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The 13C n.m.r. spectra of several norbornyl derivatives have been recorded to examine the variation of I3C shieldings with molecular geometry. Since it is well established that nonbonded interactions between vicinal carbon nuclei lead to pronounced upfield shifts, the so-called y effects, series of methyl-substituted norbornanes, norbornenes, norbornan-2-ones (norcamphors), and norborn-5-en-2-ones were prepared a s model systems having a variety of y interactions between vicinal methyl groups. The observed shifts of these methyl carbons are considered in terms of the dihedral angle relating the vicinal nuclei. The use of specific deuterationfor unequivocal signal assignments ofcarbons geminal and vicinal to the site of deuteration is illustrated.Les spectres 1.m.n. I3C de plusieurs derives du norbornyle ont ete enregistres afin d'etudier la variation de I'effet de blindage du I3C en fonction de la geometrie moleculaire. Puisqu'il est bien connu que d e s interactions non-likes entre des carbones vicinaux entrainent des deplacements du signal vers des champs Cleves, relation connue sous le nom effets-y plusieurs norbornanes, norbornenes, norbornanones-2 (norcamphres) et norbornkne-5 ones-2 substituis par des groupes methyles ont i t 6 prCpares afin de servir d e modkles posskdant diffkrentes interactions y entre des groupes methyles vicinaux. O n a utilis6 la deutCration spicifique pour attribuer sans arnbiguite les signaux se rattachant aux carbones gCmines et vicinaux au site d e deuteration.[Traduit par le journal]Can. J . Chem., 51, 2893Chem., 51, (1973

Cloud point extraction has been used for the preconcentration of manganese, after the formation of a complex with 1-(2-thiazolylazo)-2-naphthol (TAN), and later analysis by flame atomic absorption spectrometry using octylphenoxypolyethoxyethanol (Triton X-114) as surfactant. The chemical variables affecting the separation phase and the viscosity affecting the detection process were optimized. Under the optimum conditions (i.e., pH = 9.2, [TAN] = 2.0 x 10(-5) mol l-1, [Triton X-114] = 0.05%, added methanol volume = 0.2 ml), preconcentration of 50 ml of sample solution permitted the detection of 0.28 ppb for manganese. The enhancement factor was 57.6. The proposed method has been applied to the determination of manganese in water samples.

This paper describes the degradation of p-chlorophenol using three different ultrasonic devices. The dissipated power in the reaction matrix was measured based on calorimetric method. The study showed that hydrogen peroxide can improve the sonochemical reaction and gases dissolved in reaction matrix can affect the process to a small extent. The reaction mechanism and kinetics of degradation were also investigated.