Method for synthesizing 5-aminotetrazole
First Claim
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1. A process for preparing 5-aminotetrazole comprising the steps of:
- (a) combining cyanamide or dicyandiamide, an azide salt, and an acid reagent in water, wherein the combined ingredients form a reaction solution;
(b) heating the reaction solution to a temperature in the range from about 75°
C. to reflux temperature;
(c) acidifying the reaction solution with a strong acid after the reaction is substantially complete to protonate the 5-aminotetrazole product; and
(d) isolating the 5-aminotetrazole product.
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Abstract
A process of preparing 5-aminotetrazole ("5-AT") which proceeds at substantially neutral pH is disclosed. In the process, cyanamide or dicyandiamide and an azide salt are reacted at elevated temperature in the presence of an acid reagent. The acid reagent has a pKa in the range from about 3 to about 7. Large quantities of hydrazoic acid are not produced during the reaction. Upon completion of the reaction, the reaction mixture is acidified to a pH less than 3 to protonate the 5-AT. Several variations of the acidification step permit control of particle size and morphology. The precipitated particles are isolated to yield 5-AT.
19 Citations
46 Claims
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1. A process for preparing 5-aminotetrazole comprising the steps of:
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(a) combining cyanamide or dicyandiamide, an azide salt, and an acid reagent in water, wherein the combined ingredients form a reaction solution; (b) heating the reaction solution to a temperature in the range from about 75°
C. to reflux temperature;(c) acidifying the reaction solution with a strong acid after the reaction is substantially complete to protonate the 5-aminotetrazole product; and (d) isolating the 5-aminotetrazole product. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 41, 42)
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26. A process for preparing 5-aminotetrazole comprising the steps of:
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(a) combining cyanamide or dicyandiamide, sodium azide, and boric acid in water, wherein the combined ingredients form a reaction solution; (b) heating the reaction solution to about reflux temperature; (c) acidifying the reaction solution with a strong acid after the reaction is substantially complete, wherein the reaction solution is well agitated during said acidification step, wherein sufficient strong acid is used to lower the reaction solution'"'"'s pH to a value of 3 or below, and wherein the strong acid is selected from HCl, H2 SO4, H3 PO4, HNO3, Cl2 CCO2 H, Cl3 CCO2 H, F3 CCO2 H, HCO2 H, HClO4, and mixtures thereof; and (d) isolating the 5-aminotetrazole product. - View Dependent Claims (27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 43, 44)
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38. A process for preparing a salt of 5-aminotetrazole comprising the steps of:
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(a) combining cyanamide or dicyandiamide, an azide salt, and an acid reagent in water, wherein the combined ingredients form a reaction solution; (b) heating the reaction solution to a temperature in the range from about 75°
C. to reflux temperature;(c) adding to the reaction solution, a compound having a metal cation capable of forming the salt of 5-aminotetrazole and a counter ion (anion) which remains in solution after the salt of 5-aminotetrazole is formed, said adding step occurring after the reaction is substantially complete; and (d) isolating the salt of 5-aminotetrazole. - View Dependent Claims (39, 40, 45, 46)
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Specification