Paraformaldehyde Petroleum ether

Fixation tissue samples for immuno histochemistry were fixed in 2% paraformaldehyde, 0.25% glutaraldehyde and 3% sucrose buffered with 0.05M phosphate buffer pH 7. After incubation for 2 hours at 25 °C and 63 hours at 5°C the specimens were washed 3 x 20 min. in phosphate buffer pH 7. Dehydration was carried out using series of ethanol washings 50, 70, 80, 96% followed by 3 x in 99% (V2 hr in each). After additional treatment with 2x2 hrs in petroleum ether (shellsol D70k, Q7712) and 2 x 2 hrs in paraffin with 7% beeswax, the samples were embedded in paraffin. Cross sections of 12.5 /im were made on a Supercut 2050 Reichart Jung pyramitome. 

A mixture of benzaldehyde la (0.53 g, 5 mmol), paraformaldehyde (1 g, 30 mmol) and solid sodium hydroxide (0.16 g, 4 mmol) were taken in an Erlen-meyer flask and placed in a commercial microwave oven operating at 2450 MHz frequency. After irradiation of the mixture for 25 s (monitored by TLC), it was cooled to room temperature, extracted with chloroform and dried over anhydrous sodium sulfate. Then the solvent was evaporated to give the corresponding ben-zylalcohol 2a in 90% yield exclusively without the formation of any side products. Preparative column chromatography with silica gel was used for further purification of the alcohols, eluting with petroleum ether (60/80)-CHCl3 (1 1). 

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