Photooxidation of Dienes Investigated in Micro Reactors

3 Photooxidation of Dienes Investigated in Micro Reactors Cas/liquid reaction 24 [CL 24] Oxidation of cyclopentadiene by singlet oxygen to 2-cyclopentene-1,4-diol 

This reachon, of industrial interest, utilizes singlet oxygen generated by irradiation in the presence of Rose Bengal [40]. An endoperoxide is formed as intermediate which is converted to 2-cyclopentene-l,4-diol by reduchon with thiourea. 

Cas/liquid reaction 25 [CL 25) [4 + 2] Cycloaddition of singlet oxygen to a-terpinene 

Using a single-channel chip micro reactor, singlet oxygen is generated by photochemical means in presence of catalytic amounts of Rose Bengal [21]. By [4 -i- 2] cycloaddition of this oxygen species to a-terpinene, the product ascaridole is obtained. 

Since the sensitizer Rose Bengal is recyclable, relatively high concentrations (5 10 M) can be used without raising cost issues and optical detection problems [21]. Under these conditions, it was shovm that molecules at any position in the micro channel have a similar photon flux. 

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