Continuous process for singlet oxygenation of hydrophobic substrates in microemulsion using a pervaporation membrane.
Chemically generated singlet oxygen (1O2, 1Deltag) is able to oxidize a great deal of hydrophobic substrates from molybdate-catalyzed hydrogen peroxide decomposition, provided a suitable reaction medium such as a microemulsion system is used. However, high substrate concentrations or poorly reactive organics require large amounts of H2O2 that generate high amounts of water and thus destabilize the system. We report results obtained on combining dark singlet oxygenation of hydrophobic substrates in microemulsions with a pervaporation membrane process. To avoid composition alterations after addition of H2O2 during the peroxidation, the reaction mixture circulates through a ceramic membrane module that enables a partial and selective dewatering of the microemulsion. Optimization phase diagrams of sodium molybdate/water/alcohol/anionic surfactant/organic solvent have been elaborated to maximize the catalyst concentration and therefore the reaction rate. The membrane selectivity towards the mixture constituents has been investigated showing that a high retention is observed for the catalyst, for organic solvents and hydrophobic substrates, but not for n-propanol (cosurfactant) and water. The efficiency of such a process is illustrated with the peroxidation of a poorly reactive substrate, viz., beta-pinene.
Caron
Laurent
L
LCOM, Equipe Oxydation & Formulation, UMR CNRS 8009, Ecole Nationale Supérieure de Chimie de Lille BP 108, F-59652 Villeneuve d'Ascq Cedex, France. l.caron@boursorama.com
Nardello
Véronique
V
Mugge
José
J
Hoving
Erik
E
Alsters
Paul L
PL
Aubry
Jean-Marie
JM
D000438:Alcohols / Q000737:chemistry; D002384:Catalysis; D004305:Dose-Response Relationship, Drug; D004655:Emulsions; D006861:Hydrogen Peroxide / Q000737:chemistry; D008566:Membranes; D008567:Membranes, Artificial; D008956:Models, Chemical; D008982:Molybdenum / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry*; D010545:Peroxides / Q000737:chemistry; D012119:Respiration; D012997:Solvents / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet; D013501:Surface-Active Agents / Q000737:chemistry; D013696:Temperature; D014867:Water / Q000737:chemistry
D000438:Alcohols; D004655:Emulsions; D008567:Membranes, Artificial; D010545:Peroxides; D012997:Solvents; D013501:Surface-Active Agents; D014867:Water; D008982:Molybdenum; C024687:sodium molybdate(VI); D006861:Hydrogen Peroxide; D010100:Oxygen