CXXX.—Carthamine. Part I

Tokuhei Kametaka, Arthur George Perkin
1910 Journal of the Chemical Society Transactions  
SAFFLOWER, the Ca~~tJ~amzis tinctorius, at one time a most important red dyestuff, on the advent of safranine quickly fell into disuse throughouJ Europe, but nevertheless large quantities aye still cultivated, more especially in India, and employed for dyeing and pigment manufacture, The red colouring matter, carthamine, is present in the flowers to the extent of 0.3 to 0.6 per cent. (Sa.lvetat, _Inn. C'T~em. Phys., 1849, [iii], 25, 337), together with a very large amount of a soluble yellow
more » ... stance, which is useless and even liarrnful in the dyeing operation. Although carthamine is specially interesting on account of its substantive dyeing properties, it appears to have received but little attention, and this is probably due to 1 he tedious and expensive character of the peculiar operations which are necessary for its isolation from the plant. For this purpose it is usual to extract the flowers, which have been previously washed with water in order to remove the yellow substance, with dilute sodium carbonate solution. I f the alkaline extract be now acidified with citric or tartaric acids, the carthamine is precipitated in so finely divided a condition that it cannot be successfully collected, and to obviate this difficulty cotton or flax is dyed with the colouring matter by immersion in the alkaline liquid, followed by a subsequent acidification of the dye-bath. The carthamine is now removed from the dyed cotton by means of sodium carbonate solution, and is deposited from this extract by means of an organic acid in a purer and more granular form. The crude material employed in this investigation was procured from Kyoto in Japan, in which country it finds considerable employment as a cosmetic. For its preparation the safflower, which is imported both from China and India, is subjected to a process very similar to that outlined above, the alkali being supplied by plant-ash extract, and the organic acid from the juice of the Japanese plum. Considerable experience appears to be necessary in neutralising the alkaline extract of the plant, and also of the dyed cotton, for, should this be carried beyond a certain point, a brown impurity is subsequently deposited, which causes a considerable deterioration of the brilliancy of the colouring matter. The yield of dyestuff varies according t o the quality of the plant, but according to figures given by the Japanese maker, 80 Ibs. of the dried flowers usually yield about 285 grams of the crude carthamine. Samples described as carthamine were also procured by purchase 5 A 2
doi:10.1039/ct9109701415 fatcat:6vl2rizv35gmlelemcg6ylsvd4