374 Mr Fenton, Oxidation in Presence of Iron. 



acids with the result that the reaction proves to be a general one, 

 that is to say, a large number of ethyl esters may be prepared by 

 the use of ethyl ether in place of alcohol, using dry hydrogen 

 bromide as dehydrating-agent. 



Characteristic colour reaction for certain carbohydrates. [Fenton 

 and Gostling, Trans. Ghem. Soc. 1898. 556, and 1901. 361.] Con- 

 tinuing the observations upon the action of hydrogen bromide in 

 ether on substances other than acids, it was found that certain 

 carbohydrates give an intense purple colour with the reagent, and 

 that the rapid production of this colour is characteristic of keto- 

 hexoses or those containing a ketohexose nucleus. 



Derivatives of Methyl- furfural and the constitution of ' cellulose.' 

 [Fenton and Gostling, Trans. Ghem. Soc, 1899. 423, and 1901. 

 807.] The cause of the remarkable purple colour mentioned in 

 the last section was the next subject of enquiry, and after con- 

 siderable initial difficulties a new substance was isolated in a 

 crystalline state, which proves to be bromo -methyl furfural, 



HC = C - CELBr 



O 

 HC=C-CHO 



This substance gives an intense purple colour with hydrogen 

 bromide, and on oxidation yields the corresponding bromopyro- 

 mucic acid. Later observations shew that the chloro-derivative 

 may be produced in a similar manner by the action of hydrogen 

 chloride on the carbohydrates mentioned. A large number of 

 typical carbohydrates have been investigated, and it is proved that 

 these methyl -furfural derivatives result only from ketohexoses 

 such as lsevulose and sorbose, or substances which give rise to 

 ketohexoses on hydrolysis, such as cane-sugar and inulin. It may 

 in fact be stated with confidence that the production of bromo- 

 or chloro-methyl-furfural in the manner described is a specific test 

 for the presence of a ketohexose nucleus. Later it has been 

 shewn that all forms of cellulose give large yields of these methyl 

 -furfural derivatives by the action of hydrogen bromide or chloride, 

 and the presence in cellulose of a ketohexose nucleus is con- 

 sequently proved. After extracting the methyl-furfural derivative 

 from the action on cellulose, the residue is found to contain 

 ordinary d. glucose (Proc. Ghem. Soc. 1901. 166), a fact of much 

 interest in view of the recent isolation of ' cellose,' C^H^On from 

 cellulose by Skraup and Konig. 



A large number of other interesting derivatives of methyl 

 -furfural have also been obtained by the authors. 



