Methods of making compounds and mixtures having antidegradant and antifatigue efficacy
View Patent ↗Methods of making antidegradant compounds are disclosed in which a p-phenylenediamine is reacted with a dicarbonyl to thereby obtain a diimine, which is reduced to obtain mixtures comprising the antidegradant compound.
1. A method of making an antidegradant compound, the method comprising:
reacting a p-phenylenediamine corresponding to formula IV:
wherein X is selected from the group consisting of alkyl, aryl, alkylaryl groups and hydrogen;
with a dicarbonyl comprising glyoxal to thereby obtain a diimine;
isolating the diimine; and
reducing the diimine to thereby obtain a mixture comprising the antidegradant compound according to formula I:
wherein each X is independently selected from the group consisting of alkyl, aryl, alkylaryl groups and hydrogen; and
wherein R 1′ and R 3 are each hydrogen.
2. The method of claim 1 , wherein the p-phenylenediamine comprises 4-aminodiphenylamine.
3. The method of claim 1 , wherein the dicarbonyl further comprises diacetyl, and wherein the p-phenylenediamine and the dicarbonyl are reacted in the presence of a solvent and an acid catalyst.
4. The method of claim 3 , wherein the acid catalyst comprises one or more of formic acid, acetic acid, propionic acid, p-toluenesulfonic acid, camphorsulfonic acid, hydrochloric acid, sulfuric acid, and phosphoric acid.
5. The method of claim 1 , wherein the diimine is reduced by hydrogenation in the presence of: (a) a solvent, (b) a homogeneous or heterogeneous metal catalyst, and (c) one or more of hydrogen gas, formic acid, or a formic acid salt.
6. The method of claim 5 , wherein the solvent comprises methylisobutylketone and the mixture comprising the antidegradant compound further comprises N-1,3-dimethylbutyl-N′-phenyl-p-phenylenediamine.
7. The method of claim 5 , wherein the solvent comprises acetone and the mixture comprising the antidegradant compound further comprises N-isopropyl-N′-phenyl-p-phenylenediamine.
8. The method of claim 1 , wherein the diimine is reduced by a reducing agent comprising di-isobutyl aluminum hydride and lithium aluminum hydride in the presence of one or more of diethyl ether, tetrahydrofuran, or tert-butylmethyl ether.
9. The method of claim 1 , wherein the diimine is reduced by a reducing agent comprising sodium borohydride, lithium borohydride, and sodium cyanoborohydride in the presence of one or more of methanol, ethanol, and isopropanol.
10. The method of claim 1 , wherein the antidegradant compound comprises N,N′-(ethane-1,2-diyl)bis(N-phenylbenzene-1,4-diamine).
11. The method of claim 1 , wherein the dicarbonyl further comprises diacetyl.