High-Pressure Mercury Arcs

Figure 9. Typical high pressure Mercury-arc spectrum.

The electron spin resonance spectra were run in nitrogen-saturated solutions of aromatic compound ca. 10" m) and nucleophile (0-05-0-1 M) in the solvent(s) indicated. Irradiation in the cavity was effected with a high pressure mercury arc. Electrolysis was performed with the platinum cathode in the cavity, tetraethyl-ammonium perchlorate as electrolyte and electric currents of 10-250 /lA. 

UV = Light from medium or high pressure mercury arc filtered through cobalt-nickel sulfate solution Xj - 220-330 nm. 

Another generally useful apparatus for carrying out photochemical reactions on a small scale consists of a 1-kW high-pressure mercury arc, such as the General Electric Company s No. AH-6, focussed on the reaction vessel from the outside. This equipment is pictured in Figure 5. 

Irradiating in the long wavelength tail of an appropriate chromophore is a useful technique for decreasing the optical density, as long as the light still results in photolysis. In our work with diacyl peroxides we typically use 313 nm radiation from a high pressure mercury arc, which has an extinction... 

Figure 7.3 Examples of emission spectra of some arc lamps (a) medium-pressure mercury arc (b) high-pressure mercury arc (c) xenon arc...

Fig. 4. The absorption spectrum of a crystalline film of salicylidene-2-chloroaniline before (full curve) and after (broken curve) irradiation. (Temperature —131 °C. irradiation 23 min. through Corning filter F 5874, 250-w. high pressure mercury arc). See ref. 21.

Pretreatments of the electrode were carried out by soaking first in HC1 for 10 s and then in H,P0a for 5 min, followed by washing with de-ionized water. The RRDE was then set in a RRDE measuring system (Nikko Keisoku, model DPGS-1). The rotation rate of the electrode was usually 1000 rpm except where specially noted. Electrolytes were of reagent grade chemicals and twice distilled water. A 500 W super high pressure mercury arc lamp (Ushio... 

C60 also reacts with silyl ketene acetals when photolyzed with a high-pressure mercury arc. The reaction, illustrated in equation 48, leads to functionalization of the fullerene as an ester, and is said to involve single electron transfer205. 

High-pressure mercury arc lamps, which operate at internal pressures of from... 

Figure 1.5 High-pressure mercury arc mounted on an optical bench.

There exists also a synthesis of cyclopentadecanone (VII/81) and ( )-mus-cone, based on a three-carbon annulation of cyclic ketones followed by the regioselective radical cleavage of the zero bridge of the so formed bicyclic system [44], The synthesis of cyclopentadecanone is summarized in Scheme VII/16. The cyclization of VII/78 to the bicyclic alcohol VII/79 proceeds best (94 % yield) with samarium diiodide in the presence of hexamethylphosphoric acid triamide and tetrahydrofuran [45], The oxidative cleavage of VII/79 to the ring expanded product VII/80, was performed by treatment with mercury(II)-oxide and iodine in benzene, followed by irradiation with a 100 Watt high pressure mercury arc. Tributyltinhydride made the de-iodination possible. 

In another lactonisation reaction, a cyclic hemiacetal or its opened ketone-alcohol equivalent (see Scheme VII/33, structures VII/172 and VII/173), is transformed to an iodo lactone VII/175 (12-iodopentadecan-15-olide) and the isomeric VII/174 (2-iodo-2-(3 -hydroxypropyl)cyclododecanone) by irradiation with high pressure mercury arc in the presence of HgO-I2 in benzene solution [114] as outlined in Scheme VII/33. 

Photolysis studies were performed using a PEK-110 100-watt high pressure mercury arc lamp. The 3660-A. line was selected by means of a Bausch and Lomb second-order interference filter. 

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