H2

succinic ether is mixed with twice its volume of a concentrated solution of ammonia, alcohol is liberated, and succinamide is deposited in the form of a granular crystalline compound. It is nearly insoluble in cold water, but is dissolved by boiling water in considerable quantity. Alcohol and ether do not dissolve it.

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2

Succinimide, or disuccinamide [(EH ̧Ð ̧)”‚H2N ̧‚2 H2O]; Fusing pt. 410° (210° C.).—The simplest method of procuring this compound consists in neutralizing a solution of succinic acid with ammonia, evaporating to dryness, and submitting the residue to distillation. It may also be obtained by causing dry ammonia to react upon succinic anhydride; during this reaction water is formed, and a considerable elevation of temperature occurs:--

When succinamide is heated, ammonia is evolved, and disuccinamide is formed :

At a temperature above 401° (205° C.), it sublimes without decomposition, and may be purified, by crystallization, from its solution in boiling water, which on cooling deposits it in beautiful, efflorescent, rhombic tables. It is freely soluble in water, and the solution has a feebly acid reaction; alcohol also dissolves it, but it is insoluble in ether. Disuccinamide is metameric with succinamic acid. It yields a crystallizable compound with silver, (€HO,)”) (C,H,O,)” N,, [=2 €H_AgNO,] ; Ag2

termed succinimidate of silver (argento-disuccinamide)

4 2

this body is obtained in needles by mixing a boiling concentrated alcoholic solution of disuccinamide, rendered slightly alkaline by ammonia, with a hot alcoholic solution of nitrate of silver: the salt is deposited as the liquid cools. It is not decomposed by potash in the cold, but on the application of heat to the mixture ammonia is evolved. Argento-disuccinamide is freely soluble in ammonia, and if the solution so obtained be left to spontaneous

488

TRISUCCINAMIDE-OXAMIC ACID.

evaporation, a syrupy alkaline liquid is left, which gradually becomes converted into a mass of rectangular prisms [2,H,AgNO,, 2 H ̧N], from which potash immediately liberates ammonia. Argentodisuccinamide is decomposed with explosion when suddenly heated : it is isomeric with succinamate of silver, into which it is converted if its ammoniacal solution be boiled for some time; it then becomes much more soluble, and is no longer explosive.

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3

Trisuccinamide [(¤ ̧H ̧Ð ̧)" ̧N2]; Fusing pt. 181° (83° C.).— When 10 parts of succinyl chloride (1302) are dissolved in twice their volume of ether, and mixed with 27 parts of argentodisuccinamide, an immediate reaction occurs, sufficient heat is emitted to volatilize the ether, and chloride of silver is formed :

Boiling ether dissolves it under pressure, and on cooling deposits it in small crystals. Water and alcohol decompose this compound, alcohol converting it into disuccinamide without the formation of succinic ether.

(d) Amidated Acids.

(1355) A single instance will sufficiently illustrate the nature of these bodies, after what has been already stated of their general properties: but the existence of this class of substances is not confined to the compounds of organic chemistry, since both sulphuric and carbonic acids yield amidated acids, viz., the sulphamic and carbamic acids; these bodies being produced by the reaction of dry ammonia upon sulphuric and carbonic anhydrides; the compounds to which the term of ammonides was applied (610) being supposed by Laurent and Gerhardt to be amidated salts of ammonium.

(1356) Oxamic Acid (H,H2N‚¤ ̧Ð ̧).—When the acid oxalate of ammonium [(H1N‚Í‚¤ ̧¤ ̧),H2O] is exposed to a carefully regulated heat, it loses its water of crystallization, and begins to undergo decomposition at a temperature of about 430° (221° C.), giving off water, carbonic acid, formic acid, and carbonic oxide. The residue in the retort, if not heated too strongly, consists of oxamide and an acid substance soluble in water. This soluble compound is oxamic acid. It may be neutralized by baryta water, or by lime water, and yields crystalline salts of these bases on evaporating the solution. If its aqueous solution be boiled, it is reconverted into the acid ammonium oxalate, H,H,NE,Ð ̧

AMIDIC ACIDS-THE ORGANIC BASES.

489

+H2O=HH ̧Ñ€,0,. Oxamic acid may be still more readily prepared by decomposing an alcoholic solution of oxalic ether by an alcoholic solution of ammonia in excess; oxamide is formed, and in a day or two the liquid deposits crystals of oxamethane (Є,H,,H,N¤ ̧Ð ̧) mixed with those of ammonium oxamate. The latter may be separated from the oxamethane by dissolving the mixture of the two substances in hot alcohol, adding an alcoholic solution of calcic chloride, and separating the sparingly soluble calcic oxamate by filtration.

5'

A large number of dibasic acids form compounds analogous to oxamic acid, such as the following:

The amido-acids, of which amido-benzoic (benzamic) is the representative, will be considered hereafter. (1436, 1614.)

§ II. THE ORGANIC BASES.

(1357) The ALKALOIDS, or organic alkalies, are not less numerous than the organic acids; they form a natural group of high interest to the chemist, not only on account of their remarkable composition, but also from their powerful effects as medicinal or poisonous agents upon the animal economy.

In the majority of instances the natural organic bases are derived from the vegetable kingdom, and constitute the active principle of the plant that contains them. They always occur in combination with some acid, which is also frequently of organic origin, and peculiar to the plant or family of plants in which it is found. In many cases the alkaloids which occur in one species of a natural family are found also in several of the other members of the same family.

The vegetable bases when in solution have generally a decidedly alkaline reaction upon test papers, and for the most part they completely neutralize the acids, forming definite and well-crystallized salts. They obey the usual law of bases when their salts

It is much to be regretted that a uniform system of nomenclature has not been adopted for these compounds; that the termination ia, for example, as in morphia and strychnia, has not been appropriated to the bases, to indicate their

are submitted to electrolytic analysis; since under these circumstances the base is liberated at the platinode of the voltaic battery. Most of these bases are dissolved sparingly by water, but are more freely soluble in alcohol, especially when it is at a boiling temperature; the alcoholic solutions as they cool generally deposit the alkaloids in the crystalline form. Some of these bases occur in two isomeric conditions, one of which is crystallizable, and the other amorphous; both forms combine with acids in the same proportion, but the crystalline variety alone yields crystalline salts.

20 24 2

The organic bases may be subdivided into two well-marked classes-1st. Those which, like aniline (ЄH,N), do not contain oxygen and 2nd. Those which, like quinia (EHNO, 3 H2O), do contain it. The bases of the first class are oily and volatile; they absorb oxygen rapidly from the air: this class has recently been augmented by the formation of numerous artificial alkaloids, many of which closely resemble aniline in properties, and may, like aniline, be regarded as derivatives of ammonia. Less is known of the derivation and rational composition of the second and more complicated class of oxidized bases.

All of the volatile bases have a powerful odour; they may be distilled either alone or with the vapour of water, without undergoing decomposition. Advantage is taken of this property in their preparation or extraction; it is sufficient to digest the plant containing them in a weak alkaline ley, and to submit the mixture to distillation. A portion of ammonia always comes over with the condensed products, which are neutralized by sulphuric acid, then evaporated, and afterwards digested with alcohol. This menstruum leaves the ammonium sulphate, but dissolves the sulphate of the organic base, which may be purified by recrystallization. If this salt be agitated with a mixture of equal parts of a strong solution of caustic potash and ether, the mixture separates on standing into two layers, the upper one consisting of an ethereal solution of the volatile base. If this ethereal solution be decanted, and placed in a retort and distilled, the

analogy with ammonia: the termination ine, might then have been restricted to the neutral principles. Both these terminations are now attached indifferently, by many writers, to the bases, and it might be attended with inconvenience were the attempt uniformly made to alter the termination familiarized by usage. In this work I have generally indicated the neutral bodies, such as salicin, amygdalin, &c., by the termination in, reserving the ending, ine, for those which have basic properties, in cases where that in ia could not well be used.

METHODS OF TESTING FOR THE ORGANIC BASES.

491

ether is first expelled, and the base may afterwards be obtained in a state of purity in the last portions which pass over.

The general process of extracting the alkaloids which are not volatile is simple. The rasped or powdered vegetable is digested with dilute sulphuric or hydrochloric acid, by which the organic salt of the alkaloid is decomposed, and a more soluble sulphate or hydrochlorate is formed. To the filtered solution, ammonia, magnesia, or sodic hydrocarbonate (NaHCO3) is added, by which a copious precipitate of the impure alkaloid is occasioned; and this, if magnesia be used, is mingled with the excess of this earth, and often with an insoluble compound of the organic acid with magnesia. The precipitate is treated with boiling alcohol, from which, on cooling, the alkali generally crystallizes: it is redissolved in sulphuric or hydrochloric acid, digested with animal charcoal, and the salt is purified by recrystallization. Animal charcoal, though it perfectly removes the colour, has in many cases, however, the serious disadvantage of retaining also a large proportion of the salt of the organic alkali; and if a great excess of charcoal be used, almost the whole of the salt may be withdrawn from the solution.

In the search for an organic base in cases of suspected poisoning by one of these substances, Stas recommends the adoption of the following method (Chem. Gaz., 1852, 350):-To the contents of the stomach add twice their weight of pure concentrated alcohol, then from 10 to 30 grains of tartaric acid, and heat the mixture in a flask to 160° or 170° (71° to 77° C.); allow it to cool completely; filter, and wash the residue with strong alcohol. Evaporate the filtrate in vacuo or in a current of air at a temperature not exceeding 90° (32° C.), filtering the solution if any fat separates; treat the dry residue with cold absolute alcohol; evaporate in vacuo; dissolve the acid residue in a few drops of water, adding hydropotassic or hydrosodic carbonate (bicarbonate) till it ceases to produce effervescence; then agitate with four or five times its bulk of pure ether. When clear, allow a portion of this ethereal solution to evaporate spontaneously in a very dry place in this way the base is obtained in a state of purity sufficient to allow of its examination by its characteristic reagents. If sulphuric acid be added to the ethereal solution, the sulphates of the following volatile bases may be separated in the crystalline form-ammonia, tetrylia, nicotylia, aniline, quinoline, and picoline; conylia sulphate is slightly soluble in ether. Stas states that he has thus successfully isolated morphia, codeia, strychnia, brucia, veratria, cmetia, atropia, hyoscyama, aconitina, and colchinia, all of which,