65038-09-7Relevant academic research and scientific papers
Oligomerization of the Thiophene-Based p-Quinodimethanes 2,5-dihydrothiophene and 2-Ethylidene-5-methylene-2,5-dihydrothiophene
Trahanovsky, Walter S.,Miller, Deborah Louise,Wang, Yili
, p. 8980 - 8986 (2007/10/03)
Flash vacuum pyrolysis (FVP) of (5-methyl-2-thiophene-yl)methyl benzoate (8) produces in ca. 75% yield 2,5-dimethylene-2,3-dihydrothiophene, S-monomer (3). S-Monomer 3 is relatively stable dissolved in carbon disulfide-chloroform at -78°C. The structure of 3 is confirmed by its spectral properties. When a 0.17 M solution of S-monomer 3 was allowed to warm to room temperature, SS-dimer 5 ([2,2](2,5)thiophenophane, 14.7%), SSS-trimer 7 ([2,2,2](2,5)thiophenophane, 44.3%), and polymer were produced. A small amount ( 1%) of an SSSS-tetramer was detected by GC/MS. The mechanism proposed for the formation of these oligomers involves the combination of two molecules of 3 to give an intermediate diradical (11) that can close to form dimer 5 or react with additional molecules of 3 to form the higher oligomers. Evidence for the trapping of diradical 11 by 2,5-dimethylene-2,5-dihydrofuran (O-monomer 2) was obtained. Co-oligomerization of S-monomer 3 and O-monomer 2 gave four compounds containing the thiophene moiety: OS-dimer 16, SS-dimer 5, OSS-trimer 17, and SSS-trimer 7. Some OO-dimer 4 was produced but no OOO-trimer 6 was observed and only a trace of OOS-trimer 18 was detected. Additional support for the diradical mechanism was obtained from the study of the oligomerization of the methyl derivatives of 3, 2-ethylidene-5-methylene-2,5-dihydrothiophene (10, E and Z isomers), prepared by the FVP of (5-ethyl-2-thiophene-yl)methyl benzoate (9). Oligomerization of 10 gave several dimers and trimers including two acyclic dimers that are accounted for by intramolecular disproportionation.
Reaction of 2,5-dimethylene-2,5-dihydrothiophene with triplet oxygen
Huang, Chin-Shui,Peng, Chun-Chieh,Chou, Chin-Hsing
, p. 4175 - 4176 (2007/10/02)
2,5-Dimethylene-2,5-dihydrothiophene (1), prepared by the pyrolysis of 5-methylthenyl benzoate (3), has been detected by low-temperature NMR spectroscopy. 1 reacts with triplet oxygen to form a cyclic bisperoxide 6. Upon healing 6 decomposes to give 2,5-bis(hydroxymethyl)thiophene (7), 2-formyl-5-hydroxymethylthiophene (8) and 2,5-diformylthiophene (9) in a ratio of 1:2:1, respectively.
Fluoride-Induced 1,6-Elimination to p-Quinodimethane. A New Preparative Method for Paracyclophane, (2.5)Furanophane and (2.5)Thiophenophane
Ito, Yoshihiko,Miyata, Satoru,Nakatsuka, Masashi,Saegusa, Takeo
, p. 1043 - 1044 (2007/10/02)
Fluoride anion induced 1,6-elimination of benzyl>trimethylammonium iodide provides a convenient method for preparation of paracyclophane, (2.5)furanophane, and (2.5)thiophenophane.
