Method for preparing isocyanate by using amine and carbonyl fluoride

Abstract

The invention discloses an efficient synthesis method for preparing corresponding isocyanate by enabling carbonyl fluoride to directly react with amine. The efficient synthesis method mainly comprises the following two steps: carrying out acylation reaction on the amine and the carbonyl fluoride according to a preferable proportion in an anhydrous inertial organic solvent under a sealed environment and a proper reaction condition, thus generating an intermediate-carbamyl fluoride; (2) carrying out dehydrofluorination on the intermediate-carbamyl fluoride under normal pressure and the proper reaction condition, thus obtaining the target isocyanate. During a reaction process, addition of a catalyst is not needed, the reaction conditions are mild, excessive carbonyl fluoride and a used solvent during the reaction process can be efficiently recycled and reused, and a by-product HF can be commercially sold after being collected and refined.

Description

technical field [0001] The invention belongs to the technical field of organic compound synthesis industry, and specifically relates to a high-efficiency industrial synthesis method for preparing corresponding isocyanates by directly reacting carbonyl fluoride with amines, and simultaneously recovering excess carbonyl fluoride and by-product hydrogen fluoride through rectification and the like. Background technique [0002] Isocyanate is a general term for various esters of isocyanates with "-N=C=O" functional groups, mainly used in the synthesis of polyurethane foams, elastomers, fibers (spandex), leather shoe resins, coatings, sealants, adhesives and artificial Wood, etc.; it can also be used as an intermediate or raw material for the synthesis of insecticides, fungicides, herbicides, hypoglycemics and other pesticides, pharmaceutical fine chemical products, and can also be used to improve the water resistance, light resistance, weather resistance etc. Among them, the rep...

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Problems solved by technology

Patent US3118923 uses carbonyl fluoride and alkali metal cyanide, cyanogen halide, inorganic cyanate and other compounds containing -CN functional groups to react with or without direct use of a catalyst to obtain the corresponding fluorine-containing isocyanate. The raw material cyanide is generally highly toxic and difficult to obtain, and the yield of the product is not high; the patent US3795689, under the catalysis of potassium fluoride, rubidium fluoride and other ionic fluoride salts, combines perfluorochloroalkylimine and carbonyl fluoride in The corresponding perfluorochloroalkyl isocyanate can be prepared by reacting in anhydrous aprotic polar medium. This method has difficulty in catalyst recovery, long reaction time, hard to obtain raw materials, and difficult to realize industrialization

Patent JP5322183 reacts carbonyl fluoride with five kinds of diamines without electron-withdrawing groups, such as toluene diamine (TDA) and methylene dianiline (MDA), and patent CN105837475A reacts carbonyl fluoride with p-toluenesulfonamide (pTSA) , the corresponding isocyanates were prepared respectively, but no experiments were conducted on whether they were suitable for the synthesis of other isocyanates, especially other special isocyanates containing electron-withdrawing groups, or -NCO functional groups not directly connected to the aromatic ring (except HDI) In addition, the former does not involve the recovery and reuse process of excess carbonyl fluoride, organic solvents, by-product HF, etc., which causes serious environmental pollution and poor economic efficiency. Although the latter is mentioned, it does not involve specific recovery processes. Examples of design and recycling effects have great limitations in guiding significance for industrial production

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