Hydrogenation of Para-Nitrotoluene on Catalytic Systems Containing Oxides of Rare Earth Elements

This work is devoted to the study of the activity of 1% platinum catalysts containing rare earth element oxides (OREE) - Gd2O3, Ce2O3 and aluminum oxide as a carrier in the hydrogenation reactions of nitro compounds on the example of n-nitrotoluene. These catalytic systems in the conditions of liquid-phase hydrogenation provide high selectivity of the process and practically quantitative yield. The process was controlled by the potentiometric method, the reaction rate was judged by the amount of hydrogen absorbed per unit time. It is found that 20% and higher aqueous alcohol solutions can be used as a solvent during hydrogenation. It was found that the initial hydrogenation rate for 1% Pt/Gd2O3 is 3.2 times higher, and for 1% Pt/Ce2O3 Cerium it is 1.6 times higher relative to the 1% Pt/Al2O3 comparison catalyst.

DETECTION OF FALSIFICATION OF HORILKA BY ADMITTANCE SPECTROSCOPY

The methods of quality control of horilka by electrical parameters, in particular, dielectric constant, specific conductivity, and imitation components are analyzed. The research results of individual samples of alcohol solutions and horilkas of different brands by the method of admittance spectroscopy were also analyzed. Based on this, methods for detecting falsification of horilka products by the method of admittance spectroscopy are proposed. The reactive component of the control object's ad is selected as an informative parameter. Two types of falsification are analyzed. The first is the falsification of the original horilka by replacing it with an aqueous-alcohol solution. The second - by replacing one brand of horilka with another. The analysis of the obtained results of researches of two types of objects on reactive components of their admittance in the frequency range 100 Hz100 kHz showed the following: characteristic features of dependencies of reactive components on frequency are revealed; they have been found to have extreme values at different frequencies. The reactive component of the admittance of aqueous-alcohol solutions reaches an extreme value at the beginning of the range. The same component of the original horilkas of different brands has extreme values at the end of the range. Based on this, methods for prompt detection of falsifications are proposed.

Spectral study of thione-thiol tautomerization of thiourea in aqueous alcohol solution

In this work we studied the equilibrium of thione–thiol tautomerization by Raman and UV spectroscopies. This type of tautomerization influences on the course and direction of the reaction between thiourea and other organic compounds. The studies were carried out in water and aqueous alcohol medium. Мethanol, ethanol, propanol-1 and propanol-2 were used as alcohols. Hydrochloric acid was used to protonate thiourea in water and aqueous alcoholic solutions. UV spectroscopy made it possible to establish the tautomer ratio in water and aqueous alcohol solutions as the ratio of the intensities of absorption bands at 236 and 200 nm. There is an increase in the content of the thiol form and a decrease of the thione form observed in the row water-methanol-ethanol-propanol-isopropyl alcohol. The addition of hydrochloric acid to the thiourea water or aqueous alcohol solutions leads to the increase of the thione form and to the decrease of the thiol form in the composition. The thione form of thiourea can be determine by Raman spectra of –C=S group. The thiol form of thiourea is difficult to detect by Raman spectroscopy due to the overlap of the –S–H bond absorption band with alcohols absorption bands.

Qualitative Analysis of Clustering in Aqueous Alcohol Solutions. II

Specific features of the clustering in aqueous solutions of monoatomic alcohols have been discussed. Main attention is focused on details of the clustering in water-ethanol solutions. The clustering degree is supposed to depend on the nteraction between ethanol and water molecules, as well as on the ordering degree of the H-bond network in water, which changes with the temperature and concentration of the alcohol. The elementary cluster volume is assumed to be smaller than the sum of the molecular volumes of components that form this cluster. The clustering degree in aqueous solutions of methanol and ethanol and its concentration and temperature dependences are determined.

Qualitative Analysis of Clustering in Aqueous Alcohol Solutions

The specific features of clustering in the aqueous solutions of monohydric alcohols with concentrations higher than that at the peculiar point are discussed. Clustering is a result of the formation of hydrogen bonds between water and alcohol molecules, the energy of which some-what exceeds the energy of hydrogen bonds in the water-water and alcohol-alcohol molecular pairs. Elementary clusters are assumed to be formed, whose composition is fixed at the solution concentrations lower than that at the peculiar point and changes according to a certain law at higher concentrations. The solution clustering degree was determined as a function of the solution concentration and the temperature.