Temperature dependent photochemical cleavage of 2,5-dimethylphenacyl esters
Language English Country Netherlands Media print
Document type Journal Article, Research Support, Non-U.S. Gov't
- MeSH
- Time Factors MeSH
- Models, Chemical MeSH
- Chemistry, Organic methods MeSH
- Esters chemistry MeSH
- Photochemistry MeSH
- Magnetic Resonance Spectroscopy MeSH
- Methanol chemistry MeSH
- Microwaves MeSH
- Spectrophotometry MeSH
- Light * MeSH
- Temperature * MeSH
- Ultraviolet Rays MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Names of Substances
- Esters MeSH
- Methanol MeSH
The study of the temperature-sensitive photochemical release of a carboxylic acid from 2,5-dimethylphenacyl ester is reported. Quantum yields of the benzoate ester degradation in benzene increased from 0.22 at room temperature to 0.28 at 50 degrees C whereas a more significant increase (nearly by a factor of 3) was observed in methanol and ethanol, reaching a high reaction efficiency (0.25) typically found in non-polar solvents. The reaction proceeds predominantly via the triplet pathway and the E-photoenol in the whole temperature range in methanol solution. A higher quantum efficiency in heated methanol is explained by enhancing the E-photoenol population. This picture was partially confirmed by the quantum chemical calculations. The 2,5-dimethylphenacyl chromophore is proposed as an efficient photoremovable protecting group for carboxylic acids in solutions under conventional or microwave-assisted heating for applications in organic synthesis, such as the solid-phase synthesis.
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