^4ISCELLANEOUS NITROGEN AND SULFUR COMPOUNDS 



279 



the marigold (Tagetes erecta) (11). Another thiophene derivative has recently been re- 

 ported in the roots of Chrystkanthenum vulgare (12). 



OlOO 



Q-terthienyl 



'Lc.'-'-<c/^C=CCH= 



CH. 



5-(3-buten-l-ynyl)-2, 2'- 

 bithienyl 



HC^C— l!^ <j JLcH= 





 11 



CHCOCH3 



methyl 



3-[ 5-(l-propynyl)-thienyl-2] 

 acrylate 



It seems clear that such compounds are derived from the acetylenic compounds which are 

 widespread in the Compositae (cf. Chap. 6). 



Disulfides and polysulfides are less volatile than the sulfides but have a more of- 

 fensive odor. They react slowly with mercuric chloride. The S-S bond is split and 

 mercaptide-like derivatives are formed. Polysulfides tend to lose sulfur and form di- 

 sulfides when they are distilled. There is no conclusive evidence for the occurrence of 

 di- and polysulfides as such in plants. Although they are found in essential oils of garlic, 

 asafetida and onion, they probably arise through secondary transformations brought about 

 by plant enzymes and the heat of distillation. Alliin, the native constituent of garlic, is 

 broken down enzymatically to allicin when the plant is crushed: 



CH9 



CH 



I 



CHo 



I ^ 



S-*0 



I 



CHo 



I 2 



CHNH. 



I 



COOH 



ALLIIN 



ALLIINASE 



II 2 

 CH 

 I 



CHo 

 I ^ 



H 



CH, 



I ^ 



C=0 -h NH. 



I 



COOH 



CHo 

 H 2 

 CH 

 2 i 

 MOLS.CH0 

 I ^ 

 S-*0 

 H 



SPONTANEOUSLY 



CH< 



II ' 



CH 



CH« 



!l 



CH 



t I 



g—S— S— CHg 



ALLICIN 



H-H^O 



