Authors:J. Locatelli, E. Rodrigues, A. Siqueira, E. Ionashiro, G. Bannach, and M. Ionashiro
Solid-state Ln(Bz)3·H2O compounds where Ln stands for trivalent yttrium or lanthanides and Bz is benzoate have been synthesized. Simultaneous thermogravimetry-differential
thermal analysis (TG-DTA), X-ray powder diffractometry, infrared spectroscopy and chemical analysis were used to characterize
and to study the thermal behaviour of these compounds. The results led to information about the composition, dehydration,
thermal stability and thermal decomposition of the isolated compounds.
Barium benzoate was synthesized in a hydrothermal reaction. The complex was characterized by elemental analysis, IR spectroscopy and X-ray powder diffraction. It was monoclinic and had a layered structure. The mechanism of thermal decomposition of the barium benzoate was studied by using TG, DTA, IR and gas chromatography-mass spectrometry. In a nitrogen atmosphere, the barium benzoate decomposed to form BaCO3 and organic compounds: mainly benzophenone, triphenylmethane, etc.
Authors:B. Ivković, J. Brborić, V. Dobričić, and O. Čudina
benzoate is generally used as a chemical preservative to prevent alteration or degradation caused by microorganisms. In acidic media (pH 2–5), sodium benzoate exhibits inhibitory activity against a wide range of fungi, yeasts, molds, and bacteria and is
], biphenylethene-4,4′-dicarboxylate [ 27 ], biphenyl-3,4,5′-tricarboxylate [ 17 ] or 4,4′-oxybis(benzoate) [ 28 – 32 ], have been employed as linkers in the multi-dimensional lanthanide coordination polymers.
In this article, this author presents a new
Authors:Lenka Findoráková, Katarína Győryová, Jana Kovářová, V. Balek, F. Nour El-Dien, and L. Halás
Novel zinc(II) complex compounds of general formula Zn(C6H5COO)2·L2 (where L=caffeine (caf) and urea (u)) were synthesized and characterized by elemental analysis and IR spectroscopy. The thermal behaviour
of the complexes was studied during heating in air by thermogravimetry. It was found that the thermal decomposition of the
anhydrous Zn(II) benzoate compounds with bioactive ligands was initiated by the release of organic ligands at various temperatures.
On further heating of the compounds up to 400°C the thermal degradation of the benzoate anions took place. Zinc oxide was
found as the final product of the thermal decomposition of all zinc(II) benzoate complex compounds heated to 600°C. Results
of elemental analysis, infrared spectroscopy, mass spectroscopy and thermogravimetry are presented.
Authors:B Raposa, R Pónusz, G Gerencsér, F Budán, Z Gyöngyi, A Tibold, D Hegyi, I Kiss, Á Koller, and T Varjas
mice ( 21 ).
Preservatives protect food from spoiling and also increase shelf life. Among the preservatives, sodium benzoate and potassium sorbate are the most frequently used preservatives in foods. They can burden the liver, cause
Summary Many years ago, thermal analysis earned its place as a current instrumentation technique in assisting/solving the analytical problems of pharmaceuticals. A relative new trend is the study of the thermal stability of food additives in connection with the molecular structure. The studied compounds were: natrium and potassium glutamate, respectively natrium, potassium and calcium benzoate. The thermogravimetric data (TG) were obtained in dynamic nitrogen atmosphere, with open Pt crucible and heating rates of 5, 7, 10 and 12 K min-1, using a Perkin-Elmer TGA7 equipment. In order to estimate the non-isothermal kinetic parameters, the Friedman's differential-isoconversional method and the method suggested by Budrugeac and Segal (based on the compensation effect) were used. A variation of the activation energy vs. conversion was observed by using Friedman's method. The discrimination between the different reaction steps was performed by the non-parametric kinetic method, suggested by Sempere, Nomen and Serra. This is due to a complex process. The thermal stability data are very important for avoiding a possible misuse by processing of the studied food additives.
Benzoic acid, lithium benzoate, and sodium benzoate were tritiated with virtually 100% regioselectivity in the ortho-positions by the T-for-H exchange reaction with HTO in the presence of RhCl3.3H2O. The labeling of both alkali metal salts was favored by a factor of about 3 over that of benzoic acid. Methyl benzoate was essentially inactive in the present reaction.