US2466276A - Manufacture of thiocarbamyl chlorides - Google Patents

Description

Patented Apr. 5, 1949 MANUFACTURE OF THIOCARBAMY L CHLORIDES Edmond .l'. Bitter, Wyandotte, Mich., assignor to Sharples Chemicals Inc., a corporation of Delaware No Drawing. Application February 2, 1946, Serial No. 645,233

Claims. 1

heretofore been made by reaction of thiophosgene with amines, but this reaction does not provide a satisfactory procedure, in view of the fact that the thiophosgene is too difficult and expensive to make to constitute a satisfactory starting material.

The present invention rests upon the discovery that the thiocarbamyl chlorides can be made by the relatively simple procedure of chlorinating the corresponding thiuram sulfides. The thiuram sulfides which can be treated most effectively in practice of the invention may be represented by the following formula:

in which at is an integer and R1, R2, R3 and R4 are hydrocarbon substituents. R1, R2, R3 and R4 may be either alkyl or aryl substituents, but R2 and R4 will ordinarily be alkyl substituents in cases in which R1 and R3 are aryl substituents. The symbols R1 and R2 may represent between them a single polymethylene radical such as pentamethylene, and the symbols R3 and R4 another such radical. Thus, the compounds which may be successfully chlorinated in practice of the invention include tetra-alkyl, symmetrical di-alkyl-di-aryl, and di-polymethylene thiuram sulfides. In the chlorination of compounds of any of these types in the practice of the invention, there is a splitting of the thiuram sulfide and combination of chlorine with the thiocarbamyl radical to form the corresponding thiocarbamyl chloride, as indicated by the following equation, which illustrates the splitting and chlorination of a disulfide.

R R R \N-GSSGN/ +013 2 \NCCI+2S l l R R i In order to facilitate an understanding of the invention, it will first be described with reference to a typical operation by which tetra-ethyl thiu- The tetra-ethyl thiuram disulfide may be placed in a flask which is immersed in a hot water bath until melted. Chlorine gas may then be introduced beneath the surface of the melted thiuram sulfide product intermittently over a period of 15 minutes until half of the amount of chlorine necessary to effect the desired chlorination has been added. If the temperature at the beginning of the chlorination procedure is 75 C., this temperature may rise to 82 C., for example, during introduction of the chlorine. The flask may then be immersed in a water bath maintained at 40 C. and chlorination continued until the theoretically necessary quantity of chlorine has been added, the temperature being maintained between and C. during this continued chlorination. After the chlorination reaction has been completed, the reaction product is preferably maintained at a temperature between 50 and C. for two hours or longer to permit sulfur and a trace of amine hydrochloride to precipitate. The product may then be filtered at a temperature of 52 0., and the filtrate distilled under vacuum to yield di-ethyl thiocarbamyl chloride of a high degree of purity.

While chlorination of various substituted thiuram sulfides such as represented by the above formula and equation may be accomplished by direct treatment of the liquid or melted thiuram sulfide, just as in the case of the tetra-ethyl thiuram disulfide discussed above, it will be desirable in many instances to suspend or dissolve the particular thiuram sulfide to be treated in a suitable solvent or diluent which is relatively inert under the conditions of the reaction. Thus, the thiuram sulfide maybe suspended in carbon tetrachloride or dissolved in benzene or chloroform, and then subjected to chlorination by introduction of a stream of gaseous chlorine or other chlorinating agent providing free chlorine.

The chlorination reaction may be performed upon thiuram sulfides of various degrees of sulfur content. Thiuram mono-sulfides, tri-sulfides or tetra-sulfides may, for example, be chlorinated in the same manner as the corresponding disulfides, the only difference in chlorination of these other sulfides being that, in the case of the mono-sulfide, only a single molecule of the desired thiocarbamyl chloride is formed by the chlorination, and in the case of triand tetrasulfides, a larger quantity of sulfur is liberated incident to formation of two molecules of thiocarbamyl chloride from a single molecule of the thiuram sulfide than is the case in chlorination of the disulfide. While the various thiuram sulfides may be chlorinated under the conditions discussed above in a manner closely analogous to that discussed by way of illustration with respect to chlorination of tetra-ethyl thiuram disulfide, it should be understood that a wide variety of conditions may be adopted in practice of the invention, both with respect to chlorinating agent, conditions of the reaction and material to be chlorinated. The following examples illustrate a number of variants which may be adopted in practice of the invention.

Example I 402 grams (1.36 moles) of tetra-ethyl thiuram disulfide were dispersed in 800 ml. of carbon tetrachloride. 96.5 grams (1.36 moles) of chlorine gas were bubbled into the resulting suspension over a period of about minutes, the temperature rising from 32 C. to 67 C. during this interval. By the time 49 grams of chlorine had been added, the remaining tetra-ethyl thiuram disuliide had become dissolved, with the result that a clear, reddish brown solution was formed. When 76 grains of chlorine had been added, the solution became cloudy due to formation of free sulfur. At the conclusion of the chlorination, sulfur was precipitated by cooling the reaction mixture on an ice bath. One-third of the solvent was then stripped off under vacuum and the solution was kept overnight at about 10 C. to precipitate further sulfur, which was removed by filtration. One-half of the remainin solvent was then stripped ofi and the residue was cooled on an ice bath and filtered. 200 grams of yellow crystals constituting crude di-ethyl thiocarbamyl chloride were obtained, having a melting point of 48-50 C. The filtrate resulting from the preceding operation was then stripped of solvent to give a second portion of product contaminated with sulfur. This crude product was remelted at 50 C., and the small quantity of sulfur precipitated in this remelting operation was removed. Upon solidification of the product, 202 grains of a light brown crystalline mass, M. P. 46.5-48.0 C. were obtained. This material was distilled at 113 C. at 10 mm. Hg. pressure. Analysis showed 23.31% Cl, 8.89% N, 21.01% S. compared to theoretical values of 23.4% C1, 9.2%% N, and 21.1% S. The total yield was 402 grams or 98%.

Example II 1118 grams (4.65 moles) of tetramethyl thiuram disulfide were dispersed in 3 liters of carbon tetrachloride. 3305 grams 1.65 moles) of chlorine gas were bubbled into the resulting suspension during a period of three hours, the temperature rising from 25 C. to 65 C. during this chlorination. No external cooling was provided. The chlorination reaction resulted in formation of a relatively clear, deep orange solution. Toward the end of the reaction, the solution became milky, due to precipitation of sulfur. The flask containing the reaction product was immersed overnight in a water bath maintained at 10 0., and the product was decanted from the large mass of sulfur thus precipitated. The solvent was removed by vacuum distillation and the residue of this distillation was maintained at 50 C. for 30 minutes to precipitate a further small amount of sulfur. 1075 grams of crude dimethyl thiocarbamyl chloride (95.3% yield) were then decanted off. Upon purification, this material was found to have an M. P. of 42.5-43.5 C.

4 Example III 296 grams (0.73 mole) of tetra-butyl thiuram disulfide were dissolved in 500 ml. of carbon tetrachloride. grams (0.73 mole) of chlorine gas were bubbled into the resulting suspension over a period or 20 minutes. The temperature rose from C. to 45 C. during introduction of the first 26 grams of chlorine, and the flask was then immersed in an ice bath and the reaction completed by introduction of the remaining 26 grams of chlorine to the reaction mixture maintained at about 30 C. Upon removal of free sulfur and solvent as in the preceding examples, a dark brown filtrate of crude di-butyl thiocarbamyl chloride weighing 260 grams (87% of theory) was obtained.

Example IV 148 grams (0.5 mole) of tetra-ethyl thiuram disulfide were suspended in 500 m1. of carbon tetrachloride. 67.5 rams (0.5 mole) of sulfuryl chloride were dissolved in 100 ml. of carbon tetrachloride, the resulting solution was added to the suspension of tetra-ethyl thiuram clisulfide over a period of 25 minutes during continued stirring of the reaction mixture. The resulting chlorination reaction was exothermic, the temperature rising from 25 C. to 36 C. during the course of the reaction. The stirring was continued for additional minutes at room temperature, with slow evolution of sulfur dioxide. The material was then heated with a low flame for 30 minutes and refluxed for one hour, and allowed to stand overnight at room temperature. About 2 grams of amorphous sulfur was filtered from the product.

The solvent was removed by vacuum distillation over a hot water bath, leaving a solid crystalline residue upon cooling. This was heated to 60 C. and the melted product was decanted from 40 precipitated sulfur, yielding upon coolin 151 grams (99.7% of theory) of crude di-ethyl thiccarbamyl chloride, MP. 48-4-9 C.

Example V 208 grams (1.0 mole) of tetra-methyl thiuram mono-sulfide were dispersed in 675 ml. of carbon tetrachloride. 76 grams (1.56 mole) of chlorine gas were bubbled into the resulting suspension over a period of one hour, and the temperature rose from 23 C. to 50 C. during the course of the chlorination. During introduction of the last half of the theoretical quantity of chlorine, the solution resulting from the chlorination already accomplished was placed on an ice bath, with the result that the chlorination was completed at a temperature of about 40 C. A large quantity of sulfur precipitated at the end of the reaction. Upon removal or" sulfur and solvent as in previous examples, 132.5 grams (53% of theory) of dimethyl thiocarbarnyl chloride were obtained.

Example VI 152 grams (0.5 mole) of tetra-methyl thiuram tetra-sulfide Were dispersed in 500 ml. of carbon tetrachloride. 35.5 grams (0.5 mole) of chlorine gas were bubbled in over a period of 20- minutes, with a resultant rise in temperature from 23 C. to 52 C. This example presented a contrast to the chlorination of tetra-ethyl thiuram disulfide, as in the preceding examples, in that a clear solution was not obtained at'any time during the course of the reaction of the present example, due to splitting out of free sulfur. Solvent and sulfur were removed as-in preceding examples, and the resulting di-methyl thiocarbamyl ch1o-,

ride weighed 58 grams (94% of theory), M. P. 41.543.0 0., as compared to a melting point of 42 C. assigned to this compound by Beilstein.

Example VII 148 grams (0.5 mole) of tetra-ethyl thiuram disulfide were dissolved in 500 ml. of benzene. 35.5 grams (0.5 mole) of chlorine gas were bubbled in over a 15 minute interval, the temperature rising from 25 C. to 60 C. Upon removal of sulfur and solvent, 142 grams (93.8% of theory) of crude di-ethyl thiocarbamyl chloride were obtained.

Example VIII 148 grams (0.5 mole) of tetra-ethyl thiuram disulfide were dissolved in 500 ml. of chloroform. 67.5 grams (0.5 mole) of sulfur monochloride were dissolved in 100 ml. of chloroform and the resulting solution was added to the tetra-ethyl thiuram disulfide solution over a period of minutes, with continued stirring. The temperature rose from 21 C. to 45 C. during introduction of the sulfur monochloride. The resulting solution was refluxed for one hour at 62 C. and then cooled and filtered. Upon purification as in preceding examples, 119 grams (79% yield) of crude di-ethyl thiocarbamyl chloride were obtained as a light brown crystalline material, M. P. 47-495 C.

Example X 148 grams (0.5 mole) of tetra-ethyl thiuram disulfide were placed in a flask which was immersed in a hot water bath until the tetra-ethyl thiuram sulfide had melted. No solvent was added. Chlorine gas was bubbled into the melted material intermittently over a period of minutes until about half of the theoretically required amount of chlorine had been added. The temperature rose from 75 C. to 82 C. during this period. The flask was now immersed in a water bath maintained at 40 C., and introduction of chlorine was resumed until the theoretically required amount of chlorine had been added, the temperature of the melted product being kept between 50 C. and 60 C. during this completion of the chlorination reaction. Sulfur precipitated at the end of the reaction. The melted product was kept at a temperature between 50 C. and 70 C. for two additional hours to permit sulfur and a trace of di-ethyl amine hydrochloride to precipitate. The melted product was then filtered at 52 C. and cooled to obtain a crystalline mass weighing 142 grams (94% of theory), M. P. 47-49 0.

Example XI 192 grams (0.5 mole) of di-pentamethylene thiuram tetra-sulfide were dispersed in 700 ml. of carbon tetrachloride. 38 grams (0.53 mole) of chlorine gas were bubbled in over a minute interval, and the temperature rose from 23 C. to 48 C. during this chlorination. A cloudy precipitate was present throughout the course of the reaction, due to splitting out of free sulfur.

Upon purification as in preceding examples, '78.

grams (95.3% of theory) of pentamethylene thiocarbamyl chloride were obtained as an orange oil having a specific gravity at 20 C. of 1.250. The reaction of this example is represented by the following equation:

0112-05 GHQ-CH2 I OH; NCSSS-S-C 0H, 01,

CHz-C g S S CHz-C 2 CHrCHg 2o 2 NCC1+4S CHz-C s Example XII 75.5 grams (0.19 mole) of symmetrical diethyl diphenyl thiuram disulfide were suspended in 300 ml. of carbon tetrachloride. 13.7 grams (0.19 mole) of chlorine gas were passed into the resulting suspension over a period of about 20 minutes. The temperature rose from 25 C. to 47 C. during introduction of the chlorine. Upon purification of the product, 75 grams (98% of theory) of ethyl phenyl thiocarbamyl chloride were obtained in the form of pale yellow crystals, M. P. 55.5-56.5 C. The reaction of this example is represented by the following equation:

C2H5 02B! ZHE NOSSO C1 NCgl 25 00 5 S S C6H5 00115 S Example XIII Into a glass lined vessel Was charged 276 lbs. (0.931 lb. mole) of tetra-ethyl thiuram disulfide and 212 lbs. of benzene. The resulting slurry, maintained betweeen 50 and 60 C. and continuously agitated, was contacted with chlorine gas. 68 lbs. (0.958 lb. mole) of the latter were introduced through a partially submerged Well-pipe over a period of minutes. After cooling the mixture and separating the sulfur which deposited, 479 lbs. of solution were obtained, containing 251 lbs. (1.66 lb. mole) of diethyl thiocarbamyl chloride. This corresponded to a yield of 89.3%.

While the invention has been described above in terms of use of gaseous chlorine, the various chlorinating agents capable of liberating free chlorine and being used in non-aqueous media may be employed in practice of the invention. The following example illustrates use of a mixture of phosphorous pentachloride and phosphorus oxychloride in this connection:

Example XIV 151 grams of tetra-ethyl thiuram disulfide, 114 grams of phosphorus pentachloride and '75 grams of phosphorus oxychloride were placed in a flask equipped with a reflux condenser and heated by means of a water bath. After being maintained at a temperature of 95-100 C. for 3 hours the material was distilled under vacuum, 202.5 grams of yellow oil being taken overhead. The residue, crude diethyl thiocarbamyl chloride, which melted at 46-48 C. amounted to 48.1 grams. This corresponded to a yield of 53.5%.

Still further modifications are possible within the scope of the invention, and I do not therefore wish to be limited except by the following claims.

I claim:

1. In the manufacture of di-alkyl thiocarbamyl chlorides, the process comprising contacting una der. substantially non-aqueous conditions a tetraalkyl thiuram sulfide with chlorine until reaction occurs between said thiurarn sulfide and said chlorine to effect splitting of said thiuram sulfide and formation of the corresponding di-alkyl thiocarbamyl chloride.

2. In the manufacture of pentamethylene t iiocarbamyl chloride, the process comprising contacting under substantially non-aqueous conditions a di-pentamethylene thiuram sulfide with chlorine until reaction occurs between said thiuram sulfide and said chlorine to effect splitting of said thiuram sulfide and formation of the desired .pentamethylene thiocarbamyl chloride.

3. In the manufacture of di-alkyl thiocarbamyl chlorides, the process comprising contacting under substantially non-aqueous conditions a tetraalkyl thiuram di-sulfide with chlorine until reaction occurs between said thiuram sulfide and said chlorine to effect splitting of said thiuram sulfide and formation of the corresponding di-alkyl thiocarbamyl chloride.

4. In the manufacture of di-alkyl thiocarbamyl chlorides, the process comprising contacting under substantially non-aqueous conditions a tetraalkyl thiuram poly-sulfide with chlorine until reaction occurs between said thiuram sulfide and said chlorine to effect splitting of said thiuram. sulfide and formation of the corresponding dialkyl thiocarbamyl chloride.

5. In the manufacture of di-ethyl thiocarbamyl chloride, the process comprising contacting under substantially non-aqueous conditions tetraethyl thiuram disulfide with chlorine until reaction occurs between said thiuram sulfide and said chlorine to effect splitting of said thiuram sulfide and formation of di-ethyl thiocarbamyl chloride.

6. .A process for the production of substituted thiocarbamyl chloride which comprises subject'-- ing to the action of a chlorinating agent in a substantially non-aqueous system a thiuram so l-- fide having the formula:

cals' and taken collectively represent a single polymethylene radical, and in which R3 and taken individually represent one of a group consisting of alkyl radicals and aryl radicals and taken collectively represent a single polymeth 8 ylene radical, and continuing the action of said chlorinating agent until splitting of said thiuram sulfide occurs with the formation of substituted thiocarbamyl chloride.

7. The process of claim 6 in which the chlorinating agent is chlorine.

8. The process of claim 6 in which a: has a value of from 1 to 4.

9. The process of claim 6 in which each of R1, R2, R3 and R4 is an alkyl radical containing from 1 to 4 carbon atoms.

10. The process of claim 6 in which R1 and R2 collectively are a polymethylene radical, and R3 and R4 collectively are a polymethylene radical.

11. The process of claim 6 in which the chlorinating agent is chlorine, in which a; has a value of from 1 to 4, and in which each of R1, R2, R3 and R4 is an alkyl radical containing from 1 to 4 carbon atoms.

12. The process of claim 11 in which the reaction takes place in the presence of a diluent which is substantially inert under the conditions obtaining in the Zone of the reaction.

13. The process of claim 6 in which the chlorinating agent is chlorine, in which a: has a value of from 1 to 4, and in which R1 and R2 collectively are a polymethylene radical and R3 and R4 collectively are a polymethylene radical.

14. The process of claim 13 in which the reaction takes place in the presence of a diluent which is substantially inert under the conditions 0btaining in the zone of the reaction.

15. The process of claim 6 in which the reaction takes place in the substantial absence of a diluent but with the thiuram sulfide in liquid phase.

EDMOND J. BITTER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS