Химия

The relevance of the research is caused by the need to develop a methodological base for determining 151Sm content in the soil cover of radioactively contaminated territories of Kazakhstan. The developed method for the determining of 151Sm will make it possible to assess the levels of soil contamination with this radionuclide, to determine the character of its spatial distribution, to allow estimating the internal exposure doses for the personnel and the population.

Optimal conditions for separation and determination by HPLC or MEKC combined fungicides thiuram and tebuconazole are selected. The method of simultaneous determination of pesticides in grain offered. The recovery of pesticides was 90–95%. Lower bounds defined by the contents of pesticides, taking into account the concentration amounted to 0.005 mg kg?1 in the MEKC method, and 0.0025 mg kg?1 in the method of HPLC. The relative standard deviation of the results of the analysis is less than 0.09, analysis of the duration of 1–1.5 h.

Sensor obtained by ion associate of vitamin B6 with tetraphenylborate ion and determined its electrochemical characteristics. Method biionnyh potentials determined selectivity coefficients of the electrode. The method of determination of the main substance in the product «Pyridoxine hydrochloride».

The ability of using cellulose diacetate (CDA) as matrix for luminescent determination of polycyclic aromatic hydrocarbons (PAH) in aqueous media was studied. PAH sorption was carried out on the example of pyrene from water solutions. Cellulose diacetate matrix was modified by anionic and cationic surfactants - sodium dodecylsulphate (SDS) and cetyltrimethylammonium bromide (CTAB). The comparative analysis of dependence of fluorescence intensity and polarity index of pyrene was carried out.

By differential scanning calorimetry (DSC) was first investigated experimentally determined complexes and phase characteristics of equilibrium points of the invariant three-phase triangles reciprocal systems of several Li,M || I,NO3 (M – Na, K, Rb). The compositions of eutectic (mol%) Li,Na || I,NO3 : (E1 ) NaNO3 – 42,5%, NaI – 5,0%, LiNO3 – 52,5% with a melting point of 178 °C. Li,K || I,NO3 (E2 ) LiNO3 – 44,0%, KI – 2,0%, KNO3 – 54,0% (mol) with a melting point of 117°.

The isothermal behavior of systems SDS – H2 O and SDS – H2 O – electrolytes has been investigated in the range 0–100 °C. The effect of the addition of sodium chloride, salicylic acid and sodium salicylate on the nature of phase transitions was shown. The viscosity of aqueous solutions of SDS (0–30 wt. %) was studied. The view about the nature of possible self-assembled structures in the systems was expressed.

The quaternary mutual system Li,K||F,MoO4 ,WO4 was partitioned into the simplexes and described the chemical interaction by conversion method and by method of ion balance. The prediction of the crystallizing phases conducted on the basis of the partition and of the equations for the reactions of conversion lines and for the method of ion balance.

An elemental composition and particle size distribution of the solid residue oil sludge are investigated, and a test samples series of a composite material is performed. The physico-chemical and operational properties of this material are investigated. Found that the characteris tics of the resulting material allow to use it in production of bituminous concrete for road construction.

In this paper is presented quantum-chemical research of the mechanism of reaction of an acylating butylmethylamine by propionyl chloride in the presence of lithium hydride. The estimate of two basic synthetic paths of an acylating butylmethylamine is made. Prereactionary complexes, transient states and reaction products are computed in program PRIRODA by a density functional theory (DFT) in approximation PBE and basis L1. Activation energies of reactions are computed. 

This work shows the possibility of synthesizing previously unknown 5-(4-bromophenyl)-3-((6-amino-2-mercaptopyrimidine)-4-amino)) methylidene-3H-furan-2-one containing a pharmacophore pyrimidine fragment by four-component one-pot reaction of malononitrile as the second methylene active component, thiourea, orthoester and 5-(4-bromophenyl)-3H-furan-2-one, which proceeds under mild conditions during thermal activation of the reaction mixture in isopropyl alcohol.