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G Nicol

Publications and source records attributed to G Nicol.

9 recordsLinked to original sources
PubMed2000

Tandem mass spectrometric study of 1,3,5-trinitrobenzene molecular ion: an unusual ortho effect involving a hydrogen atom from the aromatic ring

Unimolecular (metastable) and collision-induced dissociation of 1,3, 5-trinitrobenzene molecular ion was studied using linked scans and mass-analyzed ion kinetic energy spectrometry on a hybrid instrument of EBEqQ geometry. An unusual ortho effect leading to the loss of OH radical from the parent molecular ion is observed as a unimolecular dissociation process only in the first-field free region between the ion source and the electric sector, although corresponding dissociation in the ion source is of negligible abundance (<0.1%). This unimolecular process is taken over by other dissociation pathways when the parent ion is collisionally activated, suggesting that this dissociation process occurs only in a very narrow energy window with a rate constant of the order of 2 x 10(5) s(-1). Copyright 2000 John Wiley & Sons, Ltd.

Journal Article↗
PubMed2000

Proton affinities of saturated aliphatic methyl esters

The kinetic method was used to determine the proton affinities of methyl esters of several saturated fatty acids. Decompositions of the proton-bound dimers of the methyl esters, AHB+, were observed under different conditions with two instruments. The proton affinities (PAs) of the methyl esters increase continually with increasing carbon number in the acid. Equilibrium and initial rate experiments were performed with a Fourier transform ion cyclotron resonance mass spectrometer on the methyl ester of the C22 saturated acid (methyl behenate). These experiments give values for PA (methyl behenate) that are perhaps slightly lower than those obtained with the kinetic method. The PAs of the methyl esters of the fatty acids could be correlated with the equation: PA (ester) = (40.0 +/- 2.5)*log(n) + (784.7 +/- 3.9) kJ/mol or PA (ester) = (864 +/- 2) - (479 +/- 41)/n, where n = number of atoms in the molecule. Proton affinities of smaller sets of 1-alkylamines and 1-alkanols can be fit to similar equations.

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