Vol. 21 No. 2 (2023): Issue in Progress
Published:
2023-05-31
Original Researches
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The Synthesis and Acid-base Properties of α-(Fluoromethyl)- and α-(Difluoromethyl)-substituted Cyclobutane Building Blocks
Aim. To synthesize cyclobutane-derived amines and carboxylic acids bearing CH2F or CHF2 groups in the α position; to determine the regularities of the effect of fluoroalkyl substituents on the acid-base properties of the title compounds.
Results and discussion. Synthetic approaches to 1-(fluoromethyl)- and 1-(difluoromethyl)cyclobutanamines, 1-(fluoromethyl)- and 1-(difluoromethyl)cyclobutanecarboxylic acids have been developed. It has been found that the pKa (pKa(H)) values measured for the title compounds, as well as for their non-substituted and CF3-substituted analogues, are consistent with the electron-withdrawing effect of the corresponding fluoroalkyl substituents.
Experimental part. The synthesis of the title compounds commenced from the known ethyl 1-(hydroxymethyl)cyclobutanecarboxylate or the product of its Swern oxidation (the corresponding aldehyde) and included fluorination, alkaline ester hydrolysis (for carboxylic acids), and modified Curtius rearrangement (for amines). The pKa value was determined from the pre-equivalence point part of the titration curve using the standard acid-base titration.
Conclusions. A newly developed synthetic approach to 1-(fluoromethyl)- and 1-(difluoromethyl)cyclobutanamines, 1-(fluoromethyl)- and 1-(difluoromethyl)cyclobutanecarboxylic acids allows to obtain the title compounds in multigram quantities (up to 97 g). With a single exception, the acid-base properties of these products, as well as their parent non-substituted and CF3-substituted analogues, change in a monotonous manner in accordance with inductive electronic effect of the fluorine atom(s). -
The Synthesis of 1-Alkyl-3-polyfluoroalkyl- 1,3-dihydrobenzimidazole-2-selenones as Potential Plant Growth Regulators
Aim. To synthesize new 1-alkyl-3-polyfluoroalkyl-1,3-dihydrobenzimidazole-2-selenones and study their biological activity as potential plant growth regulators.
Results and discussion. 1-Alkyl-3-polyfluoroalkyl-1,3-dihydrobenzimidazole-2-selenones were obtained from the corresponding 1-alkyl-3-polyfluoroalkylbenzimidazolium iodides by the action of elemental selenium in the presence of a base. The preliminary biological tests for the growth-regulating activity of the compounds obtained were conducted.
Experimental part. The structure of the compounds synthesized was proven by 1H and 19F NMR spectroscopy methods, as well as by the elemental analysis. The biological studies were done on model plants of winter wheat of the “bezosta” variety.
Conclusions. A convenient method for obtaining 1-alkyl-3-polyfluoroalkyl-1,3-dihydro-benzimidazole-2-selenones has been developed. Biological studies have shown that the compounds synthesized have a diverse effect on the plant growth. -
The Quantitative Determination of Oxacillin Using Kinetiс-Spectrophotometric and Redox Titration Methods
The search for new analytical reactions and finding out the optimal conditions for their course, which can be used as the basis for quantitative analytical determinations of penicillins, is a very urgent task.
Aim. To develop methods for the quantitative determination of Oxacillin.
Materials and methods. The study object was Oxacillin sodium salt powder in vials for preparing a solution for injections
(0.5 g). Peroxomonosulfate acid as triple potassium salt 2КНSO5∙КНSO4∙K2SO4 (Oxone®) of “extra pure” grade was used as an oxidant. The methods of kinetic spectriphotometry and redox titration were used.
Results and discussion. A simple procedure for the quantitative determination of the Oxacillin pure substance by the kinetic spectrophotometry and redox titration methods using potassium hydrogen peroxomonosulfate (KHSO5) has been developed. The results of the drug analysis obtained by newly developed and current methods are in good agreement with each other; δ (correctness) = (0.45 – 0.86) %.
Conclusions. Using the methods of kinetic spectrophotometric and redox titration, two independent procedures for the
quantitative determination of oxacillin in the substance and the drug product have been developed using potassium hydrogen peroxomonosulfate as an analytical reagent (KHSO5). A relative standard deviation RSD = (1.24 – 2.17) %.
