Zn-Nx sites on N-doped carbon for aerobic oxidative cleavage and esterification of C(CO)-C bonds

Abstract

Selective cleavage of C-C bonds is very important in organic chemistry, but remains challenging because of their inert chemical nature. Herein, we report that Zn/NC-X catalysts, in which Zn2+ coordinate with N species on microporous N-doped carbon (NC) and X denotes the pyrolysis temperature, can effectively catalyze aerobic oxidative cleavage of C(CO)-C bonds and quantitatively convert acetophenone to methyl benzoate with a yield of 99% at 100 °C. The Zn/NC-950 can be applied for a wide scope of acetophenone derivatives as well as more challenging alkyl ketones. Detail mechanistic investigations reveal that the catalytic performance of Zn/NC-950 can be attributed to the coordination between Zn2+ and N species to change the electronic state of the metal, synergetic effect of the Zn single sites with their surrounding N atoms, as well as the microporous structure with the high surface area and structural defects of the NC.

Catalytic oxidative dehydrogenation of N-heterocycles with nitrogen/phosphorus co-doped porous carbon materials

“…To gain information on the active sites of the catalyst material as well as to evaluate its robustness against deactivation, several experiments were performed with thiophene, thiourea, and KSCN as potentially binding molecules, which are well-known poisoning reagents for catalysts with metal-centered active sites. 51 Thus, 2 eq of thiophene, thiourea, KSCN, or high concentration of the KSCN (5 eq) were added into the reaction mixture; however the yield of quinoline decreased only slightly ( Fig. 1 ).…”

Highly efficient C(CO)–C(alkyl) bond cleavage in ketones to access esters over ultrathin N-doped carbon nanosheets

“…Moreover, the reactivity of the alcohols decreased with the increase of the carbon chain length of the alcohols, which was consistent with some reported results. 7 These results probably resulted from that the dissociation energy of the O–H bond and the steric hindrance increased with the increase of the alkyl chain. Thus, further optimization was required to make this CN-800 catalytic system effective for various alcohols.…”

“…Thus, a catalyst was needed to increase the acidification of the β-C sp 3 –H. 7 The graphitic-N with higher electron density could enhance the acidification of the β-C sp 3 –H originating from the carbonyl groups, thus promoting the abstraction of β-C sp 3 –H, which was beneficial for the reaction. Therefore, CN-800, having more content of more negatively charged graphitic-N species, provided the highest catalytic activity in the oxidative conversion of ketones into esters.…”

“…Generally, ketones can be transformed into various value-added chemicals through the reconstruction of the C–H, C–O, or C(CO)–C bond. 1–7 Molecular editing via the cleavage of the C(CO)–C bond is an emerging strategy to convert ketones into various value-added products, e.g. , esters, acids, nitriles, and amides.…”

Solar-driven aromatic aldehydes: green production from mandelic acid derivatives by a Co(ii)/C3N4 combined catalyst in aqueous media

“… 12 The conversion rate and aromatic aldehyde selectivity of MADs can reach 85% and 70–80%, respectively, when various nanoparticles, such as Bi(0), Co( ii ), and Cu( ii ), are employed to catalytically convert MADs in DMSO. 13–17 During this process, the introduction of organic solvents causes potential environmental problems. Silica-encapsulated Cu–Al hydrotalcite (SECuAlHT) was developed as an efficient catalyst to catalytically oxidize 4-hydroxy-3-methoxymandelic acid in a.q.…”