Photochemistry in synthesis: Where, when, and why

Protti, Stefano; Dondi, Daniele; Fagnoni, Maurizio; Albini, Angelo

doi:10.1351/pac200779111929

Cited by 47 publications

(25 citation statements)

References 64 publications

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“…Bromination methods considered in Figure 1: Entries 1-4 (Method I, neat bromine), Entries 5-12 (Method II, carrying agent), and Entries 13-24 (Method III, in situ generation of bromine). [47] No. 19 [39] 9a [27] 20 [40] 9b [27] 21 [42] [g] 10a [28] 22 [43] [f] 10b [28] [h] 23a [44] 11a [29] 23b [45] 11b [29] 24 [46] [a] poly(vinylpyrrolidone)-bromine complex.…”

Section: Resultsmentioning

confidence: 99%

Electrophilic Bromination of Alkenes: Environmental, Health and Safety Aspects of New Alternative Methods

Eissen

Lenoir

2008

Chemistry A European J

103

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More than twenty new alternative methods for bromination of alkenes have been evaluated taking into consideration their resource demands, waste production as well as environmental, health and safety aspects. The cost of bromine and the substances designated to circumvent the application of molecular bromine have also been taken into account. As bromine is only one of several problematic substances being used, its avoidance-by applying bromine supported on solid material or by performing the in situ generation of bromine-does not significantly reduce the technological requirements. On the contrary, the resource demands and amount of waste produced by most new methods are significantly higher compared to the standard methods, especially if the recycling of a carrying agent is not efficient. The method using hydrobromic acid and hydrogen peroxide can be regarded as a competitive alternative to the standard method. The application of certain carrying agents could be interesting, because solvents such as carbon tetrachloride or chloroform used during synthesis could be replaced with less problematic ones during work-up. However, problems associated with these alternatives are not resolved as yet.

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Section: Resultsmentioning

confidence: 99%

Electrophilic Bromination of Alkenes: Environmental, Health and Safety Aspects of New Alternative Methods

Eissen

Lenoir

2008

Chemistry A European J

103

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“…In many cases, the molecular transformations achieved would require additional synthetic steps. 80 Absorption of photons does not necessarily depend on solvent, so photochemistry expands the range of possible solid-to-solid chemical reactions. 81 Sunlight-the most abundant source of energy on the planet-can be used to produce useful chemicals on the multi-kilogram scale.…”

Section: Energy Impactsmentioning

confidence: 99%

Green Chemistry: A design framework for sustainability

Beach

Cui

Anastas

2009

Energy Environ. Sci.

200

100

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In this review we will highlight some of the science that exemplifies the principles of Green Chemistry, in particular the efficient use of materials and energy, development of renewable resources, and design for reduced hazard. Examples are drawn from a diverse range of research fields including catalysis, alternative solvents, analytical chemistry, polymer science, and toxicology. While it is impossible for us to be comprehensive, as the worldwide proliferation of Green Chemistry research, industrial application, conferences, networks, and journals has led to a wealth of innovation, the review will attempt to illustrate how progress has been made toward solving the sustainability goals of the 21st century by engaging at the molecular level.

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“…In general, the use of photochemistry has advantages compared to traditional thermochemical ways, such as higher selectivities, high conversions, and mild process conditions. [1,2] Photochemistry enables multi-step syntheses by providing reaction pathways, inaccessible by traditional thermochemical ways. [2,3] In addition, downstream purification regarding excess reagents is avoided as the incident photons are traceless reagents.…”

Section: Introductionmentioning

confidence: 99%

Principles of co‐axial illumination for photochemical reactions: Part 1. Model development

Meir

Leblebici

Fransen

et al. 2020

J Adv Manuf & Process

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Photochemical reactors with conventional homogeneous illumination suffer from a light efficiency problem, which is inherent to their design: Dark zones arise near the reagent-rich inlet whereas the reagent depleted outlet is overilluminated. Any attempt to mitigate dark zones at the inlet will only increase photon losses further downstream. This study reports the principles and model equations for co-and counter-current illumination in photochemical reactors, along with an optimization study to determine the most efficient and productive operating point. This work proves that the use of co-and counter-current illuminated reactors increases the energy efficiency while easing scalability by implementing larger path lengths, without altering the reactor's geometry. We report a simple model to determine the conversion obtained by such novel illumination techniques and compare it to the current state-of-the-art. Two nondimensional groups where derived that describe all possible reactor configurations, these are the initial absorbance (A) and the quantum photon balance (ρϕ). Variation of both parameters leads for noncompetitive photochemical reactions to an optimal point for the current state-of-the-art as well as the novel co-axial illumination. Ultimately, we recommend the use of an initial absorbance value (A) of at least 1, and a quantum photon balance (ρϕ) equal to 1 to introduce sufficient light and enable near complete absorption of light.

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Photochemistry in synthesis: Where, when, and why

Cited by 47 publications

References 64 publications

Electrophilic Bromination of Alkenes: Environmental, Health and Safety Aspects of New Alternative Methods

Electrophilic Bromination of Alkenes: Environmental, Health and Safety Aspects of New Alternative Methods

Green Chemistry: A design framework for sustainability

Principles of co‐axial illumination for photochemical reactions: Part 1. Model development

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