Benzothioxanthene dyes with improved application and toxicological properties
A C. I. Solvent Orange 63 with reduced corrosive behavior during the processing in plastics can be obtained by controlling the residual amount of organic bromine in by-products resulting from di-bromo content of the raw material. The C. I. Solvent Orange 63 thus obtained is negative in mutagenicity and sensititzation tests, allowing an improved industrial hygiene during handling and processing and a safer end use in regulated end uses such as the coloration of consumer goods, food packaging and toys.
1 . A consumer goods or food packaging colorant comprising a benzothioxanthene dye composition, wherein the benzothioxanthene dye composition contains at least 99.0% by weight of a compound of formula (1)
and not more than 0.5% by weight of a compound of formula (2)
wherein
R1 and R2 independently of each other are hydrogen, methyl, ethyl, methoxy, ethoxy or chlorine;
the weight percentages being based on the total weight of the benzothioxanthene dye composition (100%).
2 . The consumer goods or food packaging colorant as claimed in claim 1 , wherein R1 and R2 are both hydrogen.
3 . The consumer goods or food packaging colorant as claimed in claim 1 , wherein the compound of formula (2) is
and R1 and R2 are both hydrogen.
4 . The consumer goods or food packaging colorant as claimed in claim 1 , wherein the benzothioxanthene dye composition is synthesized from a 3-bromobenzanthrone having a maximum amount of 0.5% by weight of a dibromobenzanthrone.
5 . The consumer goods or food packaging colorant as claimed in claim 4 , wherein the dibromobenzanthrone is 3,9-dibromobenzanthrone.
6 . A method for preparing a non-corrosive, non-mutagenic and non-sensitizing benzothioxanthene dye composition containing at least 99.0% by weight of a compound of formula (1)
and not more than 0.5% by weight of a compound of formula (2)
wherein
R1 and R2 independently of each other are hydrogen, methyl, ethyl, methoxy, ethoxy or chlorine,
comprising the steps of: condensating 2-aminothiophenol with a 3-bromobenzanthrone having a maximum amount of 0.5% by weight of a dibromobenzanthrone to form the dye composition, diazotizing the dye composition, and
cyclizing the dye composition.
7 . The method as claimed in claim 6 , wherein the 3-bromobenzanthrone having a maximum amount of 0.5% by weight of dibromobenzanthrone is obtained by dispersing the 3-bromobenzanthrone, washing the 3-bromobenzanthrone and filtrating the 3-bromobenzanthrone.
8 . The method as claimed in claim 7 , wherein the organic solvent is a dialkylated carbonamide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, N-methyl-piperidone-2, N-formyl-morpholin, dimethylsulfoxide, sulfolan, acetonitril, propionitril, or a mixture thereof.
9 . A non-corrosive, non-mutagenic and non-sensitizing benzothioxanthene dye composition prepared by the method as claimed in any of claim 6 .
10 . The method as claimed in claim 6 , wherein the 3-dibromobenzanthrone is 3,9-dibromobenzanthrone.