The chemical synthesis of vital products and the interrelations between organic compounds : Vol. 1 / by Raphael Meldola.

  • Meldola Raphael, 1849-1915.
Date:
1904
Catalogue details

Licence: In copyright

Credit: The chemical synthesis of vital products and the interrelations between organic compounds : Vol. 1 / by Raphael Meldola. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

    24/368 page 4
    as vital products, although the glucoside itself may not have been hitherto synthesised in all cases. The necessity for this treatment will be recognised when it is con- sidered that the constituent atomic complexes of easily resolvable mole- cules are very likely hereafter to be found in the free state in nature, and in many instances are actually known, as in the case of glucose, to exist as individual compounds. Thus, to mention another example, hydroquinone (quinol) [7l] was at first entered as occurring only in the form of the glucoside arbutin. While this work was in course of preparation it was announced by Hesse (Ann. 290, 317) that this phenol occurs in the South African ‘sugar bush,’ Protea mellifera. As the products from animals and plants are more and more investi- gated it is certain that such instances will be multiplied. On considering the published records as to the occurrence of vital products it also became evident that in very large numbers of cases it was extremely doubtful in what form the compound was actually produced by the animal or plant. In other words, it is uncertain whether many compounds isolated, identified, and recorded as of natural occurrence may not have resulted from the resolution of more complex and unstable molecules by the action of enzymes or of the chemical reagents employed in their extraction—whether in fact they may not have resulted from secondary changes or decompositions taking place after removal from the organism. In view of this state of affairs it must be admitted that a vital product is not so easily definable as appears at first sight, and that in the present condition of knowledge it is not always possible to say whether a particular compound is of biochemical origin or whether it is a secondary product. Under these circumstances it has been deemed advisable, in order to make this work as comprehensive as possible, to assume that the complex of atoms present in the molecule of the vital product as isolated is of biochemical origin, even if the compound is not directly synthesised as such by the animal or plant. This view will no doubt commend itself to both chemists and physiologists. From the chemical standpoint it is certainly justifiable to believe that if a complex molecule is so unstable as to break down readily into simpler molecules, the atomic groupings present in the latter pre-exist in their generator. Moreover, molecular instability is a phenomenon of degree, and it has been found practically impossible to define the conception narrowly in terms of the agents necessary for causing the resolution of the compounds. It is not possible, for example, to draw a hard and fast line between, on the one hand, the action of enzymes and of acids or alkalies at ordinary temperatures, and, on the other hand, the action of acids or alkalies at high tempera- tures, or even, in the case of the more stable cyclic compounds, the action of fused alkali. For this reason the conception of a vital product has been enlarged so as to include every atomic complex
    digitised image 1
    digitised image 2
    digitised image 3