110 Proceedings of the Roj^al Irish Academy. 



Collie explains the reaction as follows, taking I as the formula for diacetyl- 



acetone : — 



. Xa . CO . CH, 



h 6 



CH3 . C^-'XC . CHs CHs . C/;\C . CHs 



I I 11 +CH3.C0Cl-> I \ - 2 XaCl 



HC^/CH HC^/CH 



C C 



1 1 



Xa . CO . CHs 



Eearrangement with the elimiuation of water then takes place with the 



formation of 





 CHs . C/\C : CHj 



I i 

 CHs . CO . C\/C . CO . CHs 



C 



Compound M. P. 75" C. 



This compound on warming with sodiimi hydroxide changes into diaceto- 

 orcinol as follows : — 



;0H H:CH 

 ---^-^ j,jj 



CHs . C/\C : CHj CHs . C C . OXa CHs . C/\C . OH 



II II I 11 



CHs. CO . C\/C.CO.CHs CHs . CO . C\^C . CO . CHs CHs . CO . C\/C . CO . CHs 



C C C 



I I I 



OH OH OH 



lutirmediate compeund, diactto-orcinol. 



The only formula which can be assigned to diaceto-orcinol prepared by 

 this method is that shown above. 



On application to Professor CoUie he was kind enough to provide a 



specimen of the compound obtained by him, and this was compared with the 



substance prepared by the aluminium chloride method. The melting-point 



of the mixed substances corresponded exactly with that of the indi\iduals, 



and in other respects the compounds were identical. It therefoie seems 



certain that the two acetyl groups are in the positions indicated in Collie's 



formula. This view is supported by the fact (Tambor, Ber., 39, 1906, p. 4038 ; 



and 41, 1908. pp. 787 and 793) that when only one acetyl group is introduced 



into orcinol it preferably enters the position between the two hydroxyls, 



thus : — 



CO . CHs 



HO/\OH 

 CH, 



