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Heats of formation of gas phase organosulfur molecules radicals and ions measured by Pipeco. Progress report, August 1981-May 31, 1982

Technical Report ·
OSTI ID:7061925
;

The O/sup 0/ K heats of formation (..delta..H/sup 0//sub fo/) in kcal/mol of CHS/sup +/ (233), CH/sub 2/S/sup +/ (235), CH/sub 3/S/sup +/ (215), C/sub 2/H/sub 3/S/sup +/ (217), C/sub 2/H/sub 4/S/sup +/ (222), C/sub 3/H/sub 5/S/sup +/ (214), and C/sub 4/H/sub 7/S/sup +/ (241) have been measured by dissociative photoionization of a number of precursor molecules. Because the ..delta..H/sup 0//sub fo/ (C/sub 2/H/sub 4/S/sup +/) is significantly lower than the known ..delta..H/sup 0//sub fo/ (c-C/sub 2/H/sub 4/S/sup +/) of 232 kcal/mol, we conclude that the C/sub 2/H/sub 4/S/sup +/ product ion has the thioacetaldehyde structure. Combining this with the known ionization energy of thioacetaldehyde gives us the first experimentally measured heat of formation of the thioacetaldehyde molecule which was found to be 15 kcal/mol at O/sup 0/ K. This compares to a ..delta..H/sup 0//sub fo/ (C-C/sub 2/H/sub 4/S) = 23 kcal/mol. Another study involved some of the oxygen analogues of the above sulfur compounds. We have synthesized a new series of vinyloxy sulfides, sulfoxides, and sulfones and have obtained estimates of the ..pi.. electron distribution at the vinylic carbons using /sup 13/C NMR spectoscopy. These results have significant implications regarding the strength of S-C bonds in unsaturated organosulfur molecules capable of exhibiting enhanced stability resulting from (2p..-->..3d)..pi.. overlap compared to the saturated analogs. An /sup 33/S NMR investigation of some of the organosulfur compounds indicate that conversion of sulfenyl sulfur to sulfonyl sulfur (-S- ..-->.. -SO/sub 2/ -) causes the /sup 33/S line widths to diminish so that rapid and accurate sulfur analyses (as sulfones) of organosulfur constituents in coal and petroleum are possible.

Research Organization:
North Carolina Univ., Chapel Hill (USA). Dept. of Chemistry
DOE Contract Number:
AS05-80ER10641
OSTI ID:
7061925
Report Number(s):
DOE/ER/10641-2; ON: DE84012949
Country of Publication:
United States
Language:
English

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Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400301* -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
CARBON 13
CARBON ISOTOPES
CHARGED PARTICLES
DISSOCIATION
ENTHALPY
EVEN-ODD NUCLEI
FORMATION HEAT
IONIZATION
IONS
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
NUCLEAR MAGNETIC RESONANCE
NUCLEI
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
PHOTOIONIZATION
PHYSICAL PROPERTIES
RADICALS
REACTION HEAT
RESEARCH PROGRAMS
RESONANCE
STABLE ISOTOPES
SULFUR 33
SULFUR ISOTOPES
THERMODYNAMIC PROPERTIES