Alcoholic fermentation / by Arthur Harden.

  • Arthur Harden
Date:
1932
Catalogue details

Licence: In copyright

Credit: Alcoholic fermentation / by Arthur Harden. Source: Wellcome Collection.

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    and on boiling with caustic soda decomposes giving a hexosazone (free from phosphorus) which is probably glucosazone, and in addition glyoxalosazone, probably as the result of a secondary decomposition. Towards acid it is remarkably stable yielding with hydrochloric acid a hexosonephosphoric ester from which the original osazone can be re- generated (Lebedev). Lebedev at first [1910] argued from the forma- tion of this osazone that the original hexosephosphate contained only one phosphoric acid group per molecule of hexose. It was, however, shown by Young [1911] and subsequently confirmed by Lebedev [ 1911, 5] that one molecule of phosphoric acid is split off during the formation of the osazone, even in neutral solution. Moreover, it has been found that in the cold hexosediphosphoric acid reacts with 3 molecules of phenylhydrazine forming the di-phenylhydrazine salt of hexosediphosphoric acid phenylhydrazone (C6H5NH, • NH • H2P04)3 • C6H7(OH)3 • N2HC6H6. This compound crystallises out when one volume of alcohol is added to a solution of three molecules of phenylhydrazine in one of the acid and forms colourless needles melting at II5°-II7.0 p-Bromophenylhy- drazine yields an analogous compound melting at I27°-I28°. Precisely the same products are given with phenylhydrazine by the hexosediphosphoric acid prepared from glucose, mannose, and fructose, proving that all these sugars yield the same hexosediphosphoric acid, a point of fundamental importance. A series of phenylosazones has been obtained by Lebedev [1924, 2] from the fermentation products of sucrose and dried yeast in presence of the primary and secondary phosphates of sodium and potassium, and of the primary phosphate with the addition of sodium sulphite, but their exact nature has not yet been made out. Direct measurements of the molecular weight of the acid by the freezing-point method, combined with the determination of the degree of dissociation by the rate of sucrose inversion, are indecisive, but indicate that the acid has a molecular weight considerably higher than that required for a triosephosphoric acid. A similar uncertainty attaches to the determination of the molecular weight from the freezing-point depression and conductivity of the acid potassium salt [Euler and Fodor, 1911 ]. Euler, however, concludes that both a hexosediphosphoric acid and a triosemonophosphoric acid are formed, but has not prepared any derivatives of the latter.
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