| 摘要 |
1,137,329. 3,3-(Alkylenedioxy or dialkoxy)- alkyl halides. F. HOFFMANN-LA ROCHE & CO. A.G. 7 June, 1967 [7 June, 1966], No. 26339/67. Heading C2C. 3,3-(Alkylenedioxy or dialkoxy)-alkyl halides of the general formula where R is a C 1-6 alkyl group, Z is (C 1-6 alkylenedioxy) - methylene or di - (C 1-6 alkoxy)-methylene, X=Cl, Br or I, are prepared by reacting HCl, HBr or HI with an alkene-(1) of general formula under anhydrous conditions and at a temperature below 25‹ C. The reaction may be performed in an alkanol or alkanediol as solvent, wherein the hydrocarbon portion is the same as that of the alkoxy groups or alkylenedioxy group in the alkene. In the example, 3,3-(ethylenedioxy) - pentene - 1 is reacted with HBr in ethylene glycol to yield 1-bromo-3,3-(ethylenedioxy)-pentane. The starting material, alkene-1, may be prepared by reacting an alkanone-3 with an alkanol or-alkanediol and then with halogen to give a 2-halo-ketal which is dehydrohalogenated with a base. |
