Gas Chromatography Columns Based on Functionalized Polymer for the Analysis of Catalytic Reaction Products

For the first time in this work, two methods of modification of poly(1-trimethylsilyl-1-propyne) (PTMSP) and the possibilities of its application for the determination of catalytic reaction products are described. Aging of PTMSP is determined by three mechanisms: physical, chemical and mechanical effects. Free volume decreases, texture characteristics change, and partial oxidation of the polymer takes place in the structure of PTMSP. The chromatographic behavior of PTMSP, which was used for 18 months, differs significantly from the properties of the freshly prepared polymer. Thermal stability and chemical inertness are the main requirements for chromatographic materials. Therefore, two methods were used to stabilize the aging process. The first method consisted of preparing a mixed phase by adding disubstituted polyacetylene poly(1-phenyl-1-propyne) (PPP) to PTMSP. The resulting sorbent Chromosorb Р NAW?+?10 wt% (97% PTMSP?+?3% PPP) is efficient for solving a wide range of chromatographic tasks such as simultaneous analysis of hydrocarbons and sulfur-containing inorganic gases, analysis of chlorine-substituted methanes in CCl₄ and thiophene in benzene, separation of hydrocarbons and aromatic compounds. It should be noted, the low selectivity of separation of oxygen-containing components on this sorbent. A second method of PTMSP modification, namely the oxidation treatment with nitrous oxide, is proposed. It was shown that the polymer is oxidized by means of its C=C double bond with the formation of ketone, carbonyl and hydroxyl groups. The increase in number of those groups in the polymer changed the polarity of PTMSP. The change in polarity of polymer led to the selectivity of separations, including oxygen-containing substances. Examples of separations of aliphatic and aromatic hydrocarbons, oxygen- and halogen-containing substances are presented. Chromatographic characteristics of the sorbent Chromosorb P NAW?+?10 wt% (97% PTMSP?+?3% PPP) and PTMSP oxidized by nitrous oxide are stable in the temperature range from 30 to 220 °C for at least 1.5 years of continuous operation.

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Capillary Columns with a Sorbent Based on Functionalized Poly(1-Trimethylsilyl-1-Propyne) for the Elution Analysis of Natural Gas

Russian Journal of Physical Chemistry A - The chromatographic properties of capillary columns prepared using functionalized poly(1- trimethylsilyl-1-propyne) (PTMSP) are evaluated and compared with...     

Synthetic transformations of sesquiterpene lactones. Controllable synthesis of 11,13-dihydroisoalantolactone azides and 13-(1,2,3-triazolyl)eudesmanolides based on sesquiterpene lactones

Chemistry of Heterocyclic Compounds - Modification of eudesmane-type lactones isoalantolactone and 4,15-epoxyisoalantolactone was carried out at the active methylene group. The reaction of...     

Design,Synthesis and Assay of Novel Methylxanthine–Alkynylmethylamine Derivatives as Acetylcholinesterase Inhibitors

Xanthine derivatives have been a great area of interest for the development of potent bioactive agents. Thirty-eight methylxanthine derivatives as acetylcholinesterase inhibitors (AChE) were designed and synthesized. Suzuki–Miyaura cross-coupling reactions of 8-chlorocaffeine with aryl(hetaryl)boronic acids, the CuAAC reaction of 8-ethynylcaffeine with several azides, and the copper(I) catalyzed one-pot three-component reaction (A³-coupling) of 8-ethynylcaffeine, 1-(prop-2-ynyl)-, or 7-(prop-2-ynyl)-dimethylxanthines with formaldehyde and secondary amines were the main approaches for the synthesis of substituted methylxanthine derivatives (yield 53–96%). The bioactivity of all new compounds was evaluated by Ellman’s method, and the results showed that most of the synthesized compounds displayed good and moderate acetylcholinesterase (AChE) inhibitory activities in vitro. The structure-activity relationships were also discussed. The data revealed that compounds 53, 59, 65, 66, and 69 exhibited the most potent inhibitory activity against AChE with IC₅₀ of 0.25, 0.552, 0.089, 0.746, and 0.121 μM, respectively. The binding conformation and simultaneous interaction modes were further clarified by molecular docking studies.     

Enzymatic esterification of saturated fatty acids with aliphatic alcohols as an alternative method of a low-temperature synthesis of esters

Russian Chemical Bulletin - low-temperature synthesis of saturated fatty acid esters with aliphatic alcohols by enzymatic esterification in the presence of heterogeneous biоcatalysts was...