Me3CNC + 3 NaCl + 3 H2O Similar reactions have been reported for aniline. Test for primary aminesAs it is only effective for primary amines, the carbylamine reaction can be used as a chemical test for their presence. In this context, the reaction is also known as Hofmann's isocyanide test.[2] In this reaction, the analyte is heated with alcoholic potassium hydroxide and chloroform. If a primary amine is present, the isocyanide (carbylamine) is formed, as indicated by a foul odor. The carbylamine test does not give a positive reaction with secondary and tertiary amines. MechanismThe mechanism involves the addition of amine to dichlorocarbene, a reactive intermediate generated by the dehydrohalogenation of chloroform. Two successive base-mediated dehydrochlorination steps result in formation of the isocyanide. See also
References1. ^{{cite journal| author = Gokel, G.W.; Widera, R.P.; Weber, W.P. | title = Phase-transfer Hofmann Carbylamine Reaction: tert-Butyl Isocyanide| volume=55|doi=10.15227/orgsyn.055.0096| pages = 232| year = 1988 }} 2. ^Carbylamine reaction 2 : Organic reactions|Chemical tests |
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