Purification of aryltriazoles
OwnerRandolph K Belterinventor
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Abstract
Impure aryltriazoles such as benzotriazole and tolyltriazole that are contaminated with dark colored impurities can be purified by conversion to an aryltriazole acid salt by treatment with aqueous acid. The aryltriazole acid salt is water soluble whereas the dark colored impurities are not. The aryltriazole acid salt solution is separated from the dark colored impurities and the aryltriazole acid salt is isolated by precipitation. The free aryltriazole may be recovered by neutralization with base.
Claims17
A process for purifying an impure aryltriazole obtained by the diazotization reaction of an ortho-phenylenediamine with a nitrite, said impure aryltriazole containing dark and colored impurities, consisting of the steps:
- 1) dissolving at a temperature of 50 to 100° C. said impure aryltriazole with an aqueous solution of at least 1 equivalent of a 10-20% aqueous solution of strong acid to form two liquid phases, one phase of said two liquid phases comprising the cationic form of said aryltriazole in an aqueous solution and other phase of said two liquid phases comprising substantially all of the dark and colored impurities;
- 2) separating the one phase of the said two liquid phases comprising said cationic form of said aryltriazole in an aqueous solution from the other phase of the liquid mixture comprising substantially all of the dark and colored impurities;
- 3) cooling said one phase of the said two liquid phases comprising said cationic form of said aryltriazole in an aqueous solution to less than 50° C., thereby forming two new phases, one phase being the solid cationic form of said aryltriazole and the other phase being an aqueous solution;
- 4) separating said solid cationic form of said aryltriazole from said aqueous solution.
A process for purifying impure tolyltriazole obtained by the diazotization reaction of an ortho-toluenediamine with a nitrite, said impure tolyltriazole containing dark and colored impurities, consisting of the steps:
- 1) dissolving at a temperature of 80 to 100° C. said impure tolyltriazole with an aqueous solution of at least 1 equivalent of a 10-20% aqueous solution of sulfuric acid to form two liquid phases, one phase of said two liquid phases comprising the cationic form of tolyltriazole in an aqueous solution and the other phase of said two liquid phases comprising substantially all of the dark and colored impurities;
- 2) separating the one phase of the said two liquid phases comprising said cationic form of tolyltriazole in an aqueous solution from the other phase of the liquid mixture comprising substantially all of the dark and colored impurities;
- 3) cooling said one phase of the said two liquid phases comprising said cationic form of tolyltriazole in an aqueous solution to less than 50° C., thereby forming two new phases, one phase being the solid cationic form of said tolyltriazole and the other phase being an aqueous solution;
- 4) separating said solid cationic form of said tolyltriazole from said aqueous solution.
Dependencies are inferred from the claim text.