Jasim M. A. Al-Rawi

Chemical structure of asphaltenes in heavy crude oils investigated by n.m.r.

Abstract 1 H and 13 C n.m.r. spectra of asphaltenes separated from a heavy crude oil using n-pentane at different temperatures were measured. Average molecular parameters and hypothetical structural models for these asphaltenes were proposed using n.m.r. measurements, calculated molecular weight of unit sheets and elemental analysis.

Novel ioneneomeric polymer liquid crystals

Abstract A new class of ioneneomeric polymer liquid crystals made by double quaternization of the trans-1,2-bis(4-pyridyl)ethene unit with an appropriate spacer, X(CH2)nX (where n = 4–10, 12; X = MeSO3 or 4-MeC6H4SO3), has been prepared. Mesophase transition temperatures and stabilities are independent of the anion and length of spacer. Differential scanning calorimetry, polarizing optical microscopy and X-ray studies reveal that these polymers exhibit disclination or extinction-band texture.

High-resolution 1H NMR spectra of bis(2,2′-bipyridine)(4,4′-dialkyl-2,2′-bipyridine) ruthenium(II) salts

Abstract High-resolution 1H NMR spectra for seven ligands having the general formula bipy-4-R-4′-R1 (bipy = 2,2′-bipyridine; R, R1 = CnH2n+1) are reported and analysed as well as that of the ruthenium(II) complexes [Ru(bipy)2(bipy-4-R-4′-R1)]X2 (X = Cl or ClO4). 2D 1H NMR and homo-decoupling are used to aid the analysis of the spectra. Complexation and solvent effects are discussed.

Mass Spectrometry Study of 7-Chloro-3,4-dihydro-4,5-dioxo-3-substituted Aryl-2-thio-2H, 5H-pyrano [3,4-e]-1,3-Oxazine, their Morpholine and Alcohol Reaction Products

Abstract Retro Diels-Alder mechanism is the main fragmentation pattern of the 7-chloro Pyrano oxazine (2),7-morpholino pyrano oxasine (3),5-morpholino carbonyl-4-oxo-3-substituted phenyl-2-thio-1-3-oxazine-6-ylacetomorpholide (4) and ethyl-6-ethoxy carbonyl methyl-4-oxo-3-(substituted phenyl)-2-thio-2H-1,3-oxazine-5-carboxylate (5). Further fragmentation routes were also discussed.

The Studies of 13C NMR Chemical Shifts and Induced Lanthanide Shift Reagent Cis-trans Isomerization of N-Cinamylidene-hexyl, t-butyl and Substituted Aryl-Amines

Abstract The Carbon-13 chemical shifts of N-Cinamylidenehexyl, t-butyl and sixteen substituted aryl amines were analysed. The lanthanide induced carbon-13 chemical shifts of the cis and trans of four N-cinamylidene substituted anilines were analysed. The spectra N-cinamylidene hexylamine showed only the trans form. The cis/trans ratio of N-cinamylidene aryl amines increased as the LSR concentration increased.

1H and 13C NMR study of a new class of bipyridinium liquid crystals

Abstract 1H and 13C NMR, as well as UV and IR, spectra of a new class of bipyridinium salts made by double quaternization of trans−1, 2-bis(4-pyridyl) ethene unit with n-alkyl salts are reported. The effect of quaternization on the 1 and 13C NMR spectra of the salts is discussed.

1H and 13C NMR study of 2-alkyl thio-5-phenyl-1,3,4-thiadiazole; The S-oxidation and dioxidation effects

Abstract High resolution proton and carbon-13 NMR spectra of 2-alkyl thio-; 2-alkyl sulfinyl, and 2-alkyl sulfonyl-5-phenyl-1, 3,4-thiadiazoles were analysed. The chirality of the sulfoxide group induced proehiralty at the oα-methylene or β-methylene carbon atom. Further more the S-oxidation and dioxidation effects on the carbon-13 chemical shifts were summarised.

The N-0xidation effect on the carbon-13 chemical shafts and. H-α in (Z)-H-Renzylidene arylamine and the orthohydroxy benzylidene analogue

Abstract N-oxidation of Z-N-Benzylidene arylamine and their ortho-hydroxybenzylidene analogue resulted in unexpected upfield shift of the H-α and C-α chemical shifts. The predominant resonance forms of the nitrones ere discussed. The N-oxidation effects on the 13C chemical shift depend upon nitrogen as well as the attached carbon hybridization.

Studies of Tertiary Amine Oxides. Part1 15. Carbon - 13 nuclear magnetic resonance spectra of some N-(4-substituted phenyl) piperidine, the corresponding N-oxides, and their thermal-rearrangement product

Abstract The carbon-13 chemical shifts of seven N-(4-substituted phenyl) piperidine; the corresponding N-oxides, and their thermal rearrangement products were analyzed and assigned. The N-oxidation effect on the carbon-13 chemical shift is discussed, a correlation of N-oxidation effect with substituent constant (σp, σm, σI and σR) has been studied; dual substituent-parameter equation produce better correlation.

Lanthanide Induced Shift 1HNMR Study of N-(O-Hydroxy Benzylidene)-P-Z-Phenylamine, N-(O-Hydroxy Benzlidene)-P-Z-Phenylamine-N-Oxides and P-Y-(N-Benzylidene)-P-Z-Phenylamine-N-Oxides

Abstract N-(O-hydroxy benzylidene)-P-Z-phenylamine (Salicylidene anilines), their N-oxides and P-Y-(N-benzylidene)-P-Z-phenyl amine-N-oxides coordinate with lanthanide shift reagents. Salicylideneanilines coordinate both with the hydroxy oxygen and the nitrogen of the C=N, but the position of coordination is found to be closer to the oxygen. Salicyclidene-N-oxides coordinate via the oxygens of the N- O and the hydroxy group. Larger molar shift values were obtained for salicylidene-N-oxides compared to salicylidene anilines. It is evident that benzylideneaniline-N-oxides on their coordination with Eu(fod)3 are in their cis form, the less sterically crowded lone pair of nitrogen. for the benzylidene aniline-N-oxides are less than those for the oniline/analogue due to the distance of N- 0.