455 



pronounced. Tliis influenoe of the symmetry- was already observed 

 more tlian once in (he plioio-chemical reduction of (lie substitution 

 products of benzophenon, l)ul it hati not lieeii recognized as such '). 

 To give a fuitlier suppoi't to this view it has been tried to make 

 di-furyl ketone, as this compound would have to possess an activity 

 equivalent to benzophenon. Unfortunately all attempts to obtain this 

 substance have failed so far '), but in this connection attention may 

 already be drawn to the much greater activity of terephtalophenon 

 compared with isophtalophenon (23 and 24). 



e. A somewhat se|)arate place among the «-/J-diketones occupies 

 camphorquinone, the activity of whicii is unexpectedly slight, 

 and moreover not reproducible. The greater or smaller purity of 

 the preparations seems to be of great influence. 



/'. (t-Hydrindon (29) and indane dioii 1.2.(31), considered as 

 internal condensation products of resp. propiophenon (7) and acetyl 

 benzoyl (20), present a greatly diminished activity. ,i-Hydrindon 

 cannot be used as object of comparison with mono-[)henyl acetone 

 on account of its great oxidisibility. 



g. The photo-activity of the examined «t-ji-y-tri-ketones is zero, or 

 so small as to be negligible (32, 33, 34)'). This phenomenon must, 

 without any doubt, be attributed to the jtaralysis of the middle 

 C=0 group caused by the solvent^), through which the compound 

 has practically quite lost its favourable properties of double «-(i-di- 

 ketone. ') 



Laboratory of Organic Chemistry 

 of the J^echnical University . 



Delft, April 1923. 



1) Compare. Cohen, Rec. 39, 258 (1920). 



=) Freundler, B1. (3) 17, 612 (1897). 



') Compare for the photo-chemical reduction of alloxane Ciamician and Silber, 

 Ber. 36, 1581 (1903). 



*) At first pentane tri-ketone and di-phenyl tri-ketone dissolve in absolute 

 alcohol with a dark yellow colour, after standing some lime the colour of the 

 solution changes into light yellow, in which very probably alcohol addition 



/OH /OH 



products GH8-C0-G< GO— GH3 and GeHj-CO-G^ CO-CoHs 



\OGjH5 \OG5H5 



which are analogous to the hydrate, are formed. 



6) Comp. Sachs, Ber. 34, 3052 (1901); 35, 3311 (1902); Von Pechmann, Ber. 



23, 3380 (1890); Wieland, Ber. 37, 1531 (1904); Biltz, Ber. 45, 3662 (1912). 



