Marcel Azzaro

Fourier transform mass spectrometric studies of isovalent rare earth ions Sc+, Y+ and Lu+ with methanol. Formation of dimethoxide—metal species M(OCH3)+2

Abstract The primary and subsequent gas-phase reactions between methanol and the isovalent rare earth metal ions Sc + , Y + and Lu + have been investigated using a Fourier transform ion cyclotron resonance mass spectrometer. The three metal ions react exothermically with methanol. Among the primary reaction products obtained, only two are common to the three metals, the hydroxide—metal ions MOH + , and the methoxide—metal ions MOCH + 3 . For Sc + and Y + , as primary products the metal oxide ions MO + , and the metal—formaldehyde complexes M(OCH 2 ) + , are also observed, as well as the formation of the metal—dihydride ion MH + 2 (only for Y + ). All the primary ions undergo subsequent reactions with methanol, and the final product is always the M(OCH 3 ) 2 (CH 3 OH) + n species ( n = 0–3). The results are analysed to yield the lower and/or upper limits for bond energies: D °(M + OH) and D °(HOM + OH) > 92 kcal mol −1 , D °(HOM + OCH 3 ) and D °(M + OCH 3 ) > 105 kcal mol −1 for M  and Lu, D °(HOSc + OCH 3 ) and D °(Sc + OCH 3 ) > 119 kcal mol −1 , D °(ScOH) −1 , D °(YOH) −1 , and D °(LuOH) −1 .

Gas-phase reactions of Sc+, Y+, and Lu+ with alcohols. Effects of the class and chain length of alcohols on the nature of primary products

The primary gas-phase reactions between methanol, ethanol, propan-1-ol, propan-2-ol, and 2-methyipropan-2-ol and the isovalent rare earth metal ions Sc+, Y+, and Lu+ generated by laser desorption-ionization of metal targets have been investigated by using a Fourier transform ion cyclotron resonance mass spectrometer. The three metal ions react exothermically with all the alcohols. The overall reactivity is controlled by the high oxophilicity of these metals, and the primary metallated ions obtained are principally oxygenated species. However, the number and the nature of these primary products depends on the electronic configuration of the metal ions as well as on the class and the principal chain length of alcohols. The order of reactivity is Y+ > Sc+ > Lu+. The Y+ and Sc+ ions principally react via C—O and O—H insertions, whereas Lu+ reacts by direct abstraction or via various five-center electrocyclic mechanisms as a function of the class and the alcohol chain length.

Two guaiane and eudesmane-type sesquiterpenoids from Neocallitropsis pancheri

Two new sesquiterpenoids with the guaiane and eudesmane carbon skeleton termed pancherione and eudesm-4(14)-en-3α, 11-diol, were isolated from the heartwood of Neocallitropsis pancheri and characterized by 1D and 2D NMR spectroscopy. Trans-dihydrocarissone and α-, β- and γ-costols were also obtained from this plant for the first time and their NMR parameters are given.

β-Acoradienol, a sesquiterpene alcohol from Neocallitropsis pancheri

Abstract The structure of a new sesquiterpene alcohol, β-acoradienol, isolated from the wood of Neocallitropsis pancheri has been established as 1-methyl-4-isopropenyl-8-hydroxymethylspiro- [4,5]-7-decene.

Volatile Constituents of Neocallitropsis pancheri (Carrière) de Laubenfels Heartwood Extracts (Cupressaceae)

ABSTRACT The chemical composition of the heartwood oil of Neocallitropsis pancheri (Cupressaceae) obtained by steam distillation, has been established using GC/MS, GC/FTIR, Kovats indices and NMR data. The major components were found to be α-eudesmol (13.26%), β-eudesmol (25.92%), γ-eudesmol (19.04%), guaiol (3.02%) elemol (4.99%), β-bisabolenol (4.93%) and bulnesol (3.69%). Almost 40 compounds have been identified, 32 of which, including three new sesquiterpenoids (β-bisabolenal, β-bisabolenol and β-acoradienol), are reported for the first time in this oil. Isolation of a concentrate of the volatiles from N. pancheri using different solvents, and steam distillation produced concentrates of different yields (6.96–12.9%) and chemical composition. Some components were found to be subject to quantitative variation in the different wood concretes.

A microcalorimetric method for the measurement of enthalpies of solution of gases in liquids

Abstract An experimental set-up for measuring enthalpies of solution of gases in liquids is described. This apparatus consists of a vacuum line for gas handling and a Tian-Calvet microcalorimeter. The gas quantities are measured by a mercury manometer. The gas is injected into the calorimeter cell through a sintered glass-mercury one-way valve. The various sources of systematic and random errors are analyzed. The experimental method allows the measurement of the reaction stoichiometry and the distinction between fast and slow reactions; on the calorimeter time-constant scale. Along with spectroscopic studies of the reaction products, these features enable a more thorough characterization of the final state than the usual calorimetric techniques used for similar studies. A summary of the applications in the fields of physical organic chemistry, polymer chemistry and natural gas refining is given.

Jinkoholic acid, a prezizane sesquiterpene from Neocallitropsis pancheri

Abstract A new sesquiterpene carboxylic acid, jinkoholic acid, has been isolated from Neocallitropsis pancheri wood and, by means of 2D NMR experiments, shown to have the prezizane skeleton.

Transmission de l'effet de substituant a travers les systèmes insaturés—II. Relations entre les paramètres r.m.n. du 1H et du 13C des cyclohexène-2-ones-1 substituées en 3 et les constantes de réactivité☆

Abstract 1 H and 13 C n.m.r. spectra of 5,5-dimethyl cyclohex-2-en-1-ones substituted in position 3 have been analysed. Correlations of the chemical shifts of the ethylenic proton, the corresponding carbon and their coupling constant with Hammett type parameters provide a consistent picture of electronic effects transmitted through the unsaturated, non aromatic system. Systematic deviations shown for particular substituents reveal structural peculiarities and also effects that are not described by reactivity parameters.

Volatile constituents of the flower concrete of Gardenia taitensis DC

ABSTRACT After fractionation by normal distillation under reduced pressure followed by silica gel chromatography, the volatile fractions of the hexane concrete of Gardenia taitensis DC were investigated using GC/MS and GC/FTIR, and more than 150 components were identified. The major oxygenated constituents were found to be linalool (4.4%), methyl salicylate (2.5%), (Z)-3-hexenyl benzoate (2.2%), dihydroconiferyl alcohol (1.1%), (Z)-3-hexenyl salicylate (0.7%), benzyl benzoate (6.2%), dihydroconiferyl acetate (12.2%), 2-phenylethyl benzoate (6.2%), benzyl salicylate (2.5%), geranyl benzoate (2.1%) and 2-phenylethyl salicylate (2.2%). The identification of numerous dihydroconiferyl esters appears to be unique to this species.

Conformational analysis using torsion angle notation : attempted prediction and interpretation of the steric course of the cleavage reaction between bicyclic aziridines and hydrogen fluoride in pyridine solution

Abstract Dynamic conformational analysis of the cleavage of methyl-substituted 7-aza bicyclo [4.1.0] heptanes by Olahs reagent (30 wt % of pyridine in hydrogen fluoride), using the torsion angle notation, allows structural and conformational prediction of the 2-fluoro cyclohexylamine products. Consequently, a mechanism for the cleavage is proposed.