Sulphur dyestuffs, a process for their manufacture and their use from hydroxy-diphenylamine compounds
AssigneeCassella Aktiengesellschaft
InventorDieter Cornelius
Life of this patent
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Abstract
New sulphur dyestuffs are prepared by reacting sulphur with a 4-hydroxydiphenylamine of the formula ##STR1## wherein R and R.sup.1 denote hydrogen or alkyl having 1 to 4 carbon atoms and the nucleus A has at least one free ortho-position in relation to the imino group, in a first stage at an elevated temperature to form a thiazine compound which is then sulphurized in a second stage in a water-soluble solvent at an elevated temperature to produce the sulphur dyestuff, and wherein a molar ratio of first stage reactants of 1:(2 to 2.4) between the 4-hydroxydiphenylamine compound and sulphur is maintained.
Claims9
Sulphur dyestuff prepared by first producing a thiazine by reacting sulphur with a 4-hydroxydiphenylamine of the formula ##STR4## at a temperature from 160.degree. to 190.degree. C. with a molar ratio of 4-hydroxydiphenylamine to sulphur being from 1:(2 to 2.4) and wherein R and R.sup.1 are hydrogen or alkyl having 1 to 4 carbon atoms and the ring nucleus A has at least one free ortho-position in relation to the imino moiety,
- and then sulphurizing said thiazine compound in a water-soluble solvent at a temperature from 130.degree. to 150.degree. C. to produce the sulphur dyestuff.
In the process for preparation of sulphur dyestuffs comprising a first stage wherein a 4-hydroxydiphenylamine of the formula ##STR5## is reacted with sulphur at a temperature from 150.degree. to 190.degree. C. to produce a thiazine compound and wherein R and R.sup.1 are hydrogen or alkyl having 1 to 4 carbon atoms and the ring nucleus A has at least one free ortho-position in relation to the imino moiety;
- and then in a second stage sulphurizing said thiazine compound in a water-soluble solvent at a temperature from 130.degree. to 150.degree. C. to produce sulphur dyestuffs,
- the improvement comprises the molar ratio between the 4-hydroxydiphenylamine compound and sulphur in the first stage is 1:(2 to 2.4).
Dependencies are inferred from the claim text.