Oxidation of toluenes to benzoic acids by oxygen in non-acidic solvents

The Molecular Basis for the Pharmacokinetics and Pharmacodynamics of Curcumin and Its Metabolites in Relation to Cancer

“…Highly suitable electron withdrawing groups are the halogens (X = F, Cl, Br, see Fig. 9) because of their halogen bonding capacity (X•••:O) (Politzer et al, 2007) and because carbohalides are not readily oxidized by O 2 or ROS [except for •OH (Merga et al, 1996)] under physiological conditions (Yang et al, 2004a) to yield radicals or enzymatically degraded in eukaryotic organisms [humans lack the necessary enzymes (Werlen et al, 1996)]. As shown in Fig.…”

An efficient aerobic oxidation for p-xylene to p-toluic acid catalyzed by cobalt (II) hydroxamates with benzo-15-crown-5

“…It is interesting that the addition of alkali metal picrate (picrate/CoL n 2 = 2:1 mol/mol) to the oxidation system enhances the catalytic activity of crowned cobalt hydroxamate CoL n 2 (n=1-3), especially in the case of CoL 1 2 (Table 2), where the highest TOF values were improved by 144%. However, the above phenomenon was not observed in the uncrowned analogue CoL 4 2 . This may be due to the sodium cation Na + (d = 1.90 Å) [10] matching well with the B15C5 cavity (d = 1.7 2.2 Å) [10] and located near to the coordination center, moreover, Na + of a positive charge may enable the molecular oxygen to be activated more easily, and resulting higher activities.…”

“…In recent years, although many studies on the oxidation of p-xylene to p-toluic acid (PTA) catalyzed by Co(OAc) 2 /NaBr/AcOH, Co(C 18 H 35 O 2 ) 2 /NH 4 Br or Schiff base complexes have been reported. The yield (<60%) and selectivity (<25%) for p-toluic acid were __________________________ very low under these conditions [3,4]. A recent work by us indicated that azacrown-functionalized Schiff base complexes showed much better catalytic oxidation activities due to the special configuration and function of the crown ether ring [5].…”

“…Compared with the crown-free analogue CoL 4 2 , the effects of the B15C5 rings appended in the ligand, the length of the methylene chain (CH 2 ) n and the added alkali metal ions into the reactive system on the catalytic oxidation performance of CoL n 2 (n=1~3) (Scheme 1) was discussed in detail. Melting points were taken on a micro-melting apparatus and uncorrected.…”

Co(II) Catalyzed Solvent Free Auto-Oxidation of Methylbenzenes to Substituted Benzoic Acids Under Phase Transfer Conditions

“…The direct oxidation of substituted toluenes to substituted benzoic acids was studied by Yang et al [10] using oxygen at one atmosphere in non-acidic solvents such as dichlorobenzene, chlorobenzene and bromobenzene using Co(C 18 H 35 O 2 ) 2 /NH 4 Br or Co(OAc) 2 /NaBr/AcOH as catalysts in the presence of a radical initiator, AIBN. These authors claimed satisfactory yields (up to 96%) of acid for number of substituted toluenes.…”