Patent GB-772486-A (GB)
Title: Improvements in the production of phosphorous acid esters
IPC: C07F9/141
Filed: 1953-12-31
Abstract: Neutral and acid polyphosphorous acid esters of polyhydric alcohols having a higher boilingpoint than chlorethanol are obtained by a transesterification reaction which comprises heating a mixture of a neutral or acid phosphorous ester of chlorethanol and a polyhydric alcohol having a higher boiling-point than chlorethanol and removing by distillation the chlorethanol formed.  The transesterification takes place readily at temperatures below 100 DEG  C. and it is preferred to operate at reduced pressure although atmospheric pressure may be employed. Transesterification catalysts such as alcoholates or metal oxides may be employed in the reaction.  When acid phosphorous esters of chlorethanol are used the products are the corresponding acid esters of the polyhydric alcohols.  The latter may also be obtained by partially hydrolysing the neutral phosphorous ester during or after the transesterification of the neutral chlorethanol ester with the polyhydric alcohol and the resulting product may be converted by heating under reduced pressure to a highly viscous acid poly-phosphorous acid ester of the polyhydric alcohol.  In examples: (1) tri-(chlorethanol-phosphorous acid ester (1 mol.) is heated with diethylene glycol (1 mol.) under reduced pressure with removal by distillation of 1 mol. of chlorethanol to form a resinous polyphosphorous acid ester which carries a chlorethanol radical on each phosphorous acid radical; (2) as in (1) except that 1,6-hexanediol is employed as the polyhydric alcohol, the product being a viscous mass which solidifies to a clear, elastic block; (3) the neutral polyester obtained in (2) is hydrolysed with water and the product heated under reduced pressure to form a highly viscous liquid which consists of the acid polyphosphorous acid ester of 1,6-hexanediol. Other polyhydric alcohols specified are ethylene glycol, triglycol, butanediols, hexanediols, glycerol, hexanetriol, pentaerythritol, tetramethylolcyclohexanol, and sorbitol.  The phosphorous acid ester products are stated to be useful as agents for preventing oxidation.ALSO:Neutral or acid phosphorous esters of alcohols having a higher boiling point than chlorethanol are obtained by a transesterification reaction which comprises heating a mixture of a neutral or acid phosphorous ester of chlorethanol and an alcohol having a higher boiling point than chlorethanol and removing by distillation the chlorethanol formed.  The transesterification takes place readily at a temperature at below 100 DEG  C. and it is preferred to operate at reduced pressure although atmospheric pressure may be employed. Transesterification catalysts such as alcoholates or metal oxides may be employed in the reaction. Suitable alcohols having a higher boiling point than chlorethanol are the hexyl, heptyl and octyl alcohols, cyclopentanol, the terpene alcohols, araliphalic alcohols such as benzyl alcohol, polyhydric alcohols such as ethylene glycol, diglycol, triglycol, butanediols, hexanediols, triols such as glycerol and hexanetriol, pentaerythritol, tetramethylol cyclohexanol, and sorbitol.  When polyhydric alcohols are used the products are highly viscous liquids or resins (see Group IV (a)).  When acid phosphorus esters of chlorethanol are used the products are the corresponding acid esters of the higher boiling alcohols.  The latter may also be obtained by partially hydrolysing the neutral phosphorus ester during or after the transesterification of the neutral chlorethanol phosphorous acid ester with the higher boiling alcohol.  When a polyphosphorous acid ester of a polyhydric alcohol is treated by hydrolysis in this way to convert it into the acid ester the product may be converted by heating under reduced pressure to a highly viscous acid polyphosphorous acid ester of the polyhydric alcohol.  Examples are given for the transesterification of tri(chlorethanol) phosphorous acid ester with (1) 2-ethylhexanol to form tri-(2-ethylhexyl) phosphorous acid ester; (2) benzyl alcohol to form the tribenzyl ester; (3) with diethylene glycol to form a resinous polyphosphorous acid ester which carries a chlorethanol radical on each phosphorous acid radical; and (4) with 1,6-hexane-diol to form a viscous mass which solidifies to a vitreous colourless block.  In another example the neutral polyphosphorous acid ester obtained in (4) is hydrolysed with water and the product heated under reduced pressure to form a highly viscous liquid consisting of the acid polyphosphorous acid ester of 1,6-hexanediol.  The phosphorous acid esters are stated to be useful as agents for preventing oxidation.  The phosphorous acid esters of trichlorethanol may be obtained by reacting ethylene oxide with phosphorous trichloride.