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US 6,867,327 B2Granted
Preparation and purification of hydroxylamine stabilizers
AssigneeBASF SE
InventorsIrl E. Ward, Danielle Anne French
Life of this patent
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Abstract
The invention relates to the preparation of ultra-high purity 1,2-diaminocyclohexanetetraacetic acid being essentially free of unwanted metal and metal ion contaminants and its use as a stabilizer for ultra-high purity hydroxylamine compounds used extensively in the production of high premium electronic components.
Claims11
A process for the preparation of 1,2-diaminocyclohexanetetraacetic acid comprising the steps of:
- (a) neutralizing chloroacetic acid in an aqueous medium with a non-metal amino or hydroxy base compound at a temperature less than 10° C.;
- (b) reacting said neutralized chloroacetic acid with 1,2-diaminohexane at temperatures less than 80° C.;
- (c) adding a non-metal amino or hydroxy base to complete neutralization so as to form an aqueous mixture;
- (d) heating the aqueous mixture at less than 100° C.;
- (e) filtering the mixture from (d);
- (f) treating the aqueous filtrate with hydrochloric acid until a precipitate forms;
- (g) filtering the aqueous filtrate;
- and then
- (h) recovering 1,2-diaminocyclohexanetetraacetic acid and optionally redissolving said 1,2-diaminocyclohexanetetraacetic acid in an aqueous solution and repeating steps (c) to (g).
6 more elements
A process for preparing 1,2-diaminocyclohexanetetraacetic acid which comprises the steps of:
- (a) neutralizing an aqueous solution of chloroacetic acid with sodium hydroxide;
- (b) reacting 1,2-diaminocyclohexane with the neutralized chloroacetic acid of step (a) at an elevated temperature;
- (c) treating the product from step (b) with a dilute solution of sodium hydroxide;
- (d) treating the resulting product of step (c) with concentrated hydrochloric acid and then;
- (e) recovering the product formed.
2 more elements
Dependencies are inferred from the claim text.