Green access to 2,3,5-p-benzoquinone using titania xerogels

MAGDALENA PALACIO; PAULA I. VILLABRILLE; PATRICIA G. VÁZQUEZ; GUSTAVO P. ROMANELLI; CARMEN V. CÁCERES

Foz do Iguacu

Conferencia; 4th Internacional IUPAC Conference on Green Chemistry; 2012

IUPAC-Sociedad Brasilera de Química

The benzoquinone structure shows biologically important properties such as cardiovascular, antigerminative, antibacterial, antitumor, and antiprotozoan activities. The oxidation of 2,3,6-trimethylphenol (2,3,6-TMP) is the key step for the production of 2,3,5-trimethylbenzoquinone (2,3,5-TMBQ), which is an especially valuable starting material for the synthesis of vitamin E1, which is used extensively as antioxidant in food, medical treatments, and cosmetics2. The objective of this work is to look for a clean synthesis of these compounds using H2O2-titania xerogels system.According to this, ceria-titania, vanadia-titania and heteropolyoxomolybdates-titania catalysts were prepared with a load of 5% (w / w) of CeO2 (Ce-T)and V2O5 (V-T) and 10% (w / w) of H3PMo12O40 (PMo-T), H4SiMo12O40 (SiMo-T) and H4PMo11VO40 (VPMo-T) by a sol-gel process.The selectivity to 2,3,5-TMBQ was kept between 95-98 % in all the cases. The conversion of 2,3,6-TMP reached 96 % and 91 % for  VPMo-T and Ce-T. catalyst, respectively,  after 4 h of reaction (Figure 2). The catalysts were recovered and reused.The hydrogen peroxide descomposition in the reaction medium without the 2,3,6-TMP was studied. It can be observed that the Ce-T catalyst maintain its activity and present the lowest H2O2 descomposition.