The cycloaddition reaction of diphenylketene and cycloheptatriene is studied. The reaction proceeds via a highly asynchronous reaction path to the zwitterionic 6 as intermediate. Subsequent CC- bond formation yields 8, ...

In this paper we shall apply modules of generalized fractions to extend the notion of the grade of an ideal, and to obtain characterizations of Gorenstein rings.

One hundred and nineteen karst springs, all with electrical conductivity of less than 500 gmhosfcm, discharging two carbonatic aquifers in Zagrosides of Iran are chosen and studied. The results indicate that the lithology ...

The organic solvent extraction of Armillaria mellea showed different highly intrinsic fluorescent compounds either in rhizomorph or in hyphae (F , F , F , MF , MF and MF ). The characterization of ultraviolet and ...

A kinetic study of the decomposition of pyridine chromium peroxide with methanol, ethanol, propanol and isopropanol has been made over the temperature range 25 to 40°C. It is found that the ligand exchange stage is the ...

The 70 ev positive and negative ion mass spectra of ring-substituted nitrobenzenes were studied. The influence of the substituent group on the fragmentation modes of the molecular ions is discussed. The effect of pressure ...

Synthetic approaches have been described for the preparation of precursors to triasterane trications and related carboxenium ions. The investigation on carbocationic intermediates from treatment of these precursors with ...

Pain is probably the immediate stimulus for more visits to the Physician's office than all other complaints combined. Since pain serves as an alert to injury, it is often the first harbinger of disease. Piperidine has ...

Thermal rearrangement of spirans (14) and (31) yields the xanthones (16,34) and diphenylrnethane (15, 32), respectively. The structure for xanthone (16), isolated from thermolysis, has been established by reduction to ...

Reductive Claisen rearrangement of 1-allyloxy-8-methoxy-9, 10-anthraquinone followed by demethylation and reduction, and of 1,8-bisallyloxy-9,lO-anthraquinone followed by reduction provides regiospecific syntheses of ...

Seventeen two-photon transitions for neon have been observed in the 580- 635 nm spectral region for use in the spectroscopic study of its higher excited levels, which are not accessible by one-photon absorption. To compare ...