Patent GB-419447-A (GB)
Title: Improvements in the manufacture and production of azo-dyestuffs
IPC: C09B29/36
Filed: 1933-04-13
Abstract: Azo dyes are prepared by coupling a diazo compound with a compound containing a pyronone ring, i.e. a 2-oxy-1 : 4-pyrone ring in the keto form.  Mono-, dis- and poly-azo dyes may be so prepared; disazo dyes may be prepared either by coupling a diazotized aminoazo compound with a component containing a pyronone ring, or by coupling a tetrazotized diamine with two molecules of the same or different components, at least one of which contains a pyronone ring.  The diazo compounds may be derived from mono- or polyamines of the benzene, naphthalene, anthracene and diphenyl series, and may be substituted by halogen atoms or by alkyl, hydroxy, alkoxy, nitro, carboxylic and/or sulphonic groups.  The dyes obtained, when they contain sulphonic groups, may be applied to wool, silk, leather or cotton; the dyes not containing sulphonic groups may be used in substance for dyeing cellulose acetate silk or for colouring oils and waxes or as pigment dyes, or they may be produced on the fibre, e.g. on cotton or cellulose acetate silk.  When o-hydroxy or o-alkoxy diazo compounds are used, the dyes may be converted into complex metal compounds, particularly chromium, cobalt or copper compounds, in substance or on the fibre.  In the examples, (1) diazotized aniline is coupled with 6-methylpyronone to yield a yellow dye useful for colouring lacquers, waxes and oils; similar dyes are obtained by using diazotized toluidines, xylidines, naphthylamines or aminoazobenzene, or by replacing the 6-methylpyronone by 5 : 6-benzopyronone (also known as chroman-2 : 4-dione or benzotetronic acid); (2) diazotized 2-amino-5-nitroanisole is coupled with 6-methylpyronone to yield an orange-yellow dye suitable for dyeing acetate silk or colouring lacquers; diazotized nitranilines and nitrotoluidines may also be p  used; (3) diazotized p-nitraniline is coupled with 6 : 7-benzochroman-2 : 4-dione (also known as naphthotetronic acid) to yield an orange - yellow pigment dye; other nitranilines, nitrotoluidines, and chloronitranilines may be used as diazo components, and 6- or 7-methylbenzotetronic acid may be used as coupling component; (4) diazotized 3-amino-6-chlorotoluene-4-sulphonic acid is coupled with 6-methylpyronone to yield a yellow dye for wool; the dye may be laked by standard processes, for instance by treatment with barium salts with addition of aluminium sulphate and soda; similar dyes are obtained by using other aromatic aminosulphonic acids or sulphonated aminoazo compounds as diazo components, or by using as coupling component benzo- or naphthotetronic acid or 7 : 8-benzo chroman-2 : 4-dione; (5) tetrazotized 4 : 4<1>-diamino - 3 : 3<1> - dimethoxydiphenyl - 6 : 6<1> - disulphonic acid is coupled with 6-methylpyronone to yield an orange-red disazo dye for silk; (6) diazotized 1-amino-2-methoxynaphthalene-6-sulphonic acid is coupled with 6-methylpyronone to yield an orange dye for wool; a red dye is obtained if the product is treated with a chromium compound, e.g. chromium formate, under conditions such that the methyl radicle of the methoxy group is removed, e.g. at 110--130 DEG  C. under pressure; (7) tetrazotized 4 : 4<1>-diaminodiphenyl-3 : 3<1>-disulphonic acid is coupled with naphthotetronic acid to yield an orange-red dye for cotton; a red-brown dye is obtained if 4 : 4<1>-diaminostilbene-3 : 3<1>-disulphonic acid is used as tetrazo component; (8) diazotized 1-amino-2-naphthol-4-sulphonic acid is coupled with 6-methylpyronone to yield a red-brown dye for wool; the dyeing becomes blue-red when aftertreated with bichromate; the chromium compound prepared in substance may be applied to animal fibres; the dye from diazotized 1-amino-6 - nitro - 2 - naphthol - 4 - sulphonic acid and 6-methylpyronone dyes wool in dark brown shades, and its chromium compound, prepared in substance or on the fibre, yields red-brown shades; (9) diazotized 2-amino-4-chlorophenol-6-sulphonic acid is coupled with 6-methylpyronone to yield a yellow-brown dye for wool, leather or silk; the chromium compound, prepared in substance or on the fibre, yields red-brown shades; the dye from diazotized 2 - amino - 4 - nitrophenol - 6 - sulphonic acid and 6-methylpyronone yields red-brown shades, and its chromium compound yields yellow-brown shades; (10) acetate silk is dyed with aminoazotoluene, which is then diazotized on the fibre and coupled with 6-methylpyronone; orange-red shades are obtained; the same treatment, applied to acetate silk dyed with aminoazobenzene or p-aminophenyl-azo-a -naphthylamine yields yellow-orange or violet shades; (11) tetrazotized o-dianisidine is coupled in turn with 2-naphthol-6-sulphonic acid and 6-methylpyronone to yield a violet-blue dye for cotton; the colour may be modified by after-treatment with copper sulphate; (12) cotton is impregnated with naphthotetronic acid or the isomeric 7 : 8 - benzochroman - 2 : 4 - dione, and then treated with diazotized p-nitraniline; orange-yellow dyeings are obtained; (13) diazotized 2 - nitro - 6 - aminophenol - 4 - sulphonic acid is coupled with naphthotetronic acid to yield a violet dye for wool; after-treatment with bichromate yields bordeaux shades; if 4-nitro-6-aminophenol-2-sulphonic acid is used as coupling component, a red-violet dye is obtained which yields red shades on after-chroming.  6-Methylpyronone in the examples may be replaced by 6-aryl- or 6-aralkyl-pyronones, and particularly by 6-phenylpyronone (obtained by heating dehydrobenzoylacetic acid with sulphuric acid) or 6-benzylpyronone (obtained similarly from dehydrophenacetylacetic acid, which is itself obtained by condensing two molecules of phenylacetylacetic ester).  The 7 : 8-benzochroman-2 : 4-dione used in examples 4 and 12 is prepared by condensing 1-acetyloxynaphthalene-2-carboxylic acid chloride with the sodium compound of malonic ester, and treating the product with sulphuric acid.  A sample has been filed under Sect. 2 (5) of a blue trisazo dye prepared by coupling tetrazotized benzidine with one molecule each of 5 : 6-naphthopyronone and 1 - amino - 8 - naphthol - 3 : 6 - disulphonic acid, and coupling the disazo dye so obtained with diazotized aniline-p-sulphonic acid.