Photosensitizers, reactions with potassium

This article reports on the synthesis of photosensitive polymers with pendant cinnamic ester moieties and suitable photosensitizer groups by cationic copolymerizations of 2-(cinnamoyloxy)ethyl vinyl ether (CEVE) (12) with other vinyl ethers containing photosensitizer groups, and by cationic polymerization of 2-chloroethyl vinyl ether (CVE) followed by substitution reactions of the resulting poly (2-chloroethyl vinyl ether) (PCVE) with salts of photosensitizer compounds and potassium cinnamate using a phase transfer catalyst in an aprotic polar solvent. The photochemical reactivity of the obtained polymers was also investigated. 

Syntheses of Polymeric Photosensitizers and Self-sensitized Polymers by the Reactions of PCVE. Photosensitizer monomers such as NPVE, NNVE and NPEVE were synthesized by the reaction of excess CVE with potassium salts of the corresponding photosensitizing compounds using TBAB as a phase transfer catalyst as described in the experimental part. Substitution reactions of chloroethyl groups in PCVE with PNP and PNN were also carried out using TBAB as a phase transfer catalyst in DMF at 80 C for 24 h. 

Table III. Reaction Conditions and Results of the Reactions of Polymeric Photosensitizers with Potassium Cinnamate3...

As shown in Figure 2, PCEVE-NPVE and PCEVE-NNVE containing about 10 mol-% of pendant sensitizer groups prepared from the reactions of PCVE with potassium cinnamate and PNP or PNN have photochemical reactivity equal to PCEVE-NPVE and PCEVE-NNVE prepared from the cationic copolymerizations, however, their photochemical reactivities were changed by the contents of photosensitizer units in the copolymers. 

From all these results, it was concluded that polymers have high photochemical reactivity and high practical photosensitivity when synthesized by the cationic copolymerizations of CEVE with NNVE or NPVE, or by the reactions of PCVE with potassium cinnamate and PNN or PNP using phase transfer catalyst in DMF. 

Fig. 6. The effect of superoxide dismutase on the photosensitized oxidation of dianisidine. The reaction mixture contained 2 X 10 M dianisidine, 1.3 x 10 M riboflavin and 0.01 M potassium phosphate, pH 7.5. The data on line I were observed in the absence of superoxide dismutase, and those on lines 2,3, and 4 were observed in the presence of 0.2, 0.5, and 1.0 p-g/ml of enzyme. (Reprinted with permission from H. P. Misra and I. Fridovich, Arch. Biochem. Biophys., 181, 308-312, 1977.)...

US EPA Method 326.0 allows the combination of suppressed conductivity detection and postcolumn derivatization for UV absorbance detection, as schematically depicted in Figure 8.45. A volume of sample (225 pL) is introduced into an ion chromatography system. After separation and eluent suppression, standard anions and oxyhalide ions are measured using conductivity detection. The suppressed effluent from the conductivity detector is then combined with an acidic solution of potassium iodide (0.26 mol/L) containing a catalytic amoimt of ammonium molybdate tetrahydrate (43 pmol/L). The mixture is heated in the knitted reaction coil to 80 °C to facilitate complete reaction. The formed triiodide is measured by its UV absorption at 352 nm. Because KI is photosensitive, the KI/Mo PCR solution develops a light yellow color with time, even when stored under helium. Therefore, the PCR reservoir has to be protected from light by covering it with aluminum foil and should be pressimzed with helium. Under... 

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