Mercury medium pressure

Photolytic. Major products reported from the photooxidation of isopropylbenzene with nitrogen oxides include nitric acid and lienzaldehyde (Altshuller, 1983). A / -hexane solution containing isopropylbenzene and spread as a thin film (4 mm) on cold water (10 °C) was irradiated by a mercury medium pressure lamp. In 3 h, 22% of the applied isopropylbenzene photooxidized into a,a-dimethylbenzyl alcohol, 2-phenylpropionaldehyde, and allylbenzene (Moza and Feicht, 1989). 

Photolytic. A n-hexane solution containing /n-xylene and spread as a thin film (4 mm) on cold water (10 °C) was irradiated by a mercury medium pressure lamp. In 3 h, 18.5% of the p-xylene photooxidized into p-methylbenzaldehyde, p-benzyl alcohol, p-benzoic acid, and p-methylacetophenone (Moza and Feicht, 1989). Glyoxal and methylglyoxal were produced from the photooxidation of p-xylene by OH radicals in air at 25 °C (Tuazon et al., 1986a). The rate constant for the reaction of p-xylene and OH radicals at room temperature was 1.22 x lO " cmVmolecule-sec (Hansen et al., 1975). A rate constant of 7.45 x 10 L/molecule-sec was reported for the reaction of p-xylene with OH radicals in the gas phase (Darnall et al, 1976). Similarly, a room temperature rate constant of 1.41 x 10 " cm /molecule-sec was reported for the vapor-phase reaction of p-xylene with OH radicals (Atkinson, 1985). At 25 °C, a rate constant of 1.29 x lO " cmVmolecule-sec was reported for the same reaction (Ohta and Ohyama, 1985). 

The cafalyst was used in aqueous suspension well mixed by means of a magnefic sfirrer. The reacting mixture was illuminated by a mercury medium-pressure lamp (t)q5e B, Helios Italquartz, Milan, Italy) coaxial with the photoreactor. A Pyrex thimble surrounding the lamp allowed the circulation of distilled water in order to cool the lamp and cutoff infrared radiation in fhese conditions fhe reactor temperature was of 295 + 2K. Lamps of 125, 500, or 1,000 W electric power were used average irradiances... 

Figure 3. Comparison of the concentration dependence of added photosensitizer on the photodegradation rate of methionine. For each case the solutions were 5 yM in methionine and were Irradiated for 2 hours using only wavelengths > 3U0 nm Isolated from a mercury medium pressure lamp. All samples were prepared In air saturated artificial seawater of ionic strength 0.7 and with pH of 8.1.

Tile only instance of isolation of a stable benzo-l,2-dithiete is the yellow crystalline compound 187, which was obtained by photolysis of 188 in heptane at -20°C using a medium-pressure mercury lamp [75JCS(CC)756 77JCS(P1)515],... 

It was found out that when the bisfuranones 299 (R = H, Me, CMc3, TMS) were irradiated in a solution of acetone saturated with ethylene (medium pressure, 125 W, mercury lamp at —78°C), the biscyclobutane adducts 300, 301, and 302... 

Irradiation of lomefloxacin 271 in dilute neutral aqueous solution (in which it exists as a zwitter ion) in Pyrex-filtered 500 W medium pressure mercury (Helios Italquartz) at 17°C gave pyrrolo[3,2,l-(/ ]quinoline 272 (99JOC5388). Under this condition, reductive defluorination via a radical anion took place. This study is important because of the phototoxicity of the fluorinated compounds which could be used as antibacterials (Scheme 49). 

The gas-phase photolysis of 2-furaldehyde in the it -n and ir <-it transitions76 proceeds with fragmentation to CO, furan and C3-hydrocarbons, but a certain amount of resinification is also noted (about 5% quantum yield with excitation of the it - n transition). The latter observation prompted a study of the vacuum liquid-phase photolysis by sunlight or by light from a medium-pressure mercury arc at room temperature24 7S. The resin obtained was submitted to fractionation and structural analysis. On the basis of the results obtained and other mechanistic evidence, the following sequence of events was postulated for the photopolymerization ... 

Complexed arenediazonium salts are stabilized against photochemical degradation (Bartsch et al., 1977). This effect was studied in the former German Democratic Republic in the context of research and development work on diazo copying processes (Israel, 1982 Becker et al., 1984) as well as in China (Liu et al., 1989). The comparison of diazonium ion complexation by 18-crown-6 and dibenzo-18-crown-6 is most interesting. Becker at al. (1984) found mainly the products of heterolytic dediazoniation when 18-crown-6 was present in photolyses with a medium pressure mercury lamp, but products of homolysis appeared in the presence of dibenzo-18-crown-6. The dibenzo host complex exhibited a charge-transfer absorption on the bathochromic slope of the diazonio band. Results on the photo-CIDNP effect in the 15N NMR spectra of isotopically labeled diazonium salts complexed by dibenzo-18-crown-6 indicate that the primary step is a single electron transfer. 

The single-electron transfer from one excited component to the other component acceptor, as the critical step prior to cycloaddition of photo-induced Diels Alder reactions, has been demonstrated [43] for the reaction of anthracene with maleic anhydride and various maleimides carried out in chloroform under irradiation by a medium-pressure mercury lamp (500 W). The (singlet) excited anthracene ( AN ), generated by the actinic light, is quenched by dienophile... 

The apparatus is dried in an oven at 140° overnight and cooled under nitrogen or argon prior to the irradiation. A Vycor filter sleeve and a 450-watt medium-pressure mercury lamp are placed in the immersion well. The Vycor filter, the quartz immersion well (catlog No. 19434), the 450-watt mercury lamp (catalog No. 679A36), and the requisite transformer are all available from Hanovia Lamp Division, Canrad-Hanovia Inc., 100 Chestnut Street, Newark, New Jersey 07105. 

By far, the most frequently used device is the ultraviolet detector. Three types are employed (23) — single wavelength with low pressure mercury source, multiwavelength filter photomer with medium pressure mercury source, and spectrophotometer. 

Since chlorinated PVC is totally transparent in the near-UV and visible range, it will not absorb at 488 nm, the emission line of the argon ion laser that we intended to use to perform the carbonization. Therefore C-PVC films were first exposed to the UV radiation of a medium pressure mercury lamp in order to produce the strongly absorbing polyenes. This irradiation was carried out at room temperature in the absence of oxygen, thus preventing the formation of undesirable oxidation products. 

Since our main objective was to remove all the chlorine and hydrogen atoms from the polymer chain, C-PVC films were further exposed to the UV radiation of the medium pressure mercury-lamp. This led to a dark brown material w.hich was found to be unable to carry an electrical current, even after extended irradiation time. Therefore we turned to a powerful laser source, a 15 W argon ion laser tuned to its continuous emission at 488.1 nm. At that wavelength, the degraded polymer film absorbs about 30 % of the incident laser photons. The sample was placed on a X-Y stage and exposed to the laser beam at scanning rates in the range of 1 to 50 cm s, in the presence of air. 

When this resin was exposed as a thin film to the UV radiation of a medium pressure mercury lamp (80 W aiH), the crosslinking polymerization was found to develop extensively within a fraction of a second (18). The kinetics of this ultra-fast reaction can be followed quantitatively by monitoring the decrease of the IR absorption at 810 an-1 of the acrylic double bond (CHCH twisting). Figure 8 shows a typical kinetic curve obtained for a 20 pm thick film coated onto a NaCl disk and exposed in the presence of air to the UV radiation at a fluence rate of 1.5 x 10 6 einstein s-1 cm 2. 

Acylimidazoles in the presence of benzophenone lead to oxetanes on irradiation with a medium-pressure mercury lamp [8]... 

The energy distribution for the commonly used 450-W Hanovia medium-pressure mercury lamp is given in Table 2.5. 

Burdick and Jackson). All solutions were photolyzed to less than 5% conversion in a standard 3 ml capacity, 1-cm path length quartz cell. Samples were irradiated with a 450-Watt medium pressure, Hanovla mercury lamp focused through an appropriate band-pass filter (280 nm or 254 nm) onto the 1-cm quartz cell with the requisite solution. Test solutions could be purged with either helium or oxygen using a needle valve assembly attached to the tapered quartz cell neck. The loss of carbamate due to photolysis and the amounts of known photoproducts were determined quantitatively by GC using eicosane as an internal standard. The columns were 6 stainless steel containing Carbowax 20M on chromosorb G. 

Watt medium pressure mercury lamp through a pyrex filter, b - Ha, Hx, He, H5, Hc and represent the integrated areas of... 

In all the solvents studied the species responsible for the color with TFA were extremely photosensitive and were bleached in a few seconds when irradiated with unfiltered light from a medium pressure mercury lamp. 

The photooxidation was carried out in a commercial weathero-meter (Q-UV, Q-panel Co., Cleveland, Ohio). This apparatus uses medium pressure mercury fluorescent UV lamps (Sunlamps F5-40, Westinghouse Electric Corp.) which emit UV light in the 273-378 nm range with a maximum intensity at 310 nm. 

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