p-Toluenesulfonic acid → 2-[(3-Iminoisoindol-1-yl)methylene]-3-methyl thiazolinium p-toluene sulfonate

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Reaction Steps

Three grams of 1,3-diiminoisoindoline were dissolved in 25 ml of methanol. The solution was treated with 5.7 grams of 2,3-dimethyl thiazolinine p-toluenesulfonate which had been dissolved in 25 ml of methanol. The resulting mixture was heated at reflux for several hours. A yellow solid was obtained upon cooling and scratching the vessel. The solid was collected and washed free of the dark colored mother liquor with methanol and acetone. The dye was then dissolved in hot water from which it was recrystallized. The dye can be converted to other salts by adding an anion, such as iodide, to give a more insoluble salt.

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