摘要:
A process for preparing N-vinylpyrrolidone by reacting 2-pyrrolidone with acetylene, wherein the 2-pyrrolidone used as a starting material (referred to hereinafter as starting 2-pyrrolidone) comprises less than 1 part by weight of γ-butyrolactone per 100 parts by weight of 2-pyrrolidone.
摘要:
A process for preparing an N-vinyl compound by vinylating a compound having at least one nitrogen atom (referred to hereinafter as compound for short) with acetylene, wherein before the vinylation, the compound is reacted with an alkali metal hydroxide in a reaction zone and the mean residence time of the alkali metal hydroxide and of the compound in the reaction zone is less than 6 minutes.
摘要:
A process for preparing an N-vinyl compound by vinylating a compound having at least one nitrogen atom (referred to hereinafter as compound for short) with acetylene, wherein before the vinylation, the compound is reacted with an alkali metal hydroxide in a reaction zone and the mean residence time of the alkali metal hydroxide and of the compound in the reaction zone is less than 6 minutes.
摘要:
The present invention relates to a solid, acid catalyst for the preparation of polytetrahydrofuran, polytetrahydrofuran copolymers, diesters or monoesters of these polymers by polymerization of tetrahydrofuran in the presence of at least one telogen and/or comonomer, which has a BET surface area of at least 160 m2/g and an acid center density of at least 0.05 mmol/g for pKa values of from 1 to 6, to a process for preparing it and to a process for the polymerization of cyclic ethers over this catalyst.
摘要:
Unsaturated ketones of the formulae Ia and Ib are prepared by a process consisting of the combination of the following reactions: a) The conventional reaction of an allyl alcohol of the formula IIa or a propargyl alcohol of the formula IIb with an isopropenyl ether of the formula III with formation of a ketal of the formula IV as a byproduct, b) preparation of the isopropenyl ether of the formula III by reacting a ketal of the formula IV with propyne or allene, or a mixture thereof in the gas phase at elevated temperatures in the presence of a heterogeneous catalyst containing zinc or cadmium together with silicon or oxygen, and c) feeding the ketal of the formula IV formed in the reaction (a) into stage (b) for the preparation of the isopropenyl ether of the formula III again.