阅读说明：本技术 一种制备氨基甲酸酯的制备方法 (Preparation method for preparing carbamate ) 是由 周玉文 于 2019-10-23 设计创作，主要内容包括：本发明涉及一种制备氨基甲酸酯的制备方法,采用碳酸二甲酯作为尿素醇解的反应原料,采用新型复合型催化剂,避免了现有技术中需要冷能排氨造成的能耗高、设备成本高的技术问题,氨基甲酸酯的收率高达96％以上。(The invention relates to a preparation method for preparing carbamate, which adopts dimethyl carbonate as a reaction raw material for urea alcoholysis and a novel composite catalyst, avoids the technical problems of high energy consumption and high equipment cost caused by the need of cold energy ammonia discharge in the prior art, and has the yield of carbamate as high as more than 96 percent.)

1. A preparation method for preparing carbamate comprises the steps of mixing urea and dimethyl carbonate according to a molar ratio of 1:1, placing the mixture into a high-pressure kettle, adding a catalyst, heating to a reaction temperature for reaction, and carrying out alcoholysis reaction on the urea and the dimethyl carbonate to obtain the carbamate, wherein the reaction formula is as follows:

NH2-CO-NH2+OCH3-CO-OCH3→2NH2-CO-OCH3

and distilling to obtain the carbamate after the reaction is finished, wherein the catalyst is Na-ZnO-ZrO 2/gamma-Al 2O 3.

2. The method according to claim 1, wherein: the addition of the catalyst is 0.1-2 wt% of the addition of the urea.

3. The method according to claim 1, wherein: the reaction temperature is 150 ℃ and 210 ℃, and the reaction time is 3-12 hours.

4. The method according to claim 1, wherein: the preparation method of the catalyst comprises the following steps:

s1, dissolving soluble zinc salt and soluble zirconium salt in a certain amount of deionized water according to a certain proportion, fully stirring and uniformly mixing, adding an alumina carrier, adjusting pH, carrying out ultrasonic dispersion for 2-5 hours, carrying out dipping reaction for 2-3 hours, drying at 80-120 ℃ for 5-10 hours, and finally roasting at high temperature to obtain a catalyst precursor;

s2, adding the catalyst precursor and sodium metal into a vacuum grinding reactor according to a certain proportion, and grinding for 3-5 hours to obtain the high-efficiency solid-phase catalyst Na-ZnO-ZrO 2/gamma-Al 2O 3.

5. The method according to claim 4, wherein: in step S1, the soluble gallium salt is gallium nitrate or gallium chloride, and the soluble cerium salt is cerium nitrate, cerium chloride or cerium sulfate; the mol ratio of the soluble gallium salt to the soluble cerium salt is 1: 20-50.

6. The method according to claim 4, wherein the pH value in step S1 is preferably 1 to 3.

7. The method according to claim 4, wherein: in the step S1, the high-temperature roasting temperature is 500-1200 ℃, and the roasting time is 2-12 hours.

8. The method according to claim 4, wherein: the amount of the metal added in step S2 is 1.5-10% by mass of the catalyst precursor.

9. The method according to claim 4, wherein: the temperature of the polishing reaction in step S2 is 200-300 ℃.

Technical Field

The invention belongs to the field of organic synthesis, and particularly relates to a preparation method for preparing carbamate.

Background

Carbamates are an important class of organic synthetic reagents and raw materials for the manufacture of pharmaceuticals. The thermal cracking method of carbamate is adopted to synthesize isocyanate, which has no environmental pollution, low requirement on equipment, great flexibility in building factories and good application prospect. In the presence of a phosphorus pentoxide dehydrating agent, the acetanilide and carbamate react to generate quinazolinone, so that the reaction yield is low. The carbamate compound reacts with acetonyl acetone to obtain the N-substituted 2, 5-dimethylpyrrole with excellent uvioresistant performance and good compatibility with rubber, plastic and various resins. The carbamate and the polyalcohol undergo ester exchange reaction to obtain the polyalcohol carbamate compound, and the structure of the polyalcohol carbamate compound is similar to that of the polyamide. The urethane of polyol and aldehyde are cross-linked to produce a polymer having a polyaminoester structure, which is useful as a coating material, an adhesive, etc. The polyurethanes synthesized by the above-described process do not contain residual toxic isocyanate groups and are referred to as non-toxic polyurethanes. Methyl carbamate and olefin are subjected to addition reaction to synthesize the N-substituted carbamate compound. Styrene and carbamate are subjected to addition reaction in the presence of mercuric nitrate to obtain N-phenethyl carbamate, and the yield is 99%. The carbamate and the isobutene are catalyzed by acidic ion exchange resin to obtain the N-tertiary butyl ethyl carbamate with the yield of 93 percent. After the benzyl carbamate, aldehyde and triphenyl phosphate react, the obtained product is reacted with hydrogen bromide to obtain aminomethyl diphenyl phosphate, and then the aminomethyl diphenyl phosphate reacts with chloroacetyl chloride to obtain the phosphorus-containing dipeptide through condensation.

Carbamates are important pharmaceuticals and pesticides. For example, urethane is a sedative and hypnotic, under the drug name urethane; polyurethanes (polyurethanes for short) obtained by the polymerization of difunctional isocyanates with diols (see polymerization) are used as synthetic leather, synthetic fibers, paints, foams and adhesives.

The carbamate pesticide has the characteristics of strong selectivity, high efficiency, broad spectrum, low toxicity to people and livestock, easy decomposition and less residual toxicity, and is widely applied to the aspects of agriculture, forestry, animal husbandry and the like. More than 1000 carbamate pesticides exist, the using amount of the carbamate pesticides exceeds that of organophosphorus pesticides, and the sale amount of the carbamate pesticides is second to that of pyrethroid pesticides. The carbamate pesticide is used in large amount such as Metolcarb, Carbaryl, Aldicarb, Carbofuran, IsoprOCarb and Pirimicarb. The carbamate pesticide is generally stable under acidic conditions, is easy to decompose when meeting alkali, is easy to decompose when being exposed to air and sunlight, and has a half-life period of several days to several weeks in soil.

Carbamates can be prepared by reacting a chloroformate with ammonia or an amine, or by reacting a carbamoyl chloride with an alcohol or a phenol. The reaction of isocyanates with alcohols or phenols is also a simple process for the preparation of carbamates.

The urea alcoholysis method is a novel synthesis method developed in recent years, has cheap raw materials and simple reaction process, and is the main direction for researching the synthesis of carbamate at present. At present, the yield of carbamate is improved by discharging ammonia through cold energy in the reaction process, but an absorption tower and cooling equipment are required to be additionally arranged, so that the equipment cost and the energy consumption are high, and the industrial production is not facilitated.

Disclosure of Invention

Aiming at the problems of low urea conversion rate and high ammonia discharge energy consumption in the prior art, the invention aims to provide a reaction for synthesizing carbamate by carrying out alcoholysis reaction on urea in dimethyl carbonate with high yield and high selectivity.

The invention provides a preparation method for preparing carbamate, which comprises the steps of mixing urea and dimethyl carbonate according to the molar ratio of 1:1, placing the mixture into a high-pressure kettle, adding a catalyst, heating to the reaction temperature for reaction, and carrying out alcoholysis reaction on the urea and the dimethyl carbonate to obtain the carbamate, wherein the reaction formula is as follows:

NH₂-CO-NH₂+CH₃O-CO-OCH₃→2NH₂-CO-OCH₃

distilling to obtain carbamate after the reaction is finished, wherein the catalyst is Na-ZnO-ZrO₂/γ-Al₂O₃。

According to the invention, dimethyl carbonate is used as a reaction raw material for urea alcoholysis, so that the raw material for urea alcoholysis is provided in the reaction process, and carbamate can be obtained by reacting with ammonia byproduct in the alcoholysis reaction.

Further, the adding amount of the catalyst is 0.2-3 wt% of the adding amount of the urea.

Further, the reaction temperature is 150 ℃ and 210 ℃, and the reaction time is 3-12 hours.

Further, the preparation method of the catalyst comprises the following steps:

s1, dissolving soluble zinc salt and soluble zirconium salt in a certain amount of deionized water according to a certain proportion, fully stirring and uniformly mixing, adding an alumina carrier, adjusting pH, carrying out ultrasonic dispersion for 2-5 hours, carrying out dipping reaction for 2-3 hours, drying at 80-120 ℃ for 5-10 hours, and finally roasting at high temperature to obtain a catalyst precursor;

s2, adding the catalyst precursor and sodium metal into a vacuum grinding reactor according to a certain proportion, and grinding for 3-5 hours to obtain the high-efficiency solid-phase catalyst Na-ZnO-ZrO 2/gamma-Al 2O 3.

Further, in step S1, the soluble gallium salt is gallium nitrate or gallium chloride, and the soluble cerium salt is cerium nitrate, cerium chloride or cerium sulfate; the mol ratio of the soluble gallium salt to the soluble cerium salt is 1: 20-50;

further, the pH value in step S1 is preferably between 1 and 3.

Further, the high-temperature calcination temperature in the step S1 is 500-1200 ℃, and the calcination time is 2-12 hours.

Further, the amount of the metal added in step S2 is 1.5-10% by mass of the catalyst precursor.

Further, the temperature of the milling reaction in step S2 is 200-300 ℃.

Compared with the prior art, the invention has the following beneficial effects:

1) the invention adopts dimethyl carbonate as the reaction raw material for alcoholysis of urea, thereby avoiding the technical problems of high energy consumption and high equipment cost caused by the need of cold energy for ammonia discharge in the prior art.

2) The prepared novel composite catalyst activates the composite metal oxidation catalysis by using the metal sodium, can further improve the yield of dimethyl carbonate, and the yield of carbamate reaches more than 96%.

Detailed Description

The technical solutions in the embodiments of the present invention are clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

[ example 1 ]

1) Preparation of the catalyst:

s1, dissolving 1mol of zinc nitrate and 20mol of zirconium nitrate in 5L of deionized water, fully stirring and uniformly mixing, adding 500g of alumina carrier, adjusting the pH to 1 by using dilute sulfuric acid, performing ultrasonic dispersion for 3 hours, performing immersion reaction for 2 hours, drying at 120 ℃ for 5 hours, and finally calcining at 1200 ℃ for 3 hours to obtain a catalyst precursor;

s2, adding 100g of catalyst precursor and 1.5g of metallic sodium into a vacuum grinding reactor, and grinding and reacting for 4 hours at 300 ℃ to obtain the high-efficiency solid-phase catalyst Na-ZnO-ZrO₂/γ-Al₂O₃

2) Preparation of carbamate:

mixing 1mol of urea and 1mol of dimethyl carbonate, placing the mixture in an autoclave, adding 0.6g of the catalyst prepared in the step S1, heating the mixture to 180 ℃ for reaction for 6 hours, carrying out alcoholysis reaction on the urea and the dimethyl carbonate to obtain carbamate, distilling the mixture after the reaction is finished to obtain 89.0g of carbamate, wherein the yield is 98.8%, and the purity of the methyl carbamate is 99.6% through HPLC detection.

[ example 2 ]

S1, dissolving 1mol of zinc chloride and 30mol of zirconium chloride in 6L of deionized water, fully stirring and uniformly mixing, adding 500g of alumina carrier, adjusting the pH to 1 by using dilute sulfuric acid, performing ultrasonic dispersion for 2 hours, performing immersion reaction for 3 hours, drying at 80 ℃ for 10 hours, and finally calcining at 1000 ℃ for 5 hours to obtain a catalyst precursor;

s2, adding 100g of catalyst precursor and 5g of metallic sodium into a vacuum grinding reactor, and grinding and reacting for 3 hours at 300 ℃ to obtain the high-efficiency solid-phase catalyst Na-ZnO-ZrO₂/γ-Al₂O₃。

2) Preparation of carbamate:

mixing 1mol of urea and 1mol of dimethyl carbonate, placing the mixture in an autoclave, adding 1.2g of the catalyst prepared in the step S1, heating the mixture to 160 ℃ for reaction for 4 hours, carrying out alcoholysis reaction on the urea and the dimethyl carbonate to obtain carbamate, distilling the mixture after the reaction is finished to obtain 88.5g of carbamate, wherein the yield is 98.3%, and the purity of the methyl carbamate is 99.5% through HPLC detection.

[ example 3 ]

S1, dissolving 1mol of zinc nitrate and 50mol of zirconium nitrate in 6L of deionized water, fully stirring and uniformly mixing, adding 300g of alumina carrier, adjusting the pH to 2, ultrasonically dispersing for 2 hours, carrying out dipping reaction for 3 hours, drying at 120 ℃ for 5 hours, and finally roasting at 800 ℃ for 12 hours to obtain a catalyst precursor;

s2, adding 100g of catalyst precursor and 8g of metallic sodium into a vacuum grinding reactor, and grinding and reacting for 3 hours at 200 ℃ to obtain the high-efficiency solid-phase catalyst Na-ZnO-ZrO 2/gamma-Al 2O 3.

2) Preparation of carbamate:

mixing 1mol of urea and 1mol of dimethyl carbonate, placing the mixture in an autoclave, adding 0.8g of the catalyst prepared in the step S1, heating the mixture to 210 ℃ for reaction for 5 hours, carrying out alcoholysis reaction on the urea and the dimethyl carbonate to obtain carbamate, distilling the mixture after the reaction is finished to obtain 87.2g of carbamate, wherein the yield is 96.8%, and the purity of the methyl carbamate is 99.3% through HPLC detection.

[ example 4 ]

S1, dissolving 1mol of zinc nitrate and 20mol of zirconium nitrate in 5L of deionized water, fully stirring and uniformly mixing, adding 500g of alumina carrier, adjusting the pH to 1 by using dilute sulfuric acid, performing ultrasonic dispersion for 3 hours, performing immersion reaction for 2 hours, drying at 120 ℃ for 5 hours, and finally calcining at 1200 ℃ for 3 hours to obtain a catalyst precursor;

s2, adding 100g of catalyst precursor into a vacuum grinding reactor, and grinding and reacting for 4 hours at 300 ℃ to obtain the high-efficiency solid-phase catalyst ZnO-ZrO₂/γ-Al₂O₃。

2) Preparation of carbamate:

mixing 1mol of urea and 1mol of dimethyl carbonate, placing the mixture in an autoclave, adding 0.6g of the catalyst prepared in the step S1, heating the mixture to 180 ℃ for reaction for 6 hours, carrying out alcoholysis reaction on the urea and the dimethyl carbonate to obtain carbamate, distilling the mixture after the reaction is finished to obtain 72.5g of carbamate, wherein the yield is 80.5%, and the purity of the methyl carbamate is 98.9% through HPLC detection.

The foregoing description has disclosed fully preferred embodiments of the present invention. It should be noted that those skilled in the art can make modifications to the embodiments of the invention without departing from the scope of the claims. Accordingly, the scope of the appended claims is not to be limited to the specific embodiments described above.