DE1143517B - Process for the production of tetrachlorothiophene - Google Patents

Description

GERMAN

PATENT OFFICE

H3600irVb / 12q

REGISTRATION DATE: MARCH 31, 1959

NOTICE THE REGISTRATION ANDOUTPUTE EDITORIAL: 14. F E B R U A R 1963

The invention relates to a process for the production of tetrachlorothiophene.

Tetrachlorothiophene has innocuous properties. The use of this product was however, so far limited by the fact that the known processes for its production little were satisfactory.

It is known that halogenated by reaction of halogenated butadienes with sulfur in the vapor phase To produce thiophenes. This method yields when using hexachlorobutadiene and Sulfur does not give satisfactory results and only low yields of tetrachlorothiophene.

According to other known processes, thiophene is converted into tetrachlorothiophene by chlorination manufactured. However, these methods have the disadvantage that the one used as the starting material Thiophene is not readily available.

In contrast to the known processes, the process according to the invention gives the Tetrachlorothiophene, based on the easily accessible hexachlorobutadiene, in almost quantitative quantities Exploit.

The process according to the invention for the preparation of tetrachlorothiophene consists in that a solution of sulfur in hexachlorobutadiene in which the molar ratio of hexachlorobutadiene to sulfur is used for the preparation
of tetrachlorothiophene

Applicant:

Hooker Chemical Corporation,
Niagara Falls, NY (V. St. A.)

Representative: Dr.-Ing. E. Hoffmann, patent attorney,
Munich 22, Widenmayerstr. 34

Emil John Geering of Grand Island, N.Y. (V. St. A.) has been named as the inventor

is not less than 1: 3, at least 5 hours at a temperature of 205 to 240 ° C under reflux heated, the forming sulfur monochloride is continuously distilled off and the resulting reaction product Purifies by distillation.

The reaction proceeds according to the following equation:

CL

Cl

, Cl

C-

-C

Il , c.

"Cl Cl '

+ S ₂ Cl ₂

It was also surprising that this reaction by the process according to the invention in almost quantitative yield, since it is known from the literature that hexachlorobutadiene is very inert is.

The preparation of the solution of the sulfur in the hexachlorobutadiene is facilitated by the fact that the hexachlorobutadiene is heated before the sulfur is added. The addition of the sulfur can either be in solid or in molten form, and it can also be continued during the reaction. It is essential that all of the sulfur goes into solution and thus takes part in the reaction. This also avoids residue problems. Complete dissolution of the sulfur is advantageous achieved by adding the sulfur in portions during the reaction.

The hexachlorobutadiene is advantageously used in excess in order to avoid difficulties to avoid heat transfer and residue build-up and to ensure that during the implementation and also towards the end of the reaction a sufficient amount of hexachlorobutadiene Available.

The reaction time depends on the type of dissolution of the sulfur, the concentration of the solution of the sulfur in the hexachlorobutadiene, the reaction temperature and the rate at which the sulfur monochloride formed is removed.
The separation of the tetrachlorothiophene formed

309 509/271

from the reaction mixture is through. Distillation made. A product of even greater purity can then be obtained when the distilled tetrachlorothiophene is subjected to a subsequent fractionation is subjected.

The method according to the invention is explained in more detail by the following exemplary embodiments.

example 1

A solution consisting of 45 mol of hexachlorobutadiene and 45 mol of sulfur was heated at reflux using a fractionator to about 220 ⁰ C. As soon as sulfur monochloride was formed, this was distilled off from the column at the top. 14.4 mol of sulfur monochloride were distilled off over the course of 13 hours. Then, under a vacuum of 7 to 8 of excess of Hexachlorbutadiens mm at 82-83 ⁰ C removed, then at 84 to 90 ⁰ C and an intermediate phase to 94 ° C distilling off the Tetrachlorthiophen at 91st A total of 98.4 percent by weight of total distillate, consisting of sulfur monochloride, hexachlorobutadiene and tetrachlorothiophene, based on the starting materials, was obtained. A comparison of the infrared spectra of the individual distillates with that of tetrachlorothiophene of known purity showed that the yield of tetrachlorothiophene was 14.8 mol (99% of theory). The portion of the distillate passed over _{at bp 8} 91 to 94 ^° C. contained the largest percentage of 12.2 mol of tetrachlorothiophene. This product had a melting point of 27 to 29 ^° C., a sulfur content of 14.4% and a chlorine content of 63.7%. In the literature, a temperature in the range from 29 to 36 ° C. is given as the melting point for tetrachlorothiophene. The calculated sulfur content is 14.4% and the chlorine content 69.3%.

Example 2

In a 121 capacity reaction vessel, 111.15 mol of sulfur were dissolved in three equal portions in 40.85 mol of hexachlorobutadiene heated to 100 to 150 ° C. using a mechanical stirrer. After each addition, the sulfur stirrer was removed and the solution under reflux, and using a packed with 0.35 cm glass helices fractionation column (91.5 x 14 cm) IO heated to 20 hours at 215-225 ⁰ C (reflux ratio 1: 4) and at the same time the sulfur monochloride formed is distilled off. The total reaction time was approximately 50 hours. The reaction product and excess of hexachlorobutadiene were then separated by distillation in Kp. ₂₃ to 25 105 to 120 ⁰ C from traces of sulfur and a low sulfur-containing residue. (8727 g) from the resulting distillate was then by fractional distillation 124 g of a ₂ 3bis25 85 to 105 ⁰ C for continuous fraction when Kp., At a Kp. _2? A portion boiling up to 25105 to 125 ° C (2553 g) and a portion boiling at bp ₂ ibis2 ₆ 117 to 124 ° C (5832 g). The fractions obtained from 105 to 125 ° C. and 117 to 124 ° C. contained 34.9 mol (94% of theory) of tetrachlorothiophene. The at Κρ. _{The fraction passed over from 26} U7 to 124 ⁰ C contained 26.5 mol of tetrachlorothiophene with a purity of more than 99.5%.

Example 3

2390 g (9.17 moles) of hexachlorobutadiene were placed in a 3-1 three-necked flask equipped with a heatable dropping funnel and a distillation column (61 x 2.2 cm) filled with 0.31 cm glass spirals Boiling heated (210 to 220 ° C), and over a period of 2 hours, 800 g (25 mol) of molten sulfur were added through the dropping funnel to the boiling hexachlorobutadiene. The reaction mixture was then refluxed for 7 hours at the above temperature, and 1088 g of sulfur monochloride were simultaneously distilled off at the top of the distillation column. The resulting residue was then distilled at Kp. ₉ bisi ₀ 87-97 ° C, whereby 1,938 g of distillate were obtained. The infrared analysis of the distillate showed that it contained 1530 g (yield 72.3% of theory) of tetrachlorothiophene.

Claims (1)

PATENT CLAIM: Process for the preparation of tetrachlorothiophene by reacting sulfur with halogenated butadiene, characterized in that a solution of sulfur in hexachlorobutadiene, in which the molar ratio of hexachlorobutadiene to sulfur is not less than 1: 3, for at least 5 hours at a temperature of 205 to 240 ° C. is heated under reflux, the sulfur monochloride which forms is continuously distilled off and the reaction product obtained is purified by distillation. Considered publications:
U.S. Patent No. 2,410,401. © 309 50 & / 271 2.63