Modified wacker TBHP oxidation of 1- DODECENE
A higher 1-olefin (1-dodecene) was oxidized to 2-dodecanone and other ketones in a modified Wacker system featured by omitting the use of copper chloride and employing tert-butylhydroperoxide (TBHP) as oxidant. Acetonitrile was the solvent of choice due to its higher selectivity towards 2-dodecanone, the reaction occurring mostly in the interface. A maximum in conversion and selectivity was measured for a ratio [CH3CN] / [1-dodecene] = 10. The temperature abatement enhances the 2-dodecanone selectivity (61% at 40ºC) because of the lower extent of the competing isomerization reactions. An optimum in 2-dodecanone selectivity was found for a [TBHP] / [1-dodecene] ratio = 7. The use of H2O2 as oxidant led towards slower oxidation rates than TBHP. Other palladium salts (PdSO4 and Pd(CH3COO)2) and several R-CN solvents (propionitrile, benzonitrile, isobutyronitrile) yielded lower performances than palladium chloride and acetonitrile, respectively. On the contrary, ß-ciclodextrin, a phase transfer catalyst, improved the selectivity towards 2-dodecanone.
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