Industrial Photochemistry

Photohalogenation. Photochemical chlorination of aUphatic hydrocarbons has been the textbook example of industrial photochemistry for decades (45). As of tiie mid-1990s it is still coimneicially impoitant and industiial-scale lialogenation has been reviewed in detail (1). In most examples of... 

Since in industrial photochemistry mostly polychromatic light sources are used, photon quantities are relatively difficult to calculate and require knowledge of the spectral distribution of the radiometric quantity measured. Assuming on the other hand that the radiometric measurements do not need to be corrected for the spectral response of the probe, the photon irradiance at a given point within the reactor volume would then be given by Eqs. (39) and (40), respectively. 

The principal aim of an up-scaling project is to increase production volume, and thus the production rate, of a given preparative procedure without major changes of previously determined reaction conditions. In our qualitative approach to industrial photochemistry, optimal conditions would have clearly been determined on a laboratory scale by using a specific reactor module. 

Besides the valuable information obtained from the companies cited in Refs. 2 and 3, cooperation with Atochem Elf-Aquitaine (Paris and Pierre-Benite, France), E. I. DuPont de Nemours Company (Wilmington, Delaware, USA) and Ems-Dottikon AG (Dottikon, Switzerland) in the domain of industrial photochemistry, as well as with Asea Brown Boveri AG (Baden, Switzerland) for the technical application of excimer light sources in photochemistry, provided many interesting discussions, new insights in problems of industrial chemistry, and valuable new tools for their solution. 

Findeling C, Viriot ML, Carre MC, Andre JC (1993) Industrial Photochemistry XXII The Best Use of Photons in Water Purification, 1. Photochem. Photobiol. 71 191-193. 

Two more papers in their unique and extensive series on industrial photochemistry have been produced by the Nancy group. One is a Monte Carlo modelling of light curing as applied to photolithography. The other deals with macroscopic transport effects on the performance of photochemical reactors. ... 

In May-June 1972 the SC was renewed, based on the election of the national representatives. Voting took place in each country based on a list of candidates prepared under the supervision of the EC. Two national representatives were elected for some countries, in order to guarantee the presence of both academic and industrial photochemistry or to cover different fields of photochemistry (e.g., organic and inorganic). 

M.S. Dinaburg s extensive tome. Photosensitive Compounds (The Focal Press, London and New York) was originally published in Russia in 1964. It and Jaromir Kosar s Light-Sensitive Systems (John Wiley Sons, New York) published in 1965 serve as excellent reviews of the status of industrial photochemistry up to that time. 

Without the basic research on hexaarylbiimidazoles at DuPont, which established that these compounds could be valuable photooxidants, it is likely that they would have remained interesting laboratory curiosities, and probably be forgotten. Remarkably, with all the possible analogs or homologs of hexaarylbiimidazoles, no similarly effective materials were ever reported in the patent literature, in spite of probably intense efforts by other companies. DuPont s contribution to industrial photochemistry should therefore be acknowledged. 

None of these treat the impact that HABI chemistry had on industrial photochemistry, nor do they go into much detail into the patent aspects of HABI based photooxidation, photopolymerization, phototackification and other reactions. Also of necessity, they do not go into much detail about the different compositions that are involved in making this chemistry happen. 

Use of coherent light sources in industrial appHcations has led to the field of photodynamic therapy as a photochemically based medical technology (9—11). The apphcation of photochemistry to information storage and communication processes is expected (12) (see Information storage materials Resist materials). 

Conventional, incoherent light sources suitable for industrial-scale photochemistry and the reactors exploiting them have been reviewed in depth (2). Subsequent improvements in traditional light sources have been incremental. 

European Photochemistry Association (EPA), 264 European Solvents hidustry Group (ESIG), See European Chemical Industry Council (CEFIC), 257 EVIK , ametryn, 67 Exaxol Chemical Corporation, 227 EXCEDRIN , asphm, 67 Excel hidustries Ltd., 171 EXOLIT , ammonium phosphates, 67 Expro Chemical Products hic., 148 EXTRAZINE , cyanazm, 67 Exxon Mobil Chemical Company, 227, 228 Exxon Mobil Coal Minerals Company, 227, 228 Exxon Mobil Corporation, 228... 

Although academic research on photochemistry dates back many years its uptake by industry has been limited this is, in part, a result of significant, unsolved, inherent problems. 

Hiroshi Fukumura received his M.Sc and Ph.D. degrees from Tohoku University, Japan. He studied biocompatibility of polymers in the Government Industrial Research Institute of Osaka from 1983 to 1988. He became an assistant professor at Kyoto Institute of Technology in 1988, and then moved to the Department of Applied Physics, Osaka University in 1991, where he worked on the mechanism of laser ablation and laser molecular implantation. Since 1998, he is a professor in the Department of Chemistry at Tohoku University. He received the Award of the Japanese Photochemistry Association in 2000, and the Award for Creative Work from The Chemical Society Japan in 2005. His main research interest is the physical chemistry of organic molecules including polymeric materials studied with various kinds of time-resolved techniques and scanning probe microscopes. 

We expect the development of the mechanistic aspects of organic photochemistry to continue at the present pace as new methods are developed to probe in increasing detail and shorter time scales the photochemical dynamics of both old and new photoreactions. Since photochemistry is no longer the sole domain of the specialist, it is relatively safe to predict a dramatic increase in the near future of the synthetic and industrial uses of organic photochemistry. 

The potentially most promising application of high pressure photochemistry is in catalysis. Most industrial processes are catalytic, and many of these require high temperatures and pressures. Activation of the catalysts by light can lead to higher activity and selectivity or to novel reaction paths which yield products not obtained under conventional thermal conditions. 

It is well known that y or X photons have energies suitable for excitation of inner electrons. We can use ultraviolet and visible radiation to initiate chemical reactions (photochemistry). Infrared radiation excites bond vibrations only whereas hyperfrequencies excite molecular rotation. In Tab. 1.1 the energies associated with chemical bonds and Brownian motion are compared with the microwave photon corresponding to the frequency used in microwave heating systems such as domestic and industrial ovens (2.45 GHz, 12.22 cm). 

Simultaneous application of UV and MW irradiation has found widespread use in industry. The techniques are based on the conventional UV lamps and MW-powered electrodeless lamps and MW devices [28], The following paragraphs discuss several patents and papers that describe industrial microwave photochemistry, such as treatment of waste water, sterilization, or industrial photo induced organic synthesis. 

In this review we have discussed how the concept of microwave photochemistry has already become an important issue in chemistry. Although still in the beginning, detailed analysis of past and present literature confirms explicitly the usefulness of this method of chemical activation. The field has been already established in industry and we hope it will also find its way into conventional chemical laboratories. 

---