Method for preparing bis(1-alkoxy-2,2,6,6-tetramethyl piperidine-4-yl) sebate

Abstract

The invention discloses a method for synthesizing bis(1-alkoxy-2,2,6,6-tetramethyl piperidine-4-yl) sebate. The bis(1-alkoxy-2,2,6,6-tetramethyl piperidine-4-yl) sebate is synthesized through transesterification by using dimethyl sebate and 1-alkoxy-2,2,6,6-tetramethylpipradrol as raw materials. According to the method, lithium hydroxide is adopted as a catalyst, a quaternary ammonium salt is adopted as a phase transfer catalyst, n-heptane is adopted as a methanol-carrying solvent, and methanol is separated continuously from the reaction system through a water knockout vessel. The process comprises the steps: adding dimethyl sebate, 1-alkoxy-2,2,6,6-tetramethylpipradrol, lithium hydroxide, the phase transfer catalyst and n-heptane to a reaction kettle with the water knockout vessel, performing heating to a reflux state so as to separate methanol continuously, stopping the reaction (about 5 hours later) until no separation of methanol, performing cooling to room temperature, performingwashing with deionized water, performing reduced pressure distillation on the oil phase so as to isolate the solvent and unreacted 1-alkoxy-2,2,6,6-tetramethylpipradrol and obtain a crude product, washing the crude product three times with a mixed solvent of methanol and water, and then performing distillation so as to isolate the solvent and obtain the final product. The method has the advantagesthat the process and the devices are simple, the catalyst has safe use, the product has easy separation, the product has high yield and high purity, and emission of three wastes is little.

Description

technical field [0001] The present invention relates to a preparation method of bis(1-alkoxy-2,2,6,6-tetramethylpiperidin-4-yl) sebacate, specifically a sebacate Acid dimethyl ester and 1-alkoxy-2,2,6,6-tetramethylpiperidinol are raw materials, lithium hydroxide is a catalyst, quaternary ammonium salt is a phase transfer catalyst, and n-heptane is a methanol solvent. The invention discloses a transesterification method in which methanol is continuously separated from a reaction system by using a water separator, and belongs to the field of fine chemical industry and macromolecule material additives. Background technique [0002] Bis(1-alkoxy-2,2,6,6-tetramethylpiperidin-4-yl) sebacate is a novel light stabilizer (Papaspyrides C D, Kiliaris P .Polymer Green Flame Retardants[M].Amsterdam:Elsevier Science Ltd edited,2014:267-288), its general chemical structure is as follows: [0003] [0004] In the formula, R=alkane group, cycloalkane group and aromatic hydrocarbon group...

AI Technical Summary

Problems solved by technology

But this reaction has the following problems: the esterification reaction produces a large amount of by-product-hydrochloric acid, in order to make the reaction normally, need to consume a large amount of acid-binding agent-triethylamine, the by-product of formation is difficult to handle, pollutes environment; It is prepared from sebacic acid and thionyl chloride as raw materials. During the preparation process, a large amount of hydrogen chloride and sulfur dioxide are produced, which is difficult to handle and seriously pollutes the environment. Sebacoyl chloride has high activity and is easy to hydrolyze. It must be anhydrous during use. more demanding

Although elemental analysis showed high product purity, HPLC analysis showed product purity was only 80%

Dibutyltin oxide is expensive and has low catalytic activity, so the esterification temperature is high (Alessandro Z, Gianluca F, Massimiliano S. Preparation of stericallyhindered amine ethers[P].US 2002009496A1.2002-07-18)

[0030] Comparing the above schemes comprehensively, the transesterification method is the most ideal method, but the process reported at present, the catalyst used and the method of separating methanol are not ideal, and the purification product by column chromatography cannot be industrialized

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