A kind of preparation method of lithium trialkyl borohydride

Abstract

The invention provides a preparation method of lithium trialkyl borohydride, comprising the following steps: Step A: respectively preparing a solution of lithium trimethoxyaluminum hydride in tetrahydrofuran ether and a solution of trialkylborane in tetrahydrofuran; Step B: condensation reaction : Add 20%-25% of the lithium trimethoxyaluminum hydride solution prepared in step A into the reaction kettle, stir and control the temperature to 21-23°C, and then according to a specific dripping scheme, the remaining ingredients in batching tank A are added. and the solution in the batching tank B were added dropwise to the reaction kettle respectively. After the dropwise addition was completed, the reaction was stirred for 0.5-2h, and then allowed to stand for 0.5-2h; solid-liquid separation was obtained to obtain the supernatant, which is trialkylboron The tetrahydrofuran ether solution of lithium hydride; the molar yield of tris(hydroxymethyl)aminomethane obtained by the present invention is more than 96%, the product content reaches more than 99.0%, and the quality is stable.

Description

technical field [0001] The invention belongs to the technical field of chemical industry, and relates to a preparation method of lithium trialkyl borohydride. Background technique [0002] Trialkylborohydrides are very powerful nucleophilic reducing agents capable of rapidly and quantitatively cleaving cyclic ethers, reducing halides, alcohols, sulfonates, epoxides and activated alkenes to desired products. Hindered and highly hindered trialkylborohydrides have very good steric control in the reduction of cyclic and bicyclic ketones, unmatched by any other reducing agent. [0003] Chinese patent CN107446003A discloses a preparation method of tri-sec-butyl lithium borohydride, the equation is [0004] (C 4 H 9 ) 3 B+LiAlG 4 +C 6 H 12 N=Li(C 4 H 9 ) 3 BH+AllH 3 ·C 6 H 12 N. , Lithium aluminum hydride is used as one of the reactants. Lithium aluminum hydride has strong activity, and the feeding process requires high technology and equipment, and there is a greater...

AI Technical Summary

Problems solved by technology

, using lithium aluminum hydride as one of the reactants. Lithium aluminum hydride has strong activity. The feeding process has high requirements on technology and equipment, and there are great safety hazards

The reaction releases a large amount of heat, and lithium aluminum hydride must be added dropwise very slowly, and the whole process must be carried out in an ice-water bath, with a long production cycle and complicated process; the by-product is triethylenediamine aluminum hydride complex, and the reaction speed Fast, the crystal grains formed are small, which makes solid-liquid separation difficult, and the final product tri-sec-butyl lithium borohydride tetrahydrofuran solution contains many impurities and the solution is turbid. That is, the preparation of tri-sec-butyl lithium borohydride by this process has a long production cycle, Problems such as low yield and low content, and great safety hazards, high requirements for equipment and other defects

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