Reactivity of Superbasic Carbanions Generated via Reductive Radical-Polar Crossover in the Context of Photoredox Catalysis

Photocatalytic reactions involving a reductive radical-polar crossover (RRPCO) generate intermediates with carbanionic reactivity. Many of these proposed intermediates resemble highly reactive organometallic compounds. However, conditions of their formation are generally not tolerated by their isolated organometallic versions and often a different reactivity is observed. Our investigations on their nature and reactivity under commonly used photocatalytic conditions demonstrate that these intermediates are indeed best described as free, superbasic carbanions capable of deprotonating common polar solvents usually assumed to be inert such as acetonitrile, dimethylformamide, and dimethylsulfoxide. Their basicity not only towards solvents but also towards electrophiles, such as aldehydes, ketones, and esters, is comparable to the reactivity of isolated carbanions in the gas-phase. Previously unsuccessful transformations thought to result from a lack of reactivity are explained by their high reactivity towards the solvent and weakly acidic protons of reaction partners. An intuitive explanation for the mode of action of photocatalytically generated carbanions is provided, which enables methods to verify reaction mechanisms proposed to involve an RRPCO step and to identify the reasons for the limitations of current methods.

Effects of phytase/ethanol treatment on aroma characteristics of rapeseed protein isolates

This study investigates enhancing the flavor of rapeseed protein isolate (RPI), a protein-rich substance with an unfavorable taste, through phytase/ethanol treatment. Comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GC × GC-TOF-MS) analysis identified 268 volatile compounds in RPI. The study found that this treatment significantly altered the content of these compounds, reducing sourness and enhancing sweetness and fruitiness. The analysis also showed that the treatment notably increased the relative odor activity values (ROAVs) of key aroma compounds, improving RPI's flavor. Sensory evaluation confirmed the positive impact of the treatment, indicating its potential to make RPI a more acceptable ingredient in the food industry.