Method of producing polymeric phenazonium compounds
View Patent ↗A process of making a polymeric phenazonium compound having the general formula: wherein R 1 , R 2 , R 4 , R 5 , R 6 , R 8 , and R 9 are the same or different, and represent hydrogen, a low alkyl or a substituted aryl, R 3 starts with NH 2 and is diazotized followed by a polymerization, R 5 and R 8 may alternatively represent monomeric or polymeric phenazonium radicals, R 7 is a carbon in the aromatic ring, R x and R y represent any combination of CH 3 , C 2 H 5 , and hydrogen, except that R x and R y cannot both be hydrogen, A is an acid radical, and n is an integer from 2 to 100, preferably from 2 to 20 is described. The polymeric phenazonium compound is usable as an additive in a metal plating bath comprising copper. The method includes the steps of a) dissolving an effective amount of an amino compound in a formic acid solution; b) adding a nitrite salt to diazotize the amino compound; and c) adding sulfamic acid to neutralize any excess nitrous acid that may be formed in step b), whereby a polymeric phenazonium compound is produced with a smaller quantity of unreacted monomer remaining in the end product than those produced using methods of the prior art.
1. A process of making a polymeric phenazonium compound to be used in a metal plating bath comprising copper, commencing with the general formula:
Wherein R 1 , R 2 , R 4 , R 5 , R 6 , R 8 , and R 9 are the same or different, and represent hydrogen, a low alkyl or a substituted aryl, R 3 starts with NH 2 and is diazotized followed by polymerization, R 5 and R 8 may alternatively represent monomeric or polymeric phenazonium radicals, R 7 is a carbon in the aromatic ring, R x and R y represent any combination of CH 3 , C 2 H 5 ,
and hydrogen, except that R x and R y cannot both be hydrogen, A is an acid radical, and n is an integer from 2 to 100, the method comprising the steps of:
a) dissolving an effective amount of an amino compound in a formic acid solution;
b) adding a nitrite salt to diazotize the amino compound; and
c) adding sulfamic acid to neutralize any excess nitrous acid that may be formed in step b),
whereby a polymeric phenazonium compound of the general formula specified above is produced.
2. The method according to claim 1 , wherein n is an integer from 2 to 20.
3. The method according to claim 1 , wherein said amino compound is selected from the group consisting of 2-methyl-3-amino-7-dimethylamino-5-phenyl-phenazonium hydrogen sulfate, 2-methyl-3-amino-7-dimethylamino-5-phenyl-phenazonium chloride, 3-amino-7-dimethylamino-5-methyl-phenazonium acetate, 2-methyl-3-amino-7-phenylamino-5-phenyl-phenazonium hydrogen sulfate, 2-methyl-3-amino-7-dimethylamino-phenazonium hydrogen sulfate, 3-amino-7-methylamino-5-phenyl-phenazonium acetate, 2-phenyl-3-amino-7-ethylamino-5-phenyl-phenazonium chloride, 1,2,6,9-tetramethyl-3-amino-7-dimethylamino-5-phenyl-phenazonium hydrogen sulfate, 2,8-dimethyl-3-amino-7-diethylamino-5-tolyl-phenazonium chloride, and 2,9-diphenyl-3-amino-6-methyl-7-dimethylamino-5-phenyl-phenazonium hydrogen sulfate.
4. The method of claim 1 , wherein the nitrite salt is sodium nitrite.
5. The method according to claim 1 , wherein the amino compound is dissolved in the formic acid at a temperature of between about −10 to about 0 C.
6. The process according to claim 1 , wherein after step b) the reaction is warmed to at least 20 C.
7. The process according to claim 1 , wherein the concentration of the amino compound in the formic acid solution is between about 100 g/L and about 200 g/L.
8. The process according to claim 7 , wherein the concentration of the amino compound in the formic acid solution is between about 120 g/L and about 185 g/L.
9. The process according to claim 1 , wherein the process of producing the polymeric phenazonium compound does not include a step of neutralizing the polymeric phenazonium compound with a base.
10. The process according to claim 1 , wherein the concentration of polymerized phenazonium compound is between about 30 g/L and about 34 g/L.