Adjustment of the acid-base properties of phosphates through nitridation, for increased selectivity in mixed aldol condensations
(2004) 4th International Symposium on Nitrides — Location: Mons(Belgium) (17.November.2003)
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- Abstract
- For aldol condensation reactions, the balance between acid and basic sites has a significant impact on selectivites. In particular, it has been reported that for mixed aldol condensations, the fine tuning of the acid- base properties allowed to improve the desired crosscondensation with respect to the unwanted self-condensation of the reactants. On the other hand, it has been previously shown that the progressive nitridation of oxide, namely the progressive substitution of oxygen by nitrogen, induces a decrease of surface acid properties and an increase of the catalysts basicity. We report here the liquid phase aldol condensation of benzaldehyde with heptanal over "AlGaPON" and "ZrPON" oxynitrides (precursors and nitrides samples). The main products are jasminaldehyde (fine chemical) (through cross-condensation) and 2-pentyl-2-nonenal (via self-condensation), indicating that aldol processes effectively take place over such catalysts. Starting with a benzaldehyde / heptanal molar ratio equal to 5, the selectivity of jasminaldehyde increases and the selectivity of 2-pentyl-2-nonenal decreases versus reaction time. We compare the activities of phosphate precursors and of several nitride phosphates and discuss the influence of nitridation on the initial activities and on the selectivities obtained at iso-conversion, in relation to the changes in the oxynitride acid-base properties induced by the substitution of oxygen by nitrogen.
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Hasni, M., Delsarte, S., Rouchaud, J., & Grange, P. (2004). Adjustment of the acid-base properties of phosphates through nitridation, for increased selectivity in mixed aldol condensations. Silicates Industriels : ceramic science and technology, 69(5-6), 77-84. https://hdl.handle.net/2078.5/23774 (Original work published 2004)