DE1568912B - Process for the preparation of 1,1,2,2, tetrachlorathane - Google Patents

Description

1 2

1,1,2,2-Tetrachloroethane is an extremely soft ethylene available at a relatively low price

term intermediate product for the manufacture of tri-. There have now been attempts to manufacture

chlorethylene. So far, 1,1,2,2-tetrachloroethane was used from 1,1,2,2-tetrachloroethane

most commonly produced by chlorination of acetylene. cheaply accessible ethylene as a starting material

However, since acetylene is an expensive starting material, 5 was carried out.

It is known to use 1,2-dichloroethane by chlorination

rials desirable. of ethylene. This chlorination can im

The object of the present invention is the general by blowing in ethylene and chlorine

position of an advantageous process for production in liquid 1,2-dichloroethane, which is a small amount

of 1,1,2,2-tetrachloroethane. io containing ferric chloride can be achieved, as by the

Recently, with the development of petrochemistry, the following reaction scheme has been shown:

: , ■,.,: C ₂ H ₄₊ Cl ₂ liquid CH ₈ CL CH ₂ Cl _;

In addition, 1,2-dichloroethane can easily be obtained by oxychlorination of ethylene with hydrogen chloride and oxygen can be produced in the gas phase as shown by the following reaction scheme:

C ₂ H ₄ + 2HCl + V ₂ O ₂ CH _{2 ClCH 2} Cl + H ₂ O (2)

It is known that by further chlorination of 25 low. To carry out the process in technical-1,2-dichloroethane under irradiation with light this on a schematic scale are therefore large systems, large men-tetrachloroethane When converted via trichloroethane, steam and large amounts of energy are required. However, it is impossible here to borrow 1,1,2,2-tetra.

obtain chloroethane in good yield. This also occurs in the case of the production of tri-

that the reaction proceeds as follows: 1,2-dichloroethylene by a high-temperature treatment Chlorethane is produced by the photochemical chlorination of 1,1,1,2-tetrachloroethane in the presence of activin 1,1,2-trichloroethane converted, as by the foliage to remove hydrogen chloride at the same time The following reaction scheme is shown: a dechlorination with the formation of 1,1-dichloroethylene

:.;: ' _T. . ■. which reduces the effectiveness of the activated carbon.

CH ₂ Cl-CH ₂ Cl ₊ Cl ₂ CHCl ₂ ■ CH ₂ Cl ₊ HCl 35 is set. In addition, the reaction produces chlorine

/ g-v formed as a by-product that the reaction vessel

corroded. The yield of trichlorethylene is therefore

Subjecting the 1,1,2-trichloroethane to a naturally low level continues.

photochemical chlorination, so are two types on the other hand, 1,1,2,2-tetrachloroethane forms very easily

formed by tetrachloroethanes, as follows. Trichlorethylene in almost quantitative yield, as by shows is: the following equation is shown:

CHCl ₂ • CH ₂ Cl + Cl ₂ iE. CHCl ₂ CHCl ₂ + HCl CHCl ₂ CHCl ₂ + V ₂ Ca (OH) ₂ (6)

(4) - > CCl ₂ : CHCl + V ₂ CaCl ₂ + H ₂ O

CHCl ₂ • CH ₂ Cl. + Cl ₂ i ^ -V CCl ₃ • CH ₂ Cl + HCl ^; CHCl ₂ • CHCl _{2 C} C1 ₂ : CHCl + HCl

The first product is the desired 1,1,2,2-Te-1,1,2,2-tetrachloroethane is therefore the starting or.

trachloroethane, but the second product is undesirable _ ₀ intermediate of choice for the manufacture of

1st 1,1,1,2-tetrachloroethane. The amount of chlorethylene formed.

on the first product is almost the same as that of the As shown above, becomes 1,2-dichloroethane

the latter product. obtained by chlorination of ethylene [cf. Formula-

Trichlorethylene can be obtained from 1,1,1,2-tetrachloroethane scheme (1) and (2)]. By pyrolysis of 1,2-dichloro

can be obtained, but the process is technical 55 Ethane vinyl chloride is obtained. This stage, which is in

very inconvenient. If 1,1,1,2-tetrachloroethane is shown together with the following reaction scheme, in the

When heated with milk of lime, it is generally used in the trichlor technique:
ethylene as in the case of 1,1,2,2-tetrachloroethane overheat

led, but the reaction rate is very CH ₂ Cl CH ₂ Cl > CHCl: CH ₂ + HCl (8)

By chlorinating vinyl chloride, 1,1,2-trichloroethane is obtained, as shown in the reaction scheme below. The stage is known and is carried out as in the case of the chlorination of ethylene.

CHCl: CH ₂ + Cl ₂ CHCl ₂ · CHCl ₂ (9)

The invention now relates to a process for the production of 1,1,2,2-tetrachloroethah, which thereby is marked that one

a) 1,1,2-trichloroethane with chlorine (at least 2 mol percent of unreacted chlorine in the hydrogen chloride gas generated during the reaction) in the presence of anhydrous aluminum chloride as a catalyst in the liquid phase at 90 to 140 ⁰ C,

or that one

b) vinyl chloride in the presence of 1,1,2-trichloroethane and / or 1,1,2,2-tetrachloroethane as solvent in the same way as specified under a).

If the reaction is carried out at 90 to 140 ° C, so it runs with a technically interesting reaction speed, however, the catalytic effect of the anhydrous aluminum chloride is rapidly reduced. With the present invention making the introduction of chlorine gas into the system in the above Reaction in such a manner that over 2 mole percent of chlorine is unreacted from the reaction system leak, the catalytic effect of anhydrous aluminum chloride in the above The temperature range is hardly affected, and the reaction liquid can be purified very easily. When the reaction liquid is washed with water or an aqueous solution of hydrochloric acid, leave aluminum chloride can easily be removed, and the aqueous phase can very easily be separated from an oil phase will. In addition, the reaction product can be taken out of the reaction system as vapor without any trouble subtracted from.

If 1,1,2-trichloroethane is treated as described above, then over time the formation of 1,1,2,2-tetrachloroethane and the concentration of this gradually increases as the concentration increases 1,1,2-trichloroethane decreases. 1,1,2,2-tetrachloroethane is very stable in the reaction system and hardly becomes further chlorinated, and thus 1,1,2,2-tetrachloroethane can be obtained in high yield.

CHCl ₂ • CH ₂ Cl + Cl ₂

AlCl ₃

CHCL

CHCl ₂ + HCl (10)

If, in the case of photochemical chlorination, even a small amount of oxygen is in the chlorine feedstock is present or a metal ion is present in the reaction liquid, the Suppressed chlorination. In the process according to the invention, on the other hand, the reaction is determined by the presence of oxygen in the chlorine feedstock or the presence of a metal ion in the reaction mixture is not suppressed, which makes the process according to the invention technically very valuable power.

The amount of anhydrous aluminum chloride can be 0.01 to 1 percent by weight, preferably 0.05 to 0.5 percent by weight, based on the weight of the reaction liquid. The reaction temperature is preferably between 95 and 120 ^° C. within the temperature range mentioned above. The unreacted chlorine can be present in the hydrogen chloride formed in an amount of more than 2 mol percent, but in particular in an amount of 10 to 20 mol percent. However, the reaction is not impaired even if the amount of unreacted chlorine is larger than the above value, but in this case the extent of the subsequent step becomes larger, which makes the process technically uneconomical. In addition, it is particularly necessary to saturate the reaction liquid with chlorine at the start of the reaction.

Metallic aluminum can also be used instead of anhydrous aluminum chloride. Admittedly metallic aluminum is converted into anhydrous aluminum chloride in the reaction liquid.

Since anhydrous aluminum chloride is immediately converted into inactive hydrate on contact with water and loses its activity, it is appropriate to use completely dried 1,1,2-trichloroethane and chlorine gas to be used as starting materials.

The process according to the invention can be carried out in a system operated in batches or in a continuously operated system. In the case of continuous implementation of the Process, the ratio of 1,1,2-trichloroethane to 1,1,2,2-tetrachloroethane in the reaction liquid can be varied appropriately. If the The concentration of 1,1,2,2-tetrachloroethane in the reaction liquid is high, the reaction rate becomes high decreased, and when the content of 1,1,2-trichloroethane is high, a large amount of 1,1,2-trir chloroethane can be separated off by distillation. Generally an economical molar ratio is from 1,1,2-trichloroethane to 1,1,2,2-tetrachloroethane from 5: 5 to 1: 9.

1,1,2-trichloroethane and chlorine are blown into the reaction liquid. That so educated 1,1,2,2-tetrachloroethane can be withdrawn from the system as vapor or liquid.

The inventive method more than 96% of the converted 1,1,2-trichloroethane in 1,1,2,2-tetrachloroethane converted, and the remainder is converted into pentachloroethane and hexachloroethane. Virtually no other materials are observed in the reaction products.

The i, l, 2-trichloroethane used as starting material can be obtained by photochemical chlorination of 1,2-dichloroethane as shown in the above reaction scheme (3).

In addition, the combination of the reactions shown in the above Reaction Schemes (9) and (10) can be used can be carried out in one step by the reaction obtained by the reaction shown in the reaction scheme (8) Vinyl chloride was introduced directly into the reaction system shown by the reaction scheme (10) is to be reacted with 2 molecules of chlorine, as in the reaction scheme below will be shown:

CHCl: CH ₂ + 2Cl ₂

AlCl ₃

CHCl ₂ CHCl ₂ + HCl (H)

As can be seen from the above statements, the method according to the invention makes it possible to Using 1,1,2,2-tetrachloroethane in high yield from cheap ethylene as a starting material.

The following examples illustrate the invention. 65

example 1

In a 1-1 five-necked flask fitted with a stirrer, a thermometer, a gas inlet and one with

5 6

a reflux condenser provided gas outlet obtained from liquid. The reaction liquid was washed with 534 g (about 4.0 mol) of 1,1,2-tri-water, a yellow-orange oil layer of chloroethane and 3 g of anhydrous aluminum chloride being obtained, which was slightly removed from the aqueous Layer placed and the system heated while separating. The composition of the 500 ml chlorine gas per minute with stirring in the system 5 oil layer was the following:
were blown in. The reaction started at about mole percent

90 ° C. After carrying out the reaction for 120 minutes, low-boiling component 0.6

while maintaining a reaction temperature 1,1,2-trichloroethane 41.5

in the range from 100 to HO ⁰ C were 2.40 moles of chloro-1,1,2,2-tetrachloroethane 57.1

Hydrogen and 0.29 mol of unreacted chlorine in the high-boiling component 0.8

Freedom set. The reaction liquid was washed twice with 200 ml of aqueous 5% hydrochloric acid, B ice ο ie 1 3
whereby a clear yellow-organic oil layer was obtained,

which can be easily removed from the aqueous layer of the wash- In a 1-1 five-necked flask filled with a liquid solution cut off. The oil, which weighed 599 g, was distilled from the continuously overflowing reaction outlet, and the composition was then liquid, a stirrer, a thermometer, a ßend determined by gas chromatography. Inlet for chlorine gas, one inlet for trichloroethane The composition of the reaction liquid was the same as that of a gas equipped with a reflux condenser the following: "outlet, 527 g of a liquid

Mol percent 20 keitsgemisches of 1,1,2-trichloroethane and 1,1,2,2-

Low-boiling component 0.5 tetrachloroethane (molar ratio of the mixture 3: 7)

1,1,2-trichloroethane 40.7 and 0.5 g of anhydrous aluminum chloride introduced,

1,1,2,2-tetrachloroethane 58.1 and the system was stirred. The system was

High-boiling component 0.7 heats, while 600 ml of chlorine gas per minute into the sy-

25 stem were blown. The reaction started at

Then, the experiment was repeated using about 90 ⁰ C. When the reaction temperature 110 ° C erobengenannte apparatus and 1,1,2-trichloroethane and handed, 2 moles of 1,1,2-trichloroethane were per hour of anhydrous aluminum chloride in the same amounts and 0.3 g of anhydrous aluminum chloride per hour were used as above while adding 300 ml of chlorine each to the reaction system while introducing the reaction minute into the system. In this ion product, the trap was continuously withdrawn from the system in the first 40 minutes. The reaction was observed for 4 hours of set chlorine, but then this occurred while the reaction temperature was maintained at 110 to 115 ° C for most of the chlorine fed as unreacted chlorine,
the system. The reaction was carried out as a whole g reaction liquid hydrogen. Obtain the amount of unreacted chlorine. Aqueous when washing the reaction liquid with wearing 1.51 mole. Removed by washing twice the reaction 5 ° / _o hydrochloric acid was the oil layer yellow tion product orange ° / _o hydrochloric acid with 200 ml of aqueous 5. It could easily be separated from the system and, as in the above case, became a clear yellow-orange layer. The composition of the oil layer was as follows: obtained, which can be easily separated from the aqueous layer - _XT . . .
let separate. The composition of the oil was the low boiling component .. Traces

the following * 1,1,2-trichloroathane 30.7 mol percent

Mole percent 1,1,2,2-tetrachloroethane 67.4 mole percent

Low-boiling component 0.3 45 pentachloroethane 1.1 mol percent

mn hexachloroethane 0.6 mol percent

'.'. ['. [['.'. '. ['.'. [ ! [\ 38.0 High-boiling component 0.2 mol percent

High-boiling component 1.8 _. . ,.

Example 4

B is ρ ie 1 2 ⁵ ° ^ ⁿ ll five-necked flask with a stirrer,

a thermometer, a supply line for chlorine gas,

In the same apparatus as in Example 1, a feed line for trichloroethane and a gas outlet

Let 534 g (about 4.0 mol) 1,1,2-trichloroethane and 0.5 g, at the upper end of a condenser for condensation

Aluminum powder (degree of purity above 99 ° / ₀ ) with a concentration of the vapors contained in the gas was attached,

such a particle size that it is fitted through a sieve of 100 55.

to 140 mesh, and the sy- In the reaction vessel, 658 g of a liquid star was stirred to form a suspension. Mixture of 1,1,2-trichloroethane and 1,1,2,2-Te-When the suspension is gradually heated under trachloroethane (mixing ratio 1: 9) and 1.3 g of 500 ml of chlorine gas per minute are introduced into the anhydrous suspension Aluminum chloride was introduced, and the pension was the aluminum powder at 50 ° C under 60 system was stirred. While 700 ml of chlorine gas was chlorinated per formation of aluminum chloride which was introduced into the system for one minute, this was dissolved in the reaction liquid. The chlorination of heated. The reaction began 1,1,2-trichloroethane began at about 90 ° C at about 9O ⁰ C .If, and the reaction temperature reached HO ⁰ C, was added 2 mol reaction was continued for 120 minutes while the 1,1,2- Trichloroethane introduced per hour, and the reaction ^{temperature was kept at 100 to 110 0} C 65 temperature was further increased. The growing was. By the reaction, 2.35 moles of chlorine were formed, reaction liquid was formed together with generated hydrogen, 0.40 mole of unreacted hydrogen chloride gas was distilled off so as to accompany the level of chlorine, and 597 g of reaction liquid became constant. The reaction

temperature was 130 ^° C. and the reaction was continued for 3 hours.

The reaction produced 4.22 moles of hydrogen chloride, accompanying 1.02 moles of unreacted chlorine, and 852 g of reaction liquid was discharged distilled off the system, with 714 g of reaction liquid remaining in the flask. The distilled Liquid was colorless and transparent, and its composition was as follows:

Mole percent

Low-boiling component 0.5

1,1,2-trichloroethane 31.3

1,1,2,2-tetrachloroethane 68.2

High-boiling component none

During washing of the product in the flask with aqueous 5 ° / _o hydrochloric acid, this was yellow-orange and was easily separated from the aqueous layer. The composition of the product was the following:

Low-boiling component .. trace

1,1,2-trichloroethane 9.3 mole percent

1,1,2,2-tetrachloroethane 86.5 mole percent

Pentachloroethane 0.7 mole percent

Hexachloroethane 2.8 mole percent

High-boiling component 0.7 mole percent

Example 5

Into a jacketed reaction vessel made of an iron tube 5 cm in diameter and 70 cm in height (the actual amount of the reaction liquid in the tube was about 11) was 10 moles of a mixture of 1,1,2-trichloroethane and 1,1,2 , 2-tetrachloroethane (molar ratio of the mixture 3: 7) and 1.6 g of anhydrous aluminum chloride were introduced, and the mixture was ^{reacted at 110 to 115 0} C, while chlorine gas, trichloroethane and anhydrous aluminum chloride was continuously fed in from the bottom of the tube under such conditions that unreacted chlorine was present in an amount greater than 2 mole percent in the hydrogen chloride formed.

The reaction was carried out for 3 hours with a feed rate of raw material, trichloroethane, of 4 moles per hour, an addition rate of anhydrous aluminum chloride of 0.6 g per hour and a rate of introduction of chlorine of 1100 ml per hour. In the The reaction produced 7.6 moles of hydrogen chloride accompanying 0.7 moles of unreacted chlorine and 3400 g Reaction liquid was obtained. The separation of the oil layer from the aqueous layer was slow Washing with water is very easy. The composition of the reaction liquid was as follows:

Mole percent

1,1,2-trichloroethane 34.8

1,1,2,2-tetrachloroethane 64.4

Pentachloroethane 0.5

Hexachloroethane 0.2

High-boiling component 0.1

When repeating the same procedure for 3 hours using the one described above Reaction vessel under the same conditions except that the rate of introduction of chlorine gas in this case was about 900 ml per minute, no unreacted chlorine was formed in the exhaust gas observed in the reaction system. The reaction produced 6.82 moles of hydrogen chloride and 3360 g Reaction liquid was obtained. The reaction liquid was washed with aqueous 5% hydrochloric acid, but the oil layer was still black. Except-

; .5 that was the separation of the oil layer from the aqueous one Layer of washing solution difficult. Part of the oil layer was subjected to steam distillation. Then the composition was determined with the following result:

ίο mole percent

Low-boiling component 0.8

1,1,2-trichloroethane 36.8

1,1,2,2-tetrachloroethane 60.6

Pentachloroethane 0.4

Hexachloroethane 0.2

High-boiling component 1,2

Example 6

ao In an apparatus for continuous operation with the same dimensions as the apparatus described in Example 3, 603 g (about 5 mol) of a mixture of 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane (mixing ratio 4: 6) and 1 g of anhydrous aluminum chloride were introduced, and the reaction was ^{carried out for 3 hours at 110 °} C., while 900 ml of chlorine per minute and 500 ml of monomeric vinyl chloride per minute were introduced into the system with stirring. In the reaction, 2.71 moles of hydrogen chloride accompanied by 0.55 moles of unreacted chlorine were formed, and 1347 g of reaction liquid was obtained. The composition of the reaction liquid was as follows:

Mole percent

Low-boiling component 0.5

1,1,2-trichloroethane 38.6

1,1,2,2-tetrachloroethane 58.9

Pentachloroethane 1.1

Hexachloroethane 0.6

High-boiling component 0.3

The yield was 96%.

Claims (4)

Patent claims: 1. A process for the production of 1,1,2,2-tetrachloroethane, characterized in that that he a) 1,1,2-trichloroethane is reacted with chlorine (at least 2 mol percent of unreacted chlorine in the hydrogen chloride gas generated during the reaction) in the presence of anhydrous aluminum chloride as a catalyst in the liquid phase at 90 to 14O ⁰ C, or that one b) vinyl chloride in the presence of 1,1,2-trichloroethane and / or 1,1,2,2-tetrachloroethane as Solvent in the same way as indicated under a), is reacted. 2. The method according to claim 1, characterized in that the anhydrous aluminum chloride used in an amount of 0.01 to 1.0 percent by weight based on the weight of the reaction liquid. 109 514/391 3. The method according to claim 1, characterized in that there is metallic instead of aluminum chloride Aluminum in an amount of 0.002 to 0.2 percent by weight, based on the weight of the Reaction liquid is used. 4. The method according to claim 2 or 3, characterized in that the chlorination of 1,1,2-trichloroethane using 1,1,2-trichloroethane and / or 1,1,2,2-tetrachloroethane as a solvent.