Solution, irradiation

While still slightly warm from the drying oven, the photolysis vessel with a water-jacketed quartz immersion well (Note 1) (section A of Figure 2) is charged with 500 ml. of anhydrous tetrahydrofuran (Note 2) and 10 ml. (8.05 g., 0.122 mole) of cyclopentadiene (Note 3). The solution is cooled in an ice bath and purged with dry nitrogen for 2 minutes. Then the vessel is sealed, the lamp inserted, and the solution irradiated at 0° for 30 minutes. During this period, sections B and C... 

Note The final pH of all solutions showed little change. However, the solutions irradiated for 24 hours changed the most, pH as compared to initial pH = 7. 

Varions possibilities were considered for the nnderlying reaction of the biradical. No radical signals grew when the biradical decayed, so H-abstraction from the matrix did not appear to be occnrring. Analysis of products formed from irradiations of 8 at 5.5 K showed both bicyclopentane 10 and cyclopentene, in a ratio of 30 1. Very similar ratios, ca. 25 1, were observed in solution irradiations at room temperature. It was noted that if the major tnnneling reaction was H-shift to produce cyclopentene, this product should be enhanced as temperatnres were lowered, in contrast to the experimental observations. Hence, it was conclnded that the observed decay of the EPR spectrum of 9 was due to ring closure to give 10. 

However, in a later study, Cohen and Kirk described a successful hydrolysis of the f-butyl derivative (34 R = rBu) using tetrafluoro-boric acid (73JA4619, 73JOC3647). The resulting 4(5)-aminoimidazole (25 R = H) was diazotized in situ, and the solution irradiated to give 4-fluoroimidazole (yield 41%). This carbamate (34 R=fBu) was also hy-... 

Moore [355] used the solvent extraction procedure of Danielson et al. [119] to determine iron in frozen seawater. To a 200 ml aliquot of sample was added lml of a solution containing sodium diethyldithiocarbamate (1% w/v) and ammonium pyrrolidine dithiocarbamate (1 % w/v) at pH to 4. The solution was extracted three times with 5 ml volumes of 1,1,2 trichloro-1,2,2 trifluoroethane, and the organic phase evaporated to dryness in a silica vial and treated with 0.1 ml Ultrex hydrogen peroxide (30%) to initiate the decomposition of organic matter present. After an hour or more, 0.5 ml 0.1 M hydrochloric acid was added and the solution irradiated with a 1000 W Hanovia medium pressure mercury vapour discharge tube at a distance of 4 cm for 18 minutes. The iron in the concentrate was then compared with standards in 0.1 M hydrochloric acid using a Perkin-Elmer Model 403 Spectrophotometer fitted with a Perkin-Elmer graphite furnace (HGA 2200). 

The ultraviolet inactivation spectrum for gramicidin has been published by Setlow and Doyle121. Sugimoto and coworkers have presented infrared, ultraviolet, visible and ESR spectra for gramicidin solutions irradiated with various amounts of ultraviolet light122. 

The (2 + 2) photocyclodimerization of substituted olefins has provided some of the most striking examples of crystal-lattice control of the stereochemistry of a reaction. This may be exemplified by a selection of derivatives of 5-phenylbutadienoic acid (61), for which it is observed that the solid-state photobehaviors of the amide 62, the methyl ester 63, and the dichlorophenyl ester 64 differ entirely from one another each affords a single stereo- and regioisomer in high yield, but with different starting materials giving different types of products (130). In solution, irradiation of 63 or other photoactive dienes yields... 

Photolysis of [ReH Cdppe) ] in Degassed Solution. Irradiation of degassed benzene solutions of the complex with 366-nm light gives a color change from yellow to gold with a corresponding intensification and shift in the absorption maximum from 320 to 310 nm. In the IR, as the irradiation proceeds,... 

Photolytic. Based on data for structurally similar compounds, acenaphthylene may undergo photolysis to yield quinones (U.S. EPA, 1985). In a toluene solution, irradiation of acenaphthylene at various temperatures and concentrations all resulted in the formation of dimers. In water, ozonation products included 1,8-naphthalene dialdehyde, 1,8-naphthalene anhydride, 1,2-epoxyacenaphthylene, and 1-naphthoic acid. In methanol, ozonation products included 1,8-naphthalene dialdehyde, 1,8-naphthalene anhydride, methyl 8-formyl-1-naphthoate, and dimethoxyacetal 1,8-naphthalene dialdehyde (Chen et al., 1979). Acenaphthylene reacts with photochemically produced OH radicals and ozone in the atmosphere. The rate constants and corresponding half-life for the vapor-phase reaction of acenaphthylene with OH radicals (500,000/cm ) at 25 °C are 8.44 x lO " cmVmolecule-sec and 5 h, respectively. The rate constants and corresponding half-life for the vapor-phase reaction of acenaphthylene with ozone at 25 °C are... 

Photolytic. In a methanolic solution irradiated with UV light >290 nm), dechlorination of 4-chlorophenyl phenyl ether resulted in the formation of diphenyl ether (Choudhry et al., 1977). Photolysis of an aqueous solution containing 10% acetonitrile with UV light (X = 230-400 nm) yielded 4-hydroxybiphenyl ether and chloride ion (Dulin et al., 1986). 

Photolytic. An aqueous solution irradiated by UV light at 50 °C for 1 d resulted in a 50.51% yield of carbon dioxide (Knoevenagel and Himmelreich, 1976). Synthetic air containing gaseous nitrous acid and exposed to artificial sunlight k = 300-450 nm) photooxidized hexane into two isomers of hexyl nitrate and peroxyacetal nitrate (Cox et al, 1980). 

Photolytic. Irradiation of styrene in solution forms polystyrene. In a benzene solution, irradiation of polystyrene will result in depolymerization to presumably styrene (Calvert and Pitts, 1966). 

Picloram rapidly degraded in irradiated aqueous solutions. Irradiation of picloram in aqueous solution by UV light (2,537 A) released two chloride ions for each molecule of picloram degraded. 

Ring closure of the diene in [Ru(phen)2(217)] using Grubb s catalyst generates a macrocyclic complex, the photochemical behavior of which has been studied in MeCN solution. Irradiation at >300 nm leads to the expulsion of [Ru(phen)2(MeCN)2], and quantitative regeneration of the macrocyclic complex can be achieved by heating in ethylene glycol. " ... 

In aqueous solutions, irradiation of 15 results in the formation of a transient absorption due to 16, with A av at 390 nm. " This absorption band is shifted to 405 nm, indicating ionization of 16 to form 17. The rate constant for forming 17 was measured to be 2 x 10 s whereas 17 decayed with a rate constant of 1.67 s In addition, photolysis of 15 in D2O leads to deuterium incorporation at the benzylic position, thus verifying the mechanism of solvent-assisted reformation of 15 from 16. °... 

The fluorescence of liquid alkanes is supposed to originate entirely from the relaxed Si state. Walter and Lipsky [154], by measuring the fluorescence yields of alkane solutions irradiated with 165 nm photons or Kr beta particles ( niax = 0-67 MeV) relative to benzene fluorescence, determined the following yields 2.3-dimethylbutane G Si) < 1.3, cyclohexane 1.4-1.7, methylcyclohexane 1.9-2.2, dodecane 3.3-3.9, hexadecane 3.3-3.9, d5-decalin 3.4, and bicyclohexyl 3.5. After reinvestigating the intrinsic quantum yield of cyclohexane fluorescence, Choi et al. published G(5 i) = 1.45 for this alkane in Ref. 155. For tra 5-decalin a G Si) value of 2.8-3.1 has been accepted [65,128,132]. The uncertainties in the values reflect the uncertainties in the intrinsic fluorescence quantum yields. 

Watanabe, R. Usami, N. Kobayashi, K. Oxidation yield of the ferrous ion in a Fricke solution irradiated with monochromatic synchrotron soft X-rays in the 1.8-10 keV region. Int. J. Radiat. Biol. 1995, 68 (2), 113-120. 

Haug75 has reported that the concentration of TpC reaches a photostationary state at 280 nm and pH 7 at about half its initial value. Three photoproducts, separable by electrophoresis and stable to heat, are formed. The quantum yield for decay of TpC is independent of wavelength of light, and is 0.006 at pH 7 and 0.002 at pH 2. Heating the solution at 80°C restores about 40% of the absorption loss at 270 nm for the solution irradiated at pH 2 and about 70% of the loss for solutions irradiated at pH 7. Irradiation at 240 nm does not increase the absorption at 270 nm. One would expect dimers and hydrates to be formed in the photolysis, but the observations summarized here are difficult to reconcile with such products exclusively and suggest deep-seated irreversible changes. 

Fig. 1. Computer trace of the time-dependence of the formation of [( )5 - 2 02 ]+ followed at 300 nm and first order plot (insert). (1M CH3C02Na, 1 x 10 3 M C0SO4, 20% NH3, N20 saturated aqueous solution irradiated with a maximum pulse.)...

Solution Photolysis of Poly(p-Formyloxystyrene) A 2.0 g sample of poly(/7-formyloxystyrene) was dissolved in 300 mis of spectral grade acetonitrile, and the solution irradiated in the Hanovia apparatus. Small aliquots of the irradiating polymer solution were withdrawn and analyzed at regular intervals as described above. 

Viscosity changes of PVME aqueous solutions irradiated by y-rays are shown in Fig. 15. The viscosity was measured with a rotational viscometer. The... 

Fig. 15. Viscosity change of PVME aqueous solutions with changing dosage of y-ray irradiation. t), rj0 viscosity of solution irradiated and nonirradiated, respectively. G gel point...

Fig. 4. EPR spectra of particles e,r and 0" in a vitreous 10 M NaOH solution ( -irradiated at 77 K. The vertical line indicates the position of the EPR line of polycrystalline a, a -diphenyl-/i-picryl hydrazil with g = 2.0036.

Fig. 31. Kinetic curves for the photobleaching [40,62] of et in a vitreous 10 M aqueous NaOH solution irradiated at 77 K in the absence (O) and in the presence (solid symbols) of acceptor additives in the coordinates of eqn. (28).

The photoisomerization of 2,4,6-cyclooctatrienone (Formula 158) is closely related to the photochemical transformations of the cyclo-heptadienones. Irradiation of Formula 158 in pentane solution gives a photoisomer (Formula 159) (63). In methanol solution irradiation of... 

Irradiations are carried out in Kimax glass ampoules. These ampoules are filled with 5 cc. of the solution, irradiated, using the apparatus previously described (7), and flame-sealed with a Perfe Keum Model HS-1 ampoule sealer. The irradiation source used for these experiments is a 1.3 X 106 curie cobalt-60 source consisting of two parallel plaques 56 inches wide by 48 inches high, spaced 16 inches apart. For most irradiations, the ampoules are placed in the center of a Masonite phantom which completely fills a No. 10 can (6 inches in diameter by 7 inches high). The can is placed in a fixed position in an aluminum carrier and transported into the irradiation cell to a predetermined position (5). The source is then elevated from the bottom of a 25-foot, water-filled pool into the irradiation position. After the desired exposure, the source is lowered to the bottom of the pool. 

The contribution of VCR to radioluminescence has been also studied in Refs. 324 and 325. The results close to those of Ref. 323 have been obtained by Zhuravleva325 in a comparative study of radioluminescence of 3-aminophthalamide (AP) in ethanol solutions irradiated by electrons with Ee = 3.5 MeV and by X rays with Eph = 50 keV. 

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