Search results for "Methanol"
showing 10 items of 1026 documents
Chemoselektive mono- und disilyletherbildung aus tertiären und sekundären silanen
1985
Abstract Tertiary and secondary silanes are O-selective. With alcohols the corresponding silyl ethers are formed. Cesium fluoride/imidazole (CsF/Im) is a better activating system than CsF alone. Primary OH groups are silylated remarkably faster under CsF/Im activation than secondary OH groups. Tertiary alcohols do not react. Primary OH groups are selectively protected also in the presence of secondary OH groups by silanes with bulky ligands such as triisopropylsilane ((i-Pr) 3 SiH ( 4 )). Ketones are neither reduced to silyl ethers nor transformed to silylenol ethers under the conditions employed. Secondary silanes form monosilyl ethers by amine activation; with CsF the formation of disilyl…
Thiophene series. Substituent effect on thiophenoxy debromination of various 2-nitro-3-bromo-5-X-thiophenes
1970
The kinetics of the reaction of a series of 2-nitro-3-bromo-5-X-thiophenes with sodium thiophenoxide in methanol were determined. The plot of log k against σ-values gave ρ-value + 4.51 at 20°. Good correlation was observed pointing out the validity of the Hammett relationship for reactions occurring directly on the thiophene ring at the β-position with respect to the heteroatom.
Efficient Resolution of Menthylamine with Inexpensive (R,R)-Tartaric Acid by Dielectrically Controlled Resolution (DCR)
2013
A practical procedure for the resolution of menthylamine 2 with (R,R)-tartaric acid [(R,R)-3] as resolving agent is presented. Variation of the solvent system allows both enantiomers of 2 to be selectively crystallized. Performing the resolution in methanol containing 6 % water leads to (–)-2·(R,R)-3·MeOH. The other, less-soluble diastereomeric salt is obtained by applying a solvent system consisting of methanol with 19 % water with a yield of 14 %. Subsequent basic workup with aqueous sodium hydroxide gave the free menthylamine compounds. Further workup of the mother liquors and an additional recrystallization step allowed the (–)-2·(R,R)-3·MeOH salt to be obtained in an overall yield of 2…
Influence of Some Ionic Liquids Containing the Trifluoromethanesulfonate Anion on the Vapor–Liquid Equilibria of the Acetone + Methanol System
2011
Isobaric vapor–liquid equilibria (VLE) for the binary systems acetone + 1-butyl-3-ethylimidazolium trifluoromethanesulfonate ([beim][triflate]), methanol + [beim][triflate], acetone + 1-butyl-1-methylpyrrolidinium trifluoromethanesulfonate ([bmpyr][triflate]), and methanol + [bmpyr][triflate] as well as the VLE for the acetone + methanol + [beim][triflate] and acetone + methanol + [bmpyr][triflate] ternary systems have been obtained at 100 kPa using a recirculating still. The addition of both ionic liquids to the solvent mixtures produced an important salting-out effect, and the azeotrope tended to disappear for small amounts of ionic liquid. The experimental binary data sets were independe…
ChemInform Abstract: Fluorinated Heterocyclic Compounds. A Photochemical Synthesis of 3-Amino-5-perfluoroaryl-1,2,4-oxadiazoles.
2010
Abstract A photochemical methodology for the synthesis of 3-amino- (or 3- N -substituted amino) 5-pentafluorophenyl-1,2,4-oxadiazoles is reported. Irradiation of 3-pentafluorobenzoylamino-4-methyl-1,2,5-oxadiazole (Furazan) at 254 nm in methanol and in the presence of ammonia, primary or secondary aliphatic amines produces 3-amino-, 3-( N -alkylamino)-, 3-( N , N -dialkylamino)-5-pentafluorophenyl-1,2,4-oxadiazoles. The photoreaction follows the fragmentation pattern of the furazan ring with the extrusion of acetonitrile and the formation of a counterpart fragment which the nitrogen nucleophile will capture. Depending on the nature of the reagent, displacement of a fluoride anion at the C(5…
Over-evaluation of total flavonoids in grape skin extracts containing sulphur dioxide
2015
Abstract Sulphur dioxide (SO 2 ) proved to increase absorbance at 280 nm of grape skin and seed extracts containing it, diluted with ethanol–HCl to assess total flavonoids and anthocyanins in the same analysis. Additional absorbance at 280 nm was also observed in acetone:H 2 O extracts, if the acetone had not completely evaporated before the extracts were diluted with a solvent. Flavonoids were correctly quantified in the extracts when SO 2 or acetone were removed by solid-phase extraction with a C 18 RP as sorbent and methanol as eluting solvent.
CCDC 1424179: Experimental Crystal Structure Determination
2016
Related Article: Adrien T. Normand, Constantin G. Daniliuc, Birgit Wibbeling, Gerald Kehr, Pierre Le Gendre, Gerhard Erker|2016|Chem.-Eur.J.|22|4285|doi:10.1002/chem.201504792
CCDC 1439186: Experimental Crystal Structure Determination
2016
Related Article: Toni Mäkelä, Miia-Elina Minkkinen, and Kari Rissanen|2016|Inorg.Chem.|55|1339|doi:10.1021/acs.inorgchem.5b02780
CCDC 619714: Experimental Crystal Structure Determination
2006
Related Article: M.Cametti, M.Nissinen, A.D.Cort, K.Rissanen, L.Mandolini|2006|Inorg.Chem.|45|6099|doi:10.1021/ic060251u
CCDC 1855151: Experimental Crystal Structure Determination
2019
Related Article: Pasi Salonen, Anssi Peuronen, Jari Sinkkonen, Ari Lehtonen|2019|Inorg.Chim.Acta|489|108|doi:10.1016/j.ica.2019.02.011