4779-86-6Relevant articles and documents
Thioether-Mediated Degenerative Chain-Transfer Cationic Polymerization: A Simple Metal-Free System for Living Cationic Polymerization
Uchiyama, Mineto,Satoh, Kotaro,Kamigaito, Masami
, p. 5533 - 5542 (2015)
Cationic degenerative chain-transfer polymerization of vinyl ethers and p-alkoxystyrenes was investigated using a series of thioethers as a reversible chain-transfer agent via the equilibrium between a growing carbocationic species and the resulting sulfonium intermediate in the presence of a small amount of triflic acid (TfOH) as a cationogen. The stable thioether, which was easily prepared from isobutyl vinyl ether (IBVE) and n-butanethiol, efficiently controls the molecular weight of the resulting poly(IBVE) up to Mn ～ 1 × 105 with narrow molecular weight distributions (MWDs) (Mw/Mn ～ 1.2). Upon increasing the bulkiness of the alkyl substituents in the thiols (R-SH; R: n-Bu 2=CHOR′, R′: ethyl isobutyl cyclohexyl), the MWDs became broader due to the slower formation of the sulfonium intermediate for the degenerative chain-transfer reaction. For p-methoxystyrene, thioethers derived from bulkier alkylthiols or more electron-rich thiophenols are more effective. A silyl-protected difunctional dithioether produced telechelic polymers possessing hydroxyl groups at both chain ends and stable thiol linkers in the middle of the polymer chains. These polymers were subsequently used in chain-extension reactions in conjunction with diisocyanates and diols as chain extenders to be converted into high molecular weight polymers linked via urethane linkages. (Figure Presented).
Stereoselective synthesis and reactions of secondary alkyllithium reagents functionalized at the 3-position
Moriya, Kohei,Didier, Dorian,Simon, Meike,Hammann, Jeffrey M.,Berionni, Guillaume,Karaghiosoff, Konstantin,Zipse, Hendrik,Mayr, Herbert,Knochel, Paul
supporting information, p. 2754 - 2757 (2015/03/04)
Secondary alkyllithium reagents bearing an OTBS group (TBS = tert-butyldimethylsilyl) at the 3-position can be prepared stereoconvergently through an I/Li exchange from a diastereomeric mixture of the corresponding secondary alkyl iodides. These lithium reagents react with a range of electrophiles, including carbon electrophiles, with retention of configuration to yield various 1,3-difunctionalized derivatives with good diastereoselectivities. Kinetic studies show that the 3- siloxy group strongly accelerates the epimerization at the lithium-substituted carbon atom. This method offers a new way to construct chiral open-chain molecules with excellent stereoselectivity.
Standard enthalpies of formation of Li, Na, K, and Cs thiolates
Leal, Joao P.
experimental part, p. 441 - 446 (2010/08/04)
The standard enthalpies of formation of alkaline metals thiolates in the crystalline state were determined by reaction-solution calorimetry. The obtained results at 298.15 K were as follows: δfH°m(MSR, cr)/kJ mol-1 = -259.0 ± 1.6 (LiSC2H5), -199.9 ± 1.8 (NaSC2H5), -254.9 ± 2.4 (NaSC4H9), -240.6 ± 1.9 (KSC2H 5), -235.8 ± 2.0 (CsSC2H5). These results where compared with the literature values for the corresponding alkoxides and together with values for δfH° m(MSR, cr) were used to derive a consistent set of lattice energies for MSR compounds based on the Kapustinskii equation. This allows the estimation of the enthalpy of formation for some non-measured thiolates.
