Derry W. Jones

Aromatic products of 340 °C supercritical-toluene extraction of two Turkish lignites: an n.m.r. study

Abstract Fractions of Elbistan and Seyitomer (Turkish) lignites, extracted with supercritical toluene at 340 °C and 8 MPa, have been separated by solvent extraction and silica-gel chromatography. Analyses by n.m.r. and i.r. spectroscopies and other methods have been combined in structural-analysis schemes to yield information about the average molecule in aromatic extracts. Carbon aromaticities, f a , derived from 22.63 MHz 1 H-decoupled pulse Fourier-transform (PFT) 13 C-n.m.r. are more widely spread for Elbistan (0.34–0.56) than for Seyitomer (0.40–0.43), and are lower than for supercritical-gas (SCG) products from bituminous coals. 13 C-n.m.r. also reveals the presence of aromatic ether-O in polar fractions. Narrow aromatic signals in 100 MHz 1 H-n.m.r. spectra suggest the presence of single-aromatic-ring average structures. In the hexane-soluble aromatics, 27% (Elbistan) and 29% (Seyitomer) of the available sites are substituted by alkyI groups, some of which are at least eight carbon atoms long; the hexane-soluble polar and asphaltene/asphaltol fractions contain fewer such groups.

Long-range spin-spin coupling in polycyclic hydrocarbons and their derivatives

Abstract Long-range spin-spin couplings have been derived from 60 and 100 Mc/s nuclear magnetic resonance spectra of 9 parent polycyclic hydrocarbons and 26 of their derivatives. Double-resonance experiments were carried out on the following compounds: anthracene (parent, 9-bromo-, and 9-methyl-derivatives); phenanthrene (parent, 1-methyl-, 1-methyl-7-isopropyl-, 3-acetyl-9,10-dimethyl-, 3-acetyl-9-bromo-, 2,7-dimethyl-, 3,6-dimethyl-, 9-methyl-, 9-fluoro-, 9,10 dihydro-, 9-formyl, and 2,2,2-, trimethoxy-4,5-(2,2′-biphenyleno)-1,3,2-dioxaphospholene); triphenylene (parent, 2-methyl-, 1,3-,2,3- and 2,7-dimethyl-, 2,3-dimethoxy-, 1,6,11-, and benz[ a ]anthracene (parent, 7-methyl-, and 7,12-dimethyl-derivatives); 1-methylpyrene; benzo[ c ]phenanthrene; dibenzo[ c , g ]phenanthrene; and fluorene. Measured values of coupling constants are tabulated as benzylic ( ortho , meta , para , or aldehydic) or inter-ring (epi, bay, or peri). A seven-bond methyl-methyl coupling is reported in 7,12-dimethylbenz[ a ]anthracene (estimated at 0·6 c/s) and also in para -methyl-benzylbromide (estimated at 0·4 c/s).

High-resolution proton magnetic resonance spectra of polynuclear heterocycles-II : Benzo [b] thiophen and dibenzothiophen☆

Abstract Full iterative analyses have been carried out of 60 MHz spectra of benzo [ b ] thiophen (I) and of 60 and 100 MHz spectra of dibenzothiophen (II) in acetone and carbon tetrachloride solutions at several concentrations. From the 33 peaks in the spectrum of I, analysed as a six-spin system with appreciable inter-ring coupling between H(3) and H(7) and between H(2) and H(6), 15 parameters were determined and 190 transitions assigned. For II, inter-ring coupling is absent but H(2) and H(3) of the ABCD system have closely similar shifts. Deshielding of protons of I and II in acetone solution relative to carbon tetrachloride is attributed to reaction-field effects; some ordering of the polar solute molecules is suggested. For the thiophen rings in I and II, currents calculated from chemical shifts remote from the CS bonds are comparable with those in benzene. In terms of partial bond fixation, the J 4,5 , J 5,6 coupling constants observed in I lead to an aromaticity comparable with that in naphthalene, and J 2,3 of II implies a β-bond equivalence approaching that in fluorene.

Cyclic organophosphorus compounds—V. High resolution nuclear magnetic resonance spectra of some 5,5-dialkyl-1,3,2-dioxaphosphorinanes and related compounds.

Abstract Proton chemical shifts, and 31 P- 1 H coupling constants through sequences of 1,2,3, and 4 chemical bonds, are reported for the 5,5-substituted-1,3-2-dioxaphosphorinanes (I: X = O or S; R 1 = R 2 = Me or Et; R 1 = Me, R 2 = ClCH 2 ; R 3 = alkyl, alkoxy, aryloxy, alkylamido, halogeno, H,). In some cases, the 4,6-methylene hydrogen resonances have been analysed by means of an ABX approximation. Comparison of the 31 P spectra of the esters (I: R 1 = R 2 = Me; X = O, S; R 3 = OMe) with that of a monothiopyrophosphate indicates that the latter has the structure (II: X = S; Y = Z = O) rather than (II: X = Z = O; Y = S).

Shpol'skii luminescence spectroscopy of extracts of coal and coal-tar pitch

Shpolskii luminescence spectra in straight-chain-alkane matrices at 77 K have been measured from carbon-disulphide extracts of nine coal macerals and a cyclohexane extract of a coal-tar pitch. Twelve individual polycyclic hydrocarbons, containing from three up to ten rings, have been identified. The Shpolskii effect, which requires little pretreatment of the sample, is particularly sensitive (0.1 ppm) to the carcinogen benz [a] pyrene.

Steric effects in the proton magnetic resonance spectra of fluorenes and bifluorenyls

Abstract High-resolution PMR spectra, measured at 60 MHz over temperatures between −80° and +160° in CS2, CDCl3 and (CD3)2SO solution, are described for bifluorenyl (IIa), 9-methyl-9,9′-bifluorenyl (IIc), 9-t-butyl-9,9′-bifluorenyl (IIb), five 9-substituted fluorenes, and two 9,9-disubstituted fluorenes. Both 9-(α-naphthyl)-fluorene (Ib) and IIb show coexistence of topographical variants at low temperatures, and comparison of 9-methyl-9-t-butyl- (Ig) and 9-ethyl-9-t-butylfluorene (Ih) spectra with that of 9-t-butylfluorene (If) indicates a reduction in primary proximity deshielding as the size of the second substituent increases. In IIb, the t-butyl resonance is broad at low temperatures, narrows with increasing temperature, and then passes through a remarkable maximum in width of 30 Hz at room temperature before sharpening at high temperatures, when rotation appears to be free about both the 9,9′ and 9-t-bntyl bonds.

Cyclic alkanes as geochemical markers in coal liquefaction products

Abstract Branched-chain/cyclic alkanes have been obtained, by solvent extraction and molecular-sieve adsorption, from a UK low-temperature (Rexco) coal tar, a USA fluidized-bed pyrolysis (FMC COED) coal tar, and a novel supercritical-gas-extract of a Turkish (Elbistan) lignite. Mass spectrometry (with gas chromatography and field-desorption) established the presence of mono-, di (including sesquiterpanes), tri-, tetra- (steranes only), and pentacyclic (triterpanes only) alkanes, including several steranes and triterpanes not previously reported as coal-tar constituents. The potential of cyclic alkanes as geochemical markers, even for commercial coal products subjected to appreciable heat treatment, is demonstrated by the identification of C 12 , C 13 , C 15 and C 16 dicyclics (including isoprenoid alkanes), C 17 -C 26 tricyclics, and C 27 and C 29 hopane-type pentacyclics (triterpanes) in FMC, and of C 16 -C 38 monocyclics, C 34 -C 36 dicyclics, C 22 -C 36 tricyclics, C 27 -C 30 tetracyclics (steranes), and C 27 , C 29 , C 30 , C 31 , C 32 , and C 33 hopane-type pentacyclics (triterpanes) in Rexco tar. Tetra- and pentacyclic alkanes were also preserved in the lignite extract.

The high-resolution proton magnetic resonance method for measurement of the magnetic susceptibility of haemoproteins

A comparison has been made between the proton magnetic resonance and Gouy methods of measuring the mass susceptibility χmass of weakly paramagnetic haemoproteins. For such solutions, terms which are negligible for more strongly paramagnetic materials assume greater importance, and the choice of marker is restricted. For methaemoglobin [Fe(III) haemoglobin] at 298 K and pH 6, the PMR method has advantages, especially if the amount of material available is limited. Consequently, the internal/external marker PMR method has been adapted so that χpara, the more important paramagnetic contribution to the susceptibility, can be measured directly. For haemoproteins in aqueous solution, the interaction factor q is small or zero, suggesting negligible interaction between ethane diol (the PMR marker) and haem-iron.

Chromatographic and spectroscopic analysis of medium and high molecular-weight coal-tar pitch components

Abstract Components of the toluene-insoluble, tetrahydrofuran-soluble fraction (THFS) of an electrode-binder coal-tar pitch have been characterized by gel-permeation and silica-gel chromatography, 1H and 13C high-resolution n.m.r., i.r. and u.v. spectroscopy, and electron-impact and field-desorption mass spectrometry. Statistically averaged molecular formulae have been proposed for this fraction of coal-tar pitch. The molecules, with molecular masses predominantly 400–900 but extending up to 1200 amu, are largely peri-condensed polynuclear aromatic hydrocarbons, some with alkyl and heteroatom substituents.

Neutron diffraction study of the crystal structure of phenanthrene

Hydrogen atoms in phenanthrene at room temperature have been located with estimated standard deviations of ±0·07 Å by neutron diffraction analysis. With carbon atoms fixed at positions determined in a previous X-ray analysis, least-squares refinement of limited neutron diffraction data led to anR index of 0·122 over 214 independent observations. An intramolecular contact of 2·03 Å is confirmed for the bay hydrogen atoms H(4) and H(5).