Abstract: A process for preparing ?-functionalized thiazolidines or oxazolidines, each of which are oxycarbonyl-functionalized in the 4-position, by adding a base to a reaction mixture comprising an oxycarbonyl-functionalized thiazolidine or oxazolidine and an electrophile at a temperature of greater than ?40° C.

Abstract: The invention relates to a novel process for hydroxymethylating noncyclic ?,?-dialkylcarboxylic acid derivatives with formaldehyde using amide bases at temperatures of from ?40° C. up to the boiling point of the solvent or solvent mixture used.

Abstract: Preparation of ?-substituted cysteine derivatives takes place by acidic hydrolysis of thiazolidines, wherein the hydrolysis is effected in the presence of a further phase comprising an organic solvent and a vapor comprising water, acid, organic solvent and aldehyde is removed from the reaction mixture, or a vapor comprising water, acid and aldehyde is removed from the reaction mixture and the vapor or its condensate is subsequently contacted with a phase comprising an organic solvent. The process requires less hydrolysis time and allows for recycle and/or recovery of acid and by product aldehyde.

Abstract: A process is provided for preparing optically active alcohols, amines and derivatives thereof by reacting aldehydes or imines at a temperature of less than 15° C. in the presence of a chiral, enantiomerically pure auxiliary with an organozinc halide which is obtained from zinc and a reactive halogen compound, and water, acid or base, or an alkylating, arylating, acylating or silylating reagent is subsequently added.

Abstract: A process for removing zinc from organic solutions comprising zinc alkoxides or zinc amides, includes admixing the solution with an alkylating, arylating, acylating or silylating agent in the presence of a precipitating reagent having at least two nitrogen donors and subsequently removing the precipitated solid.

Abstract: A process is provided for preparing an enantiopure 1,3-dioxolan-4-one or 1,3-oxathiolan-5-one derivative, which includes bringing a mixture containing enantiomeric 1,3-dioxolan-4-one or 1,3-oxathiolan-5-one derivatives and an enzyme with hydrolytic activity into contact in the presence of a nucleophile. Cleaving a dioxolanone/oxathiolanone ring of one enantiomer occurs by the enzyme with hydrolytic activity and, after the cleavage of one enantiomer has taken place, the uncleaved enantiomer of the 1,3-dioxolan-4-one or 1,3-oxathiolan-5-one derivative is isolated.

Abstract: Silanes of the formula Ra1R4-a-xSiLx??(I) where each R is identical or different and is a monovalent, optionally substituted hydrocarbon radical which is free of aliphatic carbon—carbon multiple bonds and has from 1 to 18 carbon atoms per radical, R1 is an optionally substituted 2-norbornyl radical, L is a leaving group, a is 1, 2 or 3 and x is 1 or 2, with the proviso that the sum of a+x?4, are useful for protecting functional groups of organic compounds (2) which have at least one functional group having an active hydrogen atom, preferably as a hydroxyl group —OH, a thiol groups —SH, an amine group —NH— or —NH2, a carboxyl group —COOH, or an amide group —CONH— or —CONH2.

Abstract: A process for reducing free aldehydes in dispersions, suspensions, emulsions and solutions which comprises including therein thioamine compound of the formula IV and optionally a thioamine of the formula III: where R1 is a C1-5 alkyl radical, an aryl radical or hydrogen, R2 is —(COO)a —E or —(CONH)a—E where a is 0 or 1 and E, R3, R4, and R5 are independently R4 and R5 together containing at least one carbon atom, and n being 0 or 1.

Abstract: An alcohol is oxidized to an aldehyde or a ketone in the presence of a nitroxyl compound as catalyst, wherein the alcohol to be oxidized is contained in an organic liquid phase, and is reacted in the presence of a nitroxyl compound with an aqueous phase comprising an oxidant. The reaction is carried out continuously at a contact time of the phases of from 0.1 s to a maximum of 15 minutes, with intensive mixing of the phases. The process produces high yields with low quantities of other oxidation byproducts.

Abstract: A process for preparing an &agr;-haloketone of the formula (1) where R1 is an optionally heteroatom-containing and optionally substituted hydrocarbon radical, R2 is a hydrogen, alkyl, aralkyl or aryl radical, and X is a halogen radical, by reacting a carboxylic acid derivative of the general formula (2) where L is a leaving group, with a mono- or dienolate of a silyl ester of the formula (3) where R3 and R4 are identical or different alkyl, aryl, alkenyl or aralkyl radicals; and hydrolyzing the reaction product immediately afterwards by adding acid and decarboxylating to (1). The product &agr;-haloketone may be reduced to the corresponding &agr;-haloalcohol.

Abstract: A process for preparing organozinc halides in solvents, includes reacting a reactive halogen compound with zinc in one or more carboxylic esters. It is also possible to prepare keto, hydroxyl and amino compounds of organozinc halides obtained in a first step from a reactive halogen compound and zinc in one or more carboxylic esters, wherein the organozinc halide obtained is reacted in a second step with an electrophilic reaction partner and the reaction product of the second step is hydrolyzed in a third step.

Abstract: A process for the preparation of an enantiomerically pure tertiary &bgr;-hydroxycarboxylic acid or its ester, wherein an enantiomer mixture of compounds is brought into contact with an enzyme, which is capable of the hydrolytic cleavage of an ester bond, in an aqueous medium such that one enantiomer of the enantiomer mixture is hydrolyzed.

Abstract: Silanes of the formula

Abstract: An alcohol is oxidized to an aldehyde or a ketone in the presence of a nitroxyl compound as catalyst, wherein the alcohol to be oxidized is contained in an organic liquid phase, and is reacted in the presence of a nitroxyl compound with an aqueous phase comprising an oxidant. The reaction is carried out continuously at a contact time of the phases of from 0.1 s to a maximum of 15 minutes, with intensive mixing of the phases. The process produces high yields with low quantities of other oxidation byproducts.

Abstract: A process for precipitating cystine from a solution in sulfuric acid, includes forming a mixture of a solution of cystine in aqueous sulfuric acid and of an aqueous solution of a base by simultaneous metering the cystine solution and the aqueous base solution into a mixing container. The metering takes place in such a way that the mixture in the container has a pH between 1.0 and 7.0 and a temperature between 30° C. and the boiling point of the mixture.

Abstract: A process for preparing an &agr;-haloketone of the formula (1) 1

Abstract: The invention relates to a process for the preparation of a carbonyl compound of the general formula (1) R1R2C═O  (1), in which a &bgr;-hydroxycarboxylic acid or its salt of the general formula (2) R1R2C(OH)—CR3R4—COOM  (2) is cleaved in the presence of a Brönstedt base which is selected from hydroxides, alkanolates, oxides, amides and hydrides of the alkali metals and alkaline earth metals, and in the presence of a hydroxyl-free solvent, R1, R2, R3, R4 and M having the meanings from claim 1.

Abstract: A process for reducing free aldehydes in dispersions, suspensions, emulsions and solutions which comprises including therein thioamine compounds of the general formula I or II 1

Abstract: The invention relates to a process for the preparation of a carbonyl compound of the general formula (1)

Abstract: Multi-component system for modifying, degrading or bleaching lignin, lignin-containing materials or similar substances, includes (a) if appropriate at least one oxidation catalyst; (b) at least one suitable oxidizing agent; and (c) at least one mediator, wherein the mediator is chosen from the group consisting of N-aryl-N-hydroxyamides.