A survey of anthocyanins. II

DURING the year following the publication of Part I [1931] of this series the progress of synthetical work has been rapid and the main diglucosidic antho- cyanins have been synthesised and found to be identical with the natural products. Thus Dr A. R. Todd [1932] in collaboration with one of us, has synthesised hirsutin, malvin, cyanin, peonin and pelargonin chlorides, whilst the preparation of cyanidin 3-cellobioside, cyanidin 3: 7-diglucoside and 5: 7-diglucoside has made it clear that mecocyanin and keracyanin are in fact, as already assumed, cyanidin 3-biosides. The established formulae for cyanin chloride (I) and mecocyanin chloride (II) are here reproduced for con- venience of reference to the numbering and nomenclature system. Acalypha bispida. Hydrolysis for a short time affords an acylated anthocyanidin; hydrolysis for several minutes under the usual conditions, or alkaline hydrolysis, affords cyanidin. The reactions are those of a 3-substituted cyanidin. The distribution number (amyl alcohol) is high and the anthocyanin is probably a 3-acyl cyanidin saccharide.