Synthesis of Glucose

Abstract

ANOTHER important acquisition to our store of knowledge has recently been made. Glucose, commonly called grape-sugar, has been artificially prepared by Drs. Emil Fischer and Julius Tafel in the chemical laboratory of the University of Würzburg. This happy achievement, which is announced in the number of the Berichte just received, is one which has long been looked forward to, and which cannot fail to give deep satisfaction in chemical circles all over the world. As is generally the case in syntheses of this description, not only has the sugar itself been actually prepared, but, what is at least quite as important, considerable light has been thrown upon that much-discussed question—the constitution of sugars. A most remarkable, and yet only to be expected, attribute of this artificial sugar is that it is found to be entirely incapable of rotating a beam of polarized light. As is well known, there are several naturally-occurring varieties of glucose, all of which may be expressed by the same empirical constitution C₆H₁₂O₆, and all possessing the power of rotating the plane of polarization: dextrose, or grape-sugar, the best-known of these varieties, as its name implies deviates the plane of polarization to the right, as do several other less important varieties; while laevulose, or fruit-sugar, rotates the plane to the left. But in artificially preparing a glucose of the composition C₆H₁₂O₆ there is just as much tendency for one kind to be formed as another, and the probability is that both dextro and laevo are simultaneously formed, and thus neutralize each other, producing a totally inactive mixture. It may be that, as in the case of racemic acid, the two kinds are formed side by side and neutralize each other in the solution; or it may even be that, as is the case with truly inactive tartaric acid, there is a true neutralization within the molecule itself; which of these hypotheses is correct is a question for further work to decide.