Electrochemical oxo-functionalization of cyclic alkanes and alkenes using nitrate and oxygen

Abstract

Direct functionalization of C(sp3)–H bonds allows rapid access to valuable products, starting from simple petrochemicals. However, the chemical transformation of non-activated methylene groups remains challenging for organic synthesis. Here, we report a general electrochemical method for the oxidation of C(sp3)–H and C(sp2)–H bonds, in which cyclic alkanes and (cyclic) olefins are converted into cycloaliphatic ketones as well as aliphatic (di)carboxylic acids. This resource-friendly method is based on nitrate salts in a dual role as anodic mediator and supporting electrolyte, which can be recovered and recycled. Reducing molecular oxygen as a cathodic counter reaction leads to efficient convergent use of both electrode reactions. By avoiding transition metals and chemical oxidizers, this protocol represents a sustainable oxo-functionalization method, leading to a valuable contribution for the sustainable conversion of petrochemical feedstocks into synthetically usable fine chemicals and commodities.

Aryl ether-free polymer electrolytes for electrochemical and energy devices

“…Further research regarding the electrochemical stability of the fragments of AEPs under various electrode potentials and operating conditions needs to be explored. 129 In addition to strongly basic environments, AEMs are also used in strongly acidic environments. HT-PEMFC applications operate in a pH range of 1–3 at elevated temperatures of 100–200 °C, while RFB applications operate at a pH below 1.…”

“…For example, the electrochemical oxidation of cyclic alkanes and cyclic olefins, such as norbornene, occurs at approximately 1.0 V, resulting in the production of cycloaliphatic ketones and aliphatic (di)carboxylic acids. 129 The electrochemical oxidation of heterocycles occurs at around 1.5 V or higher, depending on the chemical environments. 130–132…”

Interfacial Micro‐Environment of Electrocatalysis and Its Applications for Organic Electro‐Oxidation Reaction

“…To date, various electrocatalysts including noble and nonnoble materials have been explored to catalyze OEOR. Noble metal-based electrocatalysts are mainly focused on the Pt, [40] Pd, [41,42] Ag, [43,44] Rh, [45] Ir [46] and Ru-based [47,48] compounds and single atom sites, [49,50] which have been demonstrated as efficient OEOR electrocatalysts with both high product selectivity and low anodic potential. However, its high price and element scarcity often make it challenging to be large-scale application.…”

“…In the past years, many works have demonstrated the role importance IME played in OEOR, [40,70,71] but how to rationally employ IME into the design of electrocatalyst is still challenging, especially for researchers who are new to this field. Hence, a timely review on IME of electrocatalysis and their OEOR applications is highly desired.…”

Selective electrochemical acceptorless dehydrogenation reactions of tetrahydroisoquinoline derivatives

“…First, according to the proposal, 1-phenyl-1,2,3,4-tetrahydroisoquinoline ( 1a ) was protonated in the presence of an acid to form 1a-H + , which was oxidized via a single-electron transfer (SET) process at the anode to generate the radical-cationic intermediate I . Since use of other Brønsted acids such as acetic, trifluoroacetic and hydrochloric acids each resulted in lower yields (Table 1, entries 2–4), the NO 3 − species might serve as a more efficient oxidation mediator 18 for this SET process. After the loss of another electron and one proton, 2a-H + was formed, which was less prone to undergo further oxidation and could deliver 1-phenyl-3,4-dihydroisoquinoline ( 2a ) after a common workup.…”