Preparation of metallic dihydroxybenzene-disulfonates
AssigneeRhodia Operations
InventorsMichel Dury, Hervé Bres
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Abstract
Metallic dihydroxybenzenedisulfonates are prepared, preferably from alkaline metals, from corresponding dihydroxybenzenedisulfonic acids, by reacting the dihydroxybenzenedisulfonic acid present in a sulfuric medium with an adequate amount of a salt including a sulfate or hydrogenosulfate anion.
Claims28
A process for the preparation of a metal dihydroxybenzenedisulfonate from a corresponding dihydroxybenzenedisulfonic acid, comprising reacting the dihydroxybenzenedisulfonic acid present in a sulfuric medium, with a sufficient amount of a salt which comprises a sulfate or hydrogen sulfate anion.
A process for the preparation of a 1,2-dihydroxy-3,5-benzenedisulfonate of an alkali metal, comprising the following stages:
- Introducing pyrocatechol into concentrated sulfuric acid or oleum thereof employed in an amount sufficient to produce the corresponding disulfonic acid,
- heating said medium at a temperature of from 50° C. to 100° C.,
- introducing water in a minimum amount but an amount sufficient to render the medium stirrable after salification,
- reacting the dihydroxybenzenedisulfonic acid obtained with a sufficient amount of a sulfate or hydrogen sulfate of an alkali metal, and
- separating the 1,2-dihydroxy-3,5-benzenedisulfonate of an alkali metal obtained.
Dependencies are inferred from the claim text.