Process for synthesizing phenyl urethane in atmospheric condition

Abstract

The invention discloses a synthesizing method of carbanilate under normal pressure condition, which comprises the following steps: adopting N, N'-diphenylurea and alkyl dicarbonate as raw material; selecting low-toxicity and high-activity catalyst to heat and reflux under normal pressure to produce carbanilate. The invention makes the reacting condition more mild and reacting course simpler, which reduces the cost for industrialized manufacturing effectively.

Description

technical field [0001] The invention belongs to a kind of method of synthesizing phenyl carbamate, specifically with N, the method for the synthesis of phenyl carbamate with N'-diphenyl urea and dialkyl carbonate. Background technique [0002] Isocyanate is an important class of organic synthesis intermediates, which can be widely used in polymer materials such as polyurethane, coatings, dyes and pesticides. In the traditional isocyanate synthesis industry, most of the above products are synthesized by the phosgene method. With the increasing environmental protection requirements, the development of non-phosgene synthesis methods has become a very important topic in the chemical industry. Among them, using phenylcarbamate as a reaction intermediate, the synthesis process of preparing isocyanate through pyrolysis of phenylcarbamate has attracted much attention. [0003] The non-phosgene synthesis process of phenylcarbamate mainly includes oxidative carbonylation of aniline, ...

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Problems solved by technology

Although this method finally eliminates the generation of by-product aniline, a large amount of methanol is used as a reactant to form a complex three-way reaction system, and a large amount of methanol is used as a solvent for recycling, which not only reduces the utilization rate of equipment and the difficulty of separation, It also increases industrial energy consumption, and the reaction temperature is also higher, and it is carried out under pressurized conditions, which is very unfavorable for industrial production

[0005] In US3627813, the carbonate method and the diphenylurea method are coupled to obtain only carbonic acid ester and diphenylurea as reaction raw materials, and chlorobenzene is used as a solvent to synthesize phenylcarbamate in the presence of an organic amine catalyst. Can reach 79%, although this reaction can be carried out under the condition of normal pressure, operation process is simple, and does not participate in other reactant, also does not have other by-product generation, has improved the atom economy of reaction greatly, but because solvent chlorobenzene The use not only reduces the utilization rate of equipment, but also increases the cost of separation, and is not conducive to environmental protection due to the use of toxic solvent chlorobenzene

[0006] People such as Sunil P.Gupte (Chem.Commun., 2001, 2620-2601) take carbonate and diphenyl urea as reaction raw materials, do not use other solvents, 150 ℃ of reaction temperature, take a kind of silica gel as solid catalyst, but get The yield of phenylcarbamate is only 18%

Anand B.Shivarkar et al. (J.Mol.Catal.A:Chem.223(2004)85-92) take carbonate and diphenylurea as reaction raw materials, do not use other solvents, reaction temperature 150 ℃, dibutyl Base tin oxide is a homogeneous catalyst, and at a reaction pressure of 3.4MPa, the yield of phenylcarbamate is 77%, but this reaction is reacted under high pressure and high temperature, which is very unfavorable for industrial production