Hydrolysis mechanism of crosslinks formed between hydroxymethylated 2-substituted 4,6-diamino-s-triazines and cotton

Hydrolysis resistance and mechanism of reaction products of hydroxymethylated 2-substituted (X) 4,6-diamino-s-triazines (MXT) with cotton fabrics has been studied. Finishing reagents used were MXT having the following substituents: X = CH₃O? (MMT), (CH₃)₂CHO? (MIPT), CH₃? (MAG), C₂H₅NH? (MEM), HOC₂H₄NH? (MHEM), and (HOC₂H₄)₂N? (MBHEM). For comparison, trimethylolmelamine (TMM), dimethylolurea (DMU), dimethylolethyleneurea (DMEU), and dimethylol-ethyltriazone (DMET) were used. Hydrolysis was carried out in buffer and NaOH solutions of various pH's for 30 min at 80°C. The order of hydrolysis resistance of crosslinked reagents was determined from the nitrogen contents retained. It was as follows: pH 1, MROT < MRNT < MRT; pH ≧ 2, MROT > MRT > MRNT; pH ≦ 13, MROT > MRNT; pH 14, MROT < MRT < MRNT, where MROT is hydroxymethylated 2-alkoxy (MMT, MIPT), MRT is hydroxymethylated 2-alkyl (MAG), and MRNT is hydroxymethylated 2-alkylamino-4,6-diamino-s-triazine (MEM, MHEM, MBHEM). This fact can be explained in terms of the basicity constant (p^K_b) of crosslinked MXT with cotton (approximately p^K_b) of 2-substituted 4,6-diamino-s-triazine (XT). The hydrolysis rates of crosslinked MMT, MAG, and MEM were determined at pH 2. The activation energies were 21.8 for MMT, 20.9 for MAG, and 21.0 kcal/mole for MEM.