نتایج جستجو برای: acidic catalyst
تعداد نتایج: 77393 فیلتر نتایج به سال:
an efficient and chemoselective procedure for the preparation of 1, 1-diacatates (acylals) from various aldehydes with acetic anhydride in the presence of brønsted acidic ionic liquid [msei]cl as a reusable catalytic system under solvent-free condition at room temperature and short periods of times with excellent yields will be described. the catalyst was easily separated in simple work-up and ...
The valorisation of technical lignins by conversion is herein demonstrated using an acidic deep eutectic solvent in the absence or presence a co-catalyst (H 2 SO 4 H O ).
Ionic liquid 1,3-disulfonic acid imidazolium trifluoroacetate ([Dsim][TFA]) has been exploited as a highly efficient catalyst for the one-pot pseudo five-component reaction of phenylhydrazine (2 eq.) with ethyl acetoacetate (2 eq.) and arylaldehydes (1 eq.) in ethanol (reflux conditions). In this reaction, 4,4′‐(arylmethylene)‐bis(3‐methyl‐1‐phenyl‐1H‐ pyrazol‐5‐ol)s have been obtained in high ...
α-Nitro-δ-keto nitriles and α-nitro-δ-keto ester were readily converted to diazabicyclo compounds having vicinal functionality upon treatment with diamines. The keto nitrile attracts the diamine nearby to an acidic hydrogen to cause the pseudo-intramolecular imination which proceeds efficiently without any catalyst at room temperature.
Fluorine-doped carbon blacks as inexpensive, high performance electrocatalysts for acidic oxygen reduction reaction were synthesized. The performance of the optimal catalyst (BP-18F) is close to the level of other reported best non-Pt electrocatalysts in acid, but with superlow H2O2 yield (<0.1%) ever. Their high performance is confirmed by quantum calculations.
Aqueous H2O2 is an ideal oxidant, when coupled with a tungstate complex and a quaternary ammonium hydrogensulfate as an acidic phase-transfer catalyst. It oxidizes alcohols, olefins, and sulfides under organic solvent- and halide-free conditions in an economically, technically, and environmentally satisfying manner.
We report a mechanistically based study of bifunctional catalyst systems in which chiral nucleophiles work in conjunction with Lewis acids to produce beta-lactams in high chemical yield, diastereoselectivity, and enantioselectivity. Chiral cinchona alkaloid derivatives work best when paired with Lewis acids based on Al(III), Zn(II), Sc(III), and, most notably, In(III). Homogeneous bifunctional ...
28 Fenton’s reagent, a solution of hydrogen peroxide and ferrous iron catalyst, is used for an 29 in-situ chemical oxidation of organic contaminants. Sulfuric acid is commonly used to 30 create an acidic condition needed for catalytic oxidation. Fenton’s reaction often involves 31 pressure buildup and precipitation of reaction products, which can cause safety hazards 32 and diminish efficiency....
multiwalled carbon nanotubes (mwcnts) have been functionalized with -so3h groups using new three steps chemical routes. firstly, oh groups have been attached to cnt surfaces through a radical reaction. the second step involves converting the hydroxyl groups into the oxide one and last step included the attachment of –so3h groups on the mwcnts surfaces in the presence of 1-butyl-3-methyl imidazo...
reduced graphene oxide film was synthesized on a glassy carbon electrode by electro reduction of graphene oxide powders in aqueous solution. then platinum nano particles were deposited on reduced graphene oxide film that was deposited on the glassy carbon electrode via electro reduction of platinum salt. the physical morphology of the platinum on reduced graphene oxide film was evaluated by sca...
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