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US 3,945,891 AGranted
Distillation process for purification of triaryl phosphate esters
AssigneeFMC Corporation
InventorsRobert A. Aal, Norman H. C. Chen, James K. Chapman, Jr.
Life of this patent
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Abstract
Crude phosphate ester products resulting from the phosphorylation of phenol, lower alkyl phenols and mixtures of same are purified to prepare triaryl phosphates substantially free of unreacted phenols by the sequential steps of flash distillation and fractional distillation under controlled conditions with removal of the phosphate ester product as a liquid underflow.
Claims8
A process for purifying triaryl phosphate esters prepared by the phosphorylation of phenol, C.sub.1 -C.sub.4 alkyl substituted phenols and mixtures of same consisting essentially of:
- a. subjecting the crude triaryl phosphate ester reaction mixture of flash distillation at a temperature of about 220.degree. to 320.degree.C and a pressure of 2 to 10 mm. Hg and removing catalyst residues and high boiling impurities in an underflow and removing at least 90% of the feedstock as an overhead distillate comprising triaryl phosphate ester product and unreacted phenols, and
- b. fractionally distilling the overhead from the flash distillation step in a fractional distillation column having a low pressure drop per theoretical stage maintained at a temperature of about 250.degree. to 300.degree.C and at a pressure of 4 to 10 mm. Hg at the base of said column and a temperature of about 60.degree. to 200.degree.C and a pressure of 2 to 4 mm. Hg at the top of said column, and
- c. removing the purified triaryl phosphate ester product as a liquid underflow from the base of said column, the product being characterized as containing less than about 100 parts per million of unreacted phenols, free phenol, and alkyl phenols.
Dependencies are inferred from the claim text.