151 results about "Hemiacetal" patented technology

The invention discloses a method for preparing polyhydroxy cyclic nitrones. The method for preparing the polyhydroxy cyclic nitrones of the structure of formula I provided by the present invention comprises the following steps: 1) reacting the hemiacetal of the structure of formula II with O-methylhydroxylamine hydrochloride under alkaline conditions to obtain The methyl oxime ether of the structure of formula III; 2) the methyl oxime ether of the structure of formula III is reacted with methanesulfonyl chloride to obtain the mesylate of the structure of formula IV; 3) The mesylate of the structure of formula IV is subjected to acidic conditions 4) The aldehyde of formula V structure reacts with hydroxylamine hydrochloride under alkaline conditions to obtain the polyhydroxy cyclic nitrone; wherein, R1, R2 and R3 is an alkyl, alkenyl, aryl or substituted aryl group. The present invention can prepare polyhydroxy cyclic nitrones with high reactivity through several steps of reactions by using sugars widely existing in nature as raw materials, thereby realizing the concise, efficient and large-scale preparation of such compounds.

Halogenated α-fluoroethers (or bis-derivatives thereof) can be produced by reacting a halogenated hemiacetal (or bis-derivative thereof) with sulfuryl fluoride (SO2F2) in the presence of an organic base. The reaction is conducted preferably in the presence of “a salt or complex of an organic base with hydrogen fluoride”, whereby the objective dehydroxyfluorination can proceed extremely favorably. It is still preferable to use as the starting substrate a halogenated hemiacetal prepared from fluoral or 3,3,3-trifluoropyruvic acid ester. Thus, industrially important halogenated α-fluoroethers can be industrially produced with high selectivity and in high yield.

This invention is directed to a process for the preparation of a crosslinker composition, comprising the steps of providing a mixture of an aliphatic alcohol A having at least one hydroxyl group and from 1 to 10 carbon atoms, with at least one multifunctional aldehyde C having at least two aldehyde groups —CHO to form a mixture AC, heating the mixture AC to convert at least a part of the multifunctional aldehyde C to its hemiacetal or to its acetal to form a mixture (AC)′, adding to the mixture (AC)′ least one cyclic urea U or the educts to produce the said cyclic urea U in situ, which cyclic urea U has at least one unsubstituted >NH group, and reacting the mixture thus obtained to form a chemical bond between the nitrogen atom of the at least one unsubstituted >NH group of the at least one cyclic urea U5 and the carbon atom of the least one aldehyde group —CHO of the multifunctional aldehyde C, and coating compositions comprising the said crosslinker composition.

Cationic polyvinyl acetals are prepared by copolymerizing one or more cationic N-alkyldiallylammonium salt monomers with one or more vinyl esters of branched or unbranched carboxylic acids having 1 to 15 carbon atoms, hydrolyzing the resulting copolymers to copolymers containing ≧50 mol % vinyl alcohol units, and acetalizating the vinyl alcohol units with one or more aliphatic aldehydes having 1 to 15 carbon atoms, their acetals, and / or hemiacetals, wherein the copolymerization takes place in a mixture of water and monovalent aliphatic alcohol having a water content of 2% to 35% by weight.