24 Dr Fenton, A Delicate Reaction for Carbohydrates. 
A delicate reaction for Carbohydrates. By H. J. H. Fenton, 
Sc.D., F.R.S., Christ’s College. 
\Read 26 November, 1906.] 
In previous communications [Fenton and Gostling, Trans. 
Chem. Soc., 1898, 554, and 1901, 807] it has been shewn that by 
the action of dry hydrogen bromide on ketohexoses, such as 
lgevulose, a product is obtained which crystallises in large 
colourless oblique prisms and gives an intense purple colour with 
strong acids. This product was found on investigation to be 
to bromo-methylfurfural CHO — C 4 ILO — CH 2 Br. The correspond- 
ing chloro-compound, or chloride, can be prepared in a similar 
way and a number of other derivatives, such as the acetate, 
benzoate, iodide and hydroxide, are readily obtained by double 
decomposition of the bromide or chloride with metallic salts. 
The halogen atom is, in fact, highly reactive and is quanti- 
tatively precipitated by action of silver nitrate in alcoholic 
solution. 
Experiments are being continued in the direction of effecting 
various syntheses by the introduction of this methylfurfural 
residue, or radicle (for which no convenient name has yet been 
suggested) into typical carbon compounds. In the course of these 
investigations it has been observed that when the bromo- or 
chloro-compound is acted upon by sodio-malonic ester, in 
alcoholic solution, considerable heat is evolved and the mixture 
turns bright red. If now the product is poured into water it 
readily dissolves, giving a solution which exhibits an intense blue 
fluorescence. The nature of this product, which has not yet been 
isolated in a pure state, is now under investigation. The formation 
of the fluorescent product is extremely characteristic and may be 
employed as a most delicate test for the presence of these methyl- 
furfural derivatives. 
It was previously mentioned ( loc . cit., 1898, 554, and 1901, 361) 
that the formation of bromo-methylfurfural, by the action of 
hydrogen bromide, affords a characteristic test for ketohexoses 
or for compounds which are capable of yielding ketohexoses on 
hydrolysis. The substance to be examined is acted upon by 
hydrogen bromide dissolved in an appropriate solvent, such as 
ether, and the production of bromo-methylfurfural is indicated by 
the intense purple colour which appears after some minutes. 
A more certain method of procedure, however, consists in isola- 
