Wakeman—Pigments of Flowering Plants. 
859 
CH CH CH COH 
Butein 1 occurs in glucosidal formation, either as such or in 
the form of butin, in the flowers of Butea frondosa. Its synthe¬ 
sis from dimethylprotocatechuic aldehyde and monomethyl re- 
sacetophenone as well as its formation from butin 2 have been dis¬ 
cussed in a previous chapter. 
Butein crystallizes in needle like crystals which melt at 
213°-215°. It is readily soluble in alcohol, somewhat soluble 
in ether, more sparingly soluble than butin in hot water. It 
dissolves in alkaline solutions with a deep orange red color. In 
alcoholic solutions with lead acetate it gives a deep red precipi¬ 
tate, with ferric chloride an olive brown coloration. In cold 
sulphuric acid it dissolves with an orange color, upon the addi¬ 
tion of water the butein is precipitated unchanged. 
Butein dyes wools mordanted with aluminum a beautiful 
orange color, with chromium a deep terra cotta, with tin a beau¬ 
tiful yellow, and with iron a brownish olive. 
I. B. 3.) The anthocyanin pigments. 
The so called anthocyanin pigments have long attracted the 
attention of both chemists and botanists, and have called forth 
considerable work from both classes of investigators. From 
time to time colored substances have been extracted from plant 
organs supposed to be colored by anthocyanin pigments and 
have been made the subject of special investigation. These 
colored substances, though sometimes crystalline, were probably 
seldom pure, so that little chemical knowledge was gained either 
of the special pigment studied or of the anthocyanins as a class. 
In' addition to the above, many theories, all of which have been 
more or less unsatisfactory, have been advanced to account for 
both the appearance and the disappearance of color in flowers, 
fruits, and autumn foliage. 
The recent exhaustive study, by Willstaetter, of anthocyanin 
1 Froc. Chem. Soc., 10, p. 11; 19, p. 133; 85, p. 1495. 
2 See Butin, Formula of saturation CnH,n-14. 
