Biodiesel from Waste Cooking Oil: Highly Efficient Homogeneous Iron(III) Molecular Catalysts

Abstract

This article presents an efficient iron(III) molecular catalyst for the production of biodiesel from waste vegetable oils. The approach involved an initial screening of eight salophen complexes with various substituents on the arene rings, leading to the selection of the simplest unsubstituted species as the most active catalyst. Under optimized conditions, this catalyst demonstrated the capability to achieve complete conversion of the oil at a low catalyst loading (0.10% mol/mol) and convenient conditions (160 °C, 20/1 MeOH/oil ratio).

Synthesis and Characterization of Zn-Salophen Complexes with Different D–A Distances: An Approach to Tuning the Intersystem-Crossing Process

“…The yellow product a was collected and dried, producing a yield of 168.37 mg (92.15%). 1 Ethanol (5 mL) as a solvent, a (18.28 mg 0.05 mmol), h-salophen [36] (10.62 mg 0.05 mmol), and zinc acetate (11.75 mg 0.06 mmol) were added to a Schlenk tube, and the reaction was carried out overnight at 82 °C. After reaction, the solid was obtained by centrifugation, recrystallized with ether three times, and dried to obtain the yellow product Zn-1, producing a yield of 26.88 mg (80.68%).…”

“…After reaction, the solid was obtained by centrifugation, recrystallized with ether three times, and dried to obtain the yellow product Zn-1, producing a yield of 26.88 mg (80.68%). 1 Ethanol (5 mL) as a solvent, a (18.28 mg 0.05 mmol), h-salophen [36] ). The amount (wt%) of zinc metal in the Zn-1-4 was determined by atomic absorption spectroscopy (AAS); zinc (wt%): 8.35%.…”

“…After reaction, the solid was obtained by centrifugation, recrystallized with ether three times, and dried to obtain the yellow product Zn-2, producing a yield of 88.26 mg (90.17%). 1…”

“…The white product a was collected and dried, producing a yield of 173.43 mg (71.61%). 1 H NMR (400 MHz, CDCl 3 ) δ 7.89 (s, 1H), 7.83 (d, J = 8.0 Hz, 1H), 7.78 (d, J = 8.0 Hz, 1H), 7.74 (d, J = 8.0 Hz, 1H), 7.62 (s, 1H), 7.56-7.53 (m, 3H), 7.27 (t, J = 8.0, 8.0 Hz, 4H), 7.17-7.14 (m, 6H), 7.04 (t, J = 4.0, 7.3 Hz, 2H), 1.54 (s, 6H), 1.38 (s, 12H). 13 5 mL, the following were added to a Schlenk tube: (4-Bromophenyl) diphenylamine (140 mg 0.43 mmol), 2,2′-(9,9-dimethyl9H-fluorene-2,7-diyl) bis (4,4,5,5-tetramethyl-1,3,2-dioxaborolane) (245 mg 0.55 mmol), K2CO3 (2 mol L −1 ), TBAB (30 mg 0.09 mmol), and Pd(PPh3)4 (60 mg 0.05 mmol) (Figure 10).…”

“…Metallosalen/salophen (bis(salicylidene)ethylenediamine and bis(salicylidene)phenyldiamine) complexes have attracted considerable attention due to their versatile applications in catalysis [1][2][3][4][5][6][7][8][9][10], supramolecular chemistry [11][12][13][14][15][16][17][18], optical materials [19][20][21], and biological sensors or therapeutics [22,23] because of their rich chemistry and ease of manipulation of organic ligands. Among these complexes, zinc (II) salen/salophen complexes are of particular interest due to the non-redox nature and d 10 closed-shell configuration of the Zn 2+ ion, making them suitable for ligand-dependent fluorescent materials [24].…”