DE1212513B - Process and device for the production of 2-chlorobutadiene- (1, 3) - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

C07c

German class: 12 o-19/02

Number: 1212513

File number: F 41618IV b / 12 ο

Filing date: December 23, 1963

Opened on: March 17, 1966

It is already known to 2-chlorobutadiene- (l, 3) by reacting l, 2-dichlorobutene- (3) with solid To manufacture alkali. However, the yields in this known process are not satisfactory, the response time is too long, and the implementation is because of the need to deal with large quantities Working solid substances in the reaction system is cumbersome. It has therefore already been suggested anhydrous alkaline solutions, especially alcoholic alkaline solutions to be used. With this production method However, expensive operations to obtain the reaction products from the alcoholic solution is necessary, which is worth seeing for the technical application. Also are the yields not satisfactory.

Working with aqueous alkaline solutions eliminates many of these disadvantages, e.g. B. are the formed salts kept in solution, and the resulting 2-chlorobutadiene (l, 3) distilled from the Reaction solution the same, but its great tendency to polymerize If you try to work continuously, the apparatus soon becomes clogged. The reaction rate is also too slow, which means that the reactants stay in for a longer period of time the hot reaction zone and increased polymerization result. This: polymeric material, which has a rubber-like structure is very difficult to remove because it is in solvents is insoluble and its formation requires frequent disassembly of the device that of removing material from it.

For this reason, some inhibitors have been proposed in a number of other known processes, that the polymerisation of 2-chlorobutadiene (l, 3) greatly reduce »but cannot completely prevent the polymerization. Since the Polymeric particles, which are slow to form at the beginning, act as nuclei for further polymerisation * the polymerization progresses rapidly after prolonged work even in the presence of inhibitors and prevents the Process.

Furthermore, organic water-soluble solvents such as 2-methoxyethanol, 2-ethoxyethanol and dioxaa have been proposed as additives to the aqueous alkaline solution. These additives increase the solubility of 1,2-dichlorobutene (3) in the reaction solution and thus lead to closer contact between the reaction partners. The reaction time is thereby considerably reduced, which results in a strong reduction in the polymerization. The methods and apparatus for production are based on the examples given
of 2-chlorobutadiene- (l, 3)

Applicant:

Paint factories Bayer Aktiengesellschaft,

Leverkusen

Named as inventor:

Dr. Rudolf Lauterbach, Cologne-Stammheim;

Dr. Herbert Schwarz, Opladen

However, even in these cases they only yield benefits of 85%, based on the 1,2-dichlorobutene- (3) used.

A process has now been found for the preparation of 2-chlorobutadiene (1,3) by reacting 1,2-dichlorobutene (3) with an aqueous alkali metal hydroxide solution at elevated temperature, which is characterized in that the reaction is carried out under exclusion of oxygen at temperatures above 80 ° C with a 8- to lO ^o / o aqueous. Alkali hydroxide solution, carried out in the presence of 0 _r 05 to 0.1 percent by weight, based on the aqueous alkali hydroxide solution used, of a water-soluble emulsifier. In this case, yields are 94-95 ⁰ Z ₀₁ of pure 2rChk> rbutadien- (l, 3 ') achieved. The reaction is preferably carried out in a temperature range from 95 to 98.degree. When 1,2-dichlorobutene- (3) is added drop by drop, a reaction occurs immediately with vigorous foaming, forming 2-chlorobutadiene- (1,3) "which escapes in gaseous form and can be obtained as an azeotrope with water. The residence time of 1,2-dichlorobutene- (3) in the alkaline solution is very short under these conditions. Around the reaction solution and the gas space above it as well as the whole. To keep the apparatus free of oxygen, nitrogen is passed in, to which 0.05% nitrogen oxide is added, and small amounts are introduced into the reaction solution. Nitrogen oxide effectively prevents the occurrence of traces of oxygen and thus the polymerization of 2-chlorobutadiene (l, ₁ 3j). The process is particularly suitable for the continuous production of 2-chlorobutadiene (3, l).

The fact that the addition of Θ · .05 to 0 _T l ^a [ _g _ of a water-soluble emulsifier to the aqueous alkaline solution accelerates the reaction by 20 to 30 times as a result is decidedly excessive.

609 538/415

surprising to denote. It couldn't have headed the apparatus into the expected steam space. The nitrogen

that such a small addition can be the same with traces of nitric oxide also from below in

or an even better ¹ -WirRühg will have how the reaction space will be pressed in. With the help of

Addition of 20 to 25 ° / _{0 of} an organic water overflow line 8 is the level of the liquid in the

soluble solvent. 5 Reaction vessel 1 set. About it is done too

If the content of alkali hydroxide is less than the drainage of the used lye. Above 8 ° / ₀ , the reaction proceeds too slowly and the tap 16 can completely empty the reaction vessel 1,2-dichlorobuteri- (3). piles up .. it lies however will be. At the packed column 2 the ent over 10%, so its density is already so great that the standing chloroprene of accompanying 1,2-dichloro, 2-dichlorobutene (3) no longer properly io butene (3) with the help of the Return divider 3 freed and distributed, which leads to a considerable slowdown running over the template 11 into the collecting vessel 12 of the reaction and leads to increased polymerization. Here the azeotrope separates under cooling. In addition to sodium hydroxide, potassium hydroxide, 2-chlorobutadiene (1,3) water, can also be used, the water being used. Care is taken to separate the water, which still contains traces of water, that the rate of addition of the 1,2-dichloro-15 crude 2-chlorobutadiene (l, 3) becomes with the addition of butene (3) to the aqueous Alkali hydroxide solution 0.1% of an effective inhibitor, for example, is dimensioned such that 1 mole of phenothiazine per mole of 1,2-dichlorobutene is distilled off over a desiccant in ice-2-chlorobutadiene (1.3). Part of the lye dried in the cupboard,
is placed in the reaction chamber and the remainder. · '-, -,
Part with the 1,2-dichlorobutene added. The 20 example 1
Ratio l, 2-Dichlorbuten- (3) · the alkali About the liquor washing vessel 4 and the Rückflußlauge is preferably maintained such that at 1 weight "> cooler 6 was for 1 hour l part by the nitrogen, 2-Dichlorbuten- ( 3) 8 parts by volume of the 8 bis apparatus were passed, then 10 weight percent alkali lye was added to the nitrogen. 0.05% nitrogen oxide was added.

The preferred concentration of the alkali solution from which brown vapors (NO ₂ ) had disappeared, e.g. B. the sodium hydroxide solution, to which 0.05 to 0.1% of the nitrogen-nitrogen oxide stream was added very small of an emulsifier, is 9 ⁰ I ₀ . The posed. It is even more effective that the weak reaction can be carried out continuously without any significant polymerization in the nitrogen-nitrogen oxide stream from below. The reaction to initiate the lye-filled reactor through a nozzle, the l, 2-dichlorobutene- (3) used is quantitative, 3 ° so that the gas is bubbled through the lye,
the yields of pure 2-chlorobutadiene (l, 3) are The 9% oxygen-free liquor in the reaction space is 94 to 95%, based on the 1,2-di- used, was then added with steam to 95 to 98 ° C (3). All substances can be heated as an emulsifier. 0.05 percent by weight of the lye were used, which lower the surface tension of the oleyl alcohol polyglycol ethers as an emulsifier in aqueous alkaline solutions, which give 35%. As soon as the desired temperature was reached, the boiling point was above 80 ° C, which was against 1,2-dichloro, one began at 14 with the dropwise addition of butene (3) and 2-chlorobutadiene (1.3) are indifferent 1,2 -Dichlorobutene- (3) and the 8O ⁰ C warm 9% and the polymerization of 2-chlorobutadiene (l, 3) sodium hydroxide solution. The 1,2-dichlorobutene- (3) were 0.2 Gem'cht promote. Ionic and percent by weight, 0.05 percent by weight of the lye, nonionic emulsifiers, such as 4 oleyl alcohol polyglycol ether added as an emulsifier, can be used as emulsifiers. Coconut fatty alkyl sulfate, lauryl sulfate, oleic acid-N-methyl- The mixing of the alkali with the 1,2-dichloric acid, alkylphenol polyglycol ether, sulfated alkyl butene (3) only took place in the inlet connection 14 and in the phenol polyglycol ether, o-benzyloxydiphenyl polygly reactor 1. The ratio of 1,2-dicol ether to be added dropwise, diethylamine oleate, oleyl alcohol polyglycol chlorobutene (3) liquor to be added dropwise was 1 ether and sulfated oleic acid dibutylamide. 45 parts by weight to 8 parts by volume.

A device for continuous through- It is advantageous to use the first 100 g of 1,2-dichloro

The figure shows how the process is carried out. buten- (3) in addition to the emulsifier 50 ml glycol mono-

Add drops of 1,2-dimethyl ether through the inlet nozzle 14. Thereby, the reaction chlorobutene and oxygen-free at 8O ⁰ C preheated immediately one, the resulting 2-Chlorbutawäßrige alkali metal hydroxide solutions escapes into the reaction 50 diene (l, 3) gaseous form and thereby provides space 1. The heating of the reaction space there is good Mixing of the reactants, which results in a continuously good conversion with steam with the aid of a reaction tube. surrounding jacket 5. Through the pipe 9, the water vapor A further addition of glycol monomethyl ether escapes through the pipe 9 'which does not occur, the emulsifier is sufficient. As soon as the non-condensed part flows through the pipe 9 ″, the reaction was in full swing, the nitrogen oxide condensation water was drained off. The temperature of the reaction amount was limited to a minimum. Nitrogen solution is read on the thermometers 10 In order to prevent an increased generation of gas bubbles and penetration of air from the outside,
This results in a better mixing of the reaction The alkali to be added must be free of oxygen, to achieve partner, are in the reaction space 60. This can be achieved either by boiling or on a thin platinum wire carbon rings 15 (= boiling point by adding 0.05 to 0.1 Weight percent wires) hung as boiling stones. The one with pyrogallol. The over-distilling azeotrope of 2-chlorine conversion formed in small amounts solid butadiene- (1,3) -water (boiling point 55 to 56 ⁰ C) by-products, which were on the surface of the, as described for the apparatus, in the reaction solution accumulate, can from time to 65 collecting vessel 12 collected under strong cooling. To be emptied into the collecting vessel 7 for a while. About 1 mol of 1,2-dichlorobutene used, 1 mol of 2-chlorobutadiene (1,3) was distilled off around the caustic washing vessel 4 and the reflux condenser 6. When nitrogen and nitrogen oxide are poured into the collecting vessel as required, the azeotrope separated into the grain

components, the water was separated off, and the still moist 2-chlorobutadiene- (l, 3) was over sodium hydroxide dried in the cold with the addition of 0.1% phenothiazine.

5 kg of 1,2-dichlorobutene- (3) were reacted continuously over the course of 49 hours, the yield on the chloroprene-water azeotrope was 3564 g. After separating the water and Drying gave 3457 g of crude, dry 2-chlorobutadiene (1,3). The gas chromatogram showed that then 2.7% by-products, mainly 1-chlorobutadiene, were still contained. It was accordingly a yield of 3364 g of pure 2-chlorobutadiene (1.3) obtained, that is 95.2% of theory.

15 Example 2

The procedure described in Example 1 was followed, except that o-benzyloxydiphenyl polyglycol ether was used as the emulsifier (in equal quantities) used.

10 kg of 1,2-dichlorobutene- (3) were reacted continuously over the course of 96 hours. The yield on the 2-chlorobutadiene- (1,3) -water azeotrope was 7072 g. After separating the water and drying, 6861 g of crude dry 2-chlorobutadiene (1,3) were obtained. If one subtracts the 2.7% By-products from, 6676 g of pure 2-chlorobutadiene (1.3) are obtained, which is 94.2 of theory.

The same results were obtained when using of lauryl sulfate or sulfated oleic acid dibutylamide as an emulsifier. In both cases remained the apparatus free of polymer. Only the boiling stones hanging on the platinum wire fought less than 1% solids, which after completion of the experiments comfortably with the boiling stones and the platinum wire could be removed from the apparatus.

Claims (3)

Patent claims: 1. A process for the preparation of 2-chlorobutadiene (l, 3) by reacting 1,2-dichlorobutene (3) with an aqueous alkali metal hydroxide solution at elevated temperature, characterized in that the reaction is carried out with the exclusion of oxygen at temperatures above 80 ⁰ C with an 8 to 10% strength aqueous alkali metal hydroxide solution, in the presence of 0.05 to 0.1 percent by weight, based on the aqueous alkali metal hydroxide solution used, of a water-soluble emulsifier. 2. The method according to claim 1, characterized in that the reaction in the presence of a Oxygen acceptor is carried out. 3. Apparatus for performing the method according to claim 1 and 2, characterized characterized in that the packed column (2), reflux divider (3), collecting vessel (7) and overflow line (8) with valve (16) provided reactor (1) an inlet nozzle (14), a heating jacket (5) and two thermometer stubs (10) connected to the boiling wires (15), wherein in height the inlet nozzle (14) the washing vessel (4) via the reflux condenser (6) with the reactor (1) connected and the return divider (3) via the line (17) with the template (11) and the collecting vessel (12) is connected. Considered publications:
German Patent No. 888,389;
W eyga η d, "Organic chemical experimental art", 443 (1948). For this purpose, 1 sheet of drawings 609 538/415 3.66 © Bundesdruckerei Berlin