The conjugation stabilization of 1,3-butadiyne is zero

[reaction: see text] In contrast to 1,3-butadiene, the textbook example of "conjugation stabilization", G3(MP2) calculations yielding the enthalpy of hydrogenation Delta(hyd)H(298) of 1,3-butadiyne indicate that it is not stabilized by the conjugated configuration of its triple bonds. Differences between ethylenic and acetylenic pi bonds are examined in the light of CAS-MCSCF calculations on 1,3-butadiene and 1,3-butadiyne.     

Design of materials for solid oxide fuel cells,permselective membranes,and catalysts for biofuel transformation into syngas and hydrogen based on fundamental studies of their real structure,transport properties,and surface reactivity

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A new γ‐polymorph of chlorpropamide: 4‐chloro‐N‐(propylaminocarbonyl)benzenesulfonamide

The structure of a new polymorph of the title compound, C₁₀H₁₃ClN₂O₃S, known as the antidiabetic drug chlorpropamide, is monoclinic, in contrast with the two previously described orthorhombic α‐ and β‐forms. The molecules in the γ‐polymorph are linked into bands by hydrogen bonds similar to those in the α‐polymorph. The conformation of the molecules in the γ‐form is close to that in the β‐polymorph.     

Invariant states for the time dynamics of a class of multidimensional lattice quantum Fermi systems

The study of invariant states of fermionic lattice systems begun earlier is contined. Under the assumption that the time dynamics corresponds to a (formal) HamiltonianH ₀ and the invariant state is a KMS state for some HamiltonianH [1], one-dimensional lattice Fermi systems were considered in the earlier work. In particular, the case whenH ₀ is not a quadratic form in the creation and annihilation operators and all nonquadratic terms inH ₀ are diagonal was studied. In this case, it was shown that up to an arbitrary diagonal quadratic formN the HamiltonianH is proportional toH ₀, i.e., that is a KMS state of H ₀+N. In this paper, we obtain a similar result for Fermi systems of arbitrary dimension by a somewhat different method to the one used earlier [1].Chelyabinsk State University. Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 94, No. 1, pp. 76–83, January, 1993.     

Isotropy of 8-dimensional quadratic forms over function fields of quadrics

Let F be a field of characteristic different from 2 and let ø be an anisotropic 8-dimensional quadratic form over F with trivial deter-minant. We study the remaining open cases in the problem of describing the quadratic forms ψ such that ø becomes isotropic over the function field (ψ).     

Inverse electron demand Diels–Alder reaction as a novel method for functionalization of natural chlorins

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Kharasch reaction: Cu-catalyzed and non-Kharasch metal-free peroxidation of barbituric acids

It was discovered that the Kharasch peroxidation of barbituric acids proceeds both with a Cu-catalyst and without a metal catalyst. Despite the presence of possible thermal-initiated side oxidation pathways, α-tert-butylperoxybarbiturates were selectively prepared from substituted barbituric acids and tert-butyl hydroperoxide.