US2064784A - Thiazyl-dithiocarbamates - Google Patents

Description

Patented Dec. 15, 1936 UNITED STATES PATENT OFFICE No Drawing. Application November 14, 1934, Serial No. 752,988

9 Claims.

This invention relates to a new and useful class of chemical compounds and to a method of preparing them. More particularly, it concerns a class of materials which may be termed thiazyl esters of dithiocarbamic acids derived from secondary amines containing a hydrogenated furane ring. Although these compounds may perhaps be prepared by other methods as Well, they are preferably formed by reacting a suitable salt of a dithiocarbamic acid derived from secondary amines containing a hydrogenated iurane ring with a halogen aryl thiazole, While the compounds of the invention may be used for any purpose for which they are suited, it has been found that they are in general good accelerators of rubber vulcanization.

Although any halogen aryl thiazole may be employed, it has been found that the l-chlor aryl thiazoles are particularly well adapted for the purposes of the invention. Of the l-chlor aryl thiazoles, l-chlor 5-nitro benzothiazole in particular has been found to give rise to products which are excellent accelerators of the vulcanization of rubher. It will, of course, be understood that other halogen aryl thiazoles may be employed in the practice of the invention, examples being l-chlor 5-methoxy benzothiazole, l-chlor benzothiazole,

l-chlor tolyl thiazole, l-chlor 4-nitro benzothiazole, l-chlor 5-ethoxy benzothiazole, l-chlor 5- 30 methyl benzothiazole, l-chlor dimethyl benzothiazoles, l-chlor 4- or 5-chlor benzothiazole, 1- chlor 3-phenyl benzothiazole, l-chlor naphtho thiazoles and their nitro derivatives, l-chlor 4- chlor 5-nitro benzothiazole and l-chlor B-methyl 5-nitro benzothiazole, These halogen aryl thiazoles may conveniently be prepared by the process disclosed in United States Patent No. 1,757,- 930.

The dithiocarbamates used in this process may 40 be represented by the formula 45 wherein R represents a radical containing a hydrogenated furane ring such as tetrahydro furfuryl; R1 is any monovalent organic radical, alicyclic, aralykyl and alkyl radicals being typical; and M is any reactive metallic radical or equiva- 50 lent group, such as sodium, potassium or ammonium, which does not seriously impair the solubility of the dithiocarbamate in the solvent employed in effecting the desired reaction.

These dithiocarbamates are prepared by known 55 methods from secondary hydrogenated furyl amines. Amines containing a, hydrogenated furane ring are generally and most easily prepared by hydrogenation processes and are those amines in which the double bonds of the furane ring are saturated, fully or partially. While the sec- 5 ondary tetrahydrofurfuryl amines are the preferred class of amines applicable for use in the practice of the invention, it will be understood that the invention extends to the partially saturated amines such as the dihydro furyl amines, 10 which, while not generally preparable by hydrogenation processes, may be obtained by synthesis.

For the purposes of simplicity the term secondary amines containing a hydrogenated furane ring is used herein to refer to those amines con- 15 taining a fully or partially saturated furane ring, however prepared. In general, any secondary amine containing a hydrogenated furane ring and in which aliphatic characteristics predominate may be employed in the practice of the in- 0 vention.

Illustrative of salts of dithiocarbamates which may be employed in the invention are potassium di(tetrahydro alpha furfuryl) dithiocarbamate, sodium di(tetrahydro alpha furfuryl) dithiocarbamate, ammonium N-cyclohexyl tetrahydro alpha furfuryl dithiocarbamate, sodium N- ethyl tetrahydro alpha furfuryl dithiocarbamate, sodium p-methoxy cyclohexyl tetrahydro alpha furfuryl dithiocarbamate, potassium isopropyl tetrahydro alpha iurfuryl dithiocarbamate, sodium methyl tetrahydro alpha furyl dithiocarbamate, potassium phenyl tetrahydro-alpha furfuryl dithiocarbamate, sodium isobutyl tetrahydro alpha furfuryl dithiocarbamate, ammonium n-propyl tetrahydro alpha furfuryl dithiocarbamate, sodium tetrahydro furfuryl methyl dithiocarbamate, ammonium isoamyl tetrahydro alpha furfuryl dithiocarbamate, sodium tetrahydro furfuryl benzyl dithiocarbamate, sodium di(2-tetrahydro alpha furyl ethyl) dithiocarbamate, ammonium di(tetrahydro alpha furyl) dithiocarbamate, ammonium n-butyl tetrahydro furfuryl dithiocarbamate, sodium deca hydro naphthyl tetrahydro furfuryl dithiocarbamate, sodium beta phenyl ethylene tetrahydro furfuryl dithiocarbamate and potassium hexahydro tolyl tetrahydro furfuryl dithiocarbamate.

The desired halogen aryl thiazole may be caused to react with any dithiocarbamate derived from a secondary amine containing a hydrogenated furane ring to produce the corresponding reaction product. Although it is not known to be true in all cases, it is believed that the reaction proceeds according to the following general equation:

In certain cases other reactions may take place to the extent of perhaps 30%, yielding products which may or may not be separated, as desired, from the main product. If desired, the total composite product may be employed as such, as for example, as an accelerator of rubber vulcanization.

The reaction product of l-chlor -nitro benzothiazole and the sodium salt of di(tetrahydro alpha furfuryl) dithiocarbamate is an example of a compound falling within the scope of the invention. It may be prepared by refluxing l-chlor 5-nitro benzothiazole, di tetrahydro alpha furfuryl amine, carbon bisulphide and an alkali such as sodium hydroxide in a solvent such as ethyl alcohol. After a period of from one half hour to four hours the reaction product precipitates as a crystalline material which may be washed with water to remove the sodium chloride formed during the reaction. The crystalline material, 5- nitro benzothioazyl 1-di(tetrahydro alpha furfuryl) dithiocarbamate, upon being further purified by crystallizing from alcohol, precipitates in the form of cream colored crystals having a melting point of 116-118 degrees C. The product upon analysis is found to contain 9.38% nitrogen and 21.51% sulphur as compared with the theoretical percentages for 5-nitro benzothiazyl 1- di tetrahydro alpha furfuryl) dithiocarbamate of 9.58% nitrogen and 21.89% sulphur. The equation representing the reaction is probably as follows:

OzN- S, o

It will be understood that the dithiocarbamate derived from a secondary amine containing a hydrogenated furane ring may be formed separately and reacted with the halogen aryl thiazole.

It is believed that by the practice of the invention any aryl thiazyl ester of a dithiocarbamic acid derived from a secondary amine containing a hydrogenated furane ring may be prepared without regard to the nature of the substituents in the aryl ring or to their position therein. However, the halogen nitro benzothiazoles have been found to be capable of being employed in the invention somewhat more conveniently than certain of the other thiazoles, the presence of the nitro group apparently facilitating the reaction. It will be understood that the brom aryl thiazoles and other halogen aryl thiazoles may be substituted for the chlor benzo' thiazoles.v Similarly, the halogen naphthothiazoles may be substituted for the halogen benzothiazoles.

Conveniently any of these new accelerators or a mixture thereof may be added to any of the ordinary rubber mixes in an amount which may be determined according to the usual methods. It has been found for example that the compounds of thepresent invention are excellent CIT-OH;

delayed action accelerators in a rubber composition of the following formula:

Parts by weight Extracted pale crepe 100 Zinc oxide 5 Sulphur 3 Stearic acid 1.5 Accelerator 0.5

Samples of the compounded rubber made up in accordance with this formula were subjected to vulcanization by steam heat in a mold after which they were subjected to physical tests to ascertain their elasticity and tensile strength.

The results of these tests are given in the following table.

5 -nitroben2othiazyl 1 -di (tetrahydroalphafurjuryl) dithiocarbamate Cure m mt tenqfle Max. Modulus in kgs/cln mins. F in kgs/cm fi g 20/260 No cure It will be understood that by the term rubber is meant any of the ordinary forms of rubber such as latex, balata, gutta percha, reclaimed rubber, and the ordinary coagulated forms of the Hevea Brasiliensis tree. It is intended that the patent shall cover, by suitable expression in the appended claims, whatever features of patentable novelty reside in the invention.

This application is in part a continuation of application Serial No. 720,100, filed April 11,

furfuryl dithiocarbamic acid prepared from a tetrahydro furfuryl secondary amine.

4. A compound having the formula S R: 5 S

c-s- N N/ R1 wherein R1 is a radical selected from the group 10 consisting of tetrahydro furyl, tetrahydro furfuryl and beta tetrahydro furyl ethyl radicals, and R2 is hydrocarbon.

5. A compound having the formula wherein R is an ortho arylene group of the henzene and naphthalene series, R1 is a tetrahydro alpha furfuryl radical and R2 is an aliphatic hydrocarbon radical.

6. The 5-nitro benzothiazole ester of a di (tetrahydro furyl) dithiocarbamic acid.

7. A benzothiazyl ester of a tetrahydro fur-- furyl dithiocarbamic acid prepared from a tetrahydro furfuryl secondary amine.

8. A nitro benzothiazyl ester of di tetrahydro alpha furfuryl dithiocarbamic acid.

9. 5-nitro benzothiazyl l-di (tetrahydro alpha furfuryD dithiocarbamate.

HOWARD I. CRAMER.