SU775101A1 - Method of chloroprene production - Google Patents

Description

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The invention relates to a method for producing 2-chloro-butadiene-1,3 (chloroprene) used in the manufacture of polymers. 5

A known method of producing chloroprene by dehydrohalogenation of 3,4-dichlorobutene-1 in the presence of sodium metal hydroxide, potassium or calcium, in a system consisting of two phases — jg aqueous and organic at 75-125 ° C 1 |.

A disadvantage of the known method of producing chloroprene is the large consumption of metal hydroxide, the presence of two phases, aqueous and organic, the laboriousness of the process, the need for careful separation of the target product and the catalyst of metal hydroxide. 20

 The closest to the described method to the technical essence and the achieved result is a method for producing chlorohydrocarbons by dehydrochlorinating the corresponding 25 chlorohydrocarbons in the vapor phase at 500-590 ° C in the presence of a catalyst of rare earth elements deposited on a carrier in an amount of 10% of carrier, with the addition of

noble metals in an amount up to 1-2 wt.% 2.

The disadvantage of this method is the presence of expensive metals in the catalytic system, a high process temperature and a small depth of conversion of the feedstock (37% at 550 ° C and 15% at 450 ° C). All this complicates the process technology.

The aim of the invention is to simplify the method of producing chloroprene by dehydrochlorinating 3,4-dichlorobutene-1.

This goal is achieved by the described method of producing chloroprene, which consists in that 3,4-dichlorobutene-1 is dehydrochlorinated. The vapor phase at 130-200 C in the presence of a catalyst of the complex compound of a rare-earth element with 2-nitroso-1-naphthol supported on a carrier , in the amount of 1-6 wt.% by weight of the carrier. Lanthanum, cerium, praseodymium, samarium, europium or neodymium are preferably used as the rare earth element.

A distinctive feature of the process is to conduct the process in the presence of the above catalyst. Complex compounds of rare earth elements of the series La, C.Pr, Nd, Sm, Eu using 2-nitroso 1-naphthol as the organic ligand were obtained for the first time. The composition of the complexes denotes the formula MeL, HL, where 1 С. Example 1. A catalytic system is obtained by impregnating y-Alvj Oj with an appropriate solution of the complex compound in dimethylforma. For example: complex compound. LaL, HL shows the catalyst preparation procedure. 20 g (by granulation, 25-0.5 mm., Pour 50 ml of a solution of LaLaHL in dimethylformamide (1 g of the complex in 50 ml of dimethyl ormamide) is kept at room temperature for 12-24 hours. Then the catalyst mass is evaporated to dryness in a water bath and dried in a drying oven at 100-120 ° C for 4-6 hours. The npiftOTOB catalyst thus prepared for the process of producing chloroprene by dehydrochlorination 3,; 4-dichloro-butene-1 contains 1-6% by weight of the complex on a carrier. dehydrochlorination system 3, with different contents of the complex 1500s, load m Based on complex compounds 1% of cerium, praseodymium, neodymium, samarium, europium. The process is carried out in a laboratory setup with a pulsed feed of raw materials, Example 2. A tubular type reactor made of molybdenum glass is charged with 0.25 g of catalyst. 1 h in a stream of inert gas (gels) at the temperature of the experiment. / Yachlorobutene is fed with a syringe to the evaporator (evaporator temperature is 180-200 C at the rate of 0.04 g / g of catalyst). Using the samples obtained on the basis of lanthanum and cerium compounds as an example, the optimal content of the complex on the carrier was selected (see table 1). As a result of studying the catalytic activity of samples containing 1-6 wt.% Of the complex obtained on the basis of lanthanum and cerium, it was found that at a 100% conversion depth of the feedstock, the highest degree of conversion of 3,4-dichlorobutene-1 to chloroprene is observed when the content of complex 4 weight. % Table 1 of chlorobutene-1 on support catalysts (synthesis temperature 0.25 g)

The following are the results of the dehydrochlorination process. 3.4-dichlorobutene-1 using

of La, Cl, Pr, Nd ,, Sni, Eu complexes with the optimum Content of complex 5 (see tab. 2). The results of experiments on dehydrochlorination of 3,4-dichlorobutene-1 congestion on catalysis with the optimum content of the complex Table;

This method of chloroprene synthesis in the vapor phase in the presence of heterogeneous metal complex catalysts, with an active component of 4% by weight of a complex based on rare-earth elements, produces chloroprene in a yield of 75-96.8% with a conversion depth of 3,4-dichlorobutene- 1 100% at atmospheric pressure.

Using this method for the synthesis of chloroprene in the presence of a heterogeneous complex catalyst based on compounds of rare-earth elements has the following advantages compared with the known method

a rather high yield of chloroprene at a 100% depth of conercia of 3,4-dichlorobutene-1,

The absence of expensive materials in the catalytic system reduces the cost of the process.

Claims (2)

1. A method of producing chloroprene by dehydrochlorinating 3,4-dichlorobutene-1 at a lower temperature and vapor phase in the presence of a catalyst of a rare-earth compound on a carrier, characterized in that, in order to simplify the process, a rare-earth compound with 2-nitroso-1-naphtol in the amount of 1-6 weight,% by weight of the carrier and the process. Lead at 130-200 C. 2. A method according to claim 1, characterized in that cerium, praseodymium, neodymium, samarium or europium are used as the rare-earth element. Sources of information taken into account in the examination 1, US Patent No. 3965203, cl. 260-655, published 1976. 2, CLJA Patent No. 3927131; cl. 260-654 ,. publish 1975 (prototype