Process for the preparation of a condensation product from phenothiazine and p-nitrosophenol
AssigneeCassella Aktiengesellschaft
InventorsGert Nagl, Joachim Ribka, Ulrich Gotsmann, Heinz Dickmanns
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Abstract
An improved process for preparation of a condensed product of phenothiazine and p-nitrosophenol which contains more than 60% by weight of indophenol S-oxide of the formula ##STR1## by condensing phenothiazine with p-nitrosophenol in sulphuric acid wherein the improvement comprises the phenothiazine being in 60 to 90% strength sulphuric acid at the time of addition of the p-nitrosophenol.
Claims5
In the process for preparation of a condensation product of phenothiazine and p-nitrosophenol which contains more than 60% by weight of indophenol-S-oxide of the formula ##STR6## by condensing phenothiazine with p-nitrosophenol in sulphuric acid wherein the improvement comprises the phenothiazine being in 60 to 90% strength sulphuric acid at the time of the addition of p-nitrosophenol in an amount of no more than 1.125 moles per mole of phenothiazine.
Dependencies are inferred from the claim text.