Methyl Oleate Epoxidation with TBHP Catalyzed by Vanadyl(IV) Diketonate and Vanadyl(IV) Salicylidene 2-Aminoterephthalate
Rival Abdul Aziz (a), Aditya Wibawa Sakti (b), Muhamad Abdulkadir Martoprawiro (a), Yessi Permana (a*)

(a) Inorganic and Physical Chemistry Research Division, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung.
*yessi[at]itb.ac.id
(b) Chemistry Department, Pertamina University

Abstract

Epoxidized fatty acid methyl ester (EFAME) is a potential PVC plasticizer that may replace phthalate based plasticizers. The general production of EFAME involves organic acids and hydrogen peroxide with a mole ratio exceeding the olefin. The reaction releases large heat in very short time. Epoxidation of FAME with tertiary butyl hydroperoxide (TBHP) catalyzed by transition metal based catalyst showed a milder and safer reaction. The conversion of internal olefins into epoxides may be facilitated by oxophilic transition metals, such as vanadium, molybdenum, tungsten, and manganese at high valent. Herein, vanadyl(IV) acetylacetonate (VO(acac)2) and vanadyl(IV) salicylidene aminoterephthalate, were examined in the epoxidation of methyl oleate. The extended tight binding (xTB) program implemented in ORCA 5.0.2 was used to study the epoxidation of methyl oleate theoretically. The study at xTB level showed that the energy barrier (323 K) for the Sharpless mechanism was 124.3 kJ/mol in hexadecane, respectively. The interaction of VO(acac)2 with excess TBHP showed the formation of a vanadium(V) complex based on the visible light spectrum and qualitative magnetic measurements. Infrared spectrum of the isolated VO(acac)2 intermediate after the contact with 2 mol of TBHP showed a characteristic of oxide vanadium. Vanadyl(IV) salicylidene aminoterephthalate was likely obtained in the one pot reaction of the ligand and VO(acac)2. The formation of the complex was observed by IR spectroscopy, measurement of magnetic properties, and gravimetric analysis. Epoxidized methyl oleate (EMO) was achieved at the highest yield when 0.3 mol percent of VO(acac)2 and 3 mol eq of TBHP were employed in the reaction at 50 C for 7 h. Complexes of VO(acac)2, VO(bzbz)2, and vanadyl(IV) salicylidene aminoterephthalate showed catalytic activity of EMO formation at 58, 55, and 62 percent, respectively.

Keywords: epoxidation, vanadyl(IV) acetylacetonate, vanadyl(IV) salicylidene 2-aminoterephthalate, GFN2-xTB

Topic: Catalytic Chemistry