Preparation of piperidine nitroxyl radical anti-polymerization inhibitor

Abstract

The invention provides a method for preparing a piperidine nitrogen oxygen-derived free radical polymerization inhibitor, which has the advantages that: firstly, the reaction time is short, the reaction condition is mild, and the operation is simpler; secondly, a catalyst has cheaper price and low cost, is convenient to separate, and can be reused; thirdly, the yield is higher; and fourthly, water is taken as a solvent, and the method for direct drying by distillation cannot generate waste solution and wastewater, does not pollute the environment, and realizes zero release in industrial production in a real sense. Therefore, the method is a method for preparing piperidine nitrogen oxygen-derived free radicals, and provides convenience for industrial production.

Description

technical field [0001] The invention relates to a preparation technology of an anti-polymerization inhibitor, in particular to a preparation method of a piperidine nitroxide free radical anti-polymerization inhibitor. Background technique [0002] Piperidine nitroxide radical is a commonly used organic chemical product. It can be used not only as a light stabilizer in organic polymerization, but also as an oxidant in organic synthesis. It can also be used as a spin label in the study of biological systems. [0003] The industrial production method of reported piperidine class nitroxide free radical mainly contains following several kinds at present, enumerates as follows: [0004] In the traditional process, sodium tungstate or phosphotungstic acid is mainly used as the catalyst, hydrogen peroxide is used as the oxidant, and methanol, water, and methanol-acetonitrile are used as the solvent, and nitrogen oxide free radicals are obtained by oxidation with hydrogen peroxide. ...

AI Technical Summary

Problems solved by technology

The disadvantages of this method are: the catalyst is expensive, the yield is low, the reaction time is long, the local heat release is severe, and by-products are easily generated so that the product quality cannot meet the requirements. At the same time, the amount of catalyst is large and cannot be separated and recovered effectively. The method obtains the product, thus produces a large amount of waste liquid to pollute the environment

[0005] US5.218.116 uses ZSM-5 as a catalyst. Although the catalyst is a heterogeneous catalyst, the catalyst is expensive, the activity decreases rapidly, the number of repetitions is small, and it cannot be regenerated, which is easy to pollute the environment.

[0006] CN1235946A has introduced a kind of method that uses ion exchange resin as catalyst, although this method has improved yield to a certain extent, still can not reach highest effect

There is still a large amount of waste liquid generated during the production process, polluting the environment

Moreover, the cost of ion exchange resin is high, and it needs to be activated and regenerated continuously, which is troublesome to operate in industrial production.

[0007] CN1683414A has introduced a kind of production method that uses hydrotalcite-like as catalyst, although the catalyst of this method can be recycled, can not cause environmental pollution, but still there is following shortcoming, and catalyst consumption is large; Because this catalyst has homogeneous ion, is difficult for separation , so the post-treatment can only use the method of crystallization, otherwise it is easy to cause the product to fail the inspection of residue on ignition

In this way, the yield will be reduced, and a large amount of waste liquid will still be left to pollute the environment

[0008] In summary, the current method for preparing piperidine nitroxide radicals is still not optimal, and it is necessary to research and develop a new catalyst and production method to meet the needs of industrial production and environmental protection

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