Solar Photooxygenations for Chemical Manufacturing: History
View Latest Version
Please note this is an old version of this entry, which may differ significantly from the current revision.
Subjects: Chemistry, Organic | Engineering, Chemical
Contributor:
Michael Oelgemoeller

Photooxygenation reactions involving singlet oxygen (1O2) are utilized industrially as a mild and sustainable access to oxygenated products. Due to the usage of organic dyes as photosensitizers, these transformations can be successfully conducted using natural sunlight. Modern solar chemical reactors enable outdoor operations on the demonstration (multigram) to technical (multikilogram) scales and have subsequently been employed for the manufacturing of fine chemicals such as fragrances or biologically active compounds. This review highlights examples of solar
photooxygenations for the manufacturing of industrially relevant target compounds and discusses current challenges and opportunities of this sustainable methodology.

  • solar chemistry
  • photooxygenations
  • solar reactor
  • chemical manufacturing

 1. Introduction

Photochemistry has recently seen a remarkable renaissance in synthetic organic chemistry [1][2][3][4]. This trend was sparked by the development of new photochemical transformations [5][6][7][8] as well as advances in photoreactor and light technologies [9][10][11][12][13]. However, the large-scale realization of photochemical manufacturing processes is hindered by their quantum yields and the significant installation and maintenance costs of artificial light sources [14][15]. As a result, industrial photochemistry is restricted to low-volume but high-value fine chemicals (such as fragrances, flavors or vitamins), or bulk but low-value chemicals (such as haloalkanes, oximes, sulfonyl chlorides and sulfonic acids) [14][15][16][17][18][19]. Natural sunlight is regarded as an alternative and sustainable energy source for a range of photochemical transformations [20][21][22][23]. Up until the early 20th century, photochemical experiments were routinely performed by placing sealed flasks and tubes in direct sunlight [24][25][26][27]. Although this ‘flask in the sun’ approach is still followed today [28][29], the small scales and prolonged exposure times result in very low productivities of the desired products. Recently, sunlight collectors and concentrators that were initially developed for energy generation [30][31][32][33] have been modified for solar photochemical experimentation [34]. Technical-scale solar degradation and detoxification processes have subsequently been successfully realized using these technologies [35][36][37][38]. In contrast, however, preparative solar chemistry for the manufacturing of chemicals is still comparably rare [39][40][41][42][43][44][45][46][47]. The main hurdles for a widespread implementation of solar synthesis are the discontinuous availability and the low UV content (<400 nm) of just 3–5% of natural sunlight [48]. Sunlight also consists largely of direct and diffuse radiation and their ratios vary with the location and weather [49]. Solar manufacturing may thus be ideally performed in the visible range (400–700 nm: 42–43% of solar spectrum [48]) for small annual production targets (<100 tons/year) that do not require continuous, year-round operation under optimal solar light conditions. Photooxygenations with singlet oxygen (1O2) combine catalytic amounts of a dye sensitizer with visible light and yield a variety of oxygenated products [50][51][52]. Photooxygenations are also performed industrially to produce low-volume fine chemicals such as fragrances, flavors or pharmaceuticals [53][54][55]. These features make photooxygenations ideal candidates for solar chemical manufacturing processes.

2. Solar Reactors for Synthetic Applications

Solar reactors are classified based on their sun concentration factor (CF) and range from non- to highly concentrating systems. Non- and low concentrating reactors are characterized by large apertures that enable them to harvest direct and diffuse radiation. The simplest non-concentrating devices are flatbed reactors with large surface areas, thin bodies, and operation volumes of up to 30 L (Figure 1a) [56]. These fixed reactors are best tilted to the latitude of the location for optimal harvest of sunlight. Improved models operate in circulation mode with an external heat exchanger. The compound parabolic collector (CPC) uses a ‘round W’-shaped polished aluminum reflector that is tilted to the local latitude and directs all available radiation onto a central received tube (Figure 1b) [57][58]. These advanced systems have a concentration factor of one sun (or slightly above) and most commonly operate in circulating batch mode on volumes of up to 100 L. Several reactors can also be connected in series to form larger units. Parabolic trough reactors utilize large reflectors that focus only direct sunlight onto a reaction tube in their focal line and can reach concentration factors of 20–150 suns [32]. More modern reactors such as the former PROPHIS loop (PaRabolic trough-facility for Organic PHotochemical synthesis, Figure 1c) operate on volumes up to 150 L and track the movement of the sun, either horizontally or three-dimensionally (horizontally and vertically) [59].

Molecules 26 01685 g001 550

Figure 1. (a) Circulating flatbed reactor with reflective back and external cooling at James Cook University in Townsville, Australia. (b) CPC reactor with a 2 m2 aperture at James Cook University in Townsville, Australia. (c) Former PROPHIS loop at the German Aerospace Center (DLR) in Cologne-Porz, Germany (modified from [60]).

While solar dish concentrators can provide very high concentration factors of up to 5000 suns, these sophisticated devices are rarely used for preparative solar photochemical applications. Since the receiver in the focal point easily reaches extreme temperature ranges, dish reactors are instead advantageous for thermochemical processes [33]. Likewise, solar furnaces can reach extreme concentration factors of 5000–20,000 suns by reflecting sunlight via a heliostat or heliostat field onto a concentrator, which then focuses the sun’s beam onto the experimental setup. The naturally extreme heat generation and the costly installation have limited the application of solar furnaces mainly to material sciences and solar thermal research activities [61][62][63].

3. Photooxygenations in Organic Synthesis

Photooxygenations, also known as Type II photosensitized oxidations [64], utilize singlet oxygen (1O2), which is generated from ground-state triplet oxygen (3O2) via photosensitization (Scheme 1) [65]. The sensitizer (Sens) initially absorbs light and undergoes intersystem crossing (ISC) to its triplet excited state (3Sens*). Subsequent energy transfer to ground state oxygen produces singlet oxygen. The dissolved oxygen concentration in most organic solvents is low [66][67] and thus, fine streams of oxygen or compressed air are constantly passed through the reaction media. Likewise, the lifetime of singlet oxygen critically depends on the reaction medium and is highest in halogenated solvents [67]. Due to the environmental hazards linked to these solvents, many industrial and solar photooxygenation processes are conducted in less harmful alcoholic solvents instead [68]. A series of photosensitizers with large absorption coefficients within the visible spectrum, suitable solubilities in a range of organic solvents, long triplet lifetimes and high quantum yields for 1O2 generation have now become available [69][70]. The most common photosensitizers methylene blue, tetraphenylporphyrin and rose bengal (as disodium salt) are shown in Scheme 1. For easy recovery and reuse, photosensitizers have also been immobilized on an inert solid support [71][72]. Photooxygenations have furthermore been successfully performed under continuous-flow conditions [73]. Thermal oxygenation processes involving 1O2 have likewise been developed but are at present less important in organic synthesis [74].

Molecules 26 01685 sch001 550

Scheme 1. Photosensitized generation of singlet oxygen and common photosensitizers.

Singlet oxygen can react with a variety of functional groups (Scheme 2) [50][51][52]. Conjugated dienes preferably undergo [4+2] cycloadditions to endoperoxides, while electron-rich olefins favor [2+2] cycloadditions to 1,2-dioxetanes. Inactivated olefins with allylic hydrogen atoms undergo Schenck-ene-type reactions to allylic hydroperoxides instead [75][76]. Thioethers and phosphines produce the corresponding sulfoxides and phosphine oxides. All reaction types incorporate molecular oxygen into a molecular entity with high to quantitative atom economies.

Molecules 26 01685 sch002 550

Scheme 2. General photooxygenation reactions.

Many of the industrially relevant photochemical processes convert naturally occurring or semi-synthetic starting materials to their corresponding oxygenated products [53][54][55]. Of these, essential oil derived starting materials are especially common [55][77], which makes photooxygenations promising applications for product diversification and value-adding in the essential oil industry [78]. This review will focus on demonstration (multigram)- to technical (multikilogram)-scale transformations conducted in purpose-designed solar reactors. Whenever available, key technical features of the solar reactor systems used have been provided. Related demonstration-scale photooxidations involving the super oxide anion radical (O2•–) or a thermal oxidation step were also included. In many cases, solar transformations were monitored, and obtained product mixtures analyzed by GC or GC–MS analysis techniques. Whenever necessary, the reported yields or conversions from these studies were rounded for consistency and to account for experimental errors.

This entry is adapted from the peer-reviewed paper 10.3390/molecules26061685

References

  1. Bonfield, H.E.; Knauber, T.; Lévesque, F.; Moschetta, E.G.; Susanne, F.; Edwards, L.J. Photons as a 21st century reagent. Nat. Commun. 2020, 11, 1–4.
  2. Griesbeck, A.G. The Future of Photochemistry: Just Bright. ChemPhotoChem 2018, 3, 8–9.
  3. Pagliaro, M. Making APIs and fine chemicals with light. Chim. Oggi—Chem. Today 2017, 35, 84–85.
  4. Bach, T. More Chemistry with light! More light in chemistry! Angew. Chem. Int. Ed. 2015, 54, 11294–11295.
  5. Balzani, V.; Bergamini, G.; Ceroni, P. Photochemistry and photocatalysis. Rend. Lincei 2017, 28, 125–142.
  6. Kärkäs, M.D.; Porco, J.A., Jr.; Stephenson, C.R.J. Photochemical approaches to complex chemotypes: Applications in natural product synthesis. Chem. Rev. 2016, 116, 9683–9747.
  7. Oelgemöller, M.; Hoffmann, N. Studies in organic and physical photochemistry—An interdisciplinary approach. Org. Biomol. Chem. 2016, 14, 7392–7442.
  8. Hoffmann, N. Photochemical Reactions as Key Steps in Organic Synthesis. Chem. Rev. 2008, 108, 1052–1103.
  9. Rehm, T.H. Reactor Technology Concepts for Flow Photochemistry. ChemPhotoChem 2019, 4, 235–254.
  10. Di Filippo, M.; Bracken, C.; Baumann, M. Continuous Flow Photochemistry for the Preparation of Bioactive Molecules. Molecules 2020, 25, 356.
  11. Politano, F.; Oksdath-Mansilla, G. Light on the Horizon: Current Research and Future Perspectives in Flow Photochemistry. Org. Process. Res. Dev. 2018, 22, 1045–1062.
  12. Oelgemöller, M.; Hoffmann, N.; Shvydkiv, O.; Oelgemoeller, M. From ‘Lab & Light on a Chip’ to Parallel Microflow Photochemistry. Aust. J. Chem. 2014, 67, 337–342.
  13. Sender, M.; Ziegenbalg, D. Light Sources for Photochemical Processes—Estimation of Technological Potentials. Chem. Ing. Tech. 2017, 89, 1159–1173.
  14. Braun, A.M.; Oller do Nascimento, C.A. Angewandte (präparative) Photochemie. Nachr. Chem. Tech. Lab. 1991, 39, 515–526.
  15. Braun, A.; Peschl, G.H.; Oliveros, E. Industrial photochemistry. In CRC Handbook of Organic Photochemistry and Photobiology, 3rd ed.; Griesbeck, A., Oelgemöller, M., Ghetti, F., Eds.; CRC Press: Boca Raton, FL, USA, 2012; Volume 1, Chapter 1; pp. 1–19.
  16. Michelin, C.; Lefebvre, C.; Hoffmann, N. Les réactions photochimiques à l’échelle industrielle. L’Act. Chim. 2019, 436, 19–27.
  17. Pfoertner, K.-H.; Oppenländer, T. Photochemistry. In Ullmann’s Encyclopedia of Industrial Chemistry; Wiley-VCH: Weinheim, Germany, 2012; pp. 1–45.
  18. Braun, A.M.; Jakob, L.; Oliveros, E.; Nascimento, C.A.O.D. Up-Scaling Photochemical Reactions. Adv. Photochem. 2007, 18, 235–313.
  19. Fischer, M. Industrial Applications of Photochemical Syntheses. Angew. Chem. Int. Ed. 1978, 17, 16–26.
  20. Mattay, J. Von der Laborsynthese zur Solarchemie. Chem. unsere Zeit 2002, 36, 98–106.
  21. Wilkins, F.W.; Blake, D.M. Use solar energy to drive chemical processes. Chem. Eng. Prog. 1994, 90, 41–49.
  22. Funken, K.-H. Solare Photoreaktionen für die chemische Technik. Nachr. Chem. Tech. Lab. 1992, 40, 793–800.
  23. Mathur, V.; Wong, E. Production of fuels and chemicals using solar photothermochemistry. Energy 1987, 12, 311–318.
  24. Albini, A.; Dichiarante, V. The ‘belle ’epoque’ of photochemistry. Photochem. Photobiol. Sci. 2009, 8, 248–254.
  25. Roth, H.D. Twentieth century developments in photochemistry. Brief historical sketches. Pure Appl. Chem. 2001, 73, 395–403.
  26. Roth, H.D. The Beginnings of Organic Photochemistry. Angew. Chem. Int. Ed. 1989, 28, 1193–1207.
  27. Ciamician, G. The photochemistry of the future. Science 1912, 36, 385–394.
  28. Protti, S.; Fagnoni, M. The sunny side of chemistry: Green synthesis by solar light. Photochem. Photobiol. Sci. 2009, 8, 1499–1516.
  29. Ravelli, D.; Protti, S.; Fagnoni, M. Application of Visible and Solar Light in Organic Synthesis. Lect. Notes Chem. 2016, 92, 281–342.
  30. Fuqiang, W.; Ziming, C.; Jianyu, T.; Yuan, Y.; Yong, S.; Linhua, L. Progress in concentrated solar power technology with parabolic trough collector system: A comprehensive review. Renew. Sustain. Energy Rev. 2017, 79, 1314–1328.
  31. Weinstein, L.A.; Loomis, J.; Bhatia, B.S.; Bierman, D.M.; Wang, E.N.; Chen, G. Concentrating Solar Power. Chem. Rev. 2015, 115, 12797–12838.
  32. Fernández-García, A.; Zarza, E.; Valenzuela, L.; Pérez, M. Parabolic-trough solar collectors and their applications. Renew. Sustain. Energy Rev. 2010, 14, 1695–1721.
  33. Roeb, M.; Neises, M.; Monnerie, N.; Sattler, C.; Pitz-Paal, R. Technologies and trends in solar power and fuels. Energy Environ. Sci. 2011, 4, 2503–2511.
  34. Funken, K.-H.; Ortner, J. Technologies for the Solar Photochemical and Photocatalytic Manufacture of Specialities and Commodities: A Review. Z. Phys. Chem. 1999, 213, 99–105.
  35. Fendrich, M.A.; Quaranta, A.; Orlandi, M.; Bettonte, M.; Miotello, A. Solar Concentration for Wastewaters Remediation: A Review of Materials and Technologies. Appl. Sci. 2018, 9, 118.
  36. Malato, S.; Maldonado, M.I.; Fernández-Ibáñez, P.; Oller, I.; Polo, I.; Sánchez-Moreno, R. Decontamination and disinfection of water by solar photocatalysis: The pilot plants of the Plataforma Solar de Almeria. Mater. Sci. Semicond. Process. 2016, 42, 15–23.
  37. Tanveer, M.; Guyer, G.T. Solar assisted photo degradation of wastewater by compound parabolic collectors: Review of design and operational parameters. Renew. Sustain. Energy Rev. 2013, 24, 534–543.
  38. Bahnemann, D. Photocatalytic water treatment: Solar energy applications. Sol. Energy 2004, 77, 445–459.
  39. Oelgemöller, M. Solar Photochemical Synthesis: From the Beginnings of Organic Photochemistry to the Solar Manufacturing of Commodity Chemicals. Chem. Rev. 2016, 116, 9664–9682.
  40. Spasiano, D.; Marotta, R.; Malato, S.; Fernandez-Ibañez, P. Solar photocatalysis: Materials, reactors, some commercial, and pre-industrialized applications. A comprehensive approach. Appl. Cat. B Environ. 2015, 170, 90–123.
  41. Oelgemöller, M.; Jung, C.; Mattay, J.; Oelgemoeller, M. Green photochemistry: Production of fine chemicals with sunlight. Pure Appl. Chem. 2007, 79, 1939–1947.
  42. Esser, P.; Pohlmann, B.; Scharf, H.-D. The Photochemical Synthesis of Fine Chemicals with Sunlight. Angew. Chem. Int. Ed. 1994, 33, 2009–2023.
  43. Mumtaz, S.; Sattler, C.; Oelgemöller, M. Solar photochemical manufacturing of fine chemicals—historical background, modern solar technologies, recent applications and future challenges. In Chemical Processes for a Sustainable Future; Letcher, T.M., Scott, J.L., Patterson, D., Eds.; Royal Society of Chemistry: Cambridge, UK, 2015; Chapter 7; pp. 158–191.
  44. Coyle, E.E.; Oelgemöller, M. Solar photochemistry from the beginnings of organic photochemistry to the solar production of chem-icals. In CRC Handbook of Organic Photochemistry and Photobiology, 3rd ed.; Griesbeck, A., Oelgemöller, M., Ghetti, F., Eds.; CRC Press: Boca Raton, FL, USA, 2012; Volume 1, Chapter 10; pp. 237–247.
  45. Oelgemöller, M.; Jung, C.; Ortner, J.; Mattay, J.; Schiel, C.; Zimmermann, E. Green photochemistry with moderately concentrated sunlight. Spectrum 2005, 18, 28–33.
  46. Oelgemöller, M.; Mattay, J.; Jung, C.; Schiel, C.; Ortner, C.; Zimmermann, E. Back to the roofs—the solarchemical production of fine chemicals with sunlight. In Proceedings of the International Solar Energy Conference, ISEC 2004 Conference, Portland, OR, USA, 11–14 July 2004; American Society of Mechanical Engineers (ASME): New York, NY, USA, 2004; pp. 523–531.
  47. Pohlmann, B.; Scharf, H.-D.; Jarolimek, U.; Mauermann, P. Photochemical production of fine chemicals with concentrated sunlight. Sol. Energy 1997, 61, 159–168.
  48. Fu, Q. Radiation (solar). In Encyclopedia of Atmospheric Sciences; Holton, J., Ed.; Academic Press: Amsterdam, The Netherlands, 2003; pp. 1859–1863.
  49. Iqbal, M. An Introduction to Solar Radiation; Academic Press: New York, NY, USA, 1983.
  50. Pibiri, I.B.; Piccionello, S.; Palumbo, A.; Pace, A. Photochemically produced singlet oxygen: Applications and perspectives. ChemPhotoChem 2018, 2, 535–547.
  51. Ghogare, A.A.; Greer, A. Using Singlet Oxygen to Synthesize Natural Products and Drugs. Chem. Rev. 2016, 116, 9994–10034.
  52. DeRosa, M.C.; Crutchley, R.J. Photosensitized singlet oxygen and its applications. Coord. Chem. Rev. 2002, 233–234, 351–371.
  53. Turconi, J.; Griolet, F.; Guevel, R.; Oddon, G.; Villa, R.; Geatti, A.; Hvala, M.; Rossen, K.; Göller, R.; Burgard, A. Semisynthetic Artemisinin, the Chemical Path to Industrial Production. Org. Process. Res. Dev. 2014, 18, 417–422.
  54. Gollnick, K. Photooxygenation and its application in industry. Chim. Ind. 1982, 64, 156–166.
  55. Rojahn, W.; Warnecke, H.-U. Die Photosensibilisierte Sauerstoffübertragung—eine Methode zur Herstellung hochwertiger Riech-stoffe. Dragoc. Rep. 1980, 27, 159–164.
  56. Demuth, M. Chemie mit Sonnenlicht—auch bei Bewölkung. In Innovationspreis Ruhrgebiet; Kommunalverband Ruhrgebiet: Essen, Germany, 2000; pp. 91–94.
  57. Blanco, J.; Malato, S.; Fernández, P.; Vidal, A.; Morales, A.; Trincado, P.; Oliveira, J.; Minero, C.; Musci, M.; Casalle, C.; et al. Compound parabolic concentrator technology development to commercial solar detoxification applications. Sol. Energy 1999, 67, 317–330.
  58. Ajona, J.; Vidal, A. The use of CPC collectors for detoxification of contaminated water: Design, construction and preliminary results. Sol. Energy 2000, 68, 109–120.
  59. Jung, C.; Funken, K.-H.; Ortner, J. Prophis: Parabolic trough-facility for organic photochemical syntheses in sunlight. Photochem. Photobiol. Sci. 2005, 4, 409–411.
  60. Funken, K.-H. Solar chemistry using concentrating solar facilities. In Proceedings of the Sixth International Summer School Solar Energy 2000, Klagenfurt, Austria, 24 July–4 August 2000; Faninger, G., Bucher, W., Wolfer, U., Eds.; Interuniversitäres Institut für interdisziplinäre Forschung und Fortbildung (IFF), Universität Klagenfurt: Klagenfurt, Austria, 2001; pp. 118–137.
  61. Neumann, A.; Groer, U. Experimenting with concentrated sunlight using the DLR solar furnace. Sol. Energy 1996, 58, 181–190.
  62. Fields, C.L.; Pitts, J.R.; Hale, M.J.; Bingham, C.; Lewandowski, A.; King, D.E. Formation of fullerenes in highly concentrated solar flux. J. Phys. Chem. 1993, 97, 8701–8702.
  63. Flamant, G.; Luxembourg, D.; Robert, J.; Laplaze, D. Optimizing fullerene synthesis in a 50 kW solar reactor. Sol. Energy 2004, 77, 73–80.
  64. Foote, C.S. Definition of type I and type II photosensitized oxidation. Photochem. Photobiol. 1991, 54, 659.
  65. Schmidt, R. Photosensitized Generation of Singlet Oxygen. Photochem. Photobiol. 2007, 82, 1161–1177.
  66. Osterberg, P.M.; Niemeier, J.K.; Welch, C.J.; Hawkins, J.M.; Martinelli, J.R.; Johnson, T.E.; Root, T.W.; Stahl, S.S. Experimental lim-iting oxygen concentrations for nine organic solvents at temperatures and pressures relevant to aerobic oxidations in the pharma-ceutical industry. Org. Process. Res. Dev. 2015, 19, 1537–1543.
  67. Montalti, M.; Credi, A.; Prodi, L.; Gandolfi, M.T. Handbook of Photochemistry, 3rd ed.; CRC Press: Boca Raton, FL, USA, 2006; pp. 542–548.
  68. Clarke, C.J.; Tu, W.-C.; Levers, O.; Bröhl, A.; Hallett, J.P. Green and Sustainable Solvents in Chemical Processes. Chem. Rev. 2018, 118, 747–800.
  69. Fresnadillo, D.G.; Lacombe, S. Reference photosensitizers for the production of singlet oxygen. In Singlet Oxygen: Applications in Biosciences and Nanosciences; Nonell, S., Flors, C., Eds.; The Royal Society of Chemistry: Cambridge, UK, 2016; Volume 1, Chapter 6; pp. 105–143.
  70. Marin, M.L.; Santos-Juanes, L.; Arques, A.; Amat, A.M.; Miranda, M.A. Organic photocatalysts for the oxidation of pollutants and model compounds. Chem. Rev. 2012, 112, 1710–1750.
  71. Lacombe, S.; Pigot, T. Materials for selective photo-oxygenation vs. photocatalysis: Preparation, properties and applications in en-vironmental and health fields. Catal. Sci. Technol. 2016, 6, 1571–1592.
  72. Wahlen, J.; De Vos, D.E.; Jacobs, P.A.; Alsters, P.L. Solid Materials as Sources for Synthetically Useful Singlet Oxygen. Adv. Synth. Catal. 2004, 346, 152–164.
  73. Malakar, P.; Deb, A.R.; Goodine, T.; Robertson, M.J.; Oelgemöller, M. Continuous-flow photooxygenations: an advantageous and sustainable oxidation methodology with a bright future. In Catalytic Aerobic Oxidations—Catalysis Series; Mejía, P., Ed.; Royal Society of Chemistry: Cambridge, UK, 2020; Chapter 7; pp. 181–251.
  74. Nardello-Rataj, V.; Alsters, P.L.; Aubry, J.-M. Industrial Prospects for the Chemical and Photochemical Singlet Oxygenation of Organic Compounds. Liq. Phase Aerob. Oxid. Catal. Ind. Appl. Acad. Persp. 2016, 22, 369–395.
  75. Alberti, M.N.; Orfanopoulos, M. Unravelling the mechanism of the singlet oxygen ene reaction: Recent computational and experi-mental approaches. Chem. Eur. J. 2010, 16, 9414–9421.
  76. Bayer, P.; Pérez-Ruiz, R.; Von Wangelin, A.J. Stereoselective Photooxidations by the Schenck Ene Reaction. ChemPhotoChem 2018, 2, 559–570.
  77. Khayyat, S.A.; Roselin, L.S. Recent progress in photochemical reaction on main components of some essential oils. J. Saudi Chem. Soc. 2018, 22, 855–875.
  78. Goodine, T.; Oelgemöller, M. Corymbia citriodora: A Valuable Resource from Australian Flora for the Production of Fragrances, Repellents, and Bioactive Compounds. ChemBioEng Rev. 2020, 7, 170–192.
More
© Text is available under the terms and conditions of the Creative Commons Attribution (CC BY) license; additional terms may apply. By using this site, you agree to the Terms and Conditions and Privacy Policy.
This entry is offline, you can click here to edit this entry!
Video Production Service
Feedback