— 157 — 



2 mol. aldehyde to i mol. ketone. Of the results, the following call 

 for attention: — 



i . In ketones substituted in ortho-position, no condensation occurred 

 with the aldehydes mentioned. 



2. Active i, 3 -methyl hexanone did not condense with the 

 chlorinated benzaldehydes, whilst the inactive ketone readily yielded 

 a condensation-product under the same conditions. The condensation- 

 products of i, 3 -methyl hexanone with m- and p-nitrobenzaldehyde 

 showed in their active and inactive forms a difference of 30 in the 

 melting points, whereas the melting points of the active and inactive 

 condensation-products with the remaining aldehydes lay close together. 



3. 0-, m- and p-nitrobenzaldehyde showed a large difference in 

 the condensation-capability. The m-compound condensed readily, the 

 p-compound much more difficultly, and the o-compound not at all. On the 

 other hand, o-chlorobenzaldehyde readily yielded condensation-products. 



4. Under the same conditions the condensation - capability with 

 benzaldehyde decreases from cyclopentanone towards cycloheptanone. 



5. When employing benzaldehyde in very dilute aqueous solution 

 and an excess of ketone, it is possible to isolate the intermediate 

 products of the condensation, the aldols: — 



/CO /|\CH 2 .C 6 H 5 



(CH 2 ) X < I .OH and (CH 2 ) X ( CO 



X C< \ I 7 OH 



\CH 2 .C 6 H 5 \C( 



Of these white, readily decomposable compounds, there have been 

 obtained up to the present: from benzaldehyde and cyclohexanone 

 the monoaldol (m. p. 101 to 102 ) and the dialdol (m. p. 161 to 162 ); 

 from benzaldehyde and inactive 1,3 -methyl hexanone, the monoaldol 

 (m. p. 106 to 107 ); and from benzaldehyde and 1,4-methyl hexanone, 

 the monoaldol (m. p. 127 ). 



6. The condensation can also be performed by means of 10 per 

 cent solution of potassium cyanide. When boiling the aldehyde-ketone 

 mixture with strong formic acid, the condensation also takes place. In 

 this manner it was found possible to condense also the otherwise not 

 reacting o-nitrobenzaldehyde with the cyclic ketones. 



7. The cyclic ketones condensed with two aldehyde radicals, give 

 with concentrated sulphuric acid colour -reactions; the condensation- 

 products of the cyclic ketones with benzaldehyde and the nitrobenz- 

 aldehydes dissolve in it with yellow, anisic aldehyde with red, piperonal 

 with carmine red, cinnamic aldehyde with violet coloration. 



A table gives a comparative review of the melting points of all 

 the condensation-productsformed. 



