Aqueous Mixtures of Deep Eutectic Solvents: Tuning the Reaction Medium and Photocatalyst for Highly Selective Amine Oxidation

Abstract

Harvesting light as a source of energy for driving chemical processes is an important aspect of tacking the looming energy crisis. The challenge lies in making the process sustainable while retaining the efficiency and selectivity. In this work, deep eutectic solvents and their aqueous mixtures are used to replace acetonitrile as the reaction medium for the photocatalyzed amine oxidation. It is observed that the use of deep eutectic solvents as reaction media leads to >90% conversion but presents issues with efficient workup due to high viscosity. The use of water a cosolvent mitigates the issue. Further modification of the catalyst surface with alizarin enables the use of higher water content (in a 1:1 ratio) and leads to high conversion (>90%) at one-tenth of irradiation intensity. The high yield and selectivity eliminate the need for tedious purification steps to isolate the product. Control experiments indicate cooperative contributions by TiO₂, 2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO), and alizarin as mechanistic factors responsible for the enhanced reactivity.

Keywords

Deep eutectic solvent - Aqueous mixture - Photocatalysis - Amine oxidation - Heterogeneous catalysis

Publication History

Received: 24 September 2024

Accepted after revision: 16 December 2024

Accepted Manuscript online:
18 December 2024

Article published online:
22 January 2025

• References

• 1 Choudhury LH, Parvin T. Tetrahedron. 2011; 67: 8213-8228
• 2 Martin SF. Pure Appl. Chem.. 2009; 81: 195-204
• 3 Yamamoto Y, Kodama S, Nomoto A, Ogawa A. Org. Biomol. Chem.. 2022; 20: 9503-9521
• 4 Chen B, Wang L, Gao S. ACS Catal.. 2015; 5: 5851-5876
• 5 Lang X, Ji H, Chen C, Ma W, Zhao J. Angew. Chem., Int. Ed.. 2011; 50: 3934-3937
• 6 Lang X, Ma W, Zhao Y, Chen C, Ji H, Zhao J. Chem. – Eur. J.. 2012; 18: 2624-2631
• 7 Li N, Lang X, Ma W, Ji H, Chen C, Zhao J. Chem. Commun.. 2013; 49: 5034
• 8 Sheng W, Wang X, Wang Y, Chen S, Lang X. ACS Catal.. 2022; 12: 11078-11088
• 9 Shi J.-L, Hao H, Li X, Lang X. Catal. Sci. Technol.. 2018; 8: 3910-3917
• 10 Shi JL, Hao H, Lang X. Sustain. Energy Fuels. 2019; 3: 488-498
• 11 Li X, Lang X. J. Chem. Phys.. 2020; 152: 044705
• 12 Wang Z, Richter SM, Rozema MJ, Schellinger A, Smith K, Napolitano JG. Org. Process Res. Dev.. 2017; 21: 1501-1508
• 13 Hazra S, Malik E, Nair A, Tiwari V, Dolui P, Elias AJ. Chem. – Asian J.. 2020; 15: 1916-1936
• 14 Zhao W, Yang C, Zhang X, Deng Y, Han C, Ma Z, Wang L, Ye L. ChemSusChem. 2020; 13: 116-120
• 15 Gautam A, Khajone VB, Bhagat PR, Kumar S, Patle DS. Environ. Chem. Lett.. 2023; 21: 3105-3126
• 16 Sheikh Asadi AM, Cichocki Ł, Atamaleki A, Hashemi M, Lutze H, Imran M, Kong L, Wang C, Boczkaj G. Water Resour. Ind.. 2024; 31: 100251
• 17 Zhang Q, De Oliveira Vigier K, Royer S, Jérôme F. Chem. Soc. Rev.. 2012; 41: 7108
• 18 Francisco M, van den Bruinhorst A, Kroon MC. Angew. Chem., Int. Ed.. 2013; 52: 3074-3085
• 19 Guajardo N, Müller CR, Schrebler R, Carlesi C, Domínguez de María P. ChemCatChem. 2016; 8: 1020-1027
• 20 Smith EL, Abbott AP, Ryder KS. Chem. Rev.. 2014; 114: 11060-11082
• 21 Valvi A, Tiwari S. Eur. J. Org. Chem.. 2018; 2018: 4933-4939
• 22 Valvi A, Tiwari S. ChemistrySelect. 2021; 6: 249-254
• 23 Allan MG, Pichon T, McCune JA, Cavazza C, Le Goff A, Kühnel MF. Angew. Chem., Int. Ed.. 2023; 62: e202219176
• 24 Gao J, Meng Y, Benton A, He J, Jacobsohn LG, Tong J, Brinkman KS. ACS Appl. Mater. Interfaces. 2020; 12: 38012-38018
• 25 Wang X, Wang Y, Li H. Asian J. Org. Chem.. 2023; 12: e202300475
• 26 Li X, Hao H, Lang X. J. Colloid Interface Sci.. 2021; 581: 826-835
• 27 Deshmukh SA, Bhagat PR. ChemistrySelect. 2022; 7: e202200189