Electrochemical Oxidative Cleavage of Alkynes to Carboxylic Acids

A sustainable method for converting terminal alkynes into their corresponding carboxylic acids is reported using synthetic electrolysis in an undivided cell at room temperature. This protocol, avoiding transition metal catalysis and stoichiometric chemical oxidants, tolerates a variety of aryl, heteroaryl, and alkyl akynes. Preliminary mechanistic studies demonstrate that sodium nitrite serves a triple role as the electrolyte, nitryl radical precursor, and a nitrosating reagent.

Poly(ethylene glycol) dimethyl ether mediated oxidative scission of aromatic olefins to carbonyl compounds by molecular oxygen

A simple, and practical oxidative scission of aromatic olefins to carbonyl compounds using O₂ as the sole oxidant with poly(ethylene glycol) dimethyl ether as a benign solvent has been developed. A wide range of monosubstituted, gem-disubstituted, 1,2-disubstituted, trisubstituted and tetrasubstituted aromatic olefins was successfully converted into the corresponding aldehydes and ketones in excellent yields even with gram–scale reaction. Some control experiments were also conducted to support a possible reaction pathway.

A simple and practical O₂ oxidized scission of monosubstituted, gem- and 1,2-disubstituted, trisubstituted and tetrasubstituted aromatic olefins to aldehydes and ketones in PEGDME has been developed.

Amphiphilic Carbon Quantum Dots as a Bridge to a Pseudohomogeneous Catalyst for Selective Oxidative Cracking of Alkenes to Aldehydes: A Nonmetallic Oxidation System

The oxidative cleavage of alkenes to the corresponding aldehydes using new amphiphilic carbon quantum dots (A-CQDs) as a pseudohomogeneous carbocatalyst is achieved for the first time through green and sustainable chemical processes. In this work, we successfully design a recyclable pseudohomogeneous catalyst based on A-CQDs, which is decorated with 1-aminopropyl-3-methyl-imidazolium chloride and stearic acid. The functionalization is conducted to introduce a hydrophilic/hydrophobic functionality on the surface of the catalyst to achieve high catalyst availability in polar and nonpolar media with the green goal of eliminating organic (co)solvents and additives. This amphiphilic carbocatalyst provides high mass transferability to the biphasic system, which is beneficial to promoting the oxidative cracking of a variety of olefins into corresponding aldehydes with a substrate/A-CQD ratio of 150. Around 87% of the substrates are converted to the related aldehydes using the carbocatalyst in the presence of H₂O₂, in pure water, without using a phase-transfer catalyst or any additives and organic solvents, which is comparable with the current metal-based cleavage systems. Surprisingly, A-CQDs exhibit high catalytic activity for the scission of electron-deficient C═C bond of coumarin derivatives, accompanied by the cleavage of C-O bonds to produce the corresponding salicylaldehyde derivatives without overoxidation to acid. As a brief conclusion, A-CQDs exhibit high conversion efficiency without significant loss of activity even after six catalytic cycles. The conversion of alkenes into aldehydes is fast and high-throughput without overoxidation to acids and is accompanied by excellent solubility and stability in various solvents. Moreover, the product and the catalyst are recoverable from the reaction medium by simple extraction. So, this pseudohomogeneous carbocatalyst promises new horizons in imminent "catalytic age". All in all, this paper provides a significant and novel advancement in carbocatalyst chemistry.

C3N4-Photocatalyzed aerobic oxidative cleavage of CC bonds in alkynes with diazonium salts leading to two different aldehydes or esters in one pot

C₃N₄-Photocatalyzed oxidative cleavage of CC bonds in alkynes with diazonium salts to obtain two different aldehydes or esters.