Abstract
This contribution addresses a frequent problem in flow photochemistry, where methodologies to determine the quantum efficiency of photoreactions are totally lacking. In spite of numerous studies being available in the literature, product reaction yields are never accompanied by measurements to determine their quantum yields. Basically, the key reagent in the reaction, light, is not measured under the experimental conditions of exposure. We report here a flow actinometer based on the photochemistry of valerophenone that can be readily implemented in the organic laboratory for irradiations in the UV region. For example for UVB lamps used in our work, the irradiance was measured as 1.1 × 10–4 einstein l−1 s−1. Our photoreactor design involves wrapping low-pressure lamps with Teflon tubbing, where the photochemistry takes place. Similar strategies could be implemented with other geometries or with lamps (e.g. LED) and actinometers with sensitivity in other spectral regions.
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Original data are available from the corresponding author upon reasonable request.
References
Scaiano, J. C. T. (2022). Photochemistry essentials. American Chemical Society.
Rabani, J., Mamane, H., Pousty, D., & Bolton, J. R. (2021). Practical chemical actinometry—a review. Photochemistry and Photobiology, 97, 873–902.
Wagner, P. J., Kelso, P. A., Kemppainen, A. E., McGrath, J. M., Schott, H. N., & Zepp, R. G. (1972). Type II photoprocesses of Phenyl Ketones. A Glimpse at the behavior of 1,4 Biradicals. Journal of the American Chemical Society, 94, 7506–7512.
Pitre, S. P., McTiernan, C. D., Vine, W., DiPucchio, R., Grenier, M., & Scaiano, J. C. (2015). Visible-light actinometry and intermittent illumination as convenient tools to study Ru(bpy)3Cl2 mediated photoredox transformations. Scientific Reports, 5, 16397.
Hatchard, C. G., & Parker, C. A. (1956). A new sensitive chemical actinometer—II. Potassium ferrioxalate as a standard chemical actinometer. Proceedings of the Royal Society of London Series A, 325, 518–536.
Wagner, P. J. (1971). Type II photoelimination and photocyclization of ketones. Accounts of Chemical Research, 4, 168–177.
Wagner, P. J., Kochevar, I. E., & Kemppainen, A. E. (1972). Type II photoprocesses of phenyl ketones. Procedures for determining meaningful quantum yields and triplet lifetimes. Journal of the American Chemical Society, 94, 7489–7494.
Small, R. D., Jr., & Scaiano, J. C. (1977). Interaction of oxygen with transient biradicals photogenerated from g-Methylvalerophenone. Chemical Physics Letters, 48, 354.
Small, R. D., Jr., & Scaiano, J. C. (1978). Differentiation of excited state and biradical processes. Photochemistry of phenyl alkyl ketones in the presence of oxygen. Journal of the American Chemical Society, 100, 4512.
Roibu, A., Fransen, S., Leblebici, M. E., Meir, G., Van Gerven, T., & Kuhn, S. (2018). An accessible visible-light actinometer for the determination of photon flux and optical pathlength in flow photo microreactors. Scientific Reports, 8, 5421.
Vandekerckhove, B., Piens, N., Metten, B., Stevens, C. V., & Heugebaert, T. S. A. (2022). Practical ferrioxalate actinometry for the determination of photon fluxes in production-oriented photoflow reactors. Organic Process Research & Development, 26, 2392–2402.
El Achi, N., Bakkour, Y., Chausset-Boissarie, L., Penhoat, M., & Rolando, C. (2017). Rapid and facile chemical actinometric protocol for photo-microfluidic systems using azobenzene and NMR spectroscopy. RSC Advances, 7, 29815–29820.
Aillet, T., Loubiere, K., Dechy-Cabaret, O., & Prat, L. (2014). Accurate measurement of the photon flux received inside two continuous flow microphotoreactors by actinometry. International Journal of Chemical Reactor Engineering, 12, 257–269.
Rehm, T. H. (2020). Flow photochemistry as a tool in organic synthesis. Chemistry--A European Journal, 26, 16952–16974.
Cambié, D., Bottecchia, C., Straathof, N. J. W., Hessel, V., & Noël, T. (2016). Applications of continuous-flow photochemistry in organic synthesis, material science, and water treatment. Chemical Reviews, 116, 10276–10341.
Wagner, P. J., Kelso, P. A., & Zepp, R. G. (1972). Type II photoprocesses of Phenyl Ketones. Evidence for a biradical intermediate. Journal of the American Chemical Society, 94, 7480–7488.
Turro, N. J., Ramamurthy, V., & Scaiano, J. C. (2010). Modern molecular photochemistry of organic molecules. University Science Publishers.
Braslavsky, S. E. (2007). Glossary of terms used in photochemistry. Pure and Applied Chemistry, 79, 293–465.
Wriedt, B., & Ziegenbalg, D. (2020). Common pitfalls in chemical actinometry. Journal of Flow Chemistry, 10, 295–306.
Gessner, F., & Scaiano, J. C. (1985). Importance of entropic terms in triplet energy transfer equilibria. Journal of the American Chemical Society, 107, 7206–7207.
Shrestha, N. K., Yagi, E. J., Takatori, Y., Kawai, A., Kajii, Y., Shibuya, K., & Obi, K. (1998). Photochemical α-cleavage reaction of benzoin and its derivatives. Journal of Photochemistry and Photobiology, A: Chemistry, 116, 179–185.
Lewis, F. D., Lauterbach, R. T., Heine, H. G., Hartmann, W., & Rudolph, H. (1975). Photochemical α-cleavage of benzoin derivatives Polar transition states for free-radical formation. Journal of the American Chemical Society, 97, 1519–1525.
Scaiano, J. C., Billone, P., Gonzalez, C. M., Maretti, L., Marin, M. L., McGilvray, K. L., & Yuan, N. (2009). Photochemical routes to silver and gold nanoparticles. Pure and Applied Chemistry, 81, 635–647.
McGilvray, K. L., Decan, M. R., Wang, D., & Scaiano, J. C. (2006). Facile photochemical synthesis of unprotected aqueous gold nanoparticles. Journal of the American Chemical Society, 128, 15980–15981.
Jockusch, S., Landis, M. S., Freiermuth, B., & Turro, N. J. (2001). Photochemistry and photophysics of a-hydroxy ketones. Macromolecules, 34, 1619–1626.
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This work was supported by the Natural Sciences and Engineering Research Council, the Canada Foundation for Innovation and the Canada Research Chairs program.
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Yaghmaei, M., Scaiano, J.C. A simple Norrish Type II actinometer for flow photoreactions. Photochem Photobiol Sci 22, 1865–1874 (2023). https://doi.org/10.1007/s43630-023-00417-1
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DOI: https://doi.org/10.1007/s43630-023-00417-1