Abstract: A process for the continuous purification of crude bisphenol which comprises (1) forming a single liquid phase comprising a hot mixture of crude bisphenol and water in a ratio substantially of from about 75% to about 85% weight of crude bisphenol to about 15% to about 25% weight water; (2) continuously feeding this mixture together with a stream of warm water to a first crystallization zone at a temperature sufficient to maintain a bisphenol-rich liquid phase, a water-rich phase and a crystalline phase comprising about 70% to about 95% of the total bisphenol in the mixture; (3) passing the three-phase mixture of bisphenol and water to a second crystallization zone operated at about 85.degree. C. to about 97.degree. C. until about 90% to about 99% of the total bisphenol is crystallized; and (4) recovering the purified bisphenol crystals.

Abstract: A process for the preparation of crystals of an adduct of a bisphenol with a phenol which comprises:(a) adding an inert volatile liquid hydrocarbon diluent and 0-1.5% weight water to a crude mixture of the bisphenol and the phenol at a temperature above the boiling temperature of the added volatile liquid diluent; and(b) allowing the volatile liquid diluent to boil in the process, thereby cooling the resulting mixture of bisphenol and phenol to a temperature at which adduct crystals form.

Abstract: Preparation of certain optically-active alpha-hydroxynitriles or a mixture enriched therein comprises treating an aldehyde with hydrogen cyanide in a substantially water-immiscible, aprotic solvent in the presence of a cyclo(D-phenylalanyl-D-histidine) as a catalyst.

Abstract: Enantiomeric selectivity is increased in chiral cyanohydrination of an aromatic aldehyde using a chiral cyclo(phenylalanylhistidine) catalyst by treating the (recycle) aldehyde to remove catalyst poisons or impurities which adversely effect enantiomeric selectivity.

Abstract: Chiral aromatic cyanohydrins are prepared by treating an aromatic aldehyde with cyanide ions in the presence of an inert, aprotic solvent and a chiral cyclo(phenylalanyl-histidine) and an alcohol. The technique is especially useful for reducing the induction period when starting-up the process, increase the rate of reaction and to produce a product of increased enantiomeric selectivity.

Abstract: Preparation of certain optically-active alpha-hydroxynitriles or a mixture enriched therein comprises treating an aldehyde with hydrogen cyanide in a substantially water-immiscible, aprotic solvent in the presence of a cyclo(D-phenylalanyl-D-histidine) as a catalyst.

Abstract: A cyanohydrination catalyst for the preparation of alphahydroxynitriles from aldehydes and ketones comprises a solid cyclo(D-phenylalanyl-D-histidine) dipeptide having a non-crystalline or amorphous component.

Abstract: Cyanohydrins or a solution thereof in an inert solvent are stabilized by treatment with organophosphoric acids.

Abstract: A cyanohydrination catalyst for the preparation of alpha-hydroxynitriles from aldehydes and ketones comprises a solid cyclo(D-phenylalanyl-D-histidine) or cyclo(L-phenylalanyl-L-histidine) dipeptide having a non-crystalline or amorphous component.

Abstract: A cyanohydrination catalyst for the preparation of alphahydroxynitriles from aldehydes and ketones comprises a solid cyclo(D-phenylalanyl-D-histidine) dipeptide having a non-crystalline or amorphous component.