89267-67-4Relevant articles and documents
Multicyclic poly(ether sulfone)s of phloroglucinol forming branched and cross-linked architectures
Kricheldorf, Hans R.,Fritsch, Detlev,Vakhtangishvili, Lali,Schwarz, Gert
, p. 4337 - 4344 (2003)
K2CO3-promoted polycondensations of phloroglucinol and 4,4′-difluorodiphenyl sulfone (DFDPS) in DMSO yielded mixtures of linear oligomers due to numerous side reactions. In contrast, polycondensations of silylated phloroglucinol under similar conditions were not plagued by such side reactions but involved various cyclization reactions with high efficiency. The MALDI-TOF mass spectra revealed the formation of various cyclic, bicyclic, and multicyclic species of complex structure up to 12000 Da. Therefore, cross-linking only occurred when a large excess (+30 mol %) of DFDPS was added. The resulting branched and cross-linked polymers mainly consisted of cyclic building blocks. Attempts to introduce sulfonic acid groups by alkylation of pendant OH groups with sultones gave only a moderate degree of substitution, due to the high degree of cyclization. For comparison two polycondensations of silylated 5-methylresorcinol were studied.
Preparation, characterization and use of 3-methyl-1-sulfonic acid imidazolium hydrogen sulfate as an eco-benign, efficient and reusable ionic liquid catalyst for the chemoselective trimethylsilyl protection of hydroxyl groups
Khaligh, Nader Ghaffari
experimental part, p. 63 - 70 (2011/12/02)
New and novel ionic liquid (3-methyl-1-sulfonic acid imidazolium hydrogen sulfate) is a recyclable and eco-benign catalyst for the chemoselective trimethylsilyl protection of hydroxyl groups under solvent-free conditions to afford trimethylsilanes in excellent yields (92-100%) and in very short reaction times (1-8 min). The catalyst was characterized by FT-IR, 1H NMR and 13C NMR studies. All the products were extensively characterized by 1H NMR, IR, GC-MS and melting point analyses. A mechanism for the catalytic activity is proposed. The catalyst can be recovered and reused without loss of activity. The work-up of the reaction consists of a simple separation, followed by concentration of the crude product and purification.
Cyclic Ions in the Mass Spectra of Trimethylsilyl Derivatives of Substituted o-Dihydroxybenzenes
Horvat, Robert J.,Senter, Samuel D.
, p. 413 - 417 (2007/10/02)
The mass spectra of trimethylsilyl (TMS) ethers/methyl esters of phenolic acids containing o-dihydroxybenzene groups have base peaks at (1+) instead of the usual (1+) and (1+) that are characteristic of TMS/methyl esters of monohydroxyphenolic acids.These ions, formed by the loss of 31+88 u from the parent ion, possess a cyclic moiety as proven by substitution of deuterium atoms for hydrogen atoms in the TMS groups of the methyl esters of 3,4,5-trihydroxybenzoic (gallic), 3,4-dihydroxybenzoic (protocatechuic) and β-(3,4-dihydroxyphenyl)propenoic (caffeic) acids.Although these cyclic ions are the base peaks in TMS-derivatized o-dihydroxyphenolic acid esters, similar ions represent intense peaks but not neccessarily the base peak in other derivatized compounds such as 1,2-dihydroxybenzene, 1,2-dihydroxy-3-methyl- and 1,2-dihydroxy-4-methyl-benzenes and flavan-3-ols that possess o-dihydroxybenzene groups.Compounds possessing m- or p-dihydroxybenzene groups do not form these cyclic ions; therefore, this procedure for derivatization and interpretation of mass spectra is valuable for the identification of compounds containing o-dihydroxybenzene groups in complex mixtures of isomeric compounds.
