Preparation method of p-chlorophenol

Abstract

The invention discloses a preparation method of p-chlorophenol. The preparation method comprises feeding chlorine gas into a mixture of phenol, copper chloride and a polar solvent under the normal pressure so that the mixture undergoes a full phenol chlorination reaction, and collecting p-chlorophenol from the chlorination reaction products, wherein the polar solvent is hydrochloric acid, dimethylsulfoxide or their mixed solvent. The preparation method utilizes a one-step reaction method, copper chloride as a chlorinating agent and the polar solvent, solves the problem that the existing copper chloride method needs harsh conditions such as high temperature and high pressure and the copper chloride conversion rate is low because of use of single copper chloride, and has high para-selectivity. After the reaction, the copper chloride-polar solvent can be used for the circular chlorination reaction.

Description

technical field

[0001] The invention relates to a preparation method of p-chlorophenol. Background technique

[0002] P-Chlorophenol is widely used in medicine, pesticide, dyestuff and other industries, and is an important organic chemical intermediate. Because the dye intermediate 1,4-dihydroxyanthraquinone has a large demand for the raw material p-chlorophenol, the domestic production of p-chlorophenol and the research on process optimization have become a hot spot.

[0003] At present, there are three preparation methods of p-chlorophenol, chlorine gas method, sulfuryl chloride method and copper chloride method. In the direct chlorination method, phenol can be chlorinated directly with chlorine gas without a catalyst to generate p-chlorophenol, o-chlorophenol and a small amount of m-chlorophenol. The reaction conditions have a great influence on the selectivity of the target product p-chlorophenol. This method is simple in process and easy to operate, but its disadvanta...

Examples

Embodiment 1

[0027] Under normal pressure, add 20g of phenol, 36g of copper chloride and 60g of hydrochloric acid to the chlorination reactor respectively, heat to the reaction temperature of 90°C, pass chlorine gas under the protection of nitrogen to react until the phenol is completely chlorinated, cool, and take out the upper organic phase , to obtain mixed chlorinated phenols, sampling GC analysis content, phenol conversion rate is 97.6%, p-chlorophenol selectivity is 81.1%, ortho-chlorophenol selectivity is 7.6%, and p-o-ratio reaches 10:1; Lower hydrochloric acid-chlorination After copper was added to phenol, the chlorination reaction was repeated under the same conditions, and the selectivity of p-chlorophenol remained stable at about 80% after repeated 8 times.

Embodiment 2

[0029] Under normal pressure, add 20g of phenol, 60g of copper chloride and 120g of dimethyl sulfoxide to the chlorination reactor respectively, heat the oil bath to 110°C, react for a certain period of time under the protection of nitrogen, cool and filter to obtain copper chloride Solid, sampling GC analysis content, the phenol conversion rate is 90.0%, the selectivity of p-chlorophenol is 82.0%, the selectivity of o-chlorophenol is 6.1%, and the ratio of o-to-o is as high as 12:1.

Embodiment 3

[0031] Under normal pressure, 20g of phenol, 36g of copper chloride, 40g of hydrochloric acid and 8g of dimethyl sulfoxide were respectively added to the chlorination reactor, heated to a reaction temperature of 90°C, and chlorine gas was introduced under the protection of nitrogen to react until the phenol was chlorinated completely. Cooling, take out upper organic phase, obtain organic solvent and mixed chlorinated phenol, sample GC analysis content, phenol transformation rate is 99.6%, p-chlorophenol selectivity is 83.5%, ortho-chlorophenol selectivity is 5.9%, para-ortho ratio reaches 12:1; the lower layer of hydrochloric acid-copper chloride was added to phenol and dimethyl sulfoxide and the chlorination reaction was repeated under the same conditions. After repeating 5 times, the selectivity of p-chlorophenol was maintained at about 82.5%, and the ratio of ortho was maintained at 12:1. keep it steady.

technical field

[0001] The invention relates to a preparation method of p-chlorophenol. Background technique

[0002] P-Chlorophenol is widely used in medicine, pesticide, dyestuff and other industries, and is an important organic chemical intermediate. Because the dye intermediate 1,4-dihydroxyanthraquinone has a large demand for the raw material p-chlorophenol, the domestic production of p-chlorophenol and the research on process optimization have become a hot spot.

[0003] At present, there are three preparation methods of p-chlorophenol, chlorine gas method, sulfuryl chloride method and copper chloride method. In the direct chlorination method, phenol can be chlorinated directly with chlorine gas without a catalyst to generate p-chlorophenol, o-chlorophenol and a small amount of m-chlorophenol. The reaction conditions have a great influence on the selectivity of the target product p-chlorophenol. This method is simple in process and easy to operate, but its disadvanta...

Examples

Embodiment 1

[0027] Under normal pressure, add 20g of phenol, 36g of copper chloride and 60g of hydrochloric acid to the chlorination reactor respectively, heat to the reaction temperature of 90°C, pass chlorine gas under the protection of nitrogen to react until the phenol is completely chlorinated, cool, and take out the upper organic phase , to obtain mixed chlorinated phenols, sampling GC analysis content, phenol conversion rate is 97.6%, p-chlorophenol selectivity is 81.1%, ortho-chlorophenol selectivity is 7.6%, and p-o-ratio reaches 10:1; Lower hydrochloric acid-chlorination After copper was added to phenol, the chlorination reaction was repeated under the same conditions, and the selectivity of p-chlorophenol remained stable at about 80% after repeated 8 times.

Embodiment 2

[0029] Under normal pressure, add 20g of phenol, 60g of copper chloride and 120g of dimethyl sulfoxide to the chlorination reactor respectively, heat the oil bath to 110°C, react for a certain period of time under the protection of nitrogen, cool and filter to obtain copper chloride Solid, sampling GC analysis content, the phenol conversion rate is 90.0%, the selectivity of p-chlorophenol is 82.0%, the selectivity of o-chlorophenol is 6.1%, and the ratio of o-to-o is as high as 12:1.

Embodiment 3

[0031] Under normal pressure, 20g of phenol, 36g of copper chloride, 40g of hydrochloric acid and 8g of dimethyl sulfoxide were respectively added to the chlorination reactor, heated to a reaction temperature of 90°C, and chlorine gas was introduced under the protection of nitrogen to react until the phenol was chlorinated completely. Cooling, take out upper organic phase, obtain organic solvent and mixed chlorinated phenol, sample GC analysis content, phenol transformation rate is 99.6%, p-chlorophenol selectivity is 83.5%, ortho-chlorophenol selectivity is 5.9%, para-ortho ratio reaches 12:1; the lower layer of hydrochloric acid-copper chloride was added to phenol and dimethyl sulfoxide and the chlorination reaction was repeated under the same conditions. After repeating 5 times, the selectivity of p-chlorophenol was maintained at about 82.5%, and the ratio of ortho was maintained at 12:1. keep it steady.

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