The kinetics, activation energy, and mechanism of esterification of cotton by mixed polycarboxylic acids, namely, 1,2,3,4-butanetetracarboxylic acid (BTCA) and citric acid (CA), were studied during the curing process of cotton fibers in comparison with the esterification by BTCA alone. The reaction rates of these two polycarboxylic acid finishing systems under different temperatures and the dependency of their reaction rate constants on temperature were studied. Consequently, in the temperature range from 120°C to 180°C, the activation energy of the mixed polycarboxylic acids (BTCA+CA) was obtained as Ea=40.7 kJ/mol, which was slightly lower than that for the BTCA finishing system. The reaction occurring between the carboxylic acid group of BTCA and the hydroxyl group of CA was proposed. To confirm and prove the speculation, experiments were conducted to investigate the changes in wrinkle recovery angle and tensile strength retention by changing the concentration of both the single polycarboxylic acid and mixed polycarboxylic acids. The results show that, besides esterification of cotton fibers, citric acid probably functioned as an extender in the curing process, when it was combined with BTCA.

Durable press (DP) finishing process of cotton fabric with 1,2,3,4-butanetetracarboxylic acid (BTCA) was investigated and optimized using the Box-Behnken design (BBD) with a response surface methodology (RSM). BBD experimental data were fitted to create the response surface regression models describing wrinkle recovery angle (WRA) and breaking strength of the finished cotton fabric. Analysis of variance (ANOVA) revealed that the concentration of BTCA was the most significant variable affecting the WRA, followed by the curing time, curing temperature, and concentration of sodium hypophosphite (SHP). Regarding breaking strength, curing time was the most significant variable, followed by the curing temperature, concentration of BTCA, and concentration of SHP. After optimal treatment, the WRA of the finished fabric was 252°, while the retention rate of breaking strength was 69%.

Pyridinecarboxylate complexes have been much investigated in recent years due to their interesting coordination chemistry, allowing for unusual structural features and leading to various physical and chemical properties. 1 The 2,6-pyridinedicarboxylate ion is an effective tridentate chelating ligand in forming stable complexes with metal ions.2,3 Mn complexes containing bis(2,6-pyridinedicarboxylate) ions have also been reported elsewhere. 4 As an extension of our research on carboxylate coordination compounds, we report here on the synthesis and crystal structure of ammonium bis(2,6-pyridinedicarboxylato)manganese(II) dihydrate (Fig. 1), based on an X-ray structural analysis.A mixture of manganese chloride tetrahydrate (40 mg, 0.2 mmol), 2,6-pyridinedicarboxylic acid (33.4 mg, 0.2 mmol), and 1-(4-(1H-imidazol-1-yl)butyl)-1H-imidazole (38 mg, 0.2 mmol), in methanol (10 ml) was refluxed for 1 h. After the reaction mixture was cooled to room temperature, a white precipitate formed. Then, aqueous ammonia was added to the precipitate until the precipitate dissolved completely. The solution was filtered and left standing at room temperature; after several days colorless block crystals appeared. Diffraction data were collected by graphite-monochromated Mo Ka radiation (l = 0.71073 Å). The crystal and experimental data are listed in Table 1. The structure was solved by automatic direct methods using SHELXS-97. 5 The structure was refined by a full-matrix least-square analysis on F 2 with SHELXL. The absorption was performed semiempirically from equivalent by means of the SADABs program. The nonhydrogen atoms were refined anisotropically, and all H atoms were placed in geometrically idealized positions and constrained to ride on their parent atoms, with N-H = 0.90 Å, O-H = 0.85 Å, and C-H = 0.93 Å. Hydrogen atoms bound to water molecules or N atoms were located in a Fourier difference map, and their distances were fixed.In this work we expected that the exobidentate ligand 1-(4-(1H-imidazol-1-yl)butyl)-1H-imidazole would coordinate to the manganese; however, this was not the case. The crystal structure . The final R value was R1 = 0.0764 for 9688 measured reflections. Additional hydrogen bonding, ion pairing, p-p, and C=O-p stacking interactions give rise to a threedimensional network structure.