Standard lamps, Hanovia

Figure 15. Variation of relative emission with wavelength for Hanovia ozone-free and standard lamps (56)...

Photochemical Treatment of FpSi(CH3)(C6Hs)Si(CH3)3 Photolysis was performed at room temperature under nitrogen at 88.6 kPa with a Hanovia 450-W medium-pressure mercury lamp. Degassed cyclohexane solutions of the complex in Pyrex 9820 test tubes were illuminated for 1.5 h. Analysis of the product distribution was made with an internal standard (toluene) on a high-pressure liquid chromatographic system (Beckman Instruments, model 332) with UV detection at 270 nm. A C18 reverse-phase column was used with CH3CN-H2O (65 35, vol/vol) as solvent. 

Methoxyphenacyl esters were first described by Sheehan and Umezawa in 1973.They studied the deprotection of a series of amino acids and found that the best yields were obtained when the photolysis was carried out in ethanol. The 4-methoxyphenacyl esters were formed by the reaction of the free acid with 4-methoxyphenacyl bromide in DMF containing triethylamine. Photolyses were carried out with a 450-W Hanovia mercury immersion lamp fitted with a Pyrex filter. The 4-methoxyphenacyl group was used in a synthesis of thymo-pentin analogues.The authors used zinc dust as the standard deprotection procedure for cleavage of phenacyl esters (see Section 2.2). 

The effect of wavelength was also studied by substltuing a Hanovia "ozone-free" lamp for ibe standard type (56). Figure 14 shows the ratio... 

A solution of 200 mg (0.41 mmol) of l,l-dicarbomethoxy-3,3,5,5-tetraphenyl-l,4-penta-diene and 8.03 g (66.9 mmol) of acetophenone in 200 mL of benzene was irradiated for 30 min through Pyrex using a 450 W Hanovia medium-pressure lamp and the standard immersion well. The solvent was removed under vacuum leaving a yellow oil. The acetophenone sensitizer was removed by bulb to bulb distillation at 0.015 Torr and 30 °C with dry ice cooling of the receiving bulb. The residue consisted of 202 mg (98%) of colorless crystals whose NMR spectrum show complete conversion. Recrystallization fix)m ether/ hexane afforded 161 mg of colorless crystals, mp 216 - 217 °C. 

In preparative-scale (10 M 1-naphthol) experiments, an Ace-Hanovia 450-W medium-pressure mercury arc was used with a Pyrex filter sleeve and a magnetically stirred Ace water-cooled reaction vessel. In experiments involving rose bengal as a sensitizer, tungsten lamp illumination was used. Ultraviolet spectral changes were measured with a Perkin-Elmer model 552A spectrophotometer. For GC-MS analysis, a Hewlett-Packard 5985A instrument was used with a fused silica capillary column coated with a bonded nonpolar polymethyl silane phase introduced directly into the electron Impact ionization source. Compounds were tentatively identified by comparison to published spectra and confirmed where possible with authentic standard materials. 

For the investigation into the Influence of u.v. radiation on the dielectric properties of polycarbonate, pressed sheets of the material were irradiated at room temperature in air by a standard Hanovia mercury lamp. The lamp provided a spectrum of wavelengths within the range 254 to 546 nm and sample intensities of 2.47 mW cm and 0.91 mW cm respectively at the principal wavelengths of 365 nm and 254 nm. A voltage-stabilized power supply assisted consistency of spectral output. 

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