81 examples of alkaloids in sentences

* RECENT STUDIES ON THE CONSTITUTION OF THE ALKALOIDS.

The alkaloids, that most important class from a medical and pharmaceutical point of view, have until quite recently been defined in the books simply as "vegetable bases, containing nitrogen."

Chemists all admitted two thingsfirst, that their constitution was very complex, and, second, that the synthesis of any of the more important medicinal alkaloids would be an eminently desirable thing to effect from every point of view.

It was early recognized that the alkaloids were complex amines or ammonia derivatives.

Hence the difficulty in acquiring a knowledge of the molecular structure of those alkaloids at all comparable with that attained in the case of other organic compounds.

Of course synthesis could not be applied until analysis had revealed something of the molecular grouping of these compounds, so the action of different classes of reagents was tried upon the alkaloids.

Before summarizing the results of this study of the decomposition and alteration products of the alkaloids, a brief reference to a related class of organic compounds will be of assistance to those unfamiliar with recent researches in this field.

Taking up the volatile alkaloids, we find with regard to conine, first, that the action of methyl iodide shows it to be a secondary amine, that is, it restrains only one replaceable hydrogen atom of the original ammonia molecule.

Nicotine, C{10}H{14}N{2}, the next simplest in formula of the alkaloids, is a tertiary base, that is, contains no replaceable hydrogen atoms in its molecule.

Potassium permanganate, chromic or nitric acid oxidises it to nicotinic acid, C{6}H{5}NO{2}, which is simply pyridine-carboxylic acid, C{5}H{4}N(COOH), and which, distilled over quick-lime, yields pyridine, C{5}H{5}N. Turning now to the non-volatile and oxygenized bases, we take up first the opium alkaloids.

Its meythl ester, which can be formed from it, is codeine, one of the accompanying alkaloids of opium.

Besides the methyl derivative, however, others are possible, and several have been recently prepared, giving rise to a class of artificial alkaloids known as codeines.

Narcotine, another of the opium alkaloids, when heated with manganese dioxide and sulphuric acid, is oxidized and splits apart into opianic acid, C{10}H{10}O{5}, and cotarnine, C{12}H{13}NO{3}.

If we go now to the cinchona alkaloids, we meet with exceedingly interesting results.

If, having completed our survey of what has been done in the way of decomposing the alkaloids by the different classes of reagents, we review the field, it will be seen that with all the alkaloids mentioned, except the last four, a more or less immediate connection with the pyridine and quinoline bases has been indicated.

The conviction accordingly forces itself upon us that, if we want to attack the problem of building up any of these important alkaloids artificially, we must turn to these bases as our starting point.

At the same time that this general agreement to consider these bases as the starting point in the endeavor to effect the synthesis of the natural alkaloids had been arrived at by chemists, it was thought well to look into the question whether these bases and their immediate derivatives had any therapeutic value of their own.

In general, the hydrogen addition products were found to be more active than the simple base, an observation entirely in accord with the theory formed by Wischnegradsky, and by Konigs, as the result of the study of the decomposition products of the alkaloids, viz., the alkaloids are in general hydrogen addition products of pyridine and quinoline, or of the two bases combined.

In general, the hydrogen addition products were found to be more active than the simple base, an observation entirely in accord with the theory formed by Wischnegradsky, and by Konigs, as the result of the study of the decomposition products of the alkaloids, viz., the alkaloids are in general hydrogen addition products of pyridine and quinoline, or of the two bases combined.

The most active workers in the field of synthetic formation of the alkaloids have been Wischnegradsky, of St. Petersburgwho, unfortunately for science, died at an untimely age in 1880Königs and Fischer, of Munich, and Ladenburg, of Kiel.

The study of the decomposition products of the cinchona alkaloids especially points quite distinctly to the probable existence in quinine of a hydrogen addition product of pyridine, in combination with a methyl-quinoline group.

It must not be supposed that no syntheses of alkaloids have been effected as yet.

The formation of a series of alkaloids under the name of codeines, by the substitution of other organic radicals instead of methyl in the codeine reaction, has already been alluded to.

Ladenburg has also formed a series of artificial alkaloids, called tropeines, by uniting the base tropine with different organic acids, as in the case of the compound of mandelic acid and tropine, known as homatropine, an alkaloid of action similar to atropine, but possessing some decided advantages in its use.

We may conclude from this reference to what has been done in the last few years, that the reproach mentioned in first speaking of the alkaloids as a class, that almost nothing was known of their constitution, will not long remain, and that as their molecular structure is laid bare in these studies now being made, keen-sighted chemists will effect their artificial formation.

81 examples of  alkaloids  in sentences