The method of producing chloroprene by dehydrochlorination of 3,4 - dichlorobutene-1


(57) Abstract:

Features a method of producing chloroprene, which finds use as an intermediate in industrial organic synthesis by dehydrochlorinating 3,4-dichlorobutene-1 (in the presence of lime and a polyol such as a glycol selected from (poly)ethylene glycol and (poly)propylene glycol, preferably ethylene glycol at 70-150oC, preferably lime, take in the amount of at least 0.58 M calcium per 1 mol of dichlorobutene. The method allows us to simplify the production of chloroprene. 4 C.p. f-crystals.

The present invention relates to a method for producing 2-chlorobutadiene-1,3 /"chloroprene"/ by dehydrochlorinating 3,4-sodium dichloro-1-butene /vers/ and, in particular, to a method for producing chloroprene, on the basis of vers in which vers dihydrochloride lime.

The present method of producing chloroprene is the dehydrochlorination vers sodium hydroxide. The consumption of sodium hydroxide stechiometric and, therefore, consumption greatly increases the cost of the whole process.

Therefore, in the past, attempts have been made to find a less expensive solution than using sodium hydroxide. In particular, it was proposed samosvesti.

Some ways to dehydrochlorinating vers, using lime as the primary reagent disclosed in patent references.

So, for example, JP-51/43705 discloses a system is represented by calcium hydroxide and sodium sulfate. This method is schematically represented by the equation:

2CH2= CH-CH(Cl)=CH2Cl + Ca(OH)2+ Na2SO4--> 2CH2=CH-C(Cl)=CH2+ CaSO4+ 2NaCl + 2H2O.

The main disadvantage of this method is that there are two by-product, namely calcium sulfate and sodium chloride.

And CaSO4insoluble in water, must be separated from the aqueous solution, which contains sodium chloride, and this stage is even more increases the overall cost of the process. In addition, the method disclosed in this patent, it is not possible to obtain quantitative conversion.

In this prior art, the applicant of this invention has been able to develop a way of dehydrocorydaline vers in the chloroprene, which is free from the above disadvantages.

In accordance with the foregoing, the present invention relates to a method for producing chloroprene by dehydrochlorinating 3,4-sodium dichloro-1-butene, characterized in that the group, consisting of /poly/ethylene glycol /poly/propylene glycol, and/or at least one sugar, with preference being given to ethylene glycol.

Under "lime" here refers to the calcium oxide or calcium hydroxide or mixtures thereof.

Under "/poly/glycol" refers to ethylene glycol or propylene glycol and polymers.

Under "sugars" refers to sucrose and its derivatives, i.e., mono-, oligo - or polysaccharides, which can be hydrogenated or dehydrogenation, and their analogues. As an example, glucose, sorbitol, glycerol and others.

The reaction dehydrochlorination is carried out at a temperature in the range from 70 to 150oC, better from 80 to 120oC.

Preferably, the reaction temperature was not below the lower threshold /too low reaction kinetics/, and not above the upper threshold /fast polymerization/.

In accordance with a preferred reactor is loaded with lime and glycol; then the mixture is heated to move to the desired temperature.

Through a special funnel to the reactor type vers. Better to add it after 10 to 60 minutes.

The necessity from the selected temperature, conversion speed and glycol. For example, in the presence of ethylene glycol at 100oC to get almost full quantitative conversion vers, the reaction takes 90 minutes.

In the process of formation of the chloroprene can be separated from the reaction mixture by distillation.

At the completion of the reaction, all the resulting chloroprene can almost fully assembled. The content of the chloroprene and vers in the residual mixture inside the reactor remains very small.

Lime should be present in an amount of at least 0,5 mole of calcium per mole of ice. However, it is better to use a slight excess of lime, preferably from 0.51 to 1.5 M of lime per mol vers.

If glycol is used, the molar amount of one-half of alkylene must be at least the same as the lime. The preferred option glycol is also used as a solvent, and therefore, in great abundance.

As polyglycols, their molecular weight is usually in the range from 200 to 1000, better from 300 to 800.

In accordance with another variant of the reaction system can be diluted with water or an inert solvent, in particular etilenglikolevykh florid calcium. Ethylene or propylene glycol can be regenerated by distillation, and polyglycols - extraction.

To further illustrate the present invention presents the following examples.

Example 1. System method consists of a glass reactor (capacity 200 cm3), equipped with a mechanical stirring means, an oil bath for heating, addition funnel and external capacitor pair.

The reactor is loaded with 100 g (1.61 M) of ethylene glycol and 10.4 g (0.14 M) Ca(OH)2).

The mixture was stirred and heated to 100oC.

Within 30 minutes of a drop funnel is added 31.25 g (0.25 M) of 3,4-sodium dichloro-1-butene (vers).

The reaction mixture is maintained at a temperature of 100oC with stirring for 1 hour.

At that time there were orditillitoro and collected from the liquid of 18.5 g, gas chromatography analysis showed that this number contains 74% of chloroprene and 8% of dichlorobutene.

Analysis of the residual mixture in the reactor shows that it contains 1.48 g of chloroprene /vers is no longer present/.

Conversion vers is 95.2% and the yield of chloroprene - 72% of the reacted dichlorobutene.

Example 2. In the education vers amounted to 97.6%, the output of the chloroprene - 68.9% of which came in response dichlorobutene.

Example 3. According to the method of Example 1 was used 0.25 vers, 0.68 M of ethoxyethanol, 0.24 M of ethylene glycol and 0.14 M Ca/OH/2.

Conversion vers amounted to 61.2%, and the entrance of the chloroprene - 46.8%.

Example 4. Was repeated in Example 1, but the ethylene glycol was replaced with 100 g of polyethylene glycol with an average molecular weight of 300.

After 4 hours the reaction mixture was addictionology 11.4 g, containing 86% of chloroprene and 3% vers.

The overall balance of the example shows that the degree of conversion of dichlorobutene is 99.2%, and the yield of chloroprene - 47%.

Example 5. According to the method of Example 1 was used 1 mol vers, 0.55 mol Ca(OH)2and 4 mol of propylene glycol.

After 90 minutes reaction at 81oC conversion vers was 99% and the yield of chloroprene was 60%.

Example 6. According to the method of Example 1 was used 1 mol vers, 0.55 mol CaO and 1.8 mol of ethylene glycol.

After 80 minutes of reaction at 90oC conversion vers was 100% and the yield of chloroprene was 24%.

Comparative example 7. In the same way of Example 1 was used 0.25 mol vers, 0,76 mol of ethoxyethanol and 0.25 mol Ca(OH)2.

After 4 hours at 1022and 4.97 mol of water.

After 4 hours of reaction at 92oC conversion vers amounted to 8% and the yield of chloroprene - 2%.

1. The method of producing chloroprene by dehydrochlorination of 3,4-dichlorobutene-1, wherein the dehydrochlorination is carried out in the presence of lime and at least one glycol selected from (poly)ethylene glycol and/or polypropyleneglycol, at a temperature of 70 - 150oC.

2. The method according to p. 1, characterized in that as the use glycol ethylene glycol.

3. The method according to p. 1, wherein the dehydrochlorination is carried out at a temperature of 80 - 120oC.

4. The method according to p. 1, characterized in that the lime charge in the amount of at least 0.5 M calcium per 1 mol of dichlorobutene.

5. The method according to p. 4, characterized in that the lime used in the amount of 0.51 - 1.5 M of calcium per 1 mol of dichlorobutene.


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