2-ethylhexyl dihydrogen phosphate

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: The final major step in the process of this invention is the hydrolysis of the di-(2-ethylhexyl) phosphorochloridate to product DEHPA. This reaction is carried out using an excess amount of water over the stoichiometric amount. Dealkylation of the DEHPA to mono-(2-ethylhexyl) phosphoric acid by HCl at elevated temperatures is a side reaction that must be controlled to produce acceptable product. This dealkylation is minimized by adjusting the amount of water so that a final HCl content below about 11 wt. % is obtained. In general, the hydrolysis reaction is carried out at 80°-100° C. Considerable amounts (above 60 wt. %) of tetra-(2-ethylhexyl) pyrophosphate are formed in this process from the reaction of DEHPC with DEHPA. This lowers product purity and causes processing problems, such as poorer phase separation. This is overcome by extending the hydrolysis time to 4-6 hours to hydrolyze the pyrophosphate to DEHPA product. An alternative and preferred method to carry out the hydrolysis is to hydrolyze the mixture, as above described for about 2 hours at about 80° C. Then the aqueous layer containing the HCl is separated. A second hydrolysis, using the same amount of water as previously stated, is carried out at 95°-100° C. for about 3 hours. a side reaction that to produce acceptable product is obtained In general, the hydrolysis reaction is carried out at 80°-100° C