| Grant number: | 06/03984-8 |
| Support Opportunities: | Research Grants - Visiting Researcher Grant - International |
| Duration: | February 01, 2007 - April 28, 2007 |
| Field of knowledge: | Physical Sciences and Mathematics - Chemistry - Organic Chemistry |
| Principal Investigator: | Dalmo Mandelli |
| Grantee: | Dalmo Mandelli |
| Visiting researcher: | Georgiy Borisovich Shulpin |
| Visiting researcher institution: | Russian Academy of Sciences (RAS), Russia |
| Host Institution: | Faculdade de Química. Pontifícia Universidade Católica de Campinas (PUC-CAMP). Campinas , SP, Brazil |
Abstract
Selective oxidation of alkanes has a large industrial interest and has been extensively studied during the last decades. The main aim of such researches is to substitute the stoichiometric oxidative by catalytic cleaner processes using green oxidants, as H2O2 that generates only water as by-products. One of the most efficient systems for the alkane oxidation was proposed and carefully studied in collaborative works of PUC-Campinas and the Semenov Institute. This system is based on dinuclear manganese(IV) derivative [L2Mn2O3](PF6)2 (L = 1,4,7-trimethyl-1,4-7-triazacyclononane, Mn-TMTACN), in the presence of acetic or oxalic acid as co-catalyst. Very recently, in a preliminary study, we have found that, unlike acetic or oxalic acid, trifluoroacetic acid used in a low concentration co-catalyzes a very efficient alkane oxidation with H2O2 in the presence of Mn-TMTACN. Moreover, we have found that certain amino acids, as picolinic, 2-pyrazinic and 2,3-dipyrazinic acids are also efficient as co-catalysts in this reaction. It is very interesting that the efficiency of the action of an amino acid depends strongly on its structure and this is in accordance with principles of enzymatic catalysis. We plan to study in detail features of these reactions and kinetics of cyclohexane oxidation, as initial rates dependence on the concentration of catalyst, co-catalyst, oxidant and substrate. The stereo-selectivity on the oxidation of cis- and trans- dimethyl-cyclohexane will be also studied. We hope that on the basis of this kinetic study (as well as on the bases of measuring the selectivities of alkane oxidations) we will be able to make conclusions on the mechanisms of the reaction in the presence of the co-catalysts mentioned above. (AU)
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