Contrastive Photoreduction Pathways of Benzophenones Governed by Regiospecific Deprotonation of Imidazoline Radical Cations and Additive Effects

Abstract

[Reaction: see text]. In the photoreaction of benzophenones with 1,3-dimethyl-2-phenylbenzimidazoline (DMPBI), benzhydrols were major products. Addition of H2O accelerated the reaction with no change in the product distribution, while AcOH, PhOH, and metal salts such as LiClO4 and Mg(ClO4)2 were effective additives to produce benzpinacols. In contrast, benzpinacols were exclusively formed regardless of the solvent and the additive in the reactions with 2-(o-hydroxyphenyl)-1,3-dimethylbenzimidazoline (o-HPDMBI). These observations are consistent with the hypothesis that DMPBI*+ donates a proton at the C2 position to the benzophenone ketyl radicals while o-HPDMBI*+ donates a phenol proton.

Investigation of excited state, reductive quenching, and intramolecular electron transfer of Ru(ii)–Re(i) supramolecular photocatalysts for CO2reduction using time-resolved IR measurements

“…All other reagents were reagent-grade quality and used without further purification. 1-Benzyl-1,4-dihydronicotinamide (BNAH), 54 , 55 1,3-dimethyl-2-phenyl-2,3-dihydro-1 H -benzo[ d ]imidazole (BIH), 56 , 57 [(dmb) 2 Ru(bpyC2bpy)Re(CO) 2 {P(OEt) 3 } 2 ](PF 6 ) 3 (dmb = 4,4′-dimethyl-2,2′-bipyridine, bpyC2bpy = 1,2-bis(4′-methyl-[2,2′-bipyridin]-4-yl)-ethane) ( RuRe(OEt) ), 10 [(dmb) 2 Ru(bpyC2bpy)Re(CO) 2 (PPh 3 ) 2 ](PF 6 ) 3 ( RuRe(Ph) ), 10 and (dmb) 2 Ru(bpyC2bpy)Re(CO) 2 {P( p -F-C 6 H 4 ) 3 } 2 ](PF 6 ) 3 ( RuRe(FPh) ) 10 were prepared according to reported methods.…”

Visible‐Light‐Driven Reduction of CO2 to CO and Its Subsequent Valorization in Carbonylation Chemistry and 13C Isotope Labeling

“…[Re cat] [50] and sacrificial electron donors [42,51,52] were prepared by literature method. [Re cat] [50] and sacrificial electron donors [42,51,52] were prepared by literature method.…”

Highly efficient, selective, and durable photocatalytic system for CO2 reduction to formic acid

“…All other reagents were of reagent-grade quality and used without further purification. Ru 2 –Ru(CO) , 6 BI(OH)H, 9 , 12 BI(O – ) + , 21 and BIH 9 , 12 were prepared according to the reported methods.…”