Photochemical treatment

Cyclization of A -methyl-3-phenyl-propanesulfonamide 95 afforded 3-phenyl-A -methyl-isothiazolidine 5,5-dioxide 96 (OOJOC(65)926). The photochemical treatment in dichloroethane with diacetoxyiodobenzene in the presence of iodine was carried out at room temperature. By using 2-phenyl-ethanesulfon-amide 97, the cyclization occurred giving the corresponding benzothiazine 5,5-dioxide 98. 

UV irradiation on a polymer surface produces chemical modification as well as wettability and bondability improvement. It causes chain scission and oxidation on polymer surfaces. -iven in the presence of an inert gas [45]. Carbonyls are found to be introduced onto polyethylenes on UV irradiation. Sivram et al. [46] have used photochemical treatments for surface modification of polymers. They have generated surfaces of vaying surface energies by simple organic reactions. 

Taylor BF, JA Amador, HS Levinson (1993) Degradation of meta-trifluoromethylbenzoate by sequential microbial and photochemical treatments. FEMS Microbiol Lett 110 213-216. 

Photochemical treatment of an N-acylimidazole results in a 1,2-shift (N-C migration) of the acyl group to give a mixture of 2- and 5-acylimidazoles (photo-Fries products) [1],[2]... 

Nature, however, has performed more than simple stepwise transformations using a combination of enzymes in so-called multienzyme complexes, it performs multistep synthetic processes. A well-known example in this context is the biosynthesis of fatty acids. Thus, Nature can be quoted as the inventor of domino reactions. Usually, as has been described earlier in this book, domino processes are initiated by the application of an organic or inorganic reagent, or by thermal or photochemical treatment. The use of enzymes in a flask for initiating a domino reaction is a rather new development. One of the first examples for this type of reaction dates back to 1981 [3], although it should be noted that in 1976 a bio-triggered domino reaction was observed as an undesired side reaction by serendipity [4]. 

Hyperactivity, sugar and, 23 478 Hyperbaric oxygenation, 77 764 Hyperbar vacuum filtration, 77 377 Hyperbilirubinemia, photochemical treatment of, 79 120... 

Newborn jaundice, photochemical treatment of, 79 120 New chemicals, pricing of, 75 641-642 New Chemicals Program (EPA), 9 456 New Drug Application (NDA), 27 574 New drug approval (NDA) process, 78 698-701... 

Studies have been conducted for the intactness of biological fluids after photochemical treatment, in particular, proteins of allantoic fluid and blood semm, by methods of spectrophotometry and gel electrophoresis. The growth properties of semm were evaluated in cell culture. The protein composition of biological fluid was shown not to undergo dramatic changes during the course of photodynamic inactivation of vimses. 

Propoxur (313) is another herbicide which can be eliminated from the environment by means of photochemical treatments. In fact, it has been shown that direct irradiation of aerated aqueous solutions of propoxur leads to formation of PFR products, disappearing almost completely the starting material. By laser flash photolysis, it has been demonstrated that the key intermediate in this reaction is the 2-isopropoxyphenoxy radical [297]. 

This complex is selectively formed as the syn isomer, but can be isomerized into a mixture of syn and anti isomers upon thermal or photochemical treatment. Note that the syn isomer displays a weak agostic interaction of the alkylidene C-H with... 

In 2004, Podlech and coworkers have reported some further advances in the photochemical treatment of Fmoc-protected diazoketones A and B, (Scheme 76), derived from leucine and alanine, respectively, with /V-(benzylidene)glycine and leucine methyl ester to produce a mixture of the corresponding diastereomeric trans-substituted p-lactams [175],... 

The use of photochemical treatment to stimulate translocation of endocytosed macromolecules into the cytosol is a novel technology to improve therapeutic efficacy. The technology as described in this review is derived from photodynamic therapy (PDT) and is named PCI. In both cases a photosensitizer is used in combination with light to exert the treatment effects. The basic mechanisms of the photosensitizers and their tissue interaction in combination with light will be described with emphasis on the properties of the photosensitizers used in PCI before describing the use of PCI for cytosolic delivery of macromolecules. 

Fig. 5 Cell death induced by disruption of lysosomes. An endocytic vesicle is ruptured by the photochemical treatment and lysosomal enzymes and the photosensitizer is released into the cytosol. Large quantities of lysosomal enzymes will rapidly degrade vital proteins and cause necrosis, while lower quantities may cleave bid (to form truncated t-bid) and thereby induce apoptosis as indicated on the figure. The photosensitizer will relocate to other organelles during light exposure and induce photodamage to these organelles...

Fig. 7 An illustration of how molecules can enter cytosol after photochemical treatment (light first principle), (a) The photosensitizer (S) is endocytosed by the cells and when exposed to light the membranes of these vesicles will rupture and the contents (L) released into the cytosol, (b) Macromolecules that are administrated after the photochemical treatment will be endocytosed and end up in intact newly formed vesicles. These vesicles may then fuse with the photochemically damaged vesicles and the contents of the fused vesicles are released into the cytosol. The pictures at the bottom shows cells stained with fluorescently labelled dextran particles delivered before or after the photochemical treatment...

Fig. 9 PCI-induced transfection utilizing branched and linear PEI as vector. HT116 colon carcinoma cells were treated with AlPcS (20 (tg/mL) for 18 h followed by a 4-h incubation with an plasmid encoding EGFP and complexed with 25 kDa branched or 22 kDa linear PEI at an N P ratio of 4 before light exposure. EGFP expression was measure by flow cytometry 2 days later. The photochemical treatment caused 40-60% cytotoxicity...

Adenovirus vectors are known to be taken into cells by endocytosis and to be released from endosomes by a well regulated process, assumed to be highly efficient [84]. It is therefore somewhat surprising that PCI is able to increase the number of adenoviral transduced cells by up to 30-fold. Nevertheless, PCI with adenoviral vectors has been tested in several different cell lines, and in all cases improved transduction has been observed [85]. The adenovirus activated by means of PCI seems to follow the same cellular pathways as for conventional adenovims infection, i.e., the fraction of transduced cells followed a linear relationship with the Coxsackie and Adenoviral Receptor (CAR) level of the cells and is integrin dependent. Furthermore, PCI increase the number of nuclearly located viral DNA molecules as measured by real-time PCR and fluorescence in situ hybridization (FISH) [86]. The results so far indicate that the main cause of the PCI effect on transduction with adenovirus is related to enhanced release of the viral particles from the endocytic vesicles into the cytosol. In accordance with what has been found for PCI of plasmids the adenovirus may be delivered after the photochemical treatment (unpublished results). However, adenovirus may be delivered up to 12 h after the photochemical treatment, which is longer than what is effective for PCI of plasmids [43, 87]. 

Stereospecific formation of 1,3-disilacyclobutanes has been observed in photochemical treatment of bimetallic disilane precursors <2000JA8327, 2002OM5859>. Photolysis of the meso bimetallic complex affords only the // / -1,3-disilacyclobutanc, while similar photolysis of the dl-ioim gives only the m-isomer (Scheme 28) <2000JA8327>. 

In conclusion, we would like to dwell on the fact that the present study demonstrates the feasability of a photochemical treatment, through a grafting reaction, of a cellulosic substrate. It is obvious that the results cannot be easily extrapolated to the case of an industrial process of surface modification of the pulps. In fact, due to its low penetration, UV light can be... 

Two unusual and complex reactions leading to the formation of a metal germanium bond involve the photochemical treatment of germylsilyl and germylsilylmethyl complexes (equations 24, 25 and 25a)108,109. 

Photolysis of Me2Sn[Mn(CO)s]2 proceeds with loss of carbon monoxide and four-membered ring closure to form 111, and similar bridging stannylene complexes 112 and 113 are formed by the photochemical treatment of related Fe and Co complexes334. 

Applied research on indirect electrolytic methods has experienced a spectacular evolution in the last decades. More efficient, faster, and/or cheaper processes than classical anodic oxidation are now operative or in pilot trials. Redox mediators such as Ag(I)/Ag(II) and Co(II)/Co(III), and on-site production of strong oxidants like ozone at the anode and EFR at the cathode, are notable examples. These methods have been specially focused on aromatic compounds, probably because they are easily oxidiz-able, through hydroxyderivatives and quinones, to aliphatic acids. A further photochemical treatment of these products in the presence of Fe(III) allows their mineralization. 

The environmental problem of dye industry wastes is highlighted by estimates that up to 50,000 tons of dye are discharged annually from dyehouses worldwide (Brown 1987). These wastes constitute a significant source of environmental pollution due to their visibility and recalcitrance, because dyes are highly coloured and designed to resist chemical, biochemical and photochemical treatments. Among dyes the aromatic azo-dyes, which contain the -N = N- chromophore, comprise about two-thirds of the total (Fernandes et al. 2004). 

The formation of nitrite/nitrous acid upon nitrate UV irradiation has been the object of some attention also because the photochemical treatment of nitrate-containing water might result in nitrite concentration above the permitted levels. However, for a reasonable initial concentration of nitrate, the limit values of nitrite are extremely unlikely to be reached [32,100,111,112]. 

In > , >y -bis(cyclopentadienyl)iron dicarbonyl the <7-bonded ligand is easily attacked by HFA with conservation of the a bond. Photochemical treatment of 147 affords 146d, in which both cyclopentadienyl rings become n bonded (76). 

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