title: Isobaric molecular formulae of C, H, and O: a view from the negative quadrants of van Krevelen space.
abstract: When compositions of an isobaric series of molecular formulae consisting of C, H, and O are displayed in a van Krevelen plot, a remarkable number of nonparallel lines of compositions can be observed. Each group of related lines converge at a point in a negative quadrant of van Krevelen space (e.g., H/C = 4, O/C = -1). These points of convergence have H/C and O/C ratios that correspond to "molecular formulae" in which the stoichiometric coefficients of some of the isotopes are negative. In this manner, a group of related low-mass moieties have been identified (CH4O(-1), C4O(-3), C2H(-8)O(-1), CH(-12), etc.). Each of these moieties has a nominal mass of zero and a very small exact mass. Furthermore, all of these low-mass moieties have compositions that fall on the line H/C = -12 - 16(O/C), which lies entirely in the negative quadrants of van Krevelen space. This paper demonstrates that all low-mass moieties consisting of C, H, and O can be expressed formally as linear combinations of any two moieties. Likewise, all molecular formulae that fall on a line that passes through a given low-mass moiety must differ compositionally by a multiple of the composition of that moiety, and their exact masses must differ by a multiple of the exact mass of the moiety. This latter relationship has been invoked for very rapid assignment of a molecular formula to an exact mass. Finally, a more comprehensive and theoretically based understanding of family scores has been developed around the concept of low-mass moieties.
authors: †Department of Chemistry, Ball State University, Muncie, Indiana 47306, United States.
authors: E Michael
authors: EM
authors: Perdue
authors: †Department of Chemistry, Ball State University, Muncie, Indiana 47306, United States.|‡School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0340, United States.
authors: Nelson W
authors: NW
authors: Green
mesh_terms: D002244:Carbon / Q000737:chemistry*; D003031:Coal; D006859:Hydrogen / Q000737:chemistry*; D008970:Molecular Weight; D010100:Oxygen / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D003031:Coal; D002244:Carbon; D006859:Hydrogen; D010100:Oxygen