The Photochemical Synthesis of Fine Chemicals with Sunlight

Abstract

The light of the sun can be used directly for changing chemical structures photochemically. Any industrial application must conform to the limitations imposed by the spectral distribution of the photons from the sun, the interruptions to the radiation due to the day/night rhythm, and the weather. In this review, we describe the photochemical potential of the sun, give a fundamental treatment of the concept of photoreactors driven by sunlight (abbreviated to solar photoreactors), and give an account of the realization of this concept in the first pilot plant on the “Plataforma Solar de Almeria” in southern Spain and in other activities in this field. Based on experimental data from photochemical investigations on the pilot plant scale, possibilities, limitations, and the potential growth of solar photochemistry are described. Solar photochemistry, in our opinion, is a technique which could make a contribution to the chemistry of the future because of its photochemical synthesis potential, the avoidance of waste products, and the direct utilization of the sun, not only as a primary energy source, but also as a reaction partner.

Enantioselektive Katalyse photochemischer Reaktionen

“…Jede der beiden Bereiche hat seine Vorteile und Anwendungen, wobei natürlich der Charme der Photochemie nach wie vor darin liegt, Molekülgerüste und Bindungen aufzubauen, die durch her-kçmmliche Verfahren nicht zugänglich sind. Wenn dazu sichtbares Licht, im Idealfall Sonnenlicht, [114] verwendet werden kann, dann ist man einer Anwendung im Sinne eines innovativen ressourcenschonenden Verfahrens bereits sehr nahe. Fast unwillkürlich kommt man daher auf G. Ciamician, einen der Urväter der Photochemie, zurück, dessen Visionen zur Nutzung der Photochemie [115] in einer Weise Realität annehmen, die ihn wahrscheinlich erstaunen ließe.…”

Photoinduced acyl transfer

“…[54] The most spectacular use of the photoinduced acylation was demonstrated by Mattay et al on a large scale using solar light (Scheme 34). [55][56][57][58][59][60] Irradiation of a solution of 1,4-naphthoquinone in tert-butanol/acetone (500 g) with butyraldehyde in a 24 m 2 mirror system for 3 days (Germany, August 1996) gave the acylated product in 90% yields without major side products. During the reaction, 300 moles of photons (between 300 and 500 nm, in the major absorption range of 1,4-quinones) were collected.…”

Development of a Photochemical Microfluidics Platform

“…Photocatalyzed reactions such as [2 + 2] cycloadditions [2], alkylations-arylations [3], selective oxidation and reduction reactions [4], and photodeprotection reactions [5] also enable facile introduction of desired functionalities and molecular frameworks. In many cases, photochemical reactions allow utilization of less reagent, little or no workup, and in some cases reactions that are otherwise energetically unfavorable under anything but extreme conditions.…”