CN116023231A - A method for preparing chloro(bromo)styrene by dehydration of chloro(bromo)phenylethanol - Google Patents

Abstract

The invention discloses a device and a process for preparing chloro (bromo) styrene by dehydrating chloro (bromo) phenethyl alcohol. The process uses KHSO ₄ The catalyst is taken as a catalyst, the catalyst, raw material chlorine (bromine) phenethyl alcohol and polymerization inhibitor are dissolved and mixed and then enter a falling film reactor together, and the raw material and KHSO are carried out by means of the larger evaporation area of the falling film reactor ₄ Fully contacting and reacting in the falling film reactor, purifying the generated chloro (bromo) styrene by a separation column with a back flow in the packing, and finally cooling by a product cooler and then entering a product tank.

Description

A method for preparing chloro(bromo)styrene by dehydration of chloro(bromo)phenylethanol

technical field

The invention belongs to the field of fine chemical manufacturing, and in particular relates to equipment and a process for preparing chloro(bromo)styrene by dehydration of chloro(bromo)phenylethanol.

Background technique

Chloro(bromo)styrene is an important monomer for the preparation of special plastics and rubbers, such as ion exchange resins, functional polymers, photosensitive polymers, polymer catalysts, etc., and is widely used as intermediates in the fields of medicine, pesticides, and chemicals. The preparation has a broad market prospect.

Literature (Fine and Specialty Chemicals 2013, 21, 37-38) reported using _KHSO4 as a catalyst, under the melting temperature of _KHSO4 at 275°C, dehydration of p-bromophenylethanol was carried out to prepare p-bromostyrene, and the product p-bromostyrene was obtained Yield 90.0%, purity 98.4%. The patent (ZL201310018762.X) reports the process and method of using modified aluminum silicate as a catalyst for dehydration. The reaction temperature is 280°C, and negative pressure operation of -0.08MPa is required, and the product purity is 96%. The patent (ZL202110710271.6) reports a route for the preparation of halogenated styrenes at 250-330°C using a supported molecular sieve catalyst, which requires toluene in the reaction system to maintain a good conversion rate and selectivity. Literature (Chemische Berichte, 1990, 123:1441-1442) reported the preparation of chloro(bromo)styrene by ylide reaction from chloro(bromo)benzaldehyde, but the raw materials are expensive and difficult to industrial application. It can also be prepared from chloro(bromo)oxirane (Organic Letters, 2012,14:22-25) or chloro(bromo)phenylacetylene (Advanced Synthesis and Catalysis, 2012,354:1542-1550) Chlorine (bromo) styrene, but also faces the problem that the raw material is not easy to obtain. From the perspective of raw materials and environmental protection, the reduction of chloro(bromo)acetophenone to obtain chloro(bromo)phenylethanol, and then the most cheap and environmentally friendly route to prepare chloro(bromo)styrene through dehydration reaction.

The method and route for preparing chloro(bromo)styrene by dehydration of chloro(bromo)phenylethanol reported in the literature at present face the problems of high operating temperature, high equipment requirements, and further improvement in product selectivity.

Contents of the invention

In order to solve the above problems, the object of the present invention is to provide a kind of equipment and technique for preparing chloro(bromo)styrene by dehydration of chloro(bromo)phenylethanol, this technique is by means of the larger evaporation area of falling film reactor, raw material and The KHSO ₄ falling film reactor fully contacts and reacts, and the chloro(bromo)styrene produced by the reaction is purified by a separation column, and finally enters the product tank after being cooled by the product cooler. The process has the characteristics of simple process, mild operating conditions and good product selectivity. KHSO ₄ has strong acidity and high catalytic dehydration reaction activity, so the operating reaction temperature is relatively mild (90-190°C), and the product is rectified through the separation column with internal reflux, so the product selectivity is good.

Technical scheme of the present invention is:

A kind of equipment and technology of dehydration of chlorine (bromine) phenylethanol to prepare chlorine (bromine) styrene, it is characterized in that: KHSO ₄ enters falling film reaction after dissolving and mixing with raw material chlorine (bromine) phenylethanol and polymerization inhibitor The device is fully contacted and reacted in the falling film reactor, and the chloro(bromo)styrene produced by the reaction is purified through a separation column equipped with packing and reflux to obtain the chloro(bromo)styrene product.

The chloro(bromo)phenylethanol raw material is one or more than two selected from the following structures.

The falling film reactor is made of inner-plated enamel material, and the evaporation area is 2-15m2.

The dehydration reaction temperature is 90-190° C. (preferably 100-160° C.), the reaction pressure is negative pressure, and the negative pressure operation range is -0.02 to -0.099 MPa.

KHSO ₄ and the raw material chloro(bromo)phenylethyl alcohol are dissolved and mixed together into the falling film reactor. The weight ratio of the raw material to KHSO 4 is 1000:1 to 5:1, preferably 100:1 to 10:1.

The chloro(bromo)styrene produced by the reaction is purified through a separation column with reflux in the packing to obtain the chloro(bromo)styrene product. The packing can be Raschig ring packing, Pall ring packing, stepped ring packing, arc Saddle packing, rectangular saddle packing, metal ring rectangular saddle packing, spherical packing, etc., preferably metal Raschig ring packing made of 304L material. The internal reflux ratio is selected as 0.1:1～1:100.

The polymerization inhibitor is selected from one of tetrachlorobenzoquinone, hydroquinone, p-tert-butylcatechol, 2,6-di-tert-butyl-p-cresol, bisphenol A, 1,4-naphthoquinone or Two or more, the amount of polymerization inhibitor added is preferably 0.1-10% of the weight of chloro(bromo)phenylethanol, more preferably 0.1-2%.

The chloro(bromo)styrene obtained by the process can be applied to the preparation of intermediates in the fields of medicine, pesticide, chemical industry and the like.

Reaction principle of the present invention:

Chloro(bromo)styrene is an important chemical intermediate, but it is very easy to polymerize, so it is difficult to prepare. The invention uses the acid salt KHSO4 with strong acidity as the catalyst, which has high catalytic dehydration reaction activity, so the operating reaction temperature is relatively mild (90-190° C.). In the falling film evaporator, the liquid descends along the wall to form a thin film and reacts with the gas in countercurrent or cocurrent contact. It has the characteristics of high evaporation efficiency and rapidity. Polymerization, so the product yield is high, and the production efficiency is also high.

The beneficial effects of the present invention are:

The method and route for preparing chloro(bromo)styrene by dehydration of chloro(bromo)phenylethanol reported in the literature at present face the problems of high operating temperature, high equipment requirements, and further improvement in product selectivity. The object of the present invention is to provide a kind of equipment and the technique that chlorine (bromine) phenylethanol dehydration prepares chlorine (bromine) styrene, and this technique is by means of the larger evaporation area of falling film reactor, raw material and _KHSO Falling film reaction Fully contact and react in the container, the reaction efficiency is high, the speed is fast, and the polymerization is less. The chloro(bromo)styrene product produced by the reaction is rectified through the separation column with internal reflux, so the product selectivity is good.

The process has the characteristics of simple process, mild operating conditions and good product selectivity. KHSO ₄ has strong acidity and high catalytic dehydration reaction activity, so the operating reaction temperature is relatively mild (90-190°C).

Description of drawings

Fig. 1 is the equipment and process diagram for preparing chloro(bromo)styrene by dehydration of chloro(bromo)phenylethanol provided by the present invention.

Detailed ways

The following examples illustrate the present invention better, but do not limit the scope of protection of the present invention.

Example 1

The equipment and process diagram for preparing chloro(bromo)styrene by dehydration of chloro(bromo)phenylethanol provided by the present invention are as shown in accompanying drawing 1.

The raw materials are fully contacted and reacted in the KHSO ₄ falling film reactor, and the chlorine and/or bromostyrene produced by the reaction are purified by the separation column, and finally cooled by the product cooler or heat exchanger, and then enter the gas-liquid separator to separate the product.

The separation column with reflux is a hollow airtight cylinder, the middle and lower part of the hollow cylinder is filled with filler, the upper part is provided with a cooling water pipe, the lower part or bottom of the cylinder is provided with a material inlet, and the upper part or top is provided with a material outlet ;

The specific operation steps are as follows:

5m2 evaporation area, enamel-coated falling film reactor, the upper rectification column is filled with a 2m high 304L metal Raschig ring, the temperature of the falling film reactor is raised to 120°C, and the operating pressure is stabilized at -0.095MPa for use .

2kg KHSO ₄ (catalyst) and 0.5kg hydroquinone (polymerization inhibitor) are dissolved in 100kg p-chlorophenylethanol (about 1% water content), enter in the above-mentioned falling film reactor behind, feed time is controlled at 1.5 hours, The volume ratio of the reflux in the upper part of the rectification column is selected as 1:1. The temperature of the product cooler is controlled at 0°C, and the product is collected in the product tank,

Example 2

In embodiment 2, except that the reaction raw material p-chlorophenylethanol is replaced with the same mass m-chlorophenylethanol, all the other processes are the same as in embodiment 1.

Example 3

In embodiment 3, except that the reaction raw material p-chlorophenylethanol is replaced with the same quality o-chlorophenylethanol, all the other processes are the same as in embodiment 1.

Example 4

In embodiment 4, except that p-bromophenylethanol is used to replace the reaction raw material p-chlorophenylethanol, all the other processes are the same as in embodiment 1.

Example 5

In embodiment 5, except that the reaction raw material p-chlorophenylethanol is replaced with the same mass m-bromophenylethanol, all the other processes are the same as in embodiment 1.

Example 6

In embodiment 6, except that the reaction raw material p-chlorophenylethanol is replaced with the same mass m-bromophenylethanol, all the other processes are the same as in embodiment 1.

The following table is the conversion rate and product selectivity of Examples 1-6, and the product has been confirmed by NMR.

Example 7

In Example 7, except that the polymerization inhibitor was replaced with bisphenol A of the same weight, other conditions and operating procedures were the same as in Example 1, the conversion rate of p-chlorostyrene was 99.8%, and the selectivity was 99.8%.

Example 8

In Example 8, except that the polymerization inhibitor was replaced with chlorobenzoquinone of the same weight, all the other conditions and operating procedures were the same as in Example 1, the conversion rate of p-chlorostyrene was 99.9%, and the selectivity was 99.6%.

Example 9

In Example 9, except that the polymerization inhibitor is replaced with 1,4-naphthoquinone of the same weight, the remaining conditions and operating process are the same as in Example 1, the conversion rate of p-chlorostyrene is 100%, and the selectivity is 99.3% .

Example 10

In Example 10, except that the polymerization inhibitor is replaced by 2,6-di-tert-butyl p-cresol of the same weight, all the other conditions and operating procedures are the same as in Example 1, and the conversion rate of p-chlorostyrene is 100%. , with a selectivity of 99.8%.

Comparative example 1

Except that the polymerization inhibitor was replaced with methyl hydroquinone of the same weight, all the other conditions and operation process were the same as in Example 1, the conversion rate of p-chlorostyrene was 93.7%, and the selectivity was 32.8%.

Comparative example 2

Except that the polymerization inhibitor was replaced with 4,4'-diphenylbiphenyl of the same weight, other conditions and operation process were the same as in Example 1, the conversion rate of p-chlorostyrene was 97.3%, and the selectivity was 79.2%.

Comparative example 3

Except that the polymerization inhibitor is replaced with 1,1-diphenyl-2-trinitrophenylhydrazine of the same weight, all the other conditions and operating procedures are the same as in Example 1, and the conversion rate of p-chlorostyrene is 67.4%. was 90.8%.

Claims (9)

1. a kind of method that chlorine or bromophenyl alcohol dehydration prepares chlorine or bromostyrene, is characterized in that: KHSO ₄ enters the falling film reactor after being dissolved and mixed with the raw material chlorine and/or bromophenylethanol and polymerization inhibitor, fully contacts and reacts in the falling film reactor, and the chlorine and/or bromostyrene produced by the reaction are processed Chlorine and/or bromostyrene products are obtained through purification on a separation column with reflux inside the filler. 2. according to the described method of claim 1, it is characterized in that: Chlorine and/or bromophenylethanol raw materials are selected from one or more of the following structures,

3. according to the described method of claim 1, it is characterized in that: The falling film reactor is made of inner-plated enamel material, and the evaporation area is 2-15m2. 4. according to the described method of claim 1, it is characterized in that: The dehydration reaction temperature is 90-190° C. (preferably 100-160° C.), the reaction pressure is negative pressure, and the negative pressure operation range is -0.02 to -0.099 MPa. 5. according to the described method of claim 1, it is characterized in that: _KHSO4 dissolves and mixes with raw material chlorine and/or bromophenylethanol and enters the falling film reactor together. The weight ratio of raw material to KHSO4 is 1000:1-5:1, preferably 100:1-10:1. 6. according to the described method of claim 1, it is characterized in that: The chlorine and/or brominated styrene that reaction generates obtains chlorine and/or brominated styrene product through the separation column purification with reflux in packing material, The separation column with reflux is a hollow airtight cylinder, the middle and lower part of the hollow cylinder is filled with filler, the upper part is provided with a cooling water pipe, the lower part or bottom of the cylinder is provided with a material inlet, and the upper part or top is provided with a material outlet ; The packing can be one or more of Raschig ring packing, Pall ring packing, stepped ring packing, arc saddle packing, rectangular saddle packing, metal ring rectangular saddle packing, spherical packing, preferably 304L metal pull West ring packing; the volume ratio of internal reflux is 0.1:1～1:100. 7. according to the described method of claim 1, it is characterized in that: The polymerization inhibitor is selected from one of tetrachlorobenzoquinone, hydroquinone, p-tert-butylcatechol, 2,6-di-tert-butyl-p-cresol, bisphenol A, 1,4-naphthoquinone or Two or more, the addition amount of the polymerization inhibitor is preferably 0.1-10% of the weight of chlorine and/or bromophenylethanol, more preferably 0.1-2%. 8. According to the method described in any one of claims 1-8, it is characterized in that: The raw materials are fully contacted and reacted in the KHSO ₄ falling film reactor, and the chlorine and/or bromostyrene produced by the reaction are purified by the separation column, and finally cooled by the product cooler or heat exchanger, and then enter the gas-liquid separator to separate the product. 9. According to the method described in any one of claims 1-8, it is characterized in that: The chlorine and/or bromostyrene obtained by the method can be applied to the preparation of intermediates in the fields of medicine, pesticide, or chemical industry.

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