183: 



III. ADDITION" OF BENZOIN TO PIPERON YLENACETONE. 



.l-.'f-<lililii tiijl-.'i-iiifi'iiiJ-4-i'i 11-^ —keto-R—he.iciK . 

 CH . Ce H3 . (CII^ 0,1 



Ce H5 . C . (OH) 



Ce Us 



^CHo 



Oue molecule (6 gr.) of beiizoiu aucl one molecale (5.9 gr. ) of piper- 

 onylenacetoue are dissolved iu hot absolute ethyl alcohol (lOOcc.) and a 

 solution (4cc) of sodium ethylatc (.5 gr. sodium in 30cc. absolute alcohol ) 

 is added. As in all these conden.sation reactions with sodium ethylate, 

 this mixture assumes a deep red coloration. Upon standing for two hours 

 rosettes of yellow needle-like crystals separate. These crystals, upon re- 

 crystallization from glacial acetic acid, are obtained in fine white glitter- 

 ing needles, melting at 240^. The substance is soluble in hot chloroform; 

 sparingly soluble in hot benzene and alcohol ; and insoluble iu ether and 

 ligroin (-10-60'). 



Calculated as C25 H^„ O^. Found. 

 C 78.12 78.00 



H 5.21 5.38 



The method above described for the preparation of 3-4-diphenyl-o- 

 piperyl— 1-oxy- ,-keto-R-hexene does not progress as smoothly and as 

 completely as when one molecule each of piperoual (4.25 gr. ) and of pure 

 acetone (1.7 gr. ) is used in place of the piperonylenacetone, and the reac- 

 tion is carried out at the temperature of the water-bath. The crystals 

 obtained by this method are very pure and clean, and the yield is almost 

 quantitative, especially if the mother liquor is treated again with more 

 sodium ethylate and the mixture again boiled. 



Ten per cent, sodium hydroxide solution also effects the condensation.^ 

 However the yield is poor. 



