US1782111A - Method of manufacturing tetra-alkylated thiuramdisulphides - Google Patents

Description

Patented Nov. 18, 1930 UNITED STATES PATENT o IcE HAROLD s. ADAMS, or LAncHivron'r, new YORK, nn LUDWIG'MEUSER, or Boom)" BROOK, NEWJERSEY, Assieivonsmo Tris NAUGATUCK CHEMICAL COMPANY, 'OF NAUGATUCK, CONNECTICUT, A conroiari'rion or. CONNECTICUT METHOD OEMANUFACTURENG TE rRaALK LATED THI nAMDISULPHIDES No Drawing.

When a di-alkyl dithiocarbamate isoxi dized to a thiuramdisulphide vby-treatment w th a halogen-or other oxidizing agent, two

molecules of amine are simultaneously-liberated. If the reaction be carried out with pure materials, the liberated amine will naturally be a secondary amine. It the-reaction is carried out by treating'a mixture of primary, secondary and tertiary amines with carbon disulphide, tion may be composed partially of secondary amine but where considerable tertiary amine v is present, the tertiary amine will remain as free amine. When oxidizing agents other than halogens are used, the amine or amlnes liberated or not reacted upon during the oxidation'are liable to oxidation, with .the resultthat the amineisfdestroyed and at. the same time a portion of the oxidizing agent is also used up; This leads to economical. difficulties and low yields of thiuramdisulphide .based upon the amount of amine originally employed. By maintainingthe reaction mixture at a low temperature, say (3., the

amines liberated ornotreacted with are less.

liable to oxidation. If the oxidizing agentbe introduced very slowly, the extent of oxidation of the amines may bereduced, but even so there is still a considerable loss of valuable.

raw materials. v v o I o I The present inventionrelatesf primarily to methods of protecting from oxidation the amines liberated in the course of theoxidation of dithiocarbamates to form disulphides. 7

Another obj ect of the inventionis to provide an I improved 'method' for manufacturing tetra-alkylated'thiuramdisulphides. A further object is to oxidize dithiocarbamates undersuch conditions that free amines injthe reaction mixtureare not destroyed. Another objectoi the invention is to provide animprovedand economical method for manufac turing tetra alkylated thiuramdisulphides by carrying out the oxidation of suitable dithiocarbamates With anoxidizing agent in the presenceof a reagent adapted toiorm'a ful raw material wlth the amines liberated during, or not entering, the r'eaot'ion of oxidation. Another object is to carryout the oxidation otsuitable dithiocarbamates to corthe'amine liberated upon oxida use- Applicaticnfiled August 4, 1925. Serial No. 48,669.

esponding thiuramdisulphides with a nonhalogen oxidizing agent in the presence of an inorganic acid. I I VVith' a preferred method in mind, but without desiring to place undue limitations upon the scope of the invention beyond What may be required by the prior art, the invention consists in'treating a secondary amine or mixture of amines containing secondary amine with carbon bisulphide to form the corresponding dithio'carbamate, oxidizing the dithiocarbamate with a non-halogen oxidizing agent in the presence of a reagent adapted to protect the liberated amine from oxidation, and continuing the several reactions until substantially all of the secondary amine has been converted into thiuramdisuhohide.

Morespeciiically, the invention consists in carrying out the oxidation of the dithiocarbamate of a secondary amine to a thiuramdisulphide by means of hydrogen peroxide in the presence of sulphuric acid. The invention alsoincludes carrying out such oxidation processfin thepresence of an excess of carbon 'disulphide, orvby theaddition of carbon bisulphide insuch a manner as to cause substantially all of the secondary amine present to become converted into tetra alkylated thiuramdisulphide.

i The salts of amines, particularly the amine salts of strong acids, are much less susceptible to oxidation than the free amines themselves. The present invention therefore aims to prepare such amine salts durlng the course of the reaction, as the amines are liberated, and thereby to'prot-ect the amines againstoxidation and loss, both of amines and of oxidizing agent." When halogen oxidizing agents are used, this 'is' accomplished automatically, for the halogen in'the presence of water gives rise ,to a halogen acid. However, the halogen oxidizing agents are expensive,

cause undesirable side reactions, and have other disadvantages. Hydrogen peroxide is a satisfactory oxidizing agent, but does not automatically neutralize and thus protect the amines which it liberates during the oxidation of a dithiocarbamate into a. thiuramdi- If an equivalent amount ofa suitsulphide.

suchas hydrochloric acid or-sulable acid,

R,Nn+1no, 3 solution) 00, mmnamsowmoaaa, solution) No reaction The oxidizing agent is most conveniently prepared by diluting 98% sulphuric acid to a convenient strength such as 1030% and cooling thoroughly before adding hydrogen peroxide thereto. This. avoids the rise of temperature which would occur were the acid added to the peroxide, or theperoxide added to the concentrated; acid.

As an illustration of the invention as applied to substantially pure dimethyl amine,

the following is given: A water solution containing 180 lbs. of dimethylamine is caused to react with 152 lbs. of carbon disulphide. The alkyl dithiocarbamate thus formed is then oxidized to tetramethylthiuramdisulphide byadding with stirring and cooling, 453 lbs. of 7 hydrogen peroxide to which has "been added l03 lbs. of 98% sulphuric acid with suitable dilution as indicated above. The tetramethylthiuramdisulphide formed "by the oxidation may thenbe filtered out, avashed and dried. Approximately of the dimethylamine" appears as tetramethylthiuramdisulphide; But the remainder of the amine, which is liberated during tllGOXllltion reaction, has become automatically combined with the sulphuric acid to form. dimethylamine sulphate. This dimethylamine sulphate remains in thefiltrate and is recoverable. If desired. the filtrate containing the lbs. of dimethylamine as sulphate may be treated with 85 lbs. of sodium hydroxide or the equivalent amount of another alkali and liberated as the tree amine. The free amine may be distilled oil and absorbed in water and used again. Another convenient method of handling the dimethylamine sulphate is to free it by treatment with an alkali hydroide and cause the tree amine to react with additional carbon bisulphide to form dithiocarbamate, and repeating the oxidation as set forth in the above example. This may be continued until practically all of the dimethylamine has been converted into tetramethylthiuramdisulphide. Towards the latter stages tertiary amine or another base may be introduced.

While dimethylamine has been given as an example, it is of course understood that other secondary amines may be employed with equal facility. The invention may also be practiced upon a mixture of primary, secondary and tertiary amines or of primary and secondary amines orof secondary and tertiary amines or secondary amines and bases in solution which are not affected by the carbon disulphide or the oxidation reactions. The claims are understood as comprehending secondary amine or a mixture containing secondary amine.

As anexample of carrying, out the invention with a mixture of amines, the following may be given: A water solution of dimethylamine,trimethylamine and methylamine, containing in total 19.3 lbs. of nitrogen, may be treated with 52.4 lbs. of carbon bisulphide. The primary and secondary amines are converted into the corresponding dithiocarbamates while the tertiary amine is not changed.

To the reaction mixture, with stirring and cooling, 156 lbs. of a 7.5% solution of hydrogen peroxide containing 34.6 lbs. of 98% sulphuric acid are added. The secondary amine is converted into the corresponding tetraalkylated thiuramdisulphide, the primary amine into the corresponding mustard oil, and'the tertiary'amine remains in solution as sulphate. The thiuramdisulphide is then filtered out, freed from the mustard oil, washed. and dried.

The invention may also be carried out by treating dimethylamine or other secondary amine with an excess of carbon bisulphide, either by starting with an excess of the carbon bisulphide,but preferably adding the necessary excess after the oxidation. Awater solution containing 90 lbs. of dimethyl amine may be treated with 76 lbs. of carbon bisulphide. The amine is converted into the corresponding dithiocarbamate which is then oxidized by treatment with l53 lbs. of a 7.5% solution of hydrogen peroxide, the latter being run in slowly with stirring and cooling. At the same time an additional 6 lbs. of

carbon bisulphide may be run in at such rate it that the total amount of carbon bisulphide is added in approximately the same time as that required for the addition'of the total amount of hydrogen peroxide. The tetramethylthiuramdisulphide thus formed may be filtered out, washed and dried. The simultaneous formation of dithiocarbamate from the dimethylamine liberated during the OXlda- Q' tion reaction, and the oxidation of thedithim carbamate to the corresponding tetramethyl j thiuramdisulphide may be continueduntil approximately all of the dimethyl aminehas been converted.

Having thus described our invention wha we claim and desire to protect by Letters Pat entis: 1 I f 1. A process for making tetra alkylated thiuramdisulphides which comprises treating.

a secondary amine with an excess ofcarbon disulphide, oxidizing the dithiocarbamate thus formed to a thiuramdisulphide and causing the liberated secondary amine to react With the excess carbon disulphide to form additional 'dithiocarbamate, oxidizing the dithiocarbamate as it forms into further thiuramdisulphide and recovering the thiuramdisulphide from the reaction mixture.

2. A process for making tetramethylthiur amdisulphide which comprises treating dimethylamine With an excess of carbonjdisulphide, oxidizing the alkyl dithiocarbamate thus formed to tetramethylthiuramdisulphide and continuously causing the liberated dimethylamine to be convertedinto additional 1 alkyl dithiocarbamate byreaction with the excess carbon disulphide and then oxidized to tetramethylthiuramdisulphide until substans tially all the dimethylamine has been con verted, and recovering tetramethylthiuramdisulphide from the reaction mixture.

3. A process for making tetramethylthiuri amdisulphide which comprises treating .di-

'methylamine with carbon disulphide, oxidizo I ing the alkyl dithiocarbamate thus formed to tetrainethylthiuramdisulphide with hydro- 1 gen peroxide and simultaneously causing the liberated dimethylamine to be converted into additional alkyldithiocarbamate by the addition of excess carbon disulphide and oxidized to tetramethylthiuramdisulphide until sub,-

stantially all the dimethylamine has been con sugmide from the reaction-mixture.

igned at New York, county of New York, 1

and State 'of New York, this 31st day of July,

, Signed. at Naugatuck, county of New Haven, State of Connecticut, this 30th day of July,

-LUDWIG MEUSER. i i

HAROLD s. ADAMs m 1