84 



for the preparation of usable odoriferous substances, and especially of 

 violet-perfumes, and that cyclic aldehydes 1 ) of the following formulae: — 



I. II. III. IV. 



CH 3 C 8 H 7 



CH 



H 2 C 

 HC 



CH 



CHXHO H 2 C 

 CHXH 3 , HC 



CH 



/\ 



CH 



CH 



CHXHO H 2 C 

 CH.CH 3 , HX 



CH 



CXHO, 



HX 



HX 



CH 



CH Q 



such as are derived from methyl and dimethyl cyclohexenone, men- 

 thone, and camphor, do not give sweet-scented condensation products 

 with acetone. Again, in the case of the molecule of cyclo-citral the 

 manner in which the aldehyde group and the side-chains are recip- 

 rocally grouped is of importance for the production of a valuable 

 perfume. Thus, for instance, among the aldehydes 2 ) of which the 

 positions are isomeric with cyclo-citral, and which are constituted as 

 follows: — 



I. II. III. 



C H q C H a C H s C H 3 C H 3 C H 3 



H 2 C 



CH, 



HX 



CHOXL JCHXH 

 CH 

 b. p. 85 to 86° 

 (11 mm.) 



CH 2 



CHOX 



H C ^ /CH«C H q 

 CXHO 

 b. p. 73 to 74 

 (7 mm.) 



CH, 



HC1 /CH* C Hg 

 CH 8 

 b. p. 101 to 102° 

 (17 mm.) 



No. II, and especially No. Ill yield , with acetone, condensation pro- 

 ducts (b. p. 130 , 6 mm., or b. p. 132 to 134 , 10 mm.) of a pro- 

 nounced odour of violets, whereas the condensation product of alde- 

 hyde I (b. p. 127 to 1 2 8°, 6 mm.) is almost odourless. As regards 

 their quality and the intensity of their odour they are not, however, 

 to be compared with irone and ionone. From the foregoing it must 

 therefore be concluded that the position of the aldehyde groups in 

 the cyclogeraniolene ring has a decisive influence upon the odoriferous 

 properties of the condensation products of acetone. The authors 

 express the law of relationships between the structure and the odour 



*) German Pat. Nos. 119862, 119879, 121975, 148206, 148207. 

 2 ) German Pat. Nos. 1 19862, 119 879, 121 975, 136873, 141 699, 141 973, 

 142 139, 158075. 



