Bioinspired oxidation of benzyl alcohol: The role of environment and nuclearity of the catalyst evaluated by multivariate analysis

Inspired by copper-containing enzymes such as galactose oxidase and catechol oxidase, in which distinct coor-dination environments and nuclearities lead to specific catalytic activities, we summarize here the catalytic properties of dinuclear and mononuclear copper species towards benzyl alcohol oxidation using a multivariate statistical approach. The new dinuclear [Cu2(mu-L1)(mu-pz)]2+ (1) is compared against the mononuclear [CuL2Cl] (2), where (L1)- and (L2)- are the respective deprotonated forms of 2,6-bis((bis(pyridin-2-ylmethyl)amino) methyl)-4-methylphenol, and 3-((bis(pyridin-2-ylmethyl)amino)methyl)-2-hydroxy-5-methylbenzaldehyde and (pz)- is a pyrazolato bridge. Copper(II) perchlorate (CP) is used as control. The catalytic oxidation of benzyl alcohol is pursued, aiming to assess the role of the ligand environment and nuclearity. The multivariate statistical approach allows for the search of optimal catalytic conditions, considering variables such as catalyst load, hydrogen peroxide load, and time. Species 1, 2 and CP promoted selective production of benzaldehyde at different yields, with only negligible amounts of benzoic acid. Under normalized conditions, 2 showed superior catalytic activity. This species is 3.5-fold more active than the monometallic control CP, and points out to the need for an efficient ligand framework. Species 2 is 6-fold more active than the dinuclear 1, and indicates the favored nuclearity for the conversion of alcohols into aldehydes.

Automated summary

Inspired by copper-containing enzymes, this study summarizes the catalytic properties of dinuclear and mononuclear copper species towards benzyl alcohol oxidation. The results show that species 1 and species 2 promote the selective production of benzaldehyde with only negligible amounts of benzoic acid. Species 2 exhibits superior catalytic activity compared to the monometallic control CP and species 1, indicating the importance of an efficient ligand framework for the conversion of alcohols into aldehydes.