2-[N-ethyl-p-[(6-methoxybenzothiazol-2-yl)azo]anilino]ethanol synthesis

Yield:13486-43-6 83%

Reaction Conditions:

Stage #1: 6-methoxybenzothiazol-2-ylaminewith nitrosylsulfuric acid;sulfuric acid;acetic acid;propionic acid in water at -10;
Stage #2: 2-( N-ethylanilino)ethanolwith sulfuric acid;aminosulfonic acid;acetic acid;propionic acid in water;

Steps:

4.1

Example 4; Preparation of Methacrylate Ester Derivative of Cl Basic Blue 41; Stage 1; 2-Amino-6-methoxybenzothiazole (18.0 g) is stirred in a mixture of acetic acid (70 ml) and propionic acid (50 ml) at 50° C. The resulting solution is cooled to -10° C. Nitrosylsulphuric acid solution (40 weight-% in sulphuric acid) (32.0 g) is added dropwise. This mixture is added to a stirred solution of N-ethyl-N-(2-hydroxyethyl) aniline and sulphamic acid (1.0 g) in acetic acid (25 ml) and ice/water (100 ml). After 20 minutes, the pH is raised to 4 by the dropwise addition of potassium hydroxide solution. A tarry residue is formed; the mixture is stirred for a further 2 hours until the tar solidifies. This solid is collected, washed with water and then dissolved in alcohol and acetone to give a deep red solution. Hot water is added to precipitate a solid which is removed by filtration. The solid is washed with cold alcohol and dried (29.5 g, 83% yield) Mp 178-179° C.

References:

US2011/297888,2011,A1 Location in patent:Page/Page column 17