Reaction of ?,?,?-trichloro- and ?,?,?,?-tetrachloroalkanes with alkali metal acylates in aprotic solvents
摘要:
Polychloroalkanes and -alkenes R(CH2)nCl (R = CHCl2CH2, CCl2 = CH, n = 1, 3) in dipolar aprotic solvents - dimethylformamide (DMF), dimethylsulfoxide (DMSO), hexamethylphosphoramide (HMPA) - at 130-150-degrees-C react selectively at the CH2Cl group with salts of carboxylic acids R'CO2K(Na) to form dichloroesters R'CO2. (CH2)nR (R = CHCl2CH2, CCl2 = CH). In tetrachloroalkanes CCl3CH2(CH2)nCl (n = 1, 3, 5) under the same conditions the selectivity of the CCl3 and CH2Cl groups relative to the nucleophile R'CO2K(Na) is altered - unsaturated esters R'CO2(CH2)nCH = CCl2 are formed in one stage with yields of 75-90%. Under the selected conditions, high conversion of polychloroalkanes to esters is attained 3 to 5 times more rapidly than in acid media. The structure of the ester obtained has been confirmed by their PMR spectra.