Methylbenzal -fluorene

Fluorene (16.6 g., 0.10 mole) is dissolved in a hot solution of 4 g. (0.17 g. atom) of sodium in 200-250 ml. of absolute ethanol. The resulting solution is held at 60-70° while 12.0 g. (0.1 mole) of p-tolualdehyde dissolved in 100 ml. of ethanol is added. The mixture is allowed to stand several hours until the product has precipitated. The solid is removed by filtration and the filtrate is diluted with water for recovery of a second portion of solid product. The material is recrystallized from acetic acid or from ethanol to give 9- (4 -methyl-benzal)-fluorene, m.p, 97.5°. The yield is in the range 50-70%. 

The following aldehydes may be condensed in similar manner to the above procedure to give the corresponding substituted 9-benzal-fluorene of the indicated melting point. o-Tolualdehyde, m.p. 109.5° p-chlorobenzaldehyde, m.p. 149.5° m-chlorobenzaldehyde, m.p. 90.5° and m-bromobenzaldehyde, m.p. 92-93°. 

A 1 °fo aqueous solution of sodium hydroxide (1.2 1.) is placed in a 2-1. flask and cooled to 8°. An atmosphere of carbon dioxide is maintained in the flhsk and the contents are stirred at high speed (2000-3000 r.p.m.) while a mixture of 60 g. (1.03 moles) of propionaldehyde and 45 g. (1.02 moles) of acetaldehyde is added. The temperature is not allowed to rise over 10°, and stirring is continued for 1 hour. The mixture is neutralized with acetic acid and extracted with ether the ethereal extract is dried over calcium chloride and distilled. There is obtained 26 g. (30%) of the aldehyde boiling at 116-119°. The compound is decomposed rapidly in contact with air. 

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