Process for preparing p-phenylenediamine color developers in a concentrated free-base form
AssigneeEastman Chemical Company
InventorsRenee Ellen Niziurski-Mann, Lucian Boldea, Phillip Montgomery Hudnall, Michael Wayne Salyer
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Abstract
An improved method for making a p-phenylenediamine color developer concentrate in a free-base form wherein the sulfate or chloride salt of the color developer is contacted with an alkali metal hydroxide includes the steps of forming a liquid free-base layer and a water layer, separating the liquid free-base layer from the water layer; and mixing the liquid free-base with a water soluble hydroxy organic solvent, wherein the p-phenylenediamine color developer concentrate has at least 0.06 mol/l of a color developing agent in the free base form.
Claims17
In a method for making a free-base form of a p-phenylenediamine color developer concentrate by contacting a sulfate or chloride salt of said color developer with an alkali metal hydroxide wherein the improvement comprises:
- a. forming liquid free-base and water layers;
- b. separating said liquid free-base layer from said water layer;
- and
- c. mixing said liquid free-base with a water soluble hydroxy organic solvent, wherein said p-phenylenediamine color developer concentrate has at least 0.06 mol/l of a color developing agent in the free base form.
In a method for making a free-base form of a p-phenylenediamine color developer concentrate by contacting a sulfate or chloride salt of said color developer with an alkali metal hydroxide wherein the improvement comprises:
- a. forming a free-base and water mixture;
- b. heating said free-base and water mixture to effect formation of a free-base layer and a water layer;
- c. separating said liquid free-base layer from said water layer;
- and
- d. mixing said liquid free-base with a water soluble hydroxy organic solvent, wherein said p-phenylenediamine color developer concentrate has at least 0.06 mol/l of a color developing agent in the free base form.
Dependencies are inferred from the claim text.