Review Journal of Chemistry (v.1, #4)
2-Thioxo-tetrahydro-4H-imidazol-4-ones, 2-alkylthio-3,5-dihydro-4H-imidazol-4-ones and their coordination compounds with transition metal ions by E. K. Beloglazkina; A. G. Majouga; E. A. Manzhelii; N. V. Zyk; N. S. Zefirov (309-343).
Data published in the past decade on the methods of synthesis of 2-thiohydantoins and 2-alkylthio-3,5-dihydro-4H-imidazol-4-ones are reviewed. Methods used to introduce various functional groups into positions 2 and 5 of thiohydantoin or 3,5-dihydro-4H-imidazol-4-ones by using the condensation and nucleophilic substitution reactions are considered. The reactions of complex formation with the participation of thiohydantoins and 3,5-dihydro-4H-imidazol-4-ones are analyzed, and the data on synthesis methods, structural types, and catalytic activity of their complexes with transition metals are presented.
Keywords: 2-thiohydantoins; imidazolones; imidazolidinones; coordination compounds
Mechanism and principles of organization of catalytic radical heterogeneous-homogeneous processes by N. A. Vasil’eva; R. A. Buyanov (344-358).
The mechanisms and regularities of unbranched radical-chain reactions are considered using the example of the pyrolysis of hydrocarbons or dichloroethane involving heterogeneous catalysts. The phenomenological model of such reactions and experimental proof of its validity are presented. An effect of “ignition” of the catalyst activity is discovered, and its nature is explained. The concept of “catalysis sphere” is introduced, and the conditions of its existence and functioning are determined. The experimental criteria for the occurrence of the sphere are found. The offered mechanism creates the possibility for a purposeful selection and synthesis of catalysts and for a choice of means of the technological organization of the heterogeneous-homogeneous processes with the participation of radicals.
Keywords: catalysis; pyrolysis; hydrocarbons; dichloroethane; chain mechanism; radical-chain process
Methods for the amination of arenes by A. V. Aksenov; N. A. Aksenov; O. N. Nadein; Yu. I. Smushkevich (359-384).
This review covers literature data on the amination of arenes and considers both multistep methods for the introduction of an amino group in the aromatic ring and the direct amination (amidation) of aromatic hydrocarbons. The main attention is drawn to the electrophilic amination (amidation) of aromatic hydrocarbons because of the lack of comprehensive reviews on recent advances in this area.
Keywords: direct electrophilic amination and amidation; aromatic amines; anilides; arenes; methods of functionalization
Biocatalytic hydrolysis of nitriles by V. G. Debabov; A. S. Yanenko (385-402).
Two pathways of enzymatic hydrolysis of nitriles to carboxylic acids are known today. Under the action of nitrilases, nitriles turn into carboxylic acids in a single step via the addition of two water molecules. Under the action of nitrile hydratases, nitriles turn into amides, which are then hydrolyzed by amidase to carboxylic acids. This review deals with the structure, substrate specificity, mechanisms of action, and industrial potential of these three enzymes. Examples of successful use of the nitrile-hydrolyzing enzymes in the large-scale manufacture of acrylamide and nicotinamide in Russia and abroad and in the industrial synthesis of α-hydroxy acids (glycolic and R-mandelic acids) are presented. The stereoselectivity and regioselectivity of the enzymes make them usable in the synthesis of chiral synthons for the production of important pharmaceuticals (statins, antimitotic agents, and enzyme inhibitors).
Keywords: enzymatic hydrolysis of nitriles; nitrile hydratases; amidases; nitrilases; use in organic synthesis