Application of a dioxo-molybdenum(VI) complex anchored on TiO2 for the photochemical oxidative decomposition of 1-chloro-4-ethylbenzene under O2

Abstract

The catalytic activity of dioxo-molybdenum(VI)-dichloro[4,4 0 -dicarboxylato-2,2 0 -bipyridine] covalently anchored through the carboxylate function to the surface of TiO 2 has been tested for the oxidative degradation of 1-chloro-4-ethylbenzene in MeCN solution under argon and UV irradiation (k = 254 nm). After 4-5 h of photochemical reaction, the Mo complex was reoxidized in the presence of O 2 in the dark, and then the reaction was continued under argon. The reaction proceeds by the intermediate formation of 4 0 -chloroacetophenone that undergoes further decomposition to chlorobenzene, plus small amounts of oxygen-containing organochlorine compounds, CO 2 and H 2 O. Similar results were obtained for the decomposition of 4 0 -chloroacetophenone under the same conditions, which also gave chlorobenzene as one of the main products. The ratio of [final product]/ [Mo complex] increases during the decomposition of 1-chloro-4-ethylbenzene (up to 350-400% for 30-35 h of reaction), which provides evidence of a catalytic process. The probable photochemical reactions are discussed.

Одностадийное Получение Дикофола

“…Среди современных разработок наиболее перспективными с экологической точки зрения считаются процессы деструктивного окисления ядохимикатов в жидкой фазе, где в качестве окисляющих агентов используют кислород [6][7][8], озон, пероксид водорода и др. Однако в случае ДДТ необходимо активирующее воздействие на реакционную систему.…”

Synthesis and X-ray diffraction data of dichloro-dioxido-(4,4′-dimethyl-2,2′-bipyridyl) molybdenum (VI)

“…These natural systems, known as molybdenum-enzymes, are the source of inspiration to synthesize different complexes called “biomimetics” that have allowed an advance in the understanding of the molecular oxygen activation mechanisms (Dupé et al, 2015; Heinze, 2015). Adapting these natural systems into analogous bio-inspired complexes, several structures of Mo VI O 2 with a variety of ligands have been synthesized and evaluated in OAT processes for substrates such as alkanes, alkenes, and phosphines (Bakhtchadjian et al, 2011; Kück et al, 2016). Recently, the photocatalytic activity of some dioxo-molybdenum complexes supported on different supports as metal-organic framework (MOF) or inorganic oxides as TiO 2 or SiO 2 were assessed in the selective epoxidation of terpenes as α - and β -pinene or limonene, using molecular O 2 as the primary oxidizing agent (Castellanos et al, 2012, 2013; Martínez et al, 2018, 2020, 2021).…”

Synthesis and X-ray diffraction data of dichlorodioxido (4,4-dimethoxycarbonyl-2,2′-bipyridyl) molybdenum(VI)

“…This property has allowed us to study the coordination sphere effect in the reactivity of the Mo = O entity (Kühn et al , 2000; Günyar et al , 2009). We have reported, over the years, the synthesis of several complexes with bypiridil ligands and studied, under homogeneous and heterogeneous conditions, their properties as oxygen atom transfer agents (Paez et al , 2008; Arzoumanian et al , 2010; Castellanos et al , 2012) Their ability to participate in catalytic oxidation has been reported in the selective oxidation of phosphines, arylalkanes and the photochemical oxidative decomposition of persistent organic pollutants (POPs) specifically using molecular O 2 as oxygen atom donor under visible light irradiation (Paez et al , 2009; Bakhtchadjian et al , 2011; Castellanos et al , 2013). In this work we report the synthesis and results on the molecular characterization (FTIR, NMR) and X-ray powder diffraction data for the compound dichlorodioxido (4,4-dimethoxycarbonyl-2,2-bipyridyl) molybdenum(VI).…”