Hanovia 450-W lamp

Powdered 1 (200 mg), crystallized from Et20, was irradiated with a Hanovia 450-W lamp for 4 h to give a mixture of unreacted 1 (142 mg), 2(18 mg) and 3 (14 mg) separated by flash chromatography on silica gel (hexane-Et20, 19 1). 

A direct solution to the problem of enantioselective furan-carbonyl photoproduct synthesis would require a photoaddition that proceeded with enantiofacial selectivity in the aldehyde or furan component and maintained the relative face selectivity that is intrinsic to the reaction. Preliminary work used host-guest chemistry to achieve this objective.In aqueous dioxane, a 1 1 1 inclusion complex of unmodified 3-cyclodextrin, furan and benzaldehyde is formed. Upon irradiation (Hanovia 450 W lamp, Vycor filter), a rapid photoaddition occurs to afford a photoproduct of 10-20% ee. 

Methyl-3-hexen-2-one irradiated 12 hrs. in ether with a Hanovia 450 w. lamp employing a Pyrex filter -> 5-melhyl-4-hexen-2-one. Y 75%. F. e. and limitations s. N. G. Yang and M. J. Jorgenson, Tetrah. Let. 1964, 1203. 

Aporphines. A mixture of N-carbethoxy-l-(6 -bromo-3, 4 -methylenedioxyben-zylidene)-6,7-methylenedioxy-l,2,3,4-tetrahydroisoquinoline, K-terr-butoxide, tert-butanol, and benzene stirred 21 hrs. under N2 with irradiation by the Corex-filtered light of a Hanovia 450 w. lamp. -> N-carbethoxydehydronorneolitsine. Y 72%. M. P. Cava, P. Stern, and K. Wakisaka, Tetrahedron 29, 2245 (1973) cyclic ketones with K-rerr-butoxide in liq. NH3, cephalotaxinone, cf. M. F. Sem-melhack, R. D. Stauffer, and T. D. Rogerson, Tetrah. Let. 1973, 4519. 

Irradiation Studies. Irradiation of l,3-diphenoxy-2-propanol (3), 0.01 M in acetonitrile, was conducted at 254 nm, utilizing a 2.5-W low pressure Hg immersion lamp (PCQ9G-1, Ultraviolet Products), and at wavelengths longer than 280vnm, utilizing a Hanovia 450-W high-pressure Hg immersion lamp (Type L) and 9700 Corex filter sleeve. Irradiation of 1,3-diphenoxy-2-methyl-2-propanol (5), 0.01 M in acetonitrile, was also conducted at 254 nm. 

Powdered single crystals of coumarins kept in a petri dish were irradiated with a Hanovia 450-W medium-pressure mercury arc lamp from a distance of about 2 ft. Samples were turned around periodically to provide uniform exposure. Progress of the irradiation was monitored by variation in melting point and NMR and IR spectra. After complete conversion, the time of which was dependent on the nature of the coumarin, the dimer was separated from the monomer by TLC. Dimers were identified by their spectral properties. 

A suspension of the compound (0.5-1 g) in distilled water (150 mL) was irradiated with stilling using a Hanovia medium-pressure 450-W lamp and a Pyrex filter for ca. 35 h. The suspension was then extracted with CH2CI2 and the residue obtained after removal of solvent was chromatographed on a silica gel column (60-120 mesh). The ketene was eluted with a mixture of ethyl acetate (5-10%) in petroleum ether (bp 60-80 °C). 

Photolysis photolysis rate k = 2.03 x 10-4 s-1 at 313 nm using a Hanovia 450-W mercury lamp in hexane solution (Dulin et al. 1986)... 

A benzene solution (500 mL) of the dione 167 (500 mg, 2.12 mmol) was carefully purged with a slow stream of nitrogen for 15 min. The solution was then irradiated with a Hanovia 450-W medium-pressure mercury vapor lamp in a quartz immersion vessel. After being irradiated for 30 min, solvent was evaporated and the residue chromatographed over silica gel (hexane) furnishing 180 mg (50%) of the crystalline diene 169. 

Photochemical reactors are commercially available or can be custom-built. They consist of an oval mirror-type wall of ca. 30 cm maximum radius equipped with two Hanovia 450-W or Philips HPT 400-W high-pressure mercury lamps inserted into a water refrigerated Pyrex flask, or equipped with a 300-W Osram sunlamp vessel (Pyrex flask). 

The submitters used a Helios Italquartz 500-W lamp which has emission characteristics similar to those of the Hanovia 450-W medium pressure mercury lamp used by the checkers. 

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. 

Lamps and filters. The combination of radiation source and filter accounts for the actual radiation wavelength to which the reaction mixture is exposed. An unavoidable filter is the glass type of the reaction vessel. In the direct irradiation of substrates not containing functionality other than the phenyl groups, wavelengths in the 280 nm region are needed. Typically a Hanovia 450 W medium-pressure mercury lamp and a 2 mm Corex cylindrical filter (X > 270 nm) are employed. Triplet-sensitized reactions need a higher cut-off, which can be obtained by the use of the same lamp with a 2 mm Pyrex filter (X > 300 nm). The Rayonet photoreactor can be equipped with 254, 300 and 350 nm lamps. 

A mixture of adenine (2 g, 14.8 mmol), DTBP (8 mL), i-PrOH (135 mL), and H O (40 mL) was irradiated (Hanovia 450-W high-pressure Hg vapor lamp, Pyrex filter) for 22 h. Excess reagents were removed under reduced pressure and the solid residue was chromatographed [silica gel (500 g), MeOH/CHClj 1 10] to give 8-(l-hydroxy-l-methylethyl)adenine yield 2.66 g (96%). 

The irradiation light source is a Hanovia 450 W medium-pressure Hg vapour lamp placed in a quartz immersion well. The reaction solution is contained in a 150 ml quartz semicircular flask mounted as closely as possible to the immersion well. No light filter is used. The entire apparatus is immersed in a large Dewar flask charged with dry ice-isopropanol with the bath temperature maintained between —60 and —40°C during irradiation. 

A solution of 9-diazo-9f/-fluorene (200 mg, 1.0 mmol) in styrene (20 mL, 18.2 g, 0.17 mol) was placed in a Pyrex outer jacket surrounding a quartz immersion well. After being purged with a dry N2 gas stream for 2 h, the solution was irradiated for 24 h with a Hanovia 450-W medium-pressure Hg lamp placed within the water-cooled immersion well and shielded by a cylindrical uranium glass filter to remove all wavelengths below 330 nm. After removal of excess styrene in vacuo, yellow crystals were observed. Purification by chromatography on a column of silica gel (230-400 mesh) with 20% benzene in hexane as eluant gave 246 mg (92%) of product mp 127 C. 

The carbene was prepared from the sodium salt of 9-xanthone 4-toIuenesulfonylhydrazone. Hanovia 450-W high-pressure Hg lamp, Pyrex. 

Hanovia 450-W high-pressure Hg lamp, Vycor tubes. 

Since the total synthesis of O-methylandrocymbine (17) was accomplished via a photolytic cyclodehydrobromination reaction of a l-(2-bromophenethyl)-7-hydroxyisoquinoline (67), many phenethylisoquinoline alkaloids have been synthesized by this reaction. Irradiation of the bromoisoquinoline 113a,b with a Hanovia 450-W mercury lamp, using a Pyrex filter, in the presence of an excess of sodium hydroxide and sodium hydrogen sulfite gave alkaloid CC-24 (83a) (68) and the homoaporphine 114 (69), respectively. 

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