The chromatographic lipophilicity (
) of eleven new 1,2,4-triazole derivatives has been determined by RP-TLC with methanol-water mobile phases containing sodium salts of the monovalent anions H
, and PF
. Addition of iodide anions to the mobile phase proved a key factor in obtaining lipophilicity indexes which correlated better with the log
scale for all the solutes investigated. Addition of neutral or strong chaotropic salts (chlorides, hexafluorophosphates), according to the
classification, improved the correlations between
. Experimental log
values were also established on the basis of calibration plots. These values were also correlated with the calculated lipophilicity log
. Highly significant improvement of this correlation was achieved for mobile phases modified with sodium iodide. The results obtained are discussed in connection with the known physicochemical properties of anions in solution — lyotropic number,
B coefficient, entropy of hydration, surface tension increment, and effective anion polarizability.
Authors:V. Bessergenev, Yu. Kovalevskaya, L. Lavrenova, and I. Paukov
Low-temperature heat capacity of the coordination compound of nickel(II) nitrate with 4-amine-1,2,4-triazole was measured in the temperature range from 11 to 317 K using a computerized vacuum adiabatic calorimeter. The thermodynamic functions have been derived from the smoothed experimental data over the whole temperature interval covered and at standard conditions. At 298.15 K, the heat capacity is 574.7±1.2 J K-1 mol-1, the entropy is 599.2±1.2 J K-1 mol-1, the enthalpy is 91070±200 J mol-1, and the reduced Gibbs energy is 293.7±1.2 J K-1 mol-1. The results on Cp(T) were compared with those for Cu(NH2trz)3(NO3)2·0.5H2O. It was revealed that the slope of the curve dCp/dT (T) changes essentially for both compounds at 110-120 K. It implies that additional degrees of freedom appear in the heat capacity at these temperatures.
Authors:B. Gaur, B. Lochab, V. Choudhary, and I. Varma
The paper describes the synthesis of low molecular mass poly(allyl chloride) (PAC) (Mn= 856-3834 g mol-1) using Lewis acid (ALCL3, FeCL3, TiCL4) and al powder. Branching in PAC was indicated on the basis of elemental analysis and 1H-NMR spectroscopy. azidation of pac could be carried out at 100°C by using NaN3 and DMSO as solvent. Curing of poly(allyl azide) (PAA) by cyclic dipolar addition reaction with EGDMA (ethylene glycol dimethacrylate,
5-45 phr) was investigated by differential scanning calorimetry and structure of cured polymer was confirmed by FTIR. A two-step
mass loss was exhibited by uncured and cured PAA in nitrogen atmosphere. A mass loss of 20-28% (155-274°C) and 50-61% (330-550°C)
Authors:G. Berezovskii, M. Bushuev, D. Pishchur, and L. Lavrenova
Low-temperature heat capacity of polynuclear Fe(HTrz)3(B10H10)·H2O (I) and trinuclear [Fe3(PrTrz)6(ReO4)4(H2O)2](ReO4)2 (II) spin crossover coordination compounds was measured in 80–300 K temperature range using a vacuum adiabatic calorimeter. For
I, an anomaly of heat capacity with a maximum at Ttrs=234.5 K (heating mode) was observed, ΔtrsH=10.1±0.2 kJ mol−1 ΔtrsS=43.0±0.8 J mol− K−1. For II, a smooth anomaly between 150 and 230 K was found, ΔtrsH=2.5±0.25 kJ mol−1 ΔtrsS=13.6±1.4 J mol− K−1. Anomalies observed in both compounds correspond to 1A1⇔5T2 spin transition.
coordination in a bidentate bridging manner which makes it possible to synthesize compounds with structures of various dimensions. Some compounds, such as complexes of iron (II) with 1,2,4-triazoles and tetrazoles, SCO is accompanied by thermochromism which is
Authors:Lin-Quan Liao, Hong-Jian Wei, Ji-Zhen Li, Xue-Zhong Fan, Ya Zheng, Yue-Ping Ji, Xiao-Long Fu, Ya-Jun Zhang, and Fang-Li Liu
benzenfuroxan (CL-14), 1,1-diamino-2,2-dinitroethylene (DADNE), and 4-amino-5-nitro-1,2,3-triazole (ANTZ) as new energetic materials were synthesized by Xi'an Modern Chemistry Research Institute with all analytically pure. The structures of all the energetic
Authors:Stanisław Zaręba, Arkadiusz Pomykalski, and Katarzyna Szarwiło
3-Mercapto-5-(2′-hydroxynaphthylazo-1′)-1,2,4-triazole (metrian); 3-mercapto-5-(3′,4′-dihydroxyphenylazo-1′)-1,2,4-triazole (metriap); 3-mercapto-5-(2′,4′-dihydroxy-3′-carboxyphenylazo-1′)-1,2,4-triazole (metriarez-γ), and 2-mercapto-5-(2′,4′-dihydroxy-5′-carboxyphenylazo-1′)-1,3,4-thiadiazole (metidarez-β) have been used to determine, by different methods, milligram quantities of Fe(II) and Zn(II), present together in pharmaceutical preparations, both multivitamin preparations and preparations containing microelements. Results from ion chromatography (IC) were compared with those from classical spectrophotometry (D
), derivative spectrophotometry (D
), and atomic absorption spectrometric (AAS). Results were analyzed statistically and compared with the declared amount. The advantages of the proposed method for determination of Fe(II) and Zn(II) include its excellent precision and the reproducibility of the results.