Theoretical organic chemistry / by Julius B. Cohen.

  • Cohen, Julius B. (Julius Berend), 1859-1935.
Date:
1902
Catalogue details

Licence: Public Domain Mark

Credit: Theoretical organic chemistry / by Julius B. Cohen. Source: Wellcome Collection.

    572/604 (page 552)
    amyl alcohol, ether, chloroform, &c. The salts, especially th chloride and nitrate, are very soluble in water, and from th solution the insoluble base is precipitated by alkalis. Th platinochlorides are yellow, crystalline, and sparingly solubl substances. Most of the alkaloids are tertiary bases and forr additive compounds with the alkyl iodides. As a rule they ar present in the plant combined with organic acids, such a malic, citric, and lactic acid, or an acid peculiar to the alkaloi with which it is associated. In cinchona bark, for example, th alkaloids are combined with quinic acid, in aconite with aconiti acid, &c. With the salts of the alkaloids are frequentl associated proteids, tannins, resins, essential oils, and othe vegetable products, which have to be dealt with in the proces of extraction. For each alkaloid a special process of extraction is employee and for costly pharmaceutical preparations the estimation of th amount of alkaloid present in the raw material is effected by recognised and carefully elaborated analytical method. 1 general scheme for extraction may be briefly indicated. Th carefully ground material is digested with water, which dis solves out the salt of the alkaloid, and the solution is the: piecipitated with an alkali or lime. If the alkaloid is volatile like conine, it is separated by distillation in steam ; otherwise i is either extracted with a volatile solvent like ether, chloroform amyl alcohol, &c., or filtered. The solvent in the first case i evaporated or shaken up with acid, which dissolves the alkaloi< as the soluble salt ; in the second case, the precipitate or it salt is recrystallised. It is seldom that a single alkaloid occur in the plant ; more frequently several are associated, and bein^ chemically related, they are often difficult to separate. The free alkaloids belong to different classes of compounds such as amides or esters of organic acids in which the basil character predominates. The amides and esters are separabh into a basic and acid constituent by hydrolysis. The basic portioi often contains a hydroxyl, methoxyl, or carboxyl, or all thre< groups. Piperine is an amide, and breaks up on hydrolysi: into the base piperidine and piperic acid (p. 553) ; atropme v. an ester, and yields the base tropine and tropic acid (p. 555) Cocaine represents a still more complex type, for the bash portion contains both a hydroxyl and carboxyl group in tin