Catalysts for C–H functionalization: Platinum, gold and even nanodiamonds

New Trends in Oxidative Functionalization of Carbon–Hydrogen Bonds: A Review

“…So-called Shilov chemistry [1,[286][287][288][289][290][291] includes two reactions (discovered in 1969 and 1972 [1]). It was demonstrated that Pt II Cl4 2− ion catalyzes H/D exchange in methane in a D2O/CD3COOD solution and, if Pt IV Cl6 2− is added, the latter oxidizes methane to methanol.…”

“…So-called Shilov chemistry [1,[286][287][288][289][290][291] m-Chloroperbenzoic acid in the presence of certain metal compounds efficiently oxidizes alkanes at low temperature with a very high degree of stereoselectivity (trans/cis << 1) [160,227,284,285]. Apparently, radicals are not produced intermediately in the course of such oxidation, which occurs via a "concerted" mechanism.…”

[2 + 1] Cycloaddition reactions of fullerene C60 based on diazo compounds

“…This allows to level out some negative features that are characteristic of heterogeneous catalysts. Thus, in dehydrogenation processes, catalytic amounts of a coordinated fullerene in metal fullerides act as a hydrogen acceptor in reactions with compounds containing activated C–H bonds [ 54 ].…”

Direct Partial Oxidation of Methane Catalyzed by an In Situ Generated Active Au(III) Complex at Low Temperature in Ionic Liquids

“…No formaldehyde (HCHO) was observed from HPLC analysis, and no CO 2 was observed in the gas phase from GC analysis after 5 h reaction, suggesting that ∼100% CH 4 utilization efficiency was achieved without overoxidation. Overoxidation in the homogeneous system has been reported to be a serious issue because of the weaker C–H bond in CH 3 OH (96 kcal/mol) than that in CH 4 (104 kcal/mol). ,, While an indirect method by forming methyl esters as intermediate products was a useful strategy to protect the product from overoxidation due to the electron-withdrawing effect of the ester group in homogeneous catalytic oxidation of CH 4 in strongly acidic media, − it is a remarkable advantage of the [Eim]­[NTf 2 ]/H 2 O 2 system discovered in this work to directly produce CH 3 OH and HCOOH by avoiding the need for strong acid to form an ester as the intermediate product. In addition to high CH 4 solubility in the hydrophobic [Eim]­[NTf 2 ], a two-phase system may be formed between [Eim]­[NTf 2 ] and H 2 O that was introduced as a bulk component of the 35 wt % H 2 O 2 solution.…”

“…Although Shilov Chemistry is based on the Pt II catalyst, the isoelectronic structure of Au III and Pt II in the same d electronic configuration and the similar preference for square-planar complexes shared by Au III and Pt II suggest that Au complexes could be potential catalyst candidates for selective C–H activation in analogous to Shilov Chemistry. − The selective oxidation of CH 4 using H 2 SeO 4 as an oxidant with dissolved Au 0 and Au 2 O 3 as catalysts in concentrated H 2 SO 4 was reported with the highest TON of 32, producing (CH 3 )­HSO 4 with CO 2 as a minor byproduct . Shilov and co-workers reported the conversion of CH 4 to CH 3 OH catalyzed by Au complexes with rutin and quercetin ligands in the presence of NADH, by mimicking the function of aurophilic microbes. ,− Overall, in the reported Shilov Chemistry system and its analogues, the necessity of having oleum or high valent metal ions as oxidants in strongly acidic media, forming esters as the primary products, the difficulty in product separation and solvent recovery, reduced activity due to weakened acidity caused by water byproduct, strong corrosivity, and low CH 4 solubility in the acidic reaction media remain the common problems to be addressed in continued research. − …”