N-oxidation process for amino-polymers

The present invention relates to a process for the N-oxidation of polyamine polymers comprising treating said polyamine polymers with an effective amount of hydrogen peroxide in an aqueous or partly aqueous solution in the presence of heavy metal ion sequestrant and a metal oxide catalyst selected from tungstate, molybdate and vanadate.

EXAMPLES 
Example 1 
In a process in accord with the invention 1 part poly L-histidine (ex 
Sigma) was added to a solution of: 
0.07 parts sodium tungstate (ex Merck(TM)) 
0.24 parts *DTPMP solution (26% active) 
and 4.43 volumes hydrogen peroxide solution (30% w/v ex Merck(TM)) 
The pH of the mix was adjusted from approx. 7 to approx. 6 with 
hydrochloric acid (15% w/w) and the resultant mix heated to 60-65 deg. C 
(when all the solid dissolved) and held for 4 hours. 
Testing with starch/potassium iodide paper indicated excess peroxide still 
present and the pH was found to have fallen to approx. 4. 
The pale yellow solution was added, with agitation, to acetone (200 
volumes) to precipitate a white solid which was filtered off, washed and 
dried. 
The dried solid was redissolved in water (4.7 volumes) and the pH adjusted 
from approx. 5 to approx. 1-2 (with conc. hydrochloric acid) when a white, 
gelatinous precipitate formed. This was removed by filtration and the 
filtrate added, with agitation, to acetone (200 volumes) to re-precipitate 
the N-oxidised product, which was filtered, washed and dried. 
Proton nmr analysis confirmed the product to be essentially 100% N-oxidised 
product. 
Example 2 
In a process in accord with the invention 10 parts poly 4-vinylpyridine 10% 
solution in 50:50 t-butanol/water (ex Cassella(TM)) from the 
polymerisation process were added to a solution of: 
0.08 parts sodium tungstate (ex Merck(TM)) 
0.36 parts *DTPMP solution (26% active) 
3.43 volumes hydrogen peroxide soln. (30% w/v ex Merck (TM)) 
The pH of the solution was adjusted from 7.1 to 5.4 (with conc. 
hydrochloric acid) and the mix refluxed for 2 hours when a pale yellow 
viscous oil separated. This was dissolved by the addition of a further 
3.43 volumes of 30%w/v hydrogen peroxide solution and the mix was refluxed 
a further 2 hours. 
After cooling the solution was added, with agitation, to acetone (200 
volumes) when a viscous yellow syrup separated. The supernatant liquors 
were decanted and the syrup further treated with acetone to form a pale 
yellow solid, which was filtered, washed and dried in vacuo. 
Proton nmr analysis indicated 80 mole% N-oxidised product. 
Example 3 
In a process in accord with the invention 1 part poly 4-vinylpyridine 
(solid ex Cassella(TM)) was added to a solution of: 
0.086 parts sodium tungstate 
0.36 parts *DTPMP solution (26% active) 
5.7 volumes hydrogen peroxide solution (30% w/v ex Merck (TM)) 
1.9 volumes ethanol. 
FNT *DTPMP=Sodium salt of diethylene triamine penta (methylene phosphonic acid) 
The mix was held at 60-65 deg C for 4 hours then allowed to cool before 
adding to acetone (200 volumes) to precipitate a pale yellow solid. The 
solid was isolated by filtration, washed with acetone and dried under 
vacuum. 
Proton nmr analysis indicated &gt;90 mole% N-oxidised product. 
Example 4 
In a process in accord with the invention a solution of: 
0.08 parts sodium molybdate dihydrate (ex Merck(TM)) 
0.095 parts ethylene diamine tetra acetic acid, disodium salt (ex 
Merck(TM)) 
5.71 volumes hydrogen peroxide solution (30% w/v ex Merck (TM)) 
5.71 volumes ethanol was made up and to this dark red solution was added: 
1.0 part poly 4-vinylpyridine (solid ex Cassella(TM)) 
The mix was heated to 60-65 deg C when the solid dissolved to form a red 
solution of pH approximately 6-7. 
After 1.5 hours at 60-65 deg C the red colour had faded to pale yellow and 
a further aliquot (2.86 volumes) of hydrogen peroxide solution was added. 
Further aliquots (2.86 volumes each) of hydrogen peroxide solution were 
required after another 45 minutes, then another 60 minutes to regenerate 
the reddish colour. 
After a total of 4.25 hours at 60-65 deg C in the presence of the red 
species, the solution (pH approximately 6) was cooled and added, with 
agitation, to acetone (150 volumes). The supernatant liquors were decanted 
and the residual yellow sticky solid was re-slurried in acetone, gravity 
filtered, washed with acetone and dried in vacuo. 
270 MHz proton nmr analysis indicated 81 mole % yield of N-oxidised 
product.