نتایج جستجو برای: phenol ortho alkylation
تعداد نتایج: 27115 فیلتر نتایج به سال:
The site-selective H/D exchange reaction of phenol in sub- and supercritical water is studied without added catalysts. In subcritical water in equilibrium with steam at 210-240 degrees C, the H/D exchange proceeds both at the ortho and para sites in the phenyl ring, with no exchange observed at the meta site. The pseudo-first-order rate constants are of the order of 10(-4) s(-1); 50% larger for...
The site-selective H/D exchange reaction of phenol in sub-and supercritical water is studied without added catalysts. In subcritical water in equilibrium with steam at 210–240 °C, the H/D exchange proceeds both at the ortho and para sites in the phenyl ring, with no exchange observed at the meta site. The pseudo-first-order rate constants are of the order of 10 Ϫ4 s Ϫ1 ; 50% larger for the orth...
Evaluation of a new proton sponge, bis-1,1,8,8-(tetramethylguanidino)naphtalene (TMGN), in substituted phenols O-alkylation by methyl iodide in DMF has been studied. Kinetic measurements were performed in N,N-dimethylformamide-d7 and followed by H NMR using stoichiometric amounts of reagents. Plot of the results shows that the reaction follows an almost perfect second order rate law. However th...
Alkyl-substituted phenolic pyrazoles such as 4-methyl-2-[5-(n-octyl)-1H-pyrazol-3-yl]phenol (L2H) are shown to function as Cu-extractants, having similar strength and selectivity over Fe(iii) to 5-nonylsalicylaldoxime which is a component of the commercially used ACORGA® solvent extraction reagents. Substitution in the phenol ring of the new extractants has a major effect on their strength, e.g...
The mono ortho-bromination of phenolic building blocks by NBS has been achieved in short reaction times (15-20 min) using ACS-grade methanol as a solvent. The reactions can be conducted on phenol, naphthol and biphenol substrates, giving yields of >86% on gram scale. Excellent selectivity for the desired mono ortho-brominated products is achieved in the presence of 10 mol % para-TsOH, and the r...
Highly enantioselective catalytic intramolecular ortho-alkylation of aromatic imines containing alkenyl groups tethered at the meta position relative to the imine directing group has been achieved using [RhCl(coe)2]2 and chiral phosphoramidite ligands. Cyclization of substrates containing 1,1- and 1,2-disubstituted as well as trisubstituted alkenes were achieved with enantioselectivities >90% e...
Pivalophenone N–H imine has been found to serve as a prominent substrate for directed C–H alkylation and arylation reactions with alkyl bromides and aryl chlorides, respectively, under cobalt–N-heterocyclic carbene (NHC) catalysis. Unlike the case of the parent pivalophenone imine, the increased steric bulk of the resulting ortho-substituted pivalophenone imines allows them to undergo clean imi...
Biodegradation of phenol is a major focus of toxic organic compound degradation by microorganisms isolated from polluted areas. An increasing number of bacteria and fungi possessing unique biodegradation capabilities have been isolated in recent years. In this study a new isolate, Rhodococcus erythropolis SKO-1, from polluted soils in the Tehran oil refinery region, is reported. Identificati...
Ruthenium(II)-catalyzed switchable ortho C−H activation of 1-arylpyrazoles with maleimides has been achieved. This divergent reaction selectively installs various succinimide and maleimide substituents on the aromatic ring 1-arylpyrazoles. Depending acidic or basic conditions, a wide range alkylation alkenylation products are obtained, without formation bis-adducts. More information can be foun...
Pseudomonas sp. strain CF600 metabolizes phenol and some of its methylated derivatives via a plasmid-encoded phenol hydroxylase and meta-cleavage pathway. The genes encoding the multicomponent phenol hydroxylase of this strain are located within a 5.5-kb SacI-NruI fragment. We report the nucleotide sequence and the polypeptide products of this 5.5-kb region. A combination of deletion analysis, ...
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