Abstract
A new method has been established for purifying Methylthymol Blue (MTB; 3, 3′-bis[N, N-bis(carboxymethyl)- aminomethyl]thymolsulfonphthalein) by liquid-liquid distribution between 1-butanol and aqueous hydrochloric acid. A free acid form of MTB, H6MTB•3H2O, was easily obtained in large scale (10mmol) with good yield (70%) and high purity, free from Semi-Methylthymol Blue (SMTB) and iminodiacetic acid (IDA). The distribution ratios of MTB, SMTB and IDA between the two phases are also reported.
