Chemistry of coal model compounds: cleavage of aliphatic bridges between aromatic nuclei catalyzed by Lewis acids. [M. S. thesis]
The condensed polynuclear aromatic clusters of coal are believed to be linked principally by straight-chain aliphatic bridges varying from 0 to 4 carbon atoms in length and the cleavage of these linkages is expected to be an important step in the coal liquefaction process. This study focuses on the means by which Lewis acid catalysts, specifically AlCl/sub 3/ and ZnCl/sub 2/, promote the cleavage of these linkages. To facilitate product identification and interpretation of reaction mechanisms, organic compounds which model the aliphatic bridges were used on substrates. All experiments were performed in a magnetically stirred autoclave under either an H/sub 2/ or N/sub 2/ atmosphere at elevated pressure to determine the role of H/sub 2/. Reaction temperatures ranging from 200 to 350/sup 0/C were used to avoid the complication of pyrolysis reactions. Reaction products were identified with the aid of gas chromatography/mass spectrometry, and quantitative product yields were determined by gas chromatography. Experiments with AlCl/sub 3/ and the substrates containing two phenyl rings linked by 0 to 4 carbon atoms showed that AlCl/sub 3/ catalyzed cleavage of all the aliphatic bridges. ZnCl/sub 2/ was totally inactive in cleaving the alkyl bridges in these compounds. Substitution of a phenyl group by a hydroxyphenyl or a naphthyl group in the model compounds promoted the cleavage of aliphatic linkages in the presence of AlCl/sub 3/. In contrast to reactions with the diphenylalkanes, ZnCl/sub 2/ was also found to catalyze the cleavage of these compounds. Plausible reaction mechanisms are proposed which explain the experimental results. The role of gaseous H/sub 2/ in these mechanisms was also investigated.
- Research Organization:
- California Univ., Berkeley (USA). Lawrence Berkeley Lab.
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 6345343
- Report Number(s):
- LBL-7807
- Country of Publication:
- United States
- Language:
- English
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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400300* -- Organic Chemistry-- (-1987)
ALUMINIUM CHLORIDES
ALUMINIUM COMPOUNDS
CARBONACEOUS MATERIALS
CATALYSTS
CATALYTIC EFFECTS
CHEMICAL BONDS
CHEMICAL REACTIONS
CHEMISTRY
CHLORIDES
CHLORINE COMPOUNDS
CHROMATOGRAPHY
CLEAVAGE
COAL
COAL LIQUEFACTION
CRYSTAL STRUCTURE
ENERGY SOURCES
FOSSIL FUELS
FUELS
GAS CHROMATOGRAPHY
HALIDES
HALOGEN COMPOUNDS
HYDROCARBONS
HYDROGEN COMPOUNDS
HYDROGEN TRANSFER
HYDROGENATION
INORGANIC ACIDS
LEWIS ACIDS
LIQUEFACTION
MASS SPECTROSCOPY
MICROSTRUCTURE
ORGANIC COMPOUNDS
SEPARATION PROCESSES
SPECTROSCOPY
STRUCTURAL CHEMICAL ANALYSIS
STRUCTURAL MODELS
THERMOCHEMICAL PROCESSES
ZINC CHLORIDES
ZINC COMPOUNDS
ZINC HALIDES