Microphotochemistry: a reactor comparison study using the photosensitized addition of isopropanol to furanones as a model reaction

Shvydkiv, Oksana; Yavorskyy, Alexander; Tan, Su Bee; Nolan, Kieran; Hoffmann, Norbert; Youssef, Ali; Oelgemöller, Michael

doi:10.1039/c1pp05024a

Cited by 52 publications

(40 citation statements)

References 35 publications

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“…Energy efficiency is one parameter for evaluating apparatus performance. As some papers have suggested, energy efficiency was determined by the reaction conversion per W h (Lamp power × irradiation time) [27,28]. In our experiment, only one of the 6 UV-LEDs used in the microreactor was used in the batch.…”

Section: Apparatus Comparisonmentioning

confidence: 99%

See 1 more Smart Citation

Diastereodifferentiating [2+2] photocycloaddition of chiral cyclohexenone carboxylates with cyclopentene by a microreactor

Terao

Nishiyama

Aida

et al. 2012

Journal of Photochemistry and Photobiology A: Chemistry

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Section: Apparatus Comparisonmentioning

confidence: 99%

“…As another means of evaluation, a space-time-yield (STY) calculation was reported by Shvydkiv et al [28] STY values are independent on apparatus geometry and are calculated using Eq. (1).…”

Section: Apparatus Comparisonmentioning

confidence: 99%

Diastereodifferentiating [2+2] photocycloaddition of chiral cyclohexenone carboxylates with cyclopentene by a microreactor

Terao

Nishiyama

Aida

et al. 2012

Journal of Photochemistry and Photobiology A: Chemistry

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“…Its absorption spectrum better overlaps with the emission spectrum of the various UVA light sources used (Fig. 1) [42]. Such electron donor substituted aromatic ketones have also been applied successfully to the photochemically induced radical addition of tertiary amines to electron deficient alkenes [43,44].…”

Section: Intermolecular Radical Addition As a Standard Reaction To Evmentioning

confidence: 98%

“…Due to its efficiency, the acetone sensitized addition of secondary alcohols to furanones was used as a model reaction to characterize and to compare different photochemical microreactor systems [41,42]. In order to be able to achieve more coherent results, 4,4′-dimethoxybenzophenone (DMBP) was used as a more effective sensitizer.…”

Section: Intermolecular Radical Addition As a Standard Reaction To Evmentioning

confidence: 99%

Photochemically induced radical reactions with furanones

Oelgemöller

Hoffmann

2015

Pure and Applied Chemistry

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Radicals are easily generated via hydrogen transfer form secondary alcohols or tertiary amines using photochemical sensitization with ketones. They can subsequently add to the electron deficient double bond of furanones. The addition of the alcohols is particularly efficient. Therefore, this reaction was used to characterize and to compare the efficiency of different photochemical continuous flow microreactors. A range of micro-structured reactors were tested and their performances evaluated. The enclosed microchip enabled high space-time-yields but its microscopic dimensions limited its productivity. In contrast, the open microcapillary model showed a greater potential for scale-up and reactor optimization. A 10-microcapillary reactor was therefore constructed and utilized for typical R&D applications. Compared to the corresponding batch processes, the microreactor systems gave faster conversions, improved product qualities and higher yields. Similar reactions have also been carried out with electronically excited furanones and other α,β-unsaturated ketones. In this case, hydrogen is transferred directly to the excited olefin. This reaction part may occur either in one step, i.e., electron and proton are transferred simultaneously, or it may occur in two steps, i.e., the electron is transferred first and the proton follows. In the first case, a C-C bond is formed in the α position of the α,β-unsaturated carbonyl compound and in the second case this bond is formed in the β position. For the first reaction, the influence of stereochemical elements of the substrate on the regioselectivity of the hydrogen abstraction on the side chain has been studied.

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“…Retention and thus irradiation times were adjusted with the flow rate. 51 The small UV-LED microchip gave the highest conversions of furanones 6a-c with a residence time of just 2.5 min. Despite much larger lamp power outputs, the other two microreactors and the batch system required a prolonged reaction time of 5 min to achieve high to quantitative conversions.…”

Section: 50mentioning

confidence: 99%

Green Photochemical Processes and Technologies for Research & Development, Scale‐up and Chemical Production

Oelgemöller

2014

J Chinese Chemical Soc

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Photochemistry is often viewed as a green chemical method since photons are regarded as a 'clean and traceless reagent'. Despite this, photochemical transformations generally suffer from a variety of 'non-green' drawbacks that have prevented their widespread adaptation in chemical manufacturing. These include the necessity for hazardous solvents, low quantum yields of photochemical transformations, high energy demands of traditional lamps and the need for high dilution due to the low penetration of light into the reaction mixture. As a result, photochemical operations generate large volumes of hazardous solvent waste, demand prolonged irradiation times and require high energy inputs. This highlight article shows recent examples of green photochemical processes and technologies that overcome these limitations. These include photodecarboxylations in water matrices with high quantum yields in an advanced 308-nm excimer falling film reactor, solar photooxygenations utilizing concentrated sunlight generated in a parabolic trough loop and photosensitized additions in resource-efficient microreactors under continuous flow conditions. The results show that photochemistry can be implemented as a truly green methodology across the entire chemical process spectrum from early R&D to scale-up and subsequently production.

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Microphotochemistry: a reactor comparison study using the photosensitized addition of isopropanol to furanones as a model reaction

Cited by 52 publications

References 35 publications

Diastereodifferentiating [2+2] photocycloaddition of chiral cyclohexenone carboxylates with cyclopentene by a microreactor

Diastereodifferentiating [2+2] photocycloaddition of chiral cyclohexenone carboxylates with cyclopentene by a microreactor

Photochemically induced radical reactions with furanones

Green Photochemical Processes and Technologies for Research & Development, Scale‐up and Chemical Production

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