| 摘要 |
<p>Process for the preparation of 1,1-dichloro-1-fluoroethane (known in the craft as HCFC-141b). The process comprises a stage consisting in reacting vinylidene chloride with an excess of anhydrous hydrogen fluoride in the presence of a catalytic quantity of a catalyst of formula RmAXnFp, in which A denotes titanium, zirconium or hafnium, R denotes an alkyl, alkenyl or aryl radical, X denotes chlorine or bromine, m is a number ranging from 0 to 2, n a number ranging from 0 to 4 and p a number ranging from 0 to 4, but at least one of the numbers n and p is not zero and the sum m + n + p satisfies the valency of A, for a period and at a temperature which are sufficient to form 1,1-dichloro-1-fluoro- methane. This compound is useful as a blowing agent for the production of thermally insulating rigid urethane foams.</p> |
