Synthesis,structure, and properties of 2-thio-4-imino-5-spirocyclohexanehydantoins

The imidazolium salt, obtained by the multicomponent condensation of benzyl isonitrile, methylamine, cyclohexanone, and thiocyanic acid, undergoes thermal recyclization to 1-methyl-2-thio-4-imino-5-spirocyclohexanehydantoin. The stereochemical and structural features and properties of the 2-thiohydantoins are analyzed on the basis of the data of x-ray structural analysis and geometrical modeling.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 485–492, April, 1989.     

Conformational properties of <Emphasis Type="Italic">ortho</Emphasis>-nitrobenzenesulfonamide in gas and crystalline phases. Intra- and intermolecular hydrogen bond

A combined gas-phase electron diffraction and quantum chemical (B3LYP/6-311+G**, B3LYP/cc-pvtz, MP2/cc-pvtz) study of molecular structure of 2-nitrobenzenesulfonamide (2-NBSA) was carried out. Quantum chemical calculations showed that 2-NBSA has four conformers, two of which are stabilized by intramolecular hydrogen bond. The latter (with the S–N bond in a close to orthogonal position around the phenyl ring and differing from each other by staggered or eclipsed positions of the N–H and S=O bonds in the SO₂NH₂ group) presented in a saturated vapor over 2-NBSA at T = 433 (3) K in commensurable amounts. Experimental internuclear distances (Ǻ) for the staggered conformer are (?): r _h1(C–H)_av. = 1.071(9), r _h1(C–C)_av. = 1.390(4), r _h1(C–S) = 1.789(8), r _h1(S=O)_av. = 1.427(6), r _h1(S–N) = 1.644(6), r _h1(N–O)_av. = 1.221(4), r _h1(C′–N) = 1.487(8), r _h1(N–H)_av. = 1.014. Calculations at B3LYP/cc-pvtz level were performed to determine the structure and the energies of the transition states between conformers. It was shown that the conformer structures of free molecule differ from those of a molecule stabilized by intermolecular hydrogen bonds in a crystal. Influence of a substituent X (X = –CH₃, –NO₂) on conformational features of the ortho-substituted benzenesulfonamide was established.     

Erratum to: “New Opportunities in Synthesis of Fullerene-Containing Polymers of Allyl Series”

Russian Journal of Applied Chemistry -     

Differential scanning calorimetry study of the solidification sequence of austenitic stainless steel

The solidification sequence of austenitic stainless steels can be predicted with thermodynamic calculations. Another way is to use models where the value of the Cr_eq./Ni_eq. ratio determines the relationship between the solidification mode and the composition factor. In this study the solidification of AISI 304LN stainless steel at different cooling rates was studied using differential scanning calorimetry (DSC). The samples were linearly heated above the liquidus temperature to 1550 °C at heating rates of 5, 10, and 25 K/min. The solidification (cooling) scans from 1550 °C involved the same selected ramps. After the DSC measurements the samples were metallographically analyzed to reveal the variations in the solidification microstructures. The microhardness of the solidified samples was also measured. It was found that the cooling rate critically influenced the solidification. The solidification behavior, which depends on the cooling rate, determines the evolution of the microstructure. At the slowest cooling rates a relief-cell morphology was observed, and at the fastest cooling rate the formation of dendrites was evident. With an increasing cooling rate the liquidus temperature decreased and the reaction enthalpy increased.     

Hydrosilylation and hydrogermylation of 3-OXO-1,2-Benzisothiazoline-2-(2-propynyl)-1,1-dioxide

The addition of triethylsilane and triethylgermane to N-propargylsaccharin in the presence of the Speier catalyst gives the gem adduct with trans configuration. This pathway accounts for 75–80% of the reaction.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2889–2891, December, 1991.     

Synthesis of N-(2-Hydroxyalkyl)trimethylsilylpropynamides

A number of previously unknown N-(2-hydroxyethyl)trimethylsilylpropynamides were synthesized by reactions of 2-aminoethyl trimethylsilyl ethers with trimethylsilylpropynoyl chloride. 2-Hydroxyethylamine reacts with trimethylsilylpropynoyl chloride at both nitrogen and oxygen atoms to afford 2-(3-trimethylsilylpropynoylamino)ethyl trimethylsilylpropynoate.     

Reaction of trimethylsilylpropynal with dialkylamines

Conclusions The reaction of trimethylsilylpropynal with dialkylamines is accompanied by heterolysis of the Si-C_sp bond and formation of -aminoacroleins.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1866–1868, August, 1987.