INFIQC   05475
INSTITUTO DE INVESTIGACIONES EN FISICO- QUIMICA DE CORDOBA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Atmospheric photooxidation of diterbutil malonate
Autor/es:
PELÁEZ WALTER; MALANCA E. FABIO; HENAO DIANA
Lugar:
Santiago
Reunión:
Congreso; 25th Inter-American Photochemical Society Meeting (25th I-APS Meeting); 2016
Institución organizadora:
I-APS Meeting
Resumen:
Introduction. Malonic acid diesters are widely used in the chemical industry as intermediates for the synthesis of a variety of organic chemicals and as the building blocks of different processes in which malonates are used as intermediates, such as pharmaceuticals, agrochemicals, vitamins, fragrances, and dyes. To improve our knowledge of the atmospheric chemistry of malonic acid diesters, we report here the kinetic results of the chlorine-atom-initiated oxidation of di-tert-butyl malonate (CH3)3COC(O)CH2C(O)COC(CH3)3 (DTBM), which allow as determine their photooxidation mechanism.Experimental procedure. The rate constant of the reaction between DTBM and chlorine atoms was measured relative to cyclohexane and pentane. Photolysis were performed in a photo-reactor using black lamps (>360 nm). Control experiments were performed in the dark for different periods of time in order to discount the among of DTBM that will disappeared by dark reactions. The identification and quantification of reactants and products were performed by infrared spectroscopy. All the experiments were carried out in gas phase. Theoretical calculations were carried out using Gaussian 09 to corroborate the main path of the mechanism reactions. Results and conclusions. The rate constant measured for DTBM with chlorine atoms gives a value of 1.45 x 10-10 (gas reference: cyclohexane) and 1.54 x 10-10 (gas reference: pentane) cm3 molec-1 s-1, leading to an average value of (1.49 +/- 0.10) x 10-10 cm3 molec-1 s-1. This value agrees with the rate constant calculated using the structure-reactivity estimation (SAR) (1.57 x 10-10 cm3 molecule-1 s-1), which is in reasonable agreement with the measured value. The identification of products (formic acid, acetone, (CH3)3CONO2, and (CH3)3CC(O)OONO2) and the kinetics analysis lead to the conclusion that chlorine atoms attack the DTBM mainly in the methyl group.The theoretical calculations explain the formation of the products of fotooxidation and agree with the experimental quantification of the main path of the mechanism reactions.References1-Notario, A.; Le Bras, G.; Mellouki, A.; J. Phys. Chem. A. 1998 (102) 3112-3117.2-Kwok, E. S. C.; Atkinson, R.; Atmos. Environ. 1995 (29) 1685-1695.