2,5-Dimethylphenacyl carbonates: A photoremovable protecting group for alcohols and phenols

Abstract

Synthesis and photochemistry of a photochemically removable protecting group for alcohols and phenols, based on the 2,5-dimethylphenacyl (DMP) chromophore, is described. DMP carbonates release the corresponding hydroxy group containing molecules in high isolated yields (>70%), with quantum yields Phi= 0.1-0.2 in methanol and Phi= 0.36-0.51 in cyclohexane. The reactions proceed predominantly by the triplet pathway via E-photoenols, the lifetimes of which of approximately 2 s or 3 ms in cyclohexane or methanol, respectively, were determined by laser flash photolysis.

Investigation of the roles of active oxygen species in photodegradation of azo dye AO7 in TiO2 photocatalysis illuminated by microwave electrodeless lamp

“…Microwave energy has exhibited its great ability to accelerate reactions and to improve yields and selectivity on synthetic organic chemistry [2]. Recently, microwave irradiation has been used to assist photochemical reactions in the degradation of organic pollutants [3][4][5][6][7][8][9][10]. The results of these experiments showed that microwave irradiation could considerably accelerate the photodegradation of organic pollutants.…”

Effect of operating parameters on microwave assisted photocatalytic degradation of azo dye X-3B with grain TiO2 catalyst

“…Horihoshi et al [10] considered that specific interactions of the microwave radiation with the UV-illuminated TiO 2 particle surface may give rise to the generation of additional surface defects that can directly increase the concentration of hydroxyl radicals or some other but equivalent reactive oxygen species in the aqueous dispersion. Moreover, chemical processes performed under microwave radiation are believed to be affected by superheating, polarization, dielectric properties, hot spots formation, nuclear spin rotation, and spin alignment [15]. On the other hand, microwave enhances the reactants mobility and diffusion leading to increased exchange of reactants between catalyst surface and solution.…”

“…The problem will be solved if microwave electrodeless lamp (MWL) substitutes traditional lamp as light source. Moreover, MWL has some unique advantages, such as, good photochemical efficiency, long life, low cost, and simple photocatalytic equipment [14,15]. The light intensity can be adjusted by variations of MW power level and irradiation wavelengths can be adjusted by the ratio and nature of the gases in electrodeless lamp [8].…”

Photo-catalytic destruction of ethylene using microwave discharge electrodeless lamp

“…There is growing interest in using microwave radiation to drive or otherwise assist chemical reactions. Various types of organic and inorganic reactions, once performed using classical heating methods, are now routinely performed using microwave radiation [10]. Recently, researches have been conducted actively to improve oxidative degradation performance by adding microwave irradiation as an effort to utilize TiO 2 photo-catalyst treatment more efficiently [11][12][13].…”