Monsanto Company

James E White

Ignatius Schumacher

Dario R Cova

Joseph W Baker

Residual PCl.sub.3 in POCl.sub.3 which has been prepared by the oxidation of PCl.sub.3 in the presence of air or oxygen-enriched air is converted to POCl.sub.3 by contacting the POCl.sub.3 /PCl.sub.3 mixture with ozone or an ozone-enriched gas.

Preparation and purification of phosphoryl chloride

Maleic anhydride is recovered in high yields from gaseous mixtures containing the maleic anhydride in the vapor phase by cooling the gaseous mixture containing the maleic anhydride to a temperature above the dew point of water in the gaseous mixture, and then scrubbing the gaseous mixture with a solvent which comprises a phthalate ester, preferably dibutyl phthalate, and up to 10 weight percent phthalic anhydride. Thereafter, the maleic anhydride is stripped from the solvent in a one-step operation, and the solvent is thereafter recycled to the scrubbing step.

Recovery of maleic anhydride

The prior art discloses a number of polymerization inhibitors for acrylic acid, acrylates and derivatives thereof, but such polymerization inhibitors have low vapor pressures. Consequently, when acrylic acid is vaporized, it tends to polymerize on cooling surfaces causing undesirable deposits on storage vessels and the like. However, when a polymerization inhibiting amount of 2,4-pentanedione is added to the monomer, the polymerization of acrylic acid on cooling surfaces is inhibited.

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Coshocton, OH, United States of America

James E White