Characteristic frequencies in the infrared spectra of pyrazolines

Pyrazolines are characterized by valence vibrations at the following frequencies: C=N (1580–1627 cm^–1), H-C³=N (3040–3063 cm^–1), H-N (3270–3305 cm^–1) and CH₃-N (2780–2805 cm^–1). Lowering of the frequencies of the valence vibrations of C=N in pyrazolines, when compared with the magnitudes characteristic of alkyledene amines and oximes, is regarded as a consequence of coupling with the unshared electron pair of the neighboring nitrogen atom. By means of the IR spectra, it is possible to determine the position of the double bonds in the pyrazoline ring, to distinguish between pyrazolines substituted and nonsubstituted in positions 1 and 3, and to establish the presence of geminate (twin) methyl groups and methyl groups in position 1.     

Formation of long-lived fluorofullerene trianions in collisions with Na

The first experimental observation of long-lived triply charged fluorofullerene anions in the gas phase obtained from C60F48 is reported. The existence of a Coloumb barrier trapping the third electron in the trianion is supposed to be responsible for detection of the species which is estimated to have negative third electron affinity.     

Limiting subhessians, limiting subjets and their calculus

We study calculus rules for limiting subjets of order two. These subjets are obtained as limits of sequences of subjets, a subjet of a function at some point being the Taylor expansion of a twice differentiable function which minorizes and coincides with at . These calculus rules are deduced from approximate (or fuzzy) calculus rules for subjets of order two. In turn, these rules are consequences of delicate results of Crandall-Ishii-Lions. We point out the similarities and the differences with the case of first order limiting subdifferentials.

     

Unusual transfoemation of trimethylsilyl ester of 5-chloromethyl-2-isoxazoline-3-carboxylic acid

Conclusions The silylation of 5-chloromethyl-2-isoxazoline-3-carboxylic acid with the usual silylating agents leads to the corresponding trimethylsilyl ester, which when heated is converted to 4-chloro-3-trimethylsiloxybutyronitrile.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2818–2819, December, 1981.     

The enthalpy of formation of fullerene fluoride C<Subscript>60</Subscript>F<Subscript>18</Subscript> and the C-F bond energy

The enthalpy of combustion of crystalline fullerene fluoride C₆₀F₁₈ was determined in an isoperibolic calorimeter with a rotating platinized bomb, and the enthalpy of formation of the compound was calculated. The enthalpy of sublimation of C₆₀F₁₈ measured earlier was used to calculate the enthalpy of formation of fullerene fluoride in the gas phase and the mean enthalpy of dissociation of C-F bonds in this compound.