Stereoelectronic control of exo/endo rate ratios in the solvolysis of 2-norbornyl p-toluenesulfonates

The variable exo/endo rate ratios observed in the solvolysis of 6-exo-substituted exo- and endo-2-norbornyl p-toluenesulfonates are due to differential transmission of polar effects in the transition state for ionization.     

Beim Nachweis von E 605 im Mageninhalt

Ohne Zusammenfassung     

The Nature of the vibronic intensity borrowing mechanism in the 1B3u(n)1Ag(X) transition of pyrazine

The transition intensities of the S₀S₁ gas phase absorption spectra of pyrazine-d₀ and -d₄ were carefully measured. A discussion of the various aspects of vibronic intensity borrowing for this unique case is presented using our new experimental results.     

Oxidation of cyclohexane with molecular oxygen using a Schiff base cobalt complex bonded to carbamate-modified silica gel

The Schiff base [1,2-bis(salicylidene amino)phenylene]cobalt(II) complex, chemically bonded to a carbamate-modified silica gel catalyst, has been prepared by a four step procedure. The oxidation of cyclohexane was studied in the presence of this catalyst under relatively mild conditions (150–200 °C, 15–20 atm) using molecular oxygen. The catalyst was found to be very selective for the production of cyclohexanol, with cyclohexanone formed in only a small amount (45:1). This is in contrast to the commercially available processes in which cyclohexanol and cyclohexanone are both formed in appreciable amounts. The t.g.a. analysis shows the catalyst to be stable up to 211 °C and atomic absorption spectroscopy indicated negligible metal loss during 50 h use of the catalyst up to 180 °C.