the authors have described the isolation, properties, and constitution of bromomethylfurfural, C6H,0,Br. It was shown that this beautifully crystalline substance results from the action of hydrogen bromide on ketohexoses, such as laevulose and sorbose, or on carbohydrates, which are capable of giving rise to ketohexoses on hydrolysis, such as cane sugar or inulin, and that it may be obtained in a similar manner from various forms of cellulose (Trans., 1901, 79, 361). The bromine in this compound is extremely reactive, so that it may be quantitatively estimated by direct precipitation with silver nitrate in the cold ; the substance itself is hydrolysed by boiling water, in presence of barium 3~2
IN a previous communication (Trans., 1898, 73, 554), i t mas shown by the present authors that certain carbohydrates, when treated with hydrogen bromide in ethereal solution, give an intense and beautiful purple colour. It was suggested that the reaction mould probably be of service i n distinguishing certain typical classes of carbohydrates, and that it might be employed for the detection of these in natural products.The examination of a considerable number of carbohydrates of various classes led to the following goneralisations.1.-With ketohexoses (Izvulose, sorbose), the purple colour appears after a few minutes, and becomes very intense in about one hour ; and substances which, by hydrolysis, are capable of giving rise t o these compounds (cane sugar, inulin) give a similar effect, only rather more slowly, the maximum colour being attnined in about two hours.Z.-HexaZdoses (dextrose, galactose), and substances capable of giving rise to them (milk sugar, maltose, dextrin), show, in the first instance, various shades of yellow, brown, or red, and i t is only after long standing that a purple colour is apparent. This colour, however, never approaches in brilliancy or intensity that obtained with substances mentioned in 1.
IT has been shown by one of the authors (Trans., 1896, 553) t h a t the ethylic salt of dihydroxymaleic acid can readily be obtained by the interaction of the free acid with anhydrous ethylic ether in presence of dry hydrogen bromide at the ordinary temperature. The product is identical in every respect with that obtained from the acid and ethylic alcohol in presence of hydrogen chloride, and the yield appears to be about the same. A similar result cannot be effected by substituting hydrogen chloride for hydrogen bromide. Ethylic ether is known, of course, to react with sulphuric, hydrochloric, and a few other inorganic acids, under certain conditions, to form ethylic salts, but no such behaviour towards organic acids appears to have been observed.
XXXV1.-The Action of Hydrogen Bromide on Carbohydrates.
IN a previous communication (Fenton and Gostling, Trans., 1901, 79, 361), it has been shown t h a t all forms of cellulose, when heated t o about 80' with a saturated solution of hydrochloric or hydrobromic acid i n chloroform or carbon tetrachloride, yield w-chlorobromomethylfurfural. It was also shown (Proc., 1901, 1'7, 166) t h a t dextrose, which could be extracted with water after separation of the methylfurfural derivative, was formed at the same time.These results conclusively proved the presence of a ketose as well as a n aldose nucleus in cellulose.In every case, about 40 per cent. of a black residue which retained the fibrous structure of the original cellulose was also left after the action of the acids.I n the hope of throwing further light on the constitution of cellulose, the nature of this residue was investigated, and in order t o ascertain whether it had a constant composition it was necessary t o prepare the residue free from any of the original cellulose by repeated treatment with hydrochloric acid until no more of the fnrfural derivative was formed.Five grams of pure cotton wool were introduced into a stzong glass bottle with a well-ground stopper and covered with about 300 C.C. of carbon tetrachloride, which was t h e n saturated with dry hydro-
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