— 152 — 



Waters 1 ), these bodies are produced by dissolving p-nitrobenzyl zinc 

 mercaptide in alcohol saturated with hydrochloric acid, and mixing 

 it with the calculated quantity of the aldehyde in question. The 

 separation mostly occurs at once, rarely only after 24 hours' standing 

 in the cold. The authors produced first of all the following bodies: — 

 From acetic aldehyde, p-nitrobenzyl ethylidene mercaptal, m. p. 82 °: 



N0 2 .C 6 H 4 .CH 2 .Sv 



)CH.CH 3 

 N0 2 .C 6 H 4 .CH 2 .S/ 



„ salicylic aldehyde, p-nitrobenzyl o-hydroxybenzylidene mercaptal, 



m.p. 152 . 

 „ cinnamic aldehyde, p-nitrobenzyl phenylpropenylidene mercaptal, 



m.p. 140 . 

 „ cuminol, p-nitrobenzyl p-isopropyl benzylidene mercaptal, m.p. 84 , 

 „ menthone, menthone p-nitrobenzyl mercaptol, m.p. 171 , 

 „ pulegone, pulegone p-nitrobenzyl mercaptol, m.p. 133 , 

 „ furfurol, p-nitrobenzyl furfurylidene mercaptal, m.p. 87 . 



With regard to the determination of aldehydes and ketones 

 according to Rother and 



With reference to the haematospectroscopic method of Bruylants 

 for the identification and determination of aldehydes, see 

 under Analytical Notes, pp. 120 and 122. 



Nonylic aldehyde. Of the normal fatty aldehydes, nonylic 

 aldehyde and decylic aldehyde are particularly important as constituents 

 of essential oils. According to P. Bagard 2 ), the former can be 

 obtained by dry distillation of a-hydroxy caprinic acid, the latter by 

 distillation of a-hydroxy undecylic acid. Starting from pelargonic acid, 

 Bagard produced hydroxy caprinic acid by first of all reducing pelargonic 

 acid according to Bouveault and Blanc 3 ), by treating its ethyl 

 ester with sodium, into nonylic alcohol. Through the nonyl bromide 

 and nonyl cyanide obtained from nonylic alcohol, he arrived at caprinic 

 acid, which was then converted by brominating into a-bromocaprinic 

 acid. The latter acid, when boiled with potassium carbonate solution, 

 yielded a-hydroxy caprinic acid. In order to obtain a-hydroxy undecylic 

 acid, he used as crude material undecylenic acid, which was first of 

 all converted into undecylic acid by addition of hydrogen iodide and 

 subsequent reduction with zinc. By brominating the undecylic acid, and 

 replacing the bromine with the hydroxyl-group as above, a-hydroxy 

 undecylic acid was formed. The yield of nonylic aldehyde was 71 °/o> 

 that of decylic aldehyde 52°/ , of the hydroxy acids. 



*) Thesis, Munich, 1905. 



2 ) Bull. Soc. Chim. IV. 1 (1907), 346. 



3 ) Compt. rend. 136 (1903), 1676. 



