acetone four microliters of that solution is spotted on a glass plate on which had been previously cast a 250 micron layer of silica gel after drying the spot is eluted with a 4 1 by volume benzene acetone solution as the dyestuff spot migrates vertically up the plate the various components of the dyestuff separate that is depending upon factors such a polarity and relative solubility in the elution liquid each component will migrate to a different height on the plate in that manner it can be verified that dyestuffs prepared according to the method of the invention are complex mixtures the chromatographs also show that the amide enters into the reaction and that the mixtures are of the same composition regardless of which of the designated amides and other reactants are employed to modify the hydroxyalkyl groups of the coupling component suitable formamides and acetamides are n n dimethylformamide n n dimethylacetamide n n diethylacetamide n n diethylformamide n n di t butylformamide and n mono t butylformamide examples of suitable alkylchlorocarbonates useful in the process of the invention are ethylchlorocarbonate methylchlorocarbonate and t butylchlorocarbonate suitable carboxylic acylhalides are for example acetyl chloride propionyl chloride benzoyl chloride and butyryl chloride illustrative of useful sulfonylchlorides are benzene sulfonylchloride methane sulfonylchloride and t butylsulfonylchloride as noted above the coupling can be carried out either before or after the modification of the coupling component the coupling reaction is carried out in the conventional manner 0 u00b0 5 u00b0 c in an aqueous acid medium with or without the use of an acid binding agent such as sodium acetate after.