Hanovia immersion reactor

In contrast, in the photolysis of3,6-diphenylpyridazine-N-oxide 28 (R1 = R2 = Ph), a mixture of 3-benzoyl-5-phenylpyrazole 31 and 2,5-diphenylfuran 32 is formed. Diazoketone 29 (R1 = R2 = Ph) undergoes two competing reactions (i) thermal internal cyclization into the pyrazole 31 or (ii) photoinduced formation of a carbene leading to the final furan 32 (Scheme 12.9) therefore, the product distribution depends heavily on the reaction conditions. Thus, the formation of pyrazole 31 (75%) is favored over that of furan 32 (3%) by irradiation in acetone in a Rayonet reactor equipped with lamps irradiating at 350 nm. On the other hand, by irradiation with a Hanovia immersion lamp the yield of 31 decreases to 27%, whereas the yield of 32 increases to 67%. Moreover, the exclusive formation of the furan derivative 32 (43%) was observed by irradiation in the Rayonet reactor at low temperatures (—65 °C) [27]. 

B. Cyclohexylidenecyclohexane. In a Hanovia 450-watt immersion photochemical reactor (Note 2), equipped with a side arm attachment to monitor gas evolution, is placed 15 g. (0.068 mole) of dispiro[5.1.5.1]tetradecane-7,14-dione dissolved in 150 ml. of methylene chloride. The sample is irradiated, and carbon monoxide starts to evolve rapidly after a few minutes. Irradiation is continued until gas evolution has ceased, usually... 

In a Hanovia 550-watt immersion photochemical reactor (Note 1) equipped with a magnetic stirrer and water condenser (Note 2) are placed 1 1. of diethyl ether, 180 g. (1.96 moles) of bicyclo[2.2. l]hepta-2,5-diene (Note 3), and 8 g. of acetophenone. The system is flushed briefly with a stream of nitrogen and then irradiated for a,bout 36-48 hours (Note 4). After irradiation, the ether is removed by distillation through a 20-cm. Vigreux column (Note 5). The residue, a clear liquid weighing about 185 g., is distilled through a spinning-band column under reduced pressure (Note 6). Quadricyclane is obtained as a colorless liquid, b.p. 70° (200 mm.). The yield is 126-145 g. (70-80%) (Note 7). 

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