Continuous production of organic phosphines

Claim 1

In a process for the continuous production of organic phosphines of the following general formula (I) or (II) ##STR4## in which formula (I) R 1 and R 2 each are selected from the group consisting of an alkyl-, cycloalkyl- or aralkyl group having 2 to 18 carbon atoms, or one of the substituents R 1 and R 2 is a hydrogen atom and the other is one of the said groups, and in which formula (II) m and n each are 1, 2 or 3, the sum of m+n being at most 5, and R 3 and R 4 , being identical or different, each are a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, wherein the formula (I) compound is made by reacting an alkylene, cycloalkylene or aralkylene having 2 to 18 carbon atoms with hydrogen phosphide, or the formula (II) compound is made by reacting a compound of the following general formula (III) ##STR5## in which m, n, R 3 and R 4 have the meanings given above, with hydrogen phosphide at elevated temperature and under elevated pressure in the presence of a free radical-yielding catalyst solution in an inert solvent, terminating the reaction and separating the resulting organic phosphine from the reaction mixture, the improvement which comprises: continuously supplying from above a pressure reactor, which is provided in its interior with mixing elements, kept free from oxygen, and subdivided so as to comprise an upper cooling zone and a lower reaction zone, with (a) a solution of the alkylene, cycloalkylene or aralkylene or of a compound of general formula (III) and the catalyst in an inert solvent, and (b) a stoichiometric excess of hydrogen phosphide, the said (a) and (b) reactants being supplied jointly with, but separately from, one another; mixing the said (a) and (b) reactants in the upper cooling zone of the reactor at a temperature of about 0° to 35° C. and under a PH 3 -pressure of about 80 to 300 bars; reacting the resulting mixture, which travels downwardly in the reactor, in the lower reaction zone at about 90° to 190° C., the reactants being allowed to remain in the reactor for a period of time about 13 to 15 times longer than the half life period of the catalyst; removing the reaction mixture through the bottom portion of the reactor and, after pressure release to atmospheric, subjecting the mixture to distillation so as to separate the organic phosphines therefrom.