9? 



liowever small, pinaeone was still formed and retained because now 

 two causes would cooperate to retard the formation of pinacone. 



It appears to us as the most probable that the direct reduction 

 product is in all cases the half pinacone molecule which afterwards : 



1. will polymerise to pinacone which remains unchanged in a 

 neutral solution and resolves into hydrole and ketone in an alkaline 

 solution ; the ketone can then again be attacked. 



2. will possibly, be further reduced to hydrole and diphenyl- 

 methane. 



We base this conception, besides on the above experiments from 

 which appears a predilection for the formation of pinacone, also on 

 observations as to the behaviour of mixtures of benzophenone and 

 absolute alcohols and other substances in direct sunliglit. 



CiAMiciAN and Silber ^) have in this way obtained pinacone quan- 

 titatively from benzophenone and ethyl alcohol ; we have been able 

 to confirm this result witli a series of other alcohols ^). Not a trace 

 of hydrole is formed in these neutral liquids absolutebj free from 

 hydroxi/l-ions. 



With benzyl alcohol and with etiier the two Italian chemists found, 

 besides pinacone, substances such as (CeHJ.COHCHCgHsOH and 

 (C6H5)3COHCHCH30C2ll5, whose formation, like that of pinacone 

 may be explained in the simplest manner by a primary addition of 

 one hydrogen-atom to the ketone-oxygen which will here be followed 

 immediately by an attachment of the molecular residues to the carbon 

 of the CO-groups. 



Hence, in the above formulated assumption it has been taken for 

 granted that the half pinacone molecule CCgHj^COH is the sole real 

 intermediate product. 



It is now very well possible that this, in an alkaline solution, is 

 straightway reduced to hydrole (2). 



But it is, however, also not excluded that the polymerisation to 

 pinacone takes place, also in alkaline solution, with such velocity that 

 this latter product is formed first also in these circumstances, then to 

 be secondary converted into hydrole in the manner suggested above. 



The two alternatives may be represented as follows : 



I (OeH3),C() -^ (C,H J.COH ^ (C«H J.CHOH. 



II(0,H3)/X)-^{C,H;),,C0H-^[(C,HJ,C0H],^(C,HJ,CH0H+(C«H,),C0. 

 If the latter is the case it is to be expected that the ketones which 

 yield pinacones that are rapidly resolved by OH-ions into a mixture 



•) B 33, 291] ; 36, 1577; 43, 1586; 44, 1557. 



-) This research will become the subject of a further communication. 



7 



Proceedings Royal Acad. Amsterdam. Vol. XVI 



