阅读说明：本技术 一种异氰酸环己酯的制备方法 (Preparation method of cyclohexyl isocyanate ) 是由 王军营 卢玉东 刘卫 周和 张玉龙 于 2020-06-16 设计创作，主要内容包括：一种异氰酸环己酯的制备方法,其特征在于：包括如下步骤：S1：将原料环己胺和足量甲苯溶剂一并投入到反应釜内,并将反应釜升温控制在80—95℃；S2：向S1中的反应釜内加液态盐酸,滴加时间控制在2.5—3小时,控制PH值在3—7；S3：S2中盐酸滴加完成后升温蒸馏脱水；S4：将S3中的产物盐和甲苯溶剂转入酯化釜,然后缓慢加入三光气,三光气加入时温度控制在95—115℃之间；S5：S4步骤中三光气加入完毕后保温反应0.5小时,同时引入氮气吹扫0.5—2.5小时；S6：S5反应完毕后进行减压精馏回收甲苯溶剂,进行循环套用,并产出异氰酸环己酯。(A preparation method of cyclohexyl isocyanate is characterized by comprising the following steps: the method comprises the following steps: s1: putting raw materials of cyclohexylamine and sufficient toluene solvent into a reaction kettle together, and heating the reaction kettle to 80-95 ℃; s2: adding liquid hydrochloric acid into a reaction kettle in S1, controlling the adding time to be 2.5-3 hours, and controlling the pH value to be 3-7; s3: after the hydrochloric acid is dropwise added in S2, heating, distilling and dehydrating; s4: transferring the product salt and the toluene solvent in the S3 into an esterification kettle, and then slowly adding triphosgene, wherein the temperature of the triphosgene is controlled between 95 and 115 ℃; s5: in the step S4, after the triphosgene is added, the reaction is carried out for 0.5 hour under the condition of heat preservation, and nitrogen is introduced for purging for 0.5 to 2.5 hours; s6: and after the S5 reaction is finished, carrying out reduced pressure rectification to recover the toluene solvent for recycling, and producing the cyclohexyl isocyanate.)

1. A preparation method of cyclohexyl isocyanate is characterized in that cyclohexylamine reacts with hydrochloric acid to prepare amine salt, and the amine salt reacts with triphosgene to prepare the cyclohexyl isocyanate, and the preparation method comprises the following steps: the method comprises the following steps:

s1: putting raw materials of cyclohexylamine and sufficient toluene solvent into a reaction kettle together, and heating the reaction kettle to 80-95 ℃;

s2: slowly dropwise adding liquid hydrochloric acid into a reaction kettle in S1, wherein the dropwise adding time of the hydrochloric acid is controlled to be 2.5-3 hours, and measuring and controlling the pH value to be 3-7;

s3: after the hydrochloric acid is dropwise added in S2, standing and preserving heat for reaction for 0.5 hour, and then heating, distilling and dehydrating to obtain a mixture of amine salt and toluene;

s4: transferring the product salt and the toluene solvent in the S3 into an esterification kettle, and then slowly adding triphosgene, wherein the temperature of the triphosgene is controlled between 95 and 115 ℃;

s5: in the step S4, after the triphosgene is added, the reaction is carried out for 0.5 hour under the condition of heat preservation, and nitrogen is introduced for purging for 0.5 to 2.5 hours;

s6: and after the S5 reaction is finished, carrying out reduced pressure rectification to recover the toluene solvent for recycling, and producing the cyclohexyl isocyanate.

2. The method for preparing cyclohexyl isocyanate according to claim 1, wherein the reaction is carried out by the following steps: the toluene added in S1 simultaneously with the cyclohexylamine can be replaced by xylene, dichloroethane, ethyl acetate.

3. The method for preparing cyclohexyl isocyanate according to claim 1, wherein the reaction is carried out by the following steps: the temperature control of the reaction vessel in S1 is preferably 85 ℃.

4. The method for preparing cyclohexyl isocyanate according to claim 1, wherein the reaction is carried out by the following steps: the pH control in S3 is preferably 5 to 7.

5. The method for preparing cyclohexyl isocyanate according to claim 1, wherein the reaction is carried out by the following steps: the triphosgene addition temperature in S4 is preferably 95-100 ℃.

6. The method for preparing cyclohexyl isocyanate according to claim 1, wherein the reaction is carried out by the following steps: the nitrogen purge time in S5 is preferably 2.5 hours.

Technical Field

The invention belongs to the field of chemical synthesis production, and particularly relates to a preparation method of cyclohexyl isocyanate.

Background

Cyclohexyl isocyanate is an important intermediate of pesticide and medicine. The pesticide is used for producing herbicides such as hexazinone and the like, and the medicine is used for producing western medicines with considerable market prospect, and the molecular formula C is₇H₁₁NO, molecular weight 125.2, CAS3173-53-3, colorless to light yellow liquid at normal temperature and pressure, and storing in a shady, dry and well ventilated non-combustible storehouse. Keeping the container sealed away from the fire and heat sources. Moisture-proof and sun-proof. Avoid andalkali, acid, oxidant, edible chemical material, etc. Is easy to dissolve in organic solvents such as toluene, dichloroethane, ethyl acetate, dichloromethane and the like, is insoluble in water but reacts with water, and is mainly used for pesticides and medical intermediates. The traditional production process takes cyclohexylamine as a raw material to directly react with phosgene or triphosgene. The reaction directly takes cyclohexylamine as a raw material, has the process defects of large solid waste production amount, high production cost, low yield and potential safety hazard.

In the prior art, a process for synthesizing amine salt by adding toluene and hydrochloric acid gas into cyclohexylamine is available, but the hydrochloric acid gas is harsh in storage condition, generally has strong corrosivity and is unsafe to transport, in addition, the amine salt generated in the reaction process of main hydrochloric acid gas and organic amine toluene solution has an inclusion phenomenon, and the residual amine reacts with cyclohexyl isocyanate product in the ester forming process to influence the yield.

Disclosure of Invention

The invention aims to provide a method for preparing cyclohexyl isocyanate with safety, low cost and high yield.

The technical scheme of the invention is as follows:

a preparation method of cyclohexyl isocyanate is characterized in that cyclohexylamine reacts with hydrochloric acid to prepare amine salt, and the amine salt reacts with triphosgene to prepare the cyclohexyl isocyanate, and the preparation method comprises the following steps: the method comprises the following steps:

s1: putting raw materials of cyclohexylamine and sufficient toluene solvent into a reaction kettle together, and heating the reaction kettle to 80-95 ℃;

s2: slowly dropwise adding liquid hydrochloric acid into a reaction kettle in S1, wherein the dropwise adding time of the hydrochloric acid is controlled to be 2.5-3 hours, and measuring and controlling the pH value to be 3-7;

s3: after the hydrochloric acid is dropwise added in S2, standing and preserving heat for reaction for 0.5 hour, and then heating, distilling and dehydrating to obtain a mixture of amine salt and toluene;

s4: transferring the product salt and the toluene solvent in the S3 into an esterification kettle, and then slowly adding triphosgene, wherein the temperature of the triphosgene is controlled between 95 and 115 ℃;

s5: in the step S4, after the triphosgene is added, the reaction is carried out for 0.5 hour under the condition of heat preservation, and nitrogen is introduced for purging for 0.5 to 2.5 hours;

s6: and after the S5 reaction is finished, carrying out reduced pressure rectification to recover the toluene solvent for recycling, and producing the cyclohexyl isocyanate.

The toluene added in S1 simultaneously with the cyclohexylamine can be replaced by xylene, dichloroethane, ethyl acetate.

The temperature control of the reaction vessel in S1 is preferably 85 ℃.

The pH control in S3 is preferably 5 to 7.

The triphosgene addition temperature in S4 is preferably 95-100 ℃.

The nitrogen purge time in S5 is preferably 2.5 hours.

The scheme of the invention has the beneficial effects that: in the preparation process of the amine salt, the cyclohexylamine and the toluene are put into the reaction kettle together to react with the liquid hydrochloric acid, so that the problem of excessive byproducts generated by the direct reaction of the cyclohexylamine and the hydrochloric acid is solved, solid waste products are reduced, and the product yield is increased. The problem of excessive inclusion of amine salt in the reaction of hydrochloric acid gas is solved, and the problem that the inclusion generated by the reaction of gaseous hydrochloric acid and the cyclohexylamine toluene solution contains residual organic amine and can perform a reactive reaction with cyclohexyl isocyanate to reduce the yield is solved. And the gasification of hydrochloric acid is avoided through temperature control, so that the final yield of the whole preparation process is improved.

Detailed Description