Standard molar enthalpies,volumes, and heat capacities of adamantane in cyclohexane,n-hexane,and carbon tetrachloride. Interpretation using the scaled-particle theory

The volumes, heat capacities, and enthalpies of solution of adamantane in cycloxane,n-hexane, and carbon tetrachloride have been measured as a function of concentration at 25°C (15, 25, and 35°C for the volumes). The results extrapolated to infinite dilution have been resolved into cavity formation and interaction terms. The former have been calculated from the equations of the scaled-particle theory. To estimate the contribution from the latter, we have assumed some proportionality between adamantane-solvent and cyclohexane-solvent interactions. This assumption has been verified with the three different solvents for the three studied thermodynamic functions. The diameter of adamantane in solution has been determined to be 6.36 Å.     

Addition nucleophile des anions d'esters α-cyanoacetiques sur les cations succinimidosulfonium: Fragmentation ionique ou radicalaire des′ σ-sulfuranes intermediaires

Reactions of substituted cyanoacetate anions 4 with S,S-dialayklsuccinimidosulfonium salts resulted generally in the formation of N-alkylthiomethylketenimines and α-alkylthiomethylesters. Coupling products were also obtained with anion 4d and only observed in the case of methyl phenylcyanoacetate anion 4b. The results were interpreted by the formation of instable σ-sulfurane intermediates. Homolytic cleavage of these intermediates gave radical pairs, then the coupling products. Heterocyclic clevage gave new sulfonium salts which rearranged via sulfonium ylides.     

Action de réactifs nucléophiles sur les phényl-5 thiéno[3,2-b]pyrannone-7 et phényl-2 benzo[b]thiéno[3,2-b]pyrannone-4

Reactions of 5-phenylthieno[3,2-b]pyran-7-one, 2-phenylbenzo[b]-thieno[3,2-b]pyran-4-one and the corresponding thiones with sodium ethylate, guanidines, hydrazines and amines are described and compared to those observed with benzopyranones.     

Enthalpies of the urea-tert-butanol-water system at 25°C

The enthalpies of solution of urea (U) in water (W)-tert-butanol (TBA) mixtures and of TBA in W-U mixtures, the enthalpies of dilution of TBA in W, and the enthalpies of mixing of U and TBA aqueous solutions were measured with a solution calorimeter and a flow microcalorimeter. Enthalpies of transfer of U and TBA to the mixed solvents were derived. Also, pair and triplet interaction parameters between the various solutes were derived from the mixing and dilution experiments. The enthalpic pair parameter h_U-TBA is positive, suggesting that the main contribution to this parameter is the decrease in hydrophobic hydration of TBA in the presence of U.     

Synthesis in the thienobenzoxazepine series. First synthesis of a diethienoxazepine

In an investigation of novel tricyclic systems, synthesis of several thieno[2,3-b][1,4]benzoxazepines and thieno[3,2-b][1,5]benzoxazepines were effected by ring closure of appropriately amino aldehyde compounds. A new oxazepine fused with two heterocyclic rings, the dithieno[3,2-b:2,3-f][1,4]oxazepine, is described.     

Chemical transport reactions in the In-Sn-S ternary system: Existence of tin (II) and tin (IV) atoms by Mössbauer effect of119Sn in the isolated compounds

Iodine vapour transport, carried out in the In-Sn-S ternary system leads to single crystals with quite different morphologies: needles, sticks, sheets and polyhedra. The two oxidation states of tin atoms are shown for all these phases by¹¹⁹Sn Mössbauer effect. A varying relative proportion of tin(IV) — tin(II) is observed according to the different crystal forms.     

Partial orientation of nitroxide biradicals in the plastic phase of cyclohexane and in frozen toluene solution

Several nitroxide biradicals have been studied by electron spin resonance, in cyclohexane solution at ?10°C and in toluene solution at ?150°C. The ESR spectra change when the sample orientation in the spectrometer cavity is changed: under favourable circumstances oriented spectra are obtained.     

Spontaneous chiral symmetry breaking for a U(N) gauge theory on a lattice

We study the breakdown of chiral invariance by calculating, in the infinite coupling, large-N limit, the generating functional of a U(N) gauge theory with one fermion, expressed on a lattice with the naive, chiral symmetric action. We compute the link integral over the gauge fields and the expression obtained after the integration over the fermions is recast under the form of a generating functional for bosonic fields. Then, a saddle-point method allows the calculation of the order parameter $\text{〈}\text{ψ}\text{ψ〉}$ for which a non-zero value signals the spontaneous breakdown of chiral symmetry. The analysis of the fluctuations around the saddle point allows one to exhibit the Goldstone modes corresponding to those global symmetries of the fermionic lattice action which are simultaneously broken.