| 摘要 |
1,219,742. Halosiloxanes. TH. GOLDSCHMIDT A.G. 13 Jan., 1969 [16 Jan., 1968], No. 1490/69. Heading C3S. Halosiloxanes of the formula where R is H or alkyl or aryl, X is halogen, a is 0 or 1, b is 1, 2 or 3 and a+b is 2 or 3, are prepared by adding dropwise b moles of a tertiary aliphatic alcohol to a mixture of 1 mole of a silane RaSiX 4-a and from 2b to 5b moles of a silane (CH 3 ) 3 SiY, where Y is halogen, at a temperature of from - 40‹ to 250‹ C., preferably below 40‹ C. The process is preferably effected in the presence of a hydrogen halide passed through the reaction mixture. The starting silanes should be pure, particularly free from iron salts. The preferred alcohol is tert.-butanol, others are specified within the C 1-8 range. The products may be converted to the corresponding hydroxy-siloxanes by hydrolysis in the presence of an acid acceptor. They may also be condensed with hydroxy-siloxanes to provide, for example, bis - (trimethylsiloxy) end - blocked siloxanes. The examples describe the preparation of 1,1,1,3,5,5 - heptamethyl - 3 - chlorotrisiloxane; 1,1,1,5,5,5 - hexamethyl - 3 - propyl-3- chlorotrisiloxane; 1,1,1,5,5,5 - hexamethyl-3,3- dichlorotrisiloxane; 1,1,1,5,5,5 - hexamethyl-3- phenyl - 3 - bromotrisiloxane; 1,1,1,5,5,5 - hexamethyl - 3 - octadecyl - 3 - chlorotrisiloxane and 1,1,1,3 - tetramethyl - 3,3 - dichlorodisiloxane. |
