112 



AROMATIC COMPOUNDS 



[CH. 



Expt. 109. Extraction of apiin, the glucoside of apigenin^ from the Parsley (Carum 

 Petroselinum). Take some Parsley leaves and boil in as little water as possible. 

 Filter off the extract and make the following tests for apigenin : 



{a) Add alkali. A lemon yellow coloration is given. 



(6) Add basic lead acetate solution. A lemon yellow precipitate is formed. 



(c) Add ferric chloride solution. A brown colour is produced. 



{d) Add ferrous sulphate solution. A reddish-brown colour is produced. 



Apiin frequently separates out in a gelatinous condition from aqueous 

 and dilute alcoholic solutions. 



Chrysin is a flavone occurring in the buds of various species of 

 Poplar {Populus). It has the formula : 



HO 



A^^''^ 



CH 



OH 



Luteolin does not appear to be widely distributed, though possibly 

 it occurs in many plants in which it has not yet been demonstrated. Its 

 formula is represented as : 



HO 



/\/''\ 



OH 



K 



OH 



XO 



OH 



It occurs in the Dyer's Weld or Wild Mignonette {Reseda luteola) 

 (Perkin, II), Dyer's Greenweed or Broom (Genista tinctoria) (Perkin, 17) 

 and in the yellow variety of flowers of the Snapdragon {Antirrhinum 

 majus) (Wheldale and Basse tt, 27). It has been much used as a yellow 

 dye: hence the names of the first two plants (Perkin and Horsfall, 14). 



The most important flavonol pigments are quercetin, kaempferol, 

 myricetin and fisetin. 



Quercetin is apparently one of the most widely distributed of the 

 whole group of yellow pigments, and has the formula : 



HO 



/\^''\ 



P» 



OH 



OH 



^' 



OH 



