نتایج جستجو برای: hammett constant
تعداد نتایج: 218513 فیلتر نتایج به سال:
We have developed an efficient protocol for copper-catalyzed olefin aziridination using 5-methyl-2-pyridinesulfonamide or 2-pyridinesulfonyl azide as the nitrenoid source. The presence of a 2-pyridyl group significantly facilitates aziridination, suggesting that the reaction is driven by the favorable formation of a pyridyl-coordinated nitrenoid intermediate. Using this chelation-assisted strat...
Heterogeneous catalysts, especially those produced with functionalized clays, can be used for methyl transesterification at moderate temperatures. The use of bentonite clay by potassium compounds (KF, KOH, K2CO3, KCl and K2SO4) in the cottonseed oil is object present study. catalysts were contacting aqueous solutions subsequent drying. characterized Hammett indicators to determine alkalinity. r...
A recombinant ketoreductase from Pichia glucozyma (KRED1-Pglu) was used for the enantioselective reduction of various mono-substituted acetophenones. Reaction rates of meta- and para-derivatives were consistent with the electronic effects described by σ-Hammett coefficients; on the other hand, enantioselectivity was determined by an opposite orientation of the substrate in the binding pocket. R...
The cationic complex [(pymox-Me(2))RuCl(2)](+)BF(4)(-) was found to be a highly effective catalyst for the C-H bond oxidation reaction of arylalkanes in water. For example, the treatment of ethylbenzene (1.0 mmol) with t-BuOOH (3.0 mmol) and 1.0 mol % of the Ru catalyst in water (3 mL) cleanly produced PhCOCH(3) at room temperature. Both a large kinetic isotope effect (k(H)/k(D) = 14) and a rel...
Intramolecular nucleophilic aromatic substitution (Truce–Smiles rearrangement) of the anions 2-benzyl benzanilides leads to triarylmethanes in an operationally simple manner. The reaction succeeds even without electronic activation ring that plays role electrophile SNAr reaction, being accelerated instead by preferred conformation imposed tertiary amide tether. substituent product may be remove...
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