Aminopyrrole zinc-lithium bimetallic catalyst, preparation method and application thereof

Abstract

The invention provides an aminopyrrole zinc-lithium bimetallic catalyst, relates to lactide ring-opening polymerization, in particular to a zinc-lithium bimetallic catalyst by taking 2-tert-butyl-aminomethylpyrrole as a ligand. A preparation method of the catalyst comprises the following steps: under protection of an inert gas and a condition of cold-water bath, using n-butyllithium to conduct lithiation on the aminopyrrole ligand, sequentially dropping diethyl zinc and TMEDA (Tetramethylethylenediamine) with equivalent amount in the obtained solution, after the reaction, filtering the reactant, carrying out vacuum concentration on the filtrate, and at last separating out colorless and transparent crystals. The preparation method of the catalyst is simple, convenient, easy to get the raw materials, mild in the reaction conditions; the obtained catalyst is of a higher catalytic activity on the lactide ring opening polymerization; the obtained polylactic acid is uniform in distribution of molecular weight, so that the catalyst is of a good application prospect.

Description

technical field [0001] The invention relates to a lactide ring-opening polymerization catalyst, in particular to a zinc-lithium bimetallic catalyst containing an aminopyrrole ligand, a preparation method and application thereof. Background technique [0002] As a typical biodegradable material, polymeric ester materials are generally obtained by ring-opening polymerization of cyclic ester compounds. Lactide is one of the most studied examples and is often used as a benchmark for the development of new catalysts. However, organozinc compounds are considered to be potentially non-toxic and non-polluting, and it is imperative to develop organozinc compounds as catalysts for the ring-opening polymerization of lactide to synthesize polylactic acid. The most important thing is that it will open up inexhaustible raw material resources for the current polymer material industry mainly based on petroleum, so it has great practical value in terms of environmental protection and resourc...

AI Technical Summary

Problems solved by technology

Although the production of polylactic acid has been industrialized now, there are still great deficiencies and improvements, such as (1) the catalytic efficiency of the catalyst needs to be further improved. Compared with the olefin polymerization catalyst, the catalytic efficiency of the lactide ring-opening polymerization catalyst The efficiency is lower by nearly 7 orders of magnitude; (2) The catalysts currently used are mainly tin 2-ethylhexanoate and aluminum triisopropoxide, and most tin compounds have strong toxicity, which greatly limits the production of The polylactic acid material prepared by 2-ethylhexanoate is used in medical applications. At the same time, because aluminum ions cannot be metabolized in humans or animals, it is suspected that it can cause diseases such as senile dementia. Therefore, it is prepared from triisopropoxide aluminum There are also many limitations in polylactic acid; (3) it is difficult to realize controllable polymerization now, that is, to prepare different polylactic acids with narrower molecular weight distributions according to different application requirements.

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