Elemental analysis, Fourier transform infrared, C13 nuclear magnetic resonance, and electrospray ionization/mass spectrometry (ESI/MS) experiments were performed on two commercial naphthenic acid mixtures in order to determine the acidity, ring type, and carbon number distribution. Critical MS/MS experimental parameters, i.e., isolation width and collision-activated dissociation energy, were optimized and fragmentation patterns elucidated for a series of acid standards and the commercial naphthenic acid mixtures. The MS/MS experiments confirm that P&B and Fluka naphthenic acid mixtures consist primarily of carboxylic acids with dominant hydrogen deficiency values of −6 and 0, respectively, with respect to an alkanoic acid reference. The MS/MS experiments validated the preponderance of carboxylic acid moieties in these samples. The approach was then used to determine the composition of a Maya crude oil extract. Surprisingly, the extract was found to contain a dominant alkylsulfonic acid homologous series.

Key indicatorsSingle-crystal X-ray study T = 298 K Mean (C-C) = 0.002 Å R factor = 0.052 wR factor = 0.167 Data-to-parameter ratio = 16.0For details of how these key indicators were automatically derived from the article, see

Key indicatorsSingle-crystal X-ray study T = 296 K Mean (C-C) = 0.002 Å R factor = 0.040 wR factor = 0.106 Data-to-parameter ratio = 16.0For details of how these key indicators were automatically derived from the article, see

The asymmetric unit of the title compound, C16H16N2O6, contains one-half mol­ecule, the mid-point of the central C—C bond being located on a crystallographic inversion center. The crystal structure shows weak inter­actions between the O atoms of the nitro groups and two different C—H groups of the benzene rings. The extended weak hydrogen-bond formation, involving the NO2 groups, generates an infinite three-dimensional network.

2005) Synthesis and crystal structure of a macrocyclic complex precursor: Bis-(2-amino-1-methyliminobenzene)1,2-ethane nickel(II) dichloride (10), c ¼ 11.045(2) Å , ¼ 94.76(10), ¼ 108.30(10), ¼ 109.86(10) , Z ¼ 2, and represents a precursor of a tetradentate azamacrocyclic complex. The structure is stabilized by a system of intramolecular and intermolecular H-bonding involving chloride ions and nitrogen atoms. The coordination geometry about nickel(II) is slightly distorted octahedral.