DE1618893C - Process for the preparation of alpha, omega-dimercaptopolythiaalkanes - Google Patents

Description

The present invention relates to a new process for the preparation of α, ω-dimercapto-polythiaalkanes the general formula

HS (CH ₂ S) _1n CH ₂ SH

in which m is 1 to 10.

From US Pat. No. 3,056,841, a Process for the preparation of such compounds is known, which in the treatment of formaldehyde with liquid hydrogen sulfide is in several molar excess; - this process is, however, expensive, because it works under pressure and not gaseous, impure hydrogen sulfide, the is available in practically unlimited quantities and cheaply in the industry. In addition, the product obtained must be treated with an acid in order to be contained in the product Remove OH groups.

From French patent 1,362,500 a method is also known dithiol polythioether be prepared from aqueous formaldehyde and hydrogen sulfide at temperatures of 70 to 90 ⁰ C after. However, this process has the disadvantage that only a mixture is obtained in which m is on average between 2 and 4 and cannot be modified.

However, there is interest in a process by which dithiols can be produced with a fixed value for m , for the dithiol polythioethers there are various fields of application, in particular in the production of phenoplasts by polycondensation with phenols or in the production of other plastic materials as well as in the Vulcanization of rubber. . ">

The invention thus relates to a process for the preparation of -x.w-dimercapto-polythiaalkanes the general formula

HS (CH _s S) _m CH, SM · '■ ■

in which in means 1 to 10, which is characterized in that a corresponding 'Vw-dihydroxy-lhiaalkane is reacted in the aqueous phase at a temperature of 25 to 100 "C with hydrogen sulfide.

In contrast to the prior art, the new process according to the invention allows an economical one and simple production of dithiol-polyhydric ethers, which no longer contain any oxygen in the molecule. It also enables connections with a fixed / «value to be obtained. FJn another The advantage of the inventive method is that it can easily be carried out with hydrogen sulfide which can be mixed with other gases, for example with nitrogen or with carbon - Dioxide is located without it being necessary to purify this hydrogen sulfide beforehand.

As a result of the absence of hydroxyl compounds, the dithiol mixtures obtained according to the invention can easily be fractionated into their constituents by distillation in vacuo. This allows the production of dithiol polythioethers with integer and constant m in the pure state. The ίο inventive method thus forms an excellent way to separate production of connec-. fertilize such as HS (CH ₂ S) ₂ H, HS (CH ₈ S) ₃ H, HS (CH ₂ S) ₄ H. On the other hand, those compounds that are solid or waxy at normal temperature can be purified by crystallization in suitable solvents will. According to the invention, industrially very useful products are mixtures of several compounds HS (CH ₂ S) ₇₇₁ H, in which a dithiol, whose m is, for example, 2, 3, 4, 5 or 6, is present in a predominant amount of 50 to 75 percent by weight finds.

The reaction that takes place can be expressed by the equation:

HO (CH ₂ S), "CH ₂ OH -I- 2H ₂ S

-> HS (CH ₂ S) _7n CH ₂ SH + 2H ₂ O

being represented.

The progress of this reaction is controlled by analysis according to one of the known methods, for example by chromatography, infrared analysis, which allows the presence of Characterize OH groups.

Because of the great inertia of this reaction

Temperatures below 25 ° C, and because one is forced about 100 ⁰ C to work under pressure is between 25 and 100 ⁰ C, in particular between 30 and 90 ⁰ C, worked.

The diol thioether used can be the diol monothioether .

4 ". HO (CH ₂ S) CH ₂ OH

d. H. the first link in the series

HO (CH ₂ S) _7n CH ₂ OH

or a diol polythioether in which m is more than 1; hi can have different values from 1 to 10.

The diols used are, depending on their chain length, ie according to the size of m, dissolved or dispersed in water. This latter condition is generally available for m values which are equal to or above 3, because the solubility in water decreases steadily from the diol trithioether onwards. The water can be an alcohol; in particular methanol, in an amount of, for example, about 1 to 30%. An industrially very practical method is to work in the same aqueous medium in which the diol was prepared. This medium generally comes from a commercially available formaldehyde solution.

The concentration of the selected diol in the aqueous to be treated with hydrogen sulfide Medium can vary. In particular, it can be in the order of 1 to 50 percent by weight, regardless of the solubility or insolubility of the diols in water. The speed of the reaction (1) can be regulated by the concentration of the diol in the aqueous medium. That speed is

the greater, the more dilute the medium is. For example, the conversion of the diol monothioäthers at 50 ⁰ C Requires 9 hours in a 30% solution, 5 hours in a I0% ig ^e ri solution and only 3 hours in a 5%> g ^s solution. While it would seem logical, from the standpoint of better utilization of the capacity of the devices, to work with solutions or suspensions which are as rich as possible in the diols to be converted, the preferred embodiment of the invention consists rather in the use of a lower concentration which it contains at the given temperature allows the production to be carried out in a reasonable time, for example in 1 to 10 hours. On the basis of this fact, the preferred concentrations of diols are generally about 5 to 40 percent by weight, based on the aqueous medium, and especially 15 to 30%.

Another factor which allows the chain length of the dithiol polythioethers to be produced to be controlled is temperature. This plays a particularly important role if the starting substance is diol moon thioether. Thus, surprisingly, the average coefficient m of the dithiols obtained is greater, the higher the temperature of the aqueous medium is during the action of the hydrogen sulfide on the diol or on the diols. For example, it can be stated that, starting from the diol monothioether, its theoretical conversion according to the equation:

HO (CH ₂ S) CH ₂ OH -I- 2H ₂ S

-> HS (CH ₂ S) ₂ H + 2H ₂ O (2)

would result in m = 2, in reality, starting from a 6, l% strength solution of this diol ^e is n:

at 50 ⁰ C an average value for m of about 2.63,
6O ⁰ C an average value for m of about 2.9,
70 ⁰ C an average value for m of about 3.5,.
8O ⁰ C an average value for m of about 3.85,
85 ° C an average value for m of about 3.95.

The inventive method is carried out by the aqueous medium, which the diol or which contains diols, is saturated with hydrogen sulfide. Although the procedure will be carried out under pressure very good results can be achieved by simply bubbling in the gaseous hydrogen sulfide into the aqueous medium at atmospheric pressure. The gas may contain other inert gases, in particular Carbon dioxide, which accompanies hydrogen sulfide in certain industrial gases.

If the introduction of hydrogen sulfide is continued until the OH groups of the diol have disappeared is, the yield of dithiol is very high, mostly quantitative.

The reaction products are separated off by decanting, filtering and / or centrifuging the heavier, organic phase. With an average of less than 5 in this phase is generally a slightly dekantierbares oil, which can be fractionated by distillation under reduced pressure in the dithiols with integer m. It is advisable to carry out the distillation without exceeding 180 ^° C. in order not to change the products produced. If m is on average equal to or greater than 5, the products are usually waxy or solid and also separate from the aqueous phase without difficulty. These products can be converted into their constituent parts with integer / n values by recrystallization from common solvents.

The following examples illustrate the invention.

Example 1 - .

A 2-liter reaction vessel, which is provided with an inlet tube for hydrogen sulfide, a temperature meter, a stirrer and a gas outlet opening and carries a rising cooler, is immersed in a thermostatic bath. A solution of 0.6 mol (56.4 g) of diol monothioether in 900 g of water is introduced into the reaction vessel. The solution is accordingly 5.9% (percent by weight). The temperature is brought to 50 ^° C., which is maintained for the entire duration of the reaction, and a stream of hydrogen sulfide is bubbled through the solution. This operation takes 10 hours. After this time, an oily liquid is obtained, which is separated off by decanting. Analysis of the product shows that it is a mixture of dithiol polythioethers which no longer contains any oxygen and whose mean value for m is 2.6. Distilling this mixture gives 25% HS (CH ₂ S) ₂ H, 70% dithiol trithioether, 1.5% dithiol monothioether and 3.5% dithiol tetrathioether.

Example 2

In the same reaction vessel as in Example 1, 0.6 mol (84 g) of dithiol dithioether, dissolved in 1 liter of water, is introduced. The temperature is brought to 8O ⁰ C, which can maintain throughout the duration of the hydrogen sulfide introduction. After 6 hours, the gas flow is stopped and the oil which has settled on the bottom of the reaction vessel is recovered by decanting. The product obtained no longer contains any OH groups. It is a dithiol HS (CH ₂ S) _7n H, the mean value of which for m is 3.0 and which gives 15% HS (CH ₂ S) ₂ H and 70% HS (CH ₂ S) ₃ H on distillation.

Example 3

In the same device as above, 0.6 mol (131 g) of diol trithioether, which is ^{suspended in 1200 cm 3 of} water, is introduced. After having brought the temperature to 8O ⁰ C, can be bubbled six hours hydrogen sulfide. The product obtained is an oil which no longer contains any OH groups. It is a mixture of dithiols, the mean value of which for m is 3.85 and which gives 58% HS (CH ₂ S) _{4 H on distillation under vacuum.}

Example 4

In the same apparatus as in the previous examples is treated 0.6 mol (158 g) diol tetrathioäther, suspended in 1200 cm ³ of water, with hydrogen sulphide, the temperature being maintained for 6 hours at 90 ⁰ C. An oil separates, which is decanted and washed. The oil is a mixture of dithiols, the mean value of which for m is 4.5. _{40% HS (CH 2} S) ₄ H is obtained by distillation of this mixture, while the remainder consists predominantly of "HS (CH ₂ S) ₅ H".

Example 5

^{2330 cni a} is poured into a 3 liter reaction vessel equipped like that in Example 1

5 6

a solution of 130 g (1.385 mol) of diol monothio- initially 100 liters of a solution of 45.2 kg (0.48 kmol) of ether, which, based on a formaldehyde diol monothioether, based on a commercial solution, is customary through the action of hydrogen sulfide Formaldehyde solution. · The temperature that was freshly prepared. The solution is boiled down to 60 ⁰ C solution is kept at 70 ⁰ C and allowed nine Stunbrac'ht and allowed hydrogen sulfide bubbled. 5 den long a mixture of 60 percent by volume sulfur. The reaction lasts 3½ hours. 142 g of hydrogen and 40 percent by volume of carbon dioxide are obtained, a mixture of dithiol polythioethers, the pearls of which. This "separation consists of 52 kg dithiol-polythioether mixture, the m- value is 2.88. The distillation of this pblyibjro'äihereenTiscTi ^ inifi ^ a mean m-value dilhiol-polythioether mixture leads to the division into:>v'oä3.6;" ^{: v} T <^, ^- ~ "f""

HS (CH ₂ S) ₂ H 18% ¹⁰ Examples. ■

Sc ^ u c ² \ ³ 2 / '' a '''''' λ IVJi ^{0 The} procedure of Example 7, but eight hours

HS (CH ₂ S) ₄ H (and m> 4) _{12/0] ang with 8} qo _q ^ _{13n increases 51 k product with a}

. . mean value for m of 3.85. The vacuum distillation

B e ι s ρ ι e 1 6 _{lg djeses} p _{ro (} juktes supplies the following dithiols:

You work as in example 5, but keep the ₁₀ , _{us n} "' _nv ""

Temperature between 25 and 30 ° C. One obtains after ² Jo "S - CH ₂ S - CH ₂ SH

54 hours a dithiol polythioether mixture with a "^ J * ™ ~ J;" «J ~ ^" ^ ~ S; "^ ^H

mean m-value of 2.63. £ Jp ψ '~ ^.? ^Η % ~ ^CH ^ ~, ² l ~ ^CH 2 ^SH

_2o 17% ^nicnt Unidentified residue.

B is ρ ie 1 7 _The main constituents of the products obtained in the above examples in a reaction vessel with a capacity of 150 liters have the inherent properties which, like the reaction vessels in the previous examples, are equipped in the following table , prepares one provides are:

Dithiol polythioether

HS (CH _a S) ₂ H. HS (CH ₂ S) ₃ H • HS (CH ₂ S) ₁ H 19.04 20.93 22.02 19.03 20.78 22.09 • 4.76 4.69 4.59 4.49 4.74 4.66 ~ 78.20 74.40 ■ 73.39 76.50 74.30. 72.90 ■ 126 172 218 127.1 ■ 172.3 223 52.30 38.30 30.20 51.70 37.90 29.70 1.637 1.661. 1.675 1,300 '1.346 1.372 3.03 10.65. 31.50 57 ° C 114 ° C 82 ° C ι 5 x 10- ¹ Torr at 1 torr. at 10- ² Torr

analysis

C ⁰ J ₀ , calculated

found

H%> calculated

found :

S ⁰ I ₀ , calculated,.

found

Molecular weight (cryoscopy)

calculated

found

HS%, calculated

found

Calculation index at 20 ⁰ C:

Density at 20 ^° C

Viscosity at 20 ⁰ C in centipoise boiling point

Claims (1)

Claim: Process for the preparation of «, co-dimercaptopolythiaalkanes the general formula HS (CH ₂ S) _7n CH ₂ SH, in the means in 1 to 10 characterized by reacting a corresponding α, ω-hydroxy-ΌΊ- thiaalkan in aqueous phase at a temperature of 25 to 100 ⁰ C with hydrogen sulfide.