Synthesis of diaminodinitropyridine
View Patent ↗A process for the preparation of diaminodinitropyridine or diaminodinitrobenzene by contacting an aminopyridine or aminobenzene with oleum and nitric acid, wherein the improvement comprises adding at least about 1% molar excess of nitric acid, based upon the aminopyridine or aminobenzene with stirring for at least two hours to form first the intermediate sulfonic acid, and then diaminodinitropyridine or diaminodinitrobenzene, and use of such products in the preparation of rigid rod polymers is disclosed.
1. In a process for the preparation of 1) diaminodinitropyridine or 2) diaminodinitrobenzene by contacting 1) an aminopyridine or 2) an aminobenzene, respectively, with oleum and nitric acid, wherein the improvement comprises adding, with stirring, at least about 1% molar excess of nitric acid based upon the aminopyridine or aminobenzene respectively, and stirring is continued for about two to about four hours to form first 1) aminonitropyridine sulfonic acid or 2) aminonitrobenzene sulfonic acid, respectively, and then 1) diaminodinitropyridine or 2) diaminodinitrobenzene respectively.
2. The process of claim 1 wherein the aminopyridine or aminobenzene is contacted with oleum prior to contacting with nitric acid.
3. The process of claim 2 wherein the nitric acid is added in two separate increments.
4. The process of claim 1 wherein the molar excess of nitric acid is from about 1% to about 3%.
5. The process of claim 1 wherein the diaminodinitropyridine contains less than 0.1% by weight of 26-diamino-3-notropyridine-5-sulfonic acid.
6. The process of claim 1 wherein the diaminodinitrobenzene contains less than 0.1% by weight of 26-diamino-3-nitrobenzene-5-sulfonic acid.
7. A composition comprising 26-diamino-3-nitropyridine-5-sulfonic acid produced by the process of claim 1 .
8. The composition of claim 7 prepared by contacting a diaminopyridine or diaminopyridine hemisulfate with oleum to form diaminopyridine sulfonic acid, and adding at least a 1% molar excess of nitric acid based upon the diaminopyridine to yield diaminonitropyridine sulfonic acid.
9. A process for purification of 1) diaminodinitropyridine which contains 26-diamino-3-nitropyridine-5-sulfonic acid or 2) diaminodinitrobenzene which contains 26-diamino-3-nitrobenzene-5-sulfonic acid comprising contacting 1) said diaminodinitropyridine or 2) said diaminodinitrobenzene respectively with oleum and at least about 1% molar excess of nitric acid based upon the diaminodinitropyridine or diaminodinitrobenzene, with stirring, and stirring is continued for about two to about 4 hours to yield 1) diaminodinitropyridine having less than about 0.1% by weight of 26-diamino-3-nitropyridine-5-sulfonic acid or 2) diaminodinitrobenzene having less than about 0.1% by weight of 26-diamino-3-nitrobenzene-5-sulfonic acid respectively.
10. The process of claim 9 wherein the nitric acid is added in two separate increments.
11. The process of claim 9 wherein the molar excess of nitric acid is from about 1% to about 3%.