نتایج جستجو برای: solvent selectivity

تعداد نتایج: 99687  

Journal: :Organic & biomolecular chemistry 2008
Vasily N Korotchenko Kay Severin Michel R Gagné

Carbonylruthenium tetrakis(pentafluorophenyl)porphyrin Ru(TPFPP)(CO) was utilized for the aerobic oxidation of alcohols. The in situ activation of the catalyst with mCPBA provided a species capable of catalyzing the oxidation of alcohols with molecular oxygen. The choice of solvent and additive was crucial to obtaining high activity and selectivity. Secondary aromatic alcohols were oxidized in ...

Journal: :Chemical communications 2011
Christopher J Borman Radu Custelcean Ben P Hay Nathan L Bill Jonathan L Sessler Bruce A Moyer

meso-Octamethylcalix[4]pyrrole (C4P) enhances sulfate selectivity in solvent extraction by Aliquat® 336N, an effect ascribed to the supramolecular preorganization and thermodynamic stability imparted by insertion of the methyl group of the Aliquat cation into the cup of C4P in its cone conformation.

2004
Sudip Mukhopadhyay Alexis T. Bell

Direct sulfonation of methane with SO3 to methanesulfonic acid (MSA) is accomplished in sulfuric acid with almost 100% selectivity in the presence of a catalyst, namely, Ce and Rh salts and molecular oxygen as the catalyst regenerator. In the absence of O2, the catalyst remains effective but the selectivity to MSA decreases to 53% and byproducts, principally CH3OSO3H, are formed. The effects of...

Journal: :The Journal of chemical physics 2011
Dong Meng Qiang Wang

Following our previous work on the solvent-response of uncharged diblock copolymer brushes (D. Meng and Q. Wang, J. Chem. Phys. 130, 134904 (2009)), we have performed continuum self-consistent field calculations to study the response (i.e., changes of brush height and surface-layer composition) of diblock brushes with only one block charged to various external stimuli, including solvent selecti...

Journal: :Analytical sciences : the international journal of the Japan Society for Analytical Chemistry 2006
Mayako Takahashi Hiromoto Watanabe Junko Kikkawa Masaki Ota Masaru Watanabe Yoshiyuki Sato Hiroshi Inomata Nobuyuki Sato

The extraction of carotenoids from Japanese persimmon peels by supercritical fluid extraction (SFE), of which the solvent was CO(2), was performed. In order to enhance the yield and selectivity of the extraction, some portion of ethanol (5 - 20 mol%) was added as an entrainer. The extraction temperature ranged from 313 to 353 K and the pressure was 30 MPa. The effect of temperature on the extra...

Journal: :Chemical communications 2016
Manikandan Thangaraj Sachin Suresh Bhojgude Manoj V Mane Akkattu T Biju

The temperature dependent selectivity switch in the reaction of arynes with aliphatic alcohols in THF has been reported. At -20 °C, arynes smoothly insert into the O-H bond of alcohols to form alkyl aryl ethers. Interestingly, at 60 °C, a highly selective multicomponent coupling occurs with the solvent THF acting as the nucleophilic trigger affording (4-(alkoxy)butoxy)arenes.

Journal: :Chemical communications 2014
Masazumi Tamura Riku Tamura Yasuyuki Takeda Yoshinao Nakagawa Keiichi Tomishige

Rh-MoOx/SiO2 is an effective heterogeneous catalyst for selective hydrogenation of amino acids to amino alcohols in a water solvent. MoOx modification of Rh drastically enhanced the activity and improved the selectivity and ee. Various amino alcohols were obtained in high yields (90-94%) with complete retention of configuration.

Journal: :Green Chemistry Letters and Reviews 2021

The synthesis of chlorins was performed by hydrogenation porphyrins using diimide generated and consumed under mechanical activation. reaction conditions achievable ball milling, absence solvent use hydrazine hydrate as source, allowed the with high conversion, selectivity, nearly ideal sustainability scores (atom economy 97% E-factor 0.96).

Journal: :Organic & biomolecular chemistry 2012
Manjunath Lamani Pradeep Devadig Kandikere Ramaiah Prabhu

A novel non-metal catalyzed oxidation of organic azides to nitriles under solvent-free conditions is presented employing catalytic amounts of KI, and DABCO in aq. TBHP at room temperature. This non-metal catalyzed oxidation of azides provides good selectivity as double and triple bonds were not oxidized under the present reaction conditions.

Journal: :Optics letters 2001
J X Cheng L D Book X S Xie

We report polarization coherent anti-Stokes Raman scattering (P-CARS) microscopy that allows vibrational imaging with high sensitivity and spectral selectivity. The nonresonant background signals from both Raman scatterers and the solvent are efficiently suppressed in P-CARS microscopy. We demonstrate P-CARS imaging of unstained cells based on the contrast of the protein amide I band.

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