Synthesis technology of tetramethylpiperidine

Abstract

The invention discloses a synthesis technology of tetramethylpiperidine, comprising the steps of: first, adding triacetonamin, a catalyst, flake caustic soda and water into a high-pressure reaction kettle; second, introducing N2 to the kettle, then introducing H2 to replace N2; third, controlling the pressure within the kettle to be maintained at 0.8MPa, when the pressure in the kettle decreases, supplementing H2 timely to a pressure of 0.8MPa, conducting stirring simultaneously to raise the temperature which is controlled between 70 to 100DEG C, then repeating the above operations till the pressure in the kettle is constant at 0.8MPa; fourth, introducing N2 into the kettle to replace H2, and simultaneously delivering cooling water into a coiled pipe inside the kettle so as to lower the temperature in the kettle below 50DEG C, the stopping stirring, filtering out the catalyst, and distilling out part of the water; fifth, stirring and cooling the left oversaturated mother solution in ice water bath for crystallization, then carrying out filtering and washing, thus obtaining tetramethylpiperidine. The tetramethylpiperidine synthesized by the technology of the invention has the advantages of high yield and purity, good color and quality, and no environmental pollution, so that the technology provided in the invention is good for promotion and application.

Description

technical field [0001] The invention relates to a synthesis process of tetramethylpiperidinol. Background technique [0002] The chemical name of tetramethylpiperidinol is 2,2,6,6-tetramethyl-4-piperidinol, which is a synthetic hindered amine light stabilizer, medicine, bleaching agent, polymerization inhibitor, epoxy resin crosslinking agent, etc. An important intermediate of the product. At present, the hindered amine light stabilizers developed in my country are all piperidine derivatives, and all of them are products with piperidinol as the intermediate. Therefore, the production of piperidinol is an important link in the development of light stabilizers in my country. Therefore, the synthesis research of piperidinol has important practical significance. [0003] The method for preparing piperidinol by reduction of piperidone by piperidone reported at home and abroad mainly contains following several kinds at present: [0004] 1. Catalytic hydrogenation, including pre...

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Problems solved by technology

[0005] 2. The chemical reduction method uses aluminum isopropoxide, sodium borohydride, etc. as reducing agents to reduce piperidinone to piperidinol, but the reducing agent is more expensive and the post-reaction treatment is more complicated, so it is rarely used in industry; 3. Electrochemical reduction method, piperidinone is reduced to piperidinol at the cathode of the electrolytic cell, but due to high production energy consumption and complex structure of the electrolytic cell, the industry generally does not use it

[0006] The main disadvantages of the current liquid-phase hydrogenation process are: catalyst Ru / C is expensive, which is not conducive to industrialization, and the loss rate of solvent xylene, toluene, methanol, etc. is greater than 20%, causing environmental pollution