formation lhuile damandes amères emploi de wöhler liebig discovery emulsin main (1 résultats)

Paris, Crochard et Comp., 1837. Orig. printed wrappers. No backstrip. In: "Annales de Chimie et de Physique, Par MM. Gay-Lussac et Arago.", tome 64, Cahier 2 (Fevrier 1837). Pp. 113-224. (Entire issue offered with printed wrappers.). Wöhler a. Liebig's papers: pp. 185-209 a. pp. 209-217. First appearance of this classic paper in organic chemistry in which Wöhler and Liebig showed how Amygdalin could be decomposed by a vegetable emulsion, the first example of a glycoside. The papers were issued at the same time in "Annalen der Physik und Chemie"."The conclusions which you have drawn from the investigation of bitter-almond oil," wrote Berzelius to Liebig and Wöhler, "are certainly the most importent which have so far been reached in the domain of vegetable chemistry, and give promise of shedding an unexpected light over this part of the science.The facts which you have set forth inspire such reflections that they may be regarded as the dawn of a new day in vegetable chemistry."(Berzelius-Wöhler Briefwechsel)."During the years that Liebig was preoccupied with the ether theory and with organic acids, he also carried out two importent investigations with Wöhler. In october 1836 Wöhler wrote that he had discovered a way to transform amygdalin to oil of bitter almonds and hydrocyanid acis, by distilling it with manganese and sulfuric acid, and he invited Liebig to join in pursuing the topic. Two days later he made a more remarkable discovery. It had occurred to him that perhaps thetransformation of amygdalin could be effected by the albumin in the almonds, in a manner similar to the action of yeast in sugar.Wöhler suspected that the decomposition was an example of what Berzelius had recently defined as catalysis. Liebig and Wöhler then divided up the detailed examination of the properties and composition of amygdalin. They precipitated from the emulsion of almonds a substance which when dissolved retain its action. They named the active substance "emulsion". Its effectiveness in very small quantities confirmed that it acted like yeast."(DSB VIII, p. 342).