Method for refining 3,5-dichlorophenyl isocyanate
A dichlorophenyl isocyanate and refining method technology, applied in the purification/separation of isocyanic acid derivatives, organic chemistry, etc., can solve the problem of large residue generation, low product purity and yield, high nitrogen and raw material consumption, etc. problems, achieve high production efficiency, convenient operation, and reduce product loss
Active Publication Date: 2015-04-22
QINGDAO UNIV OF SCI & TECH +1
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Problems solved by technology
[0003] The purpose of the present invention is to overcome the shortcomings of the prior art, and according to the problems of large nitrogen and raw material consumption, large residue generation, low product purity and yield, etc. The refining method of chlorophenyl isocyanate is to use the rectification tower to operate the dephosphorization gas, and the phosgene containing a small amount of solvent is extracted from the top gas phase and enters the phosgene washing device, which is washed and absorbed with a solvent; and the distilled solvent is refined again, Remove the phosgene dissolved in the solvent, and then recycle it back to the phosgenation reaction part to apply it mechanically. The purity of the solvent can reach more than 99.9%. The product is extracted from the side line of the product refining tower. When the middle distillate accumulates to a certain concentration, part of the liquid phase is extracted to prevent the accumulation of the middle distillate
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Embodiment 1
[0024] In this example, the photochemical solution after photochemical reaction in the process of synthesizing 3,5-dichlorophenyl isocyanate by phosgene method is purified. The weight concentration of each substance in the photochemical solution after photochemical reaction: 3,5-dichlorophenyl isocyanate The content of phenyl isocyanate is 7.4%, the content of solvent is 89.7%, the content of phosgene is 2.4%, the content of residue is 0.4%, and the content of monochlorophenyl isocyanate is 180ppm; the feed rate of photochemical liquid is 394kg / h, the specific The refining process is:
[0025] (1), the photochemical liquid after the photochemical reaction enters the dephosgene tower 1 by the 4th plate position of the upper part of the dephosgenation tower 1 and goes out of the phosgene to obtain the crude product after the dephosgene, and the tower top gas phase is extracted 10.2kg / h, The phosgene content at the bottom of the tower is 1000ppm; the theoretical plate number of t...
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The invention belongs to the technical field of preparation of 3,5-dichlorophenyl isocyanate and relates to a method for refining 3,5-dichlorophenyl isocyanate. The method comprises the following steps: feeding a phosgenation liquid into a phosgene removal tower from the upper part of the phosgene removal tower for removing phosgene and sequentially removing solvents through a first-stage solvent removal tower and a second-stage solvent removal tower to obtain a solvent removed crude product; storing the removed solvent in a temporary solvent storage tank, removing phosgene by virtue of a solvent refining tower, feeding the solvent removed crude product into a product refining tower for refining and extracting analyzed and qualified products, namely, 3,5-dichlorophenyl isocyanate, through a pipeline lateral line. The preparation process is simple, convenient to operate and has the advantages of scientific principle, high production efficiency, low energy consumption and low cost and refined 3,5-dichlorophenyl isocyanate is high in purity and environment-friendly.
Description
Technical field: [0001] The invention belongs to the technical field of preparation of 3,5-dichlorophenyl isocyanate, and relates to a purification method of 3,5-dichlorophenyl isocyanate, in particular to a process for synthesizing 3,5-dichlorophenyl isocyanate by phosgene method in the refining method. Background technique: [0002] 3,5-Dichlorophenyl isocyanate is an important intermediate of medicine, pesticide and polymer material, and has a good market prospect. 3,5-dichlorophenyl isocyanate is usually formed by the reaction of excess phosgene with 3,5-dichloroaniline in a solvent environment, and the solvent and excess phosgene need to be recycled. In addition to the solvent, it also includes the side reaction product monochlorophenyl isocyanate and residue. If the circulating solvent contains phosgene and isocyanate substances in the product refining process, the amount of residue generated during the reaction process will increase and the product yield will be redu...
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Login to View More IPC IPC(8): C07C265/12C07C263/20
Inventor 孔令启李玉刚郑世清格士瑾曹传波
Owner QINGDAO UNIV OF SCI & TECH