Preparation of 2,3-dimethylene-2,3-dihydrothiophenes by the flash vacuum pyrolysis of substituted thiophenemethyl benzoates
Flash vacuum pyrolysis (FVP) of 3-methyl-2-thenyl benzoate and 2-methyl-3-thenyl benzoate provides a convenient method for the generation of the previously unknown 2,3-dimethylene-2,3-dihydrothiophene (1) and consequently the isolation of its (4+2) spiro-dimer 41a as the major product. The consistently low yield (ca. 20%) of the formation of the spiro-dimer and our inability to trap (1) intermolecularly clearly indicate that (1) is an extremely reactive species which dimerizes and polymerizes at very low temperatures. In the pyrolysis of 3-methyl-..cap alpha..-phenyl-2-thenyl benzoate, the 2,3-dimethylene-2,3-dihydrothiophene moiety is cleanly trapped by its phenyl substituent and subsequently affords naphtho (2,3-b) thiophene as the major product.
- Research Organization:
- Ames Lab., IA (USA)
- DOE Contract Number:
- W-7405-ENG-82
- OSTI ID:
- 6364273
- Report Number(s):
- IS-T-1139; ON: DE85007077
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400301* -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
CHEMICAL REACTIONS
DECOMPOSITION
DIMERIZATION
ESTERS
HETEROCYCLIC COMPOUNDS
MAGNETIC RESONANCE
NUCLEAR MAGNETIC RESONANCE
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
POLYCYCLIC SULFUR HETEROCYCLES
POLYMERIZATION
PYROLYSIS
RESONANCE
SYNTHESIS
THERMOCHEMICAL PROCESSES