| 摘要 |
<p>1. Process for the preparation of alkyl glyoxylate semi-acetals of the general formula see diagramm : EP0099981,P7,F1 in which R denotes an alkyl radical with 1 to 10 C atoms and R1 an alkyl radical with 1 to 4 C atoms, by ozonolysis of a maleic acid derivative followed by catalytic hydrogenation of the ozonolysis products, characterised in that a) a dialkyl maleate with 1 to 10 C atoms in the alkyl radical is dissolved in an aliphatic alcohol of the formula R1 OH, wherein R1 has the abovementioned meaning, and is reacted at temperatures of - 80 to + 20 degrees C with an equivalent amount of ozone, after which b) the resulting peroxide-containing solution is fed continuously into a suspension of the hydrogenation catalyst in the alcohol of the formula R1 OH, used in the ozonolysis in stage a), R1 having the abovementioned meaning, at a rate of addition such that over the entire course of the hydrogenation a peroxide content of at most 0.1 mole/l is set up, and maintained, in the hydrogenation reactor, the hydrogenation being carried out at pH 2 to pH 7 at temperatures of 15 degrees C to 45 degrees C under a pressure of 1 to 20 bar.</p> |
