SU381219A1 - METHOD OF OBTAINING MERCAPTANS - Google Patents

Description

one

This invention relates to a process for the preparation of mercaptans used as intermediates for the synthesis of insecticides, herbicides, repellents, rubber vulcanizers and surfactants.

A known method for producing mercaptans by reacting hydrogen sulfide and olefin with at least one double bond in the presence of trialkylphosphite as a promoter when initiating the reaction with ultraviolet rays. However, when converting an olefin to 98%, the yield of cervical mercaptan is only 3.4%.

In order to increase the yield of primary mercaptans, it is proposed to use an azo or peroxide compound as an initiator, and an organic compound of trivalent phosphorus of the general formula

/ (y) bR

R (X), - P

(Z)

where X, Y and Z - chalcophilic elements with an atomic weight of 14-33; a, b, c - O, or 1; R, R, R - hydrocarbon radicals containing 1-20 carbon atoms.

The yield of the target product is 70%.

Examples of organic compounds of trivalent phosphorus used are al.kyl- or arylphosphines, phosphites, phosphonites and phosphinites, naimer trimethyl-, tributyl- and triphenylphosphine, trimethyl-, tributyl-, trihexyl-, and tritolylphosphite, trimethyl-, triphenyl counts, tri-methyl, triphenylphosphine, triphenylphosphine, trifenylphosphine, trifenylphosphine. In addition, thio-derivatives of phosphites, phosphonites and phosphinites, such as triphenyl, trimethyl and tributylthiophosphite, triphenylthiophosphonite may be used.

And the most preferred promoters are trimethyl, triethyl, tripropyl, tributyl and triphenyl phosphite.

Free radical type initiators can be peroxide compounds, organic azo compounds, peracids and percarbonates. Azo compounds may contain an acyclic azo group —N — N—, bound

with various non-aromatic organic residues, for example with aliphatic OR cycloaliphatic radicals, through carbon atoms, at least one of which is tertiary. As an example may be mentioned azobisisobutyronitrile, azobis (a-y-dimethylvaleronitrile), azobis (a-methyl-ss-karboksibutironitril), azobis (izobutiramidin hydrochloride) azobitsiklogeksankarbonitril, a- (karbamidazo) -izobutironitril, a- (karbamilazo) -a, u-dimethylvaleramide, hexyl-cc- (carbamylazo) -a.-dimethylvalerate, a, a-isobis- (a-1metnlanentiitrile), a, a-azobis- (a-ethylbutyronitrile), a, aazobis- (cyclopropylpropionitrile ), a, a-azobis- (a, y-dimethylcapronitrile) and 1,1-azobicycloheptaicarbonitrile. Azobisisobutyropitrile and azobis- (a, 7-dimethylvaleronitrile) are the most preferred azozoedipieces.

Effective initiators of the free radical process are not only ditreg-alkyl peroxides, for example tert-butyl nerexium, but also dialkyl peroxides, alkyl peroxides, alkyl neroxy esters and diacyl non-peroxides. Examples of peroxide organic compounds include greg-butyl, benzoyl, lauryl, capryl, acetyl, methyl ethyl ketone, dicumyl, pinava, cumene hydroperoxide, citrus, gret-butyl, p-menthane, peroxide / peroxide, peroxide / g-chlorobenzoyl, and 2,4-dichloro-benzoyl hydroxides; , diperoxide dibenzal, methyl isobutyl ketone peroxide and cyclohexanol. The most preferred peroxide compounds are peroxide and gret-butyl hydroperoxide. Of the free radical type initiators, percarbonates can also be used, peracids are complex peracid sugars, which are 10 hours at temperatures below the half-life.

Examples of these initiators include isopropyl percarbonate, diisopronyl peroxydicarbonate, tert-butylperoxyisopropyl percarbonate; Treg-butyl ester nerbenzoynoy acid Greg-butyl ester neroksitrimetiluksusnoy acid (Treg-butylperoxy pivalate), heat-butyl ester with peracetic acid, di-Greta butildiperftalat, tert-butilpermaleinova acid, Greg-peroxyisobutyrate and Greg-butilperftaleva acid.

The olefinic hydrocarbon feed may contain one, two or more olefinic bonds, such as 1,3-butadiene, isoprene, 1,5-hexadiene, 1,7-octadiene, vinylcyclohexene. The carbon atoms of the olefinic bond may contain linear and branched alkyl, cycloalkyl, aryl, aryl-alkyl and aryl substituents. In addition, they can be substituted for cyano, carboxyl, carbonyl, halide, greg-amine, sulfoxide, sulfone group, hydroxyl, ether (for example, alkoxy, aryloxy, aralkoxy, alkylaryloxy), simple thioether, ester (for example, carbalkoxy) and amide group. The hydrocarbon may also contain any organic compound of trivalent or pyvalent phosphorus associated with it.

Primary mercaptans are obtained from a-olefrosts containing 1-30 carbon atoms, for example, from 1-butene, 1-butanethiol is obtained in high yield. Similarly, 1-octanethiol and 1-dodecanethiol are synthesized from 1-octene and 1-dodecene, respectively.

Olefins used to synthesize mercaptans include ethylene, propylene, 1-butene, isobutene, 1-pentene, 2-pentene, 1-hexene, 1-octene, 1-nonene, styrene, 1-dodecene, 1-decene , 1-tridecene, 1-undecene, 1-heptadecene, 2-methylhex-, 3-methyl-2-ethyl-1-pentene, 3 W-dime 10 tnl-1-heptene, 4-.methyl-2-pronyl-1 -pentene, vinylcyclohexane, 3-phenyl-1-pentene, 1,3-butadiene, 1,3-pentadiene, 1,5-hexadiene, 1,6-octadiene, 3,4-diethyl-1,5-hexadiene, dimer trimer and propylene tetramer, 3-chloro-1-hexane, 5-nitro15 1-pentene, p-chlorostyrol, and-nitrostyrene and 5 cyano-1-pentene.

Of the olefins containing substituents on the carbon atoms linked by a double bond, mention may be made of vinyl chloride, vinyl bromide,

0 3-ethoxypenthen-2, 2-chloreicosene-2, 2-butenylphenyl ethyl ether, methyl vinyl ether (methyl vinyl oxide), divinyl ether, acrylic acid, ethyl acrylate, methyl methacrylate,. Maleic acid, ethyl methacrylate, 2-cya5 but-2-butene.

Synthesis can be carried out batchwise and continuously or in a series of reactors arranged in series. All reagents (hydrogen sulfide, olefin, free-di-dipole initiator and promoter) can be loaded into one reactor at the same time, lefin and hydrogen sulfide can be introduced in separate streams into a continuously operating reactor system, to which initiator and promoter are also added, which are introduced into the reactor independently or with olefin or hydrogen sulfide. The reaction can be carried out in a coil reactor, into which the initiator is injected at various points. It is possible And € 0 to use organic compounds of trivalent phosphorus used as promoters directly by adding the corresponding phosphine to the olefin. The amount of promoter - organic

5 of the trivalent phosphorus compound depends on the chemical nature of the promoter, the amount of free-radical initiator and the temperature. It should be sufficient to promote the reaction, but should not be

0 above the value at which the promoter begins to react with the mercaptan formed. Typically, the amount of promoter is 0.001-1.0 mol per 1 mol of the starting olefin. When the concentration of the promoter in the reaction

5 mixtures above 1.0 mol, the yield of mercaptan drops sharply due to the interaction of the promoter with mercaptan.

The number of free-radical initiator depends on the type of initiator, the number

promoter and reaction temperature. In most cases, the amount of initiator is 0.0001-0.25 mol per 1 mol olefin. The preparation of mercaptans is preferably carried out in an inert diluent medium, for example, saturated aliphatic, cycloaliphatic and aromatic hydrocarbons, such as pentane, hexane, heptane, octane, cyclohexane, benzene, toluene, xylene, petroleum ether, tetralin.

To synthesize a stainless steel autoclave, equipped with a glass test tube, acting as a glass lining, and equipped with a Bpod gas tube, a thermocouple, a coke, and a safety valve, load a catalyst, 500 ml of inergly diluent (for example, benzene, or hexane), hermetically close it, pump out the air, cool the autoclave with liquid nitrogen, introduce the appropriate olefin and hydrogen sulfide, heat to the required temperature for 1 to 3 hours, and withstand a certain time. The maximum overpressure in the autoclave at 90-100 ° C and the use of ethylene reaches 1200 psi. inch; when using propylene under the same conditions, 800 psi. inch. The overpressure in an autoclave depends on the number of carbon atoms in the starting olefin: the larger the molecular weight of the starting olefin, the lower the overpressure in the autoclave.

Examples 1-8. In all experiments, 0.2 mol of olefin, 1.0 mol of hydrogen sulfide, 0.1 g of azobisisobutyronitrile dissolved in 50 ml of benzene, and 2 g of promoter are used. The reaction temperature is 90-100 C.

The results are shown in

tab. one.

Table 1

 Used 1 g pro1 otor,

Examples 9-11. At PO-140 ° C, experiments were carried out using other peroxide initiators instead of azobisisobutyronitrile.

In all experiments, 0.2 mol of ethylene, 1.0 mol of hydrogen sulfide, 0.5 g of a peroxide ipitator and 2 g of promoter are used.

The results of the experiments are given in table. 2

The data given in table. 1 and tab. 2 show that the promoting effect of the proposed organophosphorus compounds is manifested when the reaction is initiated ;: both azobisisobutyronitrile and organic peroxide compounds.

Example 12-18. Using different amounts of the free-radical initiator and promoter, the dependence of Table 2 is determined.

ten

the course of the mercaptan and the conversion of the olefin on the amount and ratio of these substances in the reaction mixture. In all experiments, 0.2 mol of ethylene and 1.0 mol of hydrogen sulfide in 50 ml of benzene were used. The reaction temperature is 85-95 ° С, the duration is 6 hours. The results of the experiments are given in table. 3

Table 3

25

thirty

The results show that the introduction of the proposed promoter can significantly reduce the amount of initiator in the reaction mixture without a noticeable decrease in the yield of mercaptan and the conversion of olefin. Even with a decrease in the amount of the initiator in the reaction mixture by 10 times, the conversion of the olefin did not decrease by one percent, and the yield of the mercaptan ulgenshils is very small. In the absence of a promoter in the reaction mixture, the yield of mercanth 11a is so small that the product cannot be isolated by conventional methods. The ethylene conversion is 8%. When the initiator content in the mixture is low, it is possible to have:; the amount of the propeller g:; tin ;; and even more without significant change in the olefin conversion values and the mercaptan output. However, when the amount of promoter in the reaction mixture is less than 1.0 g by 0.2 mol of ethylene, its promoter effect begins to decrease, which results in less conversion of the olefin and a decrease in the yield of mercaptan. Even with the use of 0.5 g of the proposed promoter, the conversion of ethylene is significantly increased by slightly increasing the amount of initiator in the reaction mixture. Examples 21-23. Determines addiction

olefin conversion and mercaptan yield versus reaction temperature using the same amount of initiator and promoter. In each experiment, except for the control, 1.0 g of trimethylphosphite, 0.01 g of azobisisobutyronitrile, 0.2 mol of ethylene and 1 m mol of hydrogen sulfide in 50 ml of benzene were used. The results of the experiments are given in table. 4. Table 4 Control experience without promoter. Propylene is used as an olefin. Experiments show that the introduction of the proposed promoters into the reaction mixture allows the process to be carried out at lower temperatures than in the absence of the latter, and to obtain one hundred percent conversion of olefin and a high yield of primary mercaptan in a shorter period (sometimes less than 1 hour). Examples 28-30 The reaction was conducted at 95 ° C and a 5: 1 molar ratio between hydrogen sulfide and ethylene using 0.008 mol of trimethyl phosphite and 0.00006 mol of azobisisobutyronitrile per 0.2 mol of ethylene. The results of the experiments are shown in Table 5. Table 5 e results show that with a significant reduction in reaction time, mercaptans can be obtained, with a sufficiently high yield with one hundred percent conversion of olefin.The use of the proposed promoter can shorten the reaction time (the time required to achieve one hundred percent conversion of olefin) by at least 10 times compared to in a known manner when such a promoter is not used. Examples 31 and 32. The reaction is carried out in the absence of a diluent at 90 ° C for 1 hour, using 0.2 mol olefin, 1.0 mol hydrogen sulfide, 0.01 g azo bisisobutyronitrile and 1.0 g of trimethylphosphite. When using ethylene and propylene, the yield of mercaptan is 84% and 71%, respectively. Conversion of olefin in both cases x 100%. The subject matter of the invention is 1. A method for producing mercaptans by reacting hydrogen sulfide with a hydrocarbon containing at least one double olefinic bond in the presence of a free radical type initiator and promoter, followed by isolating the target product in a known manner, characterized in that, in order to increase the yield of primary mercaptans, an azo or a peroxide compound is used as an initiator, and an organic compound of trivalent phosphorus is used as a promoter, its formulas are ((YY). R (X), R where X, Y and Z are chalcof oxygen elements with an atomic weight of 14–33; a, b, s - O or 1; R, R, - hydrocarbon radicals containing 1-20 carbon atoms. 2. A process according to claim 1, characterized in that 0.001-1.0 mol of organic phosphorus compound is used per I mol of the starting olefin. 3. Method according to paragraphs. 1 and 2, characterized in that the process is carried out in an inert diluent medium.