112359-25-8Relevant articles and documents
An Improved Scale of Solvent Nucleophilicity Based on the Solvolysis of the S-Methyldibenzothiophenium Ion
Kevill, Dennis N.,Anderson, Steven W.
, p. 1845 - 1850 (1991)
A scale of solvent nucleophilicity (NT values) based upon the specific rates of solvolysis of the S-methyldibenzothiophenium ion is presented.A comparison of this scale with the originally developed solvent nucleophilicity scale based upon methyl p-toluenesulfonate solvolysis (NOTs values) strongly suggests that the appropriate m value for methyl p-toluenesulfonate solvolysis for incorporation into the extended (two-term) Grunwald-Winstein equation is 0.55.Revised NOTs values (termed N'OTs) are in good agreement with NT values.Good linear free energy relationships are obtained in comparisons of the specific rates of solvolysis of other RX+ substrates with NT values.Suggestions, by Acheson and by Kurz, that the solvolyses of S-methyl- and S-ethylthiophenium ions involve little charge development at the transition state on the nucleophilic oxygen of the attacking solvent molecules are refuted and conventional SN2 mechanisms, in which general-base catalysis is an important consideration, are proposed.
Dibenzothienobisbenzothiophene - A novel fused-ring oligomer with high field-effect mobility
Sirringhaus, Henning,Friend, Richard H.,Wang, Changsheng,Leuninger, Joerg,Muellen, Klaus
, p. 2095 - 2101 (2007/10/03)
Conjugated oligomers with rigid, fused-ring structure are of interest for organic field-effect transistors where strong π-π interaction between adjacent molecules is required to obtain high charge carrier mobilities. Dibenzo[b,b']thieno[2,3-f:5,4-f']bis[1]benzothiophene (DBTBT) has been synthesized by a novel route, the key step of which is the acid-induced intramolecular cyclization reaction of aromatic methyl sulfoxides. Field- effect transistors (FETs) with thin, polycrystalline DBTBT films deposited by vacuum sublimation exhibit high field-effect mobilities of 0.15 cm2 (Vs)-1 and ON-OFF current ratios > 106. The coupling reaction is not regioselective and different regioisomers have been identified. Degraded FET performance is observed when the sublimed films contain a mixture of different isomers.
Kinetic study of trifluoromethylation with S-(trifluoromethyl) dibenzothiophenium salts
Ono, Taizo,Umemoto, Teruo
, p. 163 - 166 (2007/10/03)
The kinetic parameters were determined for C-trifluoromethylation of aniline with S-(trifluoromethyl)dibenzothiophenium triflate (1), its 3,7-dinitro derivative (2) and S-(trifluoromethyl)diphenylsulfonium triflate (3) in DMF-d7. The higher reactivity of heterocyclic 1 compared with non-heterocyclic 3 could be explained on the basis of its greatly enhanced activation entropy (ΔS≠: -11.2 cal mol-1 K-1 for 1; -47.1 for 3), but not its enhanced activation enthalpy (ΔH≠: 21.2 kcal mol-1 for 1; 12.1 for 3). The aromatic delocalization of the heterocyclic ring may thus be only slightly disturbed by the S-trifluoromethyl substituent. The high reactivity of 2 was attributed to the great electron deficiency caused by two nitro groups in addition to the heterocyclic salt system (ΔH≠ 17.0 kcal mol-1, ΔS≠ -9.1 cal mol-1 K-1 for 2). The reaction mechanism is discussed; the conventional SN2 attack mechanism was ruled out and a mechanism for a side-on attack to the CF3-S bond may possibly be applicable.
