Abstract: 1 A process for producing a purified organophosphorus alkyl ester compound in which the reaction mixture obtained by reacting a dichlorophosphine derivative with (meth)acrylic acid is esterified with a lower monool, and the resulting reaction mixture is neutralized with an alkali metal hydroxide or alkaline earth metal hydroxide either in a solid form or in the form of an aqueous solution and purified; 2 a process for producing a purified organophosphorus hydroxyalkyl ester compound or an alkylene glycol solution thereof which comprises subjecting the purified organophosphorus alkyl ester compound obtained by process 1 to transesterification with an alkylene glycol; 3 a reactive flame retardant comprising the purified organophosphorus alkyl ester compound obtained by process 1; and 4 a reactive flame retardant comprising the purified organophosphorus hydroxyalkyl ester compound or alkylene glycol solution obtained by process 2.

Abstract: A phosphine derivative of the following general formula ( I ): ##STR1## (wherein R.sup.1 is an alkyl group having 1 to 18 carbon atoms or an aryl group having 6 to 18 carbon atoms, and the aryl group may have an alkyl group having 1 to 18 carbon atoms or an alkenyl group having 2 to 18 carbon atoms) is reacted with acrylic acid or methacrylic acid in the presence of a catalyst selected from the group consisting of an organic peroxide and an azo-compound, and the resulting reaction product is hydrolyzed with water, thereby to obtain a phosphinyl-carboxylic acid derivative of the following general formula (III): ##STR2## (wherein R.sup.1 is as defined above, and R.sup.2 is a hydrogen atom or a methyl group). Based on the reaction above-mentioned, ester of free acid and a cyclic acid anhydride can also be obtained. Accordingly, the target compound can be obtained at a relatively low reaction temperature in a short period of time with high yield.

Abstract: The present invention relates to 1-hydroxy-.omega.-(alkyl- or arylphosphinico)alkane-1,1-diphosphonic acids of the general formula I ##STR1## and to the salts of these acids of the general formula II ##STR2## where, in these formulae, R.sup.1 denotes an alkyl radical having 1 to 6 carbon atoms, a cycloalkyl radical having 5 to 7 carbon atoms or an aryl radical having 6 to 10 carbon atoms, R.sup.2 denotes a straight-chain or branched alkylene radical having 1 to 6 carbon atoms and A denotes a monovalent equivalent of a cation of an inorganic or organic base. In addition, processes are described for the preparation of these novel compounds.

Abstract: The invention relates to a process for the preparation of 2-chloroethanephosphonyl dichloride by reaction of an ester of 2-chloroethanephosphonic acid of the formula ##STR1## or a mixture of the two esters with thionyl chloride at a temperature of 60.degree. to 160.degree. C. Phosphine oxides are employed as catalysts therein. The thionyl chloride is added to the initially introduced ester.