60 Proceedings of the Royal Irish Academy. 



Since the compound C 25 H M Oj is not decomposed on prolonged boiling 

 with dilute, or concentrated potash, it cannot be a /3-diketone derivative ; 

 and, as it adds on only two atoms of bromine, it probably contains only one 

 non-aromatic double bond. 



The formation of the addition compound with hydroxylamine instead of 

 the expected oxime indicates the existence in the compound of the group 



- C : C — C — ; and the fact that the hydrochloride forms an unstable red 



II 

 



addition compound with hydrochloric acid points to the presence in the 



complex of a pyrone ring. 



A compound having the empirical formula G. 5 H 23 2 CI may be derived 



from dimethyl-acetylacetone according to either of the following equations : — 



(1) 2C 6 H 5 . CHO . + 2CH 3 . CO . C(CH 3 ) 2 . CO . CH 3 + 4 HC1 



= CHoOjCl + 3CH 3 C1 + 4H 2 0. 



(2) 3C 6 H 5 CHO + CH 3 . CO . C(CH 3 ), . CO . CH 3 + 2HC1 



= C 25 H 23 2 C1 +■ CH 3 C1 + CH.COOH + 2H,0. 



As we have found experimentally that dimethylacetylacetone may be 

 replaced by monomethyl-acetylacetone without altering the resulting product, 

 it is evident that one or more methyl radicles must in fact get split off during 

 the reaction. 



Of the above equations we prefer the second for two reasons : — 



1. The yield of the compound, when three molecular quantities of 

 benzaldehyde to one of the dimethyl-acetylacetone are taken, is much 

 greater than when equimolecular quantities are employed. 



2. Whilst it is easy to formulate according to the second equation 

 a compound C 25 H 22 0, containing only one non-aromatic double bond, 

 to do so according to the first equation would be very difficult, if not 

 impossible. 



Bearing these facts in mind, the reactions may be simply interpreted as 

 follows : — 



C 6 H 5 CHO + CH 3 . CO . C(CH 3 ) 2 . CO . CH 3 + HC1 



= C 6 H 5 • CH = L'H . CO . CHfCH.) . CO . CH 3 + CH 3 C1 + H 2 

 C 6 H S . CH : CH . CO . CH(CH 3 ) . CO . CH 3 + H 2 



= C 6 H 5 . CH : CH . CO . CH 2 . OH, + CH 3 . COOH. 

 C C H 5 . CH : CH . CO . CH 2 . CH 3 + C 6 H 5 . CHO 



= C 6 H 5 . CH : CH . CO . CH . CH 3 



HO . CH . C 6 H 5 . 



