I. Spectroscopic and theoretical studies of heterolytic and homolytic N-H and C-H bond cleavage in heterocycles. II. Photooxidation of sulfur-containing coal model compounds

Thesis/Dissertation · Thu Dec 31 23:00:00 EST 1992

OSTI ID:7029608

Dobrowolski, P

Theoretical estimation of proton affinities for the two types of urazole conjugate bases failed to predict which of the protons present in urazole (hydrazyl vs imide) is more acidic. Analogous calculations performed for hydantoin and thiourazole gave results that are in good agreement with the experimental pK[sub a] measurements. A comparison of [sup 13]C NMR spectra for the urazoles and related nitrogen acids with those obtained for the conjugate bases derived from these compounds confirm previous estimates of the high acidity of the hydrazyl protons. An excellent linear correlation is observed for the [sup 13]C[double bond]O and [sup 13]C[double bond]S NMR signals in a hydantoin-thiohydantoin series. [sup 13]C NMR results for the urazole-thiourazole series appear to correlate with [delta][sub C[double bond]O]/[delta][sub C[double bond]S] data for hydantoin-thiohydantoin anions. Ab initio molecular orbital calculations have been conducted for syn and anti conformers of methyl acetate, and corresponding radical, to evaluate the magnitude of cyclization effect on the homolytic C-H bond strength in the Meldrum's acid. In analogous calculations, conducted for anions and radicals, the results obtained for butanone conformers are in agreement with the experimental data, but fail for propionamide. Two methods of photooxidation in a series of coal model sulfides have been examined. Singlet oxygen reactions generally do not produce sulfoxides and sulfones with satisfactory yields. Superoxide oxygenations have been found to be more efficient. These reactions produce polymeric products for thiophene and benzothiophene, but for dibenzothiophene result in selective formation of the corresponding sulfoxide and sulfone with good yields. Efficient photooxidation of dibenzothiophene is also observed in the anthracene-sensitized reaction, which is of importance for coal photochemistry.

• Research Organization: Southern Illinois Univ., Carbondale, IL (United States)
• OSTI ID: 7029608
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
010600* -- Coal
Lignite
& Peat-- Properties & Composition
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500 -- Photochemistry
CARBONACEOUS MATERIALS
CHEMICAL BONDS
CHEMICAL REACTIONS
COAL
CYCLIZATION
ENERGY SOURCES
FOSSIL FUELS
FUELS
HETEROCYCLIC COMPOUNDS
MATERIALS
NMR SPECTRA
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
OXIDATION
PH VALUE
PHOTOCHEMICAL REACTIONS
SPECTRA