3910-35-8Relevant articles and documents
Preparation of an MCM-41/nafionρ composite material; a selective catalyst for α-methylstyrene dimerization
Fujiwara,Kuraoka,Yazawa,Xu,Tanaka,Souma
, p. 1523 - 1524 (2000)
A MCM-41/Nafion composite prepared from tetraethoxysilane and Nafion gel solution with cetyltrimethylammonium surfactant, is a highly selective catalyst for α-methylstyrene dimerization to form the corresponding acyclic dimer.
Synthesis and Structure of a New Stable Carbocation Stabilized by Two Neighboring Sulfur Atoms. Dimethyl-9,9-bis(methylthio)-1-fluorenylcarbenium Ion
Hojo, Masaru,Ichi, Tadaaki,Shibato, Kishio
, p. 1478 - 1482 (1985)
9,9-Bis(methylthio)-1-isopropenylfluorene (3) and the corresponding alcohol 2 generate a carbocation 1 in trifluoroacetic acid solution at room temperature.This ion is sufficiently stable to be observed spectroscopically in this solution.A stable crystalline hexachloroantimonate of 1 was isolated.In trifluoroacetic acid-d at room temperature, the two C+-methyl groups of 1 undergo H-D isotopic exchange to give the corresponding hexadeuterio cation.On the basis of electronic and 1H NMR spectroscopic data at temperatures from 40 to -60 deg C, it is concluded that ion 1 is not a sulfonium species but exists as a carbocation stabilized by electrons from the two neighboring sulfur atoms.Carbon-13 NMR data show that the positive charge is extensively delocalized over the neighboring sulfur atoms, with small amount remaining on the carbon atom.The possibility is suggested that 1 is a pentacoordinated carbon species that resembles the transition states in SN2 displacements.
A chemoselective route to either 4-methyl-2,4-diphenyl-2-pentene or 1,1,3-trimethyl-3-phenylindane from 2-phenylpropan-2-ol mediated by BiBr 3: A mechanistic study
Howard, Fredrick,Sawadjoon, Supaporn,Samec, Joseph S.M.
, p. 4208 - 4210 (2010)
The reaction of 2-phenylpropan-2-ol mediated by BiBr3 can, through control of the temperature, yield selectively either 4-methyl-2,4-diphenyl-2-pentene or 1,1,3-trimethyl-3-phenylindane. A reaction mechanism that proceeds via 1-methylstyrene is disclosed.
Preparation of a platinum nanoparticle catalyst located near photocatalyst titanium oxide and its catalytic activity to convert benzyl alcohols to the corresponding ethers
Akiyama, Toshiki,Arisawa, Mitsuiro,Harada, Kazuo,Honma, Tetsuo,Naka, Hiroshi,Saito, Susumu,Wada, Yuki
, p. 22230 - 22237 (2021/07/02)
A novel platinum nanoparticle catalyst closely located near the surface of titanium oxide, PtNP/TiO2, has been prepared. This catalyst has both the properties of a photocatalyst and a metal nanoparticle catalyst, and acquired environmentally friendly catalytic activity, which cannot be achieved by just one of these catalysts, to afford ethers from benzyl alcohols under the wavelength of 420 nm.
Selective dimerization of a-methylstyrene by tunable bis(catecholato)germane Lewis acid catalysts
Baines, Kim M.,Boyle, Paul D.,Cosby, Taylor P. L.,Henry, Andrew T.
supporting information, p. 15906 - 15913 (2021/12/02)
The synthesis of a variety of bis(catecholato)germanes is reported. The Lewis acidity of the bis(catecholato)germanes was assessed using the experimental Gutmann-Beckett method and computational FIA and GEI methods. The oligomerization of alkenes using bis(catecholato)germanes demonstrates the use of these complexes in catalysis. The use of donor additives in the dimerization of a-methylstyrene resulted in selectivity control comparable to transition metal catalyst systems. This journal is
Samarium triflate-catalyzed dimerization of vinylarenes
Chang, Meng-Yang,Tsai, Yu-Lin
, p. 200 - 211 (2020/02/13)
We report the preparation of substituted indanes and their dimeric isomers via the samarium triflate-mediated [Sm(OTf)3, 10 mol%] self-dimerization of vinylarenes in MeNO2 at 25 oC for 10 h. The diverse products were obtained in moderate to high yields. The synthesis involves a (3+2) annulation via the formation of carbon-carbon bonds. Plausible mechanisms are proposed and discussed. The investigation of various rare metal triflates catalyst loadings, reaction conditions, and substrate scope led to an operationally easy one-pot Friedel-Crafts reaction protocol.
Lewis Acid Catalyzed Transfer Hydromethallylation for the Construction of Quaternary Carbon Centers
Walker, Johannes C. L.,Oestreich, Martin
supporting information, p. 15386 - 15389 (2019/10/28)
The design and gram-scale synthesis of a cyclohexa-1,4-diene-based surrogate of isobutene gas is reported. Using the highly electron-deficient Lewis acid B(C6F5)3, application of this surrogate in the hydromethallylation of electron-rich styrene derivatives provided sterically congested quaternary carbon centers. The reaction proceeds by C(sp3)?C(sp3) bond formation at a tertiary carbenium ion that is generated by alkene protonation. The possibility of two concurrent mechanisms is proposed on the basis of mechanistic experiments using a deuterated surrogate.
Decarbonylation of phenylacetic acids by high valent transition metal halides
Bartalucci, Niccolò,Marchetti, Fabio,Zacchini, Stefano,Pampaloni, Guido
, p. 5725 - 5734 (2019/05/10)
Triphenylacetic acid underwent unusual decarbonylation when allowed to react with a series of halides of group 4-6 metals in their highest oxidation state, in dichloromethane at ambient temperature. Thus, the reaction of CPh3COOH with MoCl5, in 1:1 molar ratio, afforded the trityl salt [CPh3][MoOCl4], 1, in 79% yield, while the 1:2 reaction of CPh3COOH with NbF5 afforded [CPh3][NbF6], 2, in 70% yield, NbOF3 being the metal co-product. CPh3COOH reacted with NbCl5, TiF4 and WOCl4 to give mixtures of compounds, however the cation [CPh3]+ was NMR identified in each case. [CPh3][NbCl6], 3, was isolated from NbCl5 and CPh3COCl, prior to being generated from CPh3COOH and PCl5. The reaction of CPh3COOH with TiCl4 was non-selective, and the salt [CPh3][Ti2Cl8(μ-κ2-O2CCPh3)], 4, was obtained in 18% yield. The decarbonylation reactions of CMePh2COCl and CMe2PhCOCl by means of NbCl5 led to the indanes 5a-b, which were isolated in 79-97% yields after hydrolysis of the mixtures and subsequent alumina filtration of the organic phases. The reactions of CH(Ph)2COOH with NbCl5 and WCl6 afforded NbCl4(OOCCHPh2), 6, and CHPh2COCl, respectively, as the prevalent species. CPh2(CH2CH2Br)COOH did not undergo CO release when allowed to interact with WCl6, instead selective intramolecular condensation to C(Ph)2C(O)OCH2CH2, 7, occurred. MeCCCOOH underwent hydrochlorination by WCl6 to give MeC(Cl)CHCOOH, 8, in 72% yield. All the products were fully characterized by elemental analysis, IR and multinuclear NMR spectroscopy. In addition, the solid state structures of 1, 2, 4, 7, and 8 were elucidated by X-ray diffraction.
Straightforward formation of carbocations from tertiary carboxylic acids: Via CO release at room temperature
Bartalucci, Niccolò,Pampaloni, Guido,Marchetti, Fabio,Bortoluzzi, Marco,Zacchini, Stefano
supporting information, p. 1574 - 1577 (2019/04/02)
We report an unprecedented mode of reactivity of carboxylic acids. A series of tertiary carboxylic acids, containing at least one phenyl α-substituent, undergo loss of carbon monoxide at room temperature (295 K), by a one pot reaction with 0.5-1 molar equivalents of WCl6 in dichloromethane. A plausible mechanism for the Ph3CCO2H/WCl6 reaction, leading to [CPh3][WOCl5] and Ph3CCl, is proposed on the basis of DFT calculations. The analogous reactions involving CEt(Ph)2CO2H, CMe(Ph)2CO2H and CMe2(Ph)CO2H selectively afforded stable hydrocarbons (alkene or indene, depending on the case), apparently resulting from the rearrangement of elusive tertiary carbocations.
Aerobic Oxidation of Secondary Alcohols with Nitric Acid and Iron(III) Chloride as Catalysts in Fluorinated Alcohol
Mo?ina, ?tefan,Iskra, Jernej
, p. 14579 - 14586 (2019/11/14)
Fluorinated alcohols as solvents strongly influence and direct chemical reaction through donation of strong hydrogen bonds while being weak acceptors. We used 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) as the activating solvent for a nitric acid and FeCl3-catalyzed aerobic oxidation of secondary alcohols to ketones. Reaction proceeded selectively with excellent yields with no reaction on the primary alcohol group. Oxidation of benzyl alcohols proceeds selectively to aldehydes with only HNO3 as the catalyst, while reaction on tertiary alcohols proceeds through dehydration and dimerization. A mechanistic study showed in situ formation of NOCl that converts alcohol into alkyl nitrite, which in the presence of Fe3+ ions and fluorinated alcohol decomposes into ketone. The study indicates that iron(III) acts also as the single-electron transfer catalyst in regeneration of NOCl reactive species.
