阅读说明：本技术 从含碘残液中回收碘甲烷的方法 (Method for recovering methyl iodide from iodine-containing residual liquid ) 是由 万欣 董礼 徐耀中 刘宇 刘子伟 常华 于 2020-07-23 设计创作，主要内容包括：本发明从含碘残液中回收碘甲烷的方法,将水解残液加热至60～65℃；维持温度60～65℃,在搅拌状态下滴加硫酸二甲酯,接收碘甲烷,直至出料温度下降停止滴加；将收集到的碘甲烷水洗两次以上,分离水洗液；加入无水氯化钙,干燥48h以上,过滤。通过将定量的硫酸二甲酯加入到含碘残液中,两者相互反应生成碘甲烷；通过预热残液,在加快反应进行的同时将生成的碘甲烷及时蒸出,促进反应的正向进行；将蒸出的碘甲烷经过多次水洗后加入无水氯化钙进行除水,过滤后得到最终产物；回收得到的碘甲烷含量在99％以上,水含量在50ppm以下,并且残液中碘的回收率在90％以上；工艺操作简便,不需要特殊的设备和复杂的化学试剂,回收率高。(The method for recovering the iodomethane from the iodine-containing residual liquid comprises the following steps of heating the hydrolysis residual liquid to 60-65 ℃; maintaining the temperature at 60-65 ℃, dropwise adding dimethyl sulfate in a stirring state, receiving methyl iodide, and stopping dropwise adding until the discharging temperature is reduced; washing the collected methyl iodide with water for more than two times, and separating water washing liquid; adding anhydrous calcium chloride, drying for more than 48h, and filtering. Quantitative dimethyl sulfate is added into iodine-containing residual liquid, and the dimethyl sulfate and the iodine-containing residual liquid react with each other to generate methyl iodide; by preheating the residual liquid, the reaction is accelerated and the generated methyl iodide is evaporated out in time, so that the forward progress of the reaction is promoted; washing the distilled methyl iodide for multiple times, adding anhydrous calcium chloride for dewatering, and filtering to obtain a final product; the content of the recovered methyl iodide is more than 99 percent, the water content is less than 50ppm, and the recovery rate of iodine in the residual liquid is more than 90 percent; the process is simple and convenient to operate, does not need special equipment and complex chemical reagents, and has high recovery rate.)

1. The method for recovering the methyl iodide from the iodine-containing residual liquid is characterized by comprising the following steps of: the method comprises the following steps:

1) heating the hydrolysis residual liquid to 60-65 ℃;

2) maintaining the temperature at 60-65 ℃, dropwise adding dimethyl sulfate in a stirring state, receiving methyl iodide, and stopping dropwise adding until the discharging temperature is reduced;

3) washing the collected methyl iodide with water for more than two times, and separating water washing liquid;

4) adding anhydrous calcium chloride, drying for more than 48h, and filtering.

2. The method of claim 1 for recovering methyl iodide from an iodine-containing raffinate, wherein: the hydrolysis residual liquid is iodine-containing residual liquid in chemical reaction.

3. The method of claim 1 for recovering methyl iodide from an iodine-containing raffinate, wherein: step 1), heating the residual liquid to 60 ℃, and starting stirring.

4. The method of claim 1 for recovering methyl iodide from an iodine-containing raffinate, wherein: and step 2), a discharge port is provided with a heat-insulating packing column, and distillate is separated.

5. The method of claim 1 for recovering methyl iodide from an iodine-containing raffinate, wherein: and 2), adding dimethyl sulfate in a molar ratio of iodine to dimethyl sulfate of 1: 1.5-1: 3.

6. The method of claim 1 for recovering methyl iodide from an iodine-containing raffinate, wherein: and 3) adding water for washing, fully stirring, standing for 1h, removing a water layer, and repeating for three times.

7. The method of claim 1 for recovering methyl iodide from an iodine-containing raffinate, wherein: and 4), adding anhydrous calcium chloride in an amount of 5-10% of the weight of the methyl iodide, standing for more than 48h, and filtering out solids.

Technical Field

The invention relates to a method for recovering methyl iodide from iodine-containing residual liquid.

Background

Methyl iodide is an important fine chemical intermediate and is widely applied in laboratories and industrial production. The compound is commonly used as a methylating agent in organic synthesis, can also be used as an initiator with good Grignard reaction, is used for the Grignard reaction initiation of inactive halides such as chlorinated aromatic hydrocarbon and the like, and can also be used as a bactericide, a herbicide, an insecticide and the like. Because methyl iodide is expensive and harmful to organisms and environment, the methyl iodide is recovered from the iodine-containing residual liquid, so that the comprehensive production cost can be reduced, an enterprise can prepare raw materials, and the waste liquid can be subjected to harmless treatment, which is imperative.

At present, in the prior art, acetic acid and elemental iodine are used as raw materials and react under the catalysis of tetraethyl lead to prepare methyl iodide, and a catalyst is expensive and has great influence on the environment; methanol and potassium iodide are used as raw materials, and the methyl iodide is prepared by reaction under the condition of an acid catalyst, so that the method has low yield, the acid cannot be recovered, and the method also has great influence on the environment. At present, no better method for recovering methyl iodide from residual liquid is disclosed.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provide the method for recovering the methyl iodide from the iodine-containing residual liquid, which has high yield, high purity and simple and convenient process operation.

The purpose of the invention is realized by the following technical scheme:

the method for recovering methyl iodide from iodine-containing residual liquid is characterized by comprising the following steps: the method comprises the following steps:

1) heating the hydrolysis residual liquid to 60-65 ℃;

2) maintaining the temperature at 60-65 ℃, dropwise adding dimethyl sulfate in a stirring state, receiving methyl iodide, and stopping dropwise adding until the discharging temperature is reduced;

3) washing the collected methyl iodide with water for more than two times, and separating water washing liquid;

4) adding anhydrous calcium chloride, drying for more than 48h, and filtering.

Further, in the method for recovering methyl iodide from the iodine-containing residual liquid, the hydrolysis residual liquid is the iodine-containing residual liquid in the chemical reaction.

Further, in the method for recovering methyl iodide from the iodine-containing residual liquid, in the step 1), the residual liquid is heated to 60 ℃, and stirring is started.

Further, in the method for recovering methyl iodide from the iodine-containing residual liquid, in the step 2), the discharge hole is provided with a heat-insulating filler column, and distillate is separated.

Further, in the method for recovering methyl iodide from the iodine-containing residual liquid, in the step 2), the addition amount of dimethyl sulfate is such that the molar ratio of iodine to dimethyl sulfate is 1: 1.5-1: 3.

Further, the method for recovering methyl iodide from the iodine-containing residual liquid comprises the step 3), adding water for washing, fully stirring, standing for 1h, removing a water layer, and repeating for three times.

Further, in the method for recovering methyl iodide from the iodine-containing residual liquid, in the step 4), the addition amount of the anhydrous calcium chloride is 5-10% of the weight of the methyl iodide, the mixture is kept stand for more than 48 hours, and the solid is filtered out.

Compared with the prior art, the invention has obvious advantages and beneficial effects, and is embodied in the following aspects:

firstly, the method for recovering the iodomethane from the iodine-containing residual liquid comprises the working procedures of residual liquid preheating, dimethyl sulfate dripping, iodomethane receiving, water washing, drying and the like, wherein on one hand, quantitative dimethyl sulfate is added into the iodine-containing residual liquid, and the two react with each other to generate the iodomethane; on the other hand, the residual liquid is preheated, so that the reaction is accelerated and the generated methyl iodide is evaporated out in time, thereby promoting the forward progress of the reaction; and the distilled methyl iodide is washed by water for many times, then anhydrous calcium chloride is added for dewatering, and a final product is obtained after filtration;

② the content of the obtained iodomethane is above 99 percent, the water content is below 50ppm, and the recovery rate of iodine in the residual liquid is above 90 percent; the recovered methyl iodide has high purity, less water content and high recovery rate;

the process is simple and convenient to operate, does not need special equipment and complex chemical reagents, and is easy to operate; the residual liquid after reaction can be directly treated, so that the safety risk in the subsequent treatment process and the storage process is greatly reduced, and a large amount of cost can be saved; the recovery rate of methyl iodide is high; from the technical index, the recovered methyl iodide can be repeatedly produced;

the method has the advantages of high yield, high purity, simple and convenient operation and the like, and is low in investment, low in cost, environment-friendly and capable of realizing large-scale industrial production.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims thereof.

Detailed Description

In order to more clearly understand the technical features, objects, and effects of the present invention, specific embodiments will now be described in detail.

The invention provides a method for recovering methyl iodide from iodine-containing residual liquid, which has the advantages of simple and practical process, high recovery rate, less investment, low cost, easy operation and environmental friendliness, and the specific process is as follows:

1) heating the iodine-containing hydrolysis residual liquid to 60-65 ℃, and starting stirring;

2) maintaining the temperature at 60-65 ℃, dropwise adding dimethyl sulfate under a stirring state, wherein the adding amount of the dimethyl sulfate is that the molar ratio of iodine to the dimethyl sulfate is 1: 1.5-1: 3; receiving methyl iodide, and stopping dripping until the discharging temperature is reduced; the discharge port is provided with a heat-insulating packed column for separating distillate;

3) washing the collected methyl iodide with water for more than two times, and separating water washing liquid;

4) adding anhydrous calcium chloride in an amount of 5-10 wt% of iodomethane, standing for over 48 hr, and filtering to remove solid.