Dibenzyl, from benzil

Benzy 1 2 carbomethoxycyclopentanone from 2 carbomethoxycyclopentanone and benzyl chloride, 45, 8 2 Benzylcyclopentanone, 46, 7 N Benzyloxycarbonylglycine, 46, 49 Benzyltnmethylammonium hydroxide as catalyst for condensation of benzil with dibenzyl ketone, 46,... 

Tetramethvlethylene, 47, 36 Tetraphenylcyclopentadienone, from dibenzyl ketone and benzil, 46, 45... 

Aliphatic aldehydes and ketones and also aliphatic-aromatic ketones can be converted into the corresponding hydrocarbons alkyl-phenols can be obtained from phenolic-aldehydes and -ketones p-hydroxy-benzophenone yields p-benzylphenol benzoin and benzil yield dibenzyl anthraquinone yields anthracene dihydride. 

Dissolve 4.2 g (0.02 mol) of benzil (Expt 6.143) and 4.2 g (0.02 mol) of dibenzyl ketone (Expt 6.127) in 30 ml of hot absolute ethanol in a 100-ml round-bottomed flask fitted with a reflux condenser. Heat the solution to near its boiling point on a steam bath and then add in portions a solution of 0.6 g (0.011 mol) of potassium hydroxide in 6 ml of absolute ethanol. Some foaming may occur. Heat the reaction mixture under reflux for 15 minutes (1) and cool to below 5 °C in an ice bath. Collect the dark crystalline product by filtration with suction, wash with three 5 ml portions of rectified spirit and dry in an oven at 50 °C. The tetraphenylcyclopentadienone has m.p. 217-220 °C and is sufficiently pure for most purposes the yield is 7.0 g (91%). Recrystallise a portion from toluene-ethanol (1 1) to obtain the pure compound as deep purple crystals, m.p. 219-200 °C Amax 340 and 510 mm, e 1.26 x 103 and 0.33 x 103 respectively. 

Preparation. The reagent is readily prepared by the condensation of benzil with dibenzyl ketone in the presence of a basic catalyst. Dilthey s original procedure, adopted by Organic Syntheses specifies ethanol as solvent and a solution of potassium hydroxide in ethanol as the base. This procedure suffers from the low boiling point of the alcohol and the limited solubility of both potassium hydroxide and the reaction product in ethanol. In an improved procedure - use of the better solvent triethylene glycol permits operation at a higher temperature, and use of the readily soluble benzyltrimethylammonium hydroxide as base eliminates the step of dissolving potassium hydroxide in ethanol, A mixture of 0.2 mole each of benzil and... 

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