Hydrolyse und Alkoholyse von Reaktivfarbstoffen: III. Sorbitolyse von Monochlortriazin-Farbstoffen. 3. Mitteilung über reaktionsmechanistische Untersuchungen an Reaktivfarbstoffen

• 1 The kinetics of the competitive reactions of three monochlorotriazine reactive dyes with water and with sorbitol have been investigated.
• 2 The reactions of the monochlorotriazine dyes with sorbitol anions and hydroxyl ions can be divided as follows: (a) With dyes without a NH-group between the triazine nucleus and the other part of the molecule, the reaction follows the simple addition-elimination mechanism (A_N2E), in which the addition of the nucleophile is ratelimiting. (b) The reactions of dyes containing a NH-group can be explained by assuming that more than one of the tautomeric isomers are reactive. With one isomer the addition of the nucleophile is the slowest step; with another the base-catalysed decomposition of the addition complex is rate-limiting.
• 3 The first acid dissociation constant of sorbitol is evaluated (pK_a = 13.14;60°).