482

TRIAMIDES-COMPOUNDS ANALOGOUS TO AMIDES.

three atoms of ammonia; but they have not been extensively studied. Citryltriamide or citramide affords an example of a primary triamide. It may be obtained by the action of ammonia. upon citric ether :

As an instance of a secondary triamide, phenylcitramide may be given; it may be obtained by acting upon phenylia (aniline) with citric acid ::

There is every reason to anticipate the formation of a class of compounds corresponding to the amides, in which phosphorus, arsenic, or antimony occupies the place of the nitrogen of the amides. Indeed, a primary monophosphoride, corresponding to a primary monamide, may be obtained by acting upon phosphuretted hydrogen with chloride of trichloracetyl :

and a tertiary monophosphoride, corresponding to a tertiary monamide, has been obtained by acting upon phosphuretted hydrogen with benzoyl chloride ::

The organic radicles in these compounds often have their place supplied by the metals. They are generally formed by the action of phosphuretted, arseniuretted, or antimoniuretted hydrogen upon solutions of the metallic salts. Thus a diphosphoride, tricuprophosphide, Eu,P, is obtained from cupric nitrate and

ACETAMIDE-COMPOUND AMIDES.

483

phosphuretted hydrogen; 2 H,P+3 (Єu 2NO3)=Єu ̧P2+6(HNO3): and a diarside, tricuprarside (Eu,As,) from cupric chloride and arseniuretted hydrogen ; 2 H ̧As + 3 EuCl2=Eu„As, +6 HCl : and a monastibide, triargentostibide (Ag,Sb) from nitrate of silver and antimoniuretted hydrogen; H,Sb+3(AgNO3)=Ag,Sb+3 (HN).

For a masterly discussion of the subject of amides and compound bases the reader is referred to Hofmann's paper on Ammonia and its Derivatives (Q. J. Chem. Soc. xi. 252).

The description of a few of the more interesting compounds belonging to the different classes of amides will suffice to give an idea of the general properties of these substances.

(a) Monamides, or Amides of the Monobasic Acids.

2 3

(1348) Acetamide [®;H;®}N=€,H,N0]; Fusing pt. 172°

(78° C.); Boiling pt. 430° (221° C.).-This compound is obtained in abundance by exposing acetic ether with an equal volume of aqueous solution of ammonia, under pressure, for six hours to a temperature of 248° or 257° (120° or 125° C.), then distilling the residue and collecting the distillate after the boiling point has risen to 430°. Acetamide forms a white solid which crystallizes in pearly leaflets after fusion. It is soluble in water, and has a cooling sweetish taste. When distilled with phosphoric acid its molecule loses one atom of water, and becomes converted into acetonitrile. If acetic ether be decomposed by admixture with ethylia and exposure to heat in sealed tubes, it forms a corresponding compound, ethylacetamide or aceto-ethylide, €,H,O

2

(192° C.)] is a limpid, colourless, neutral liquid, which is obtained by heating cyanic ether with acetic anhydride to about 3920, in a sealed tube. Carbonic anhydride escapes on opening the tube when cold: :

Ethyl cyanate. Acetic anhydride.

6 3

Ethyldiacetamide.

€ H.€NᎾ + € HᎾ, = ᏟᎾ, + €H, NᎾ. Trichloracetamide [€,H,C1‚N>=CN; Fusing pt. 275°

2

H2

(135° C.)] is the compound procured by decomposing trichloracetic ether with ammonia; but it is also obtained by acting upon several other perchlorinated ethylic ethers, such as the perchlo

484

MONAMIDES-BENZAMIDE.

rinated formic, carbonic, oxalic, and succinic ethers: perchloraldehyd likewise yields it when treated with ammonia. It is a crystallizable compound with a sweet taste; it is very soluble in alcohol and in ether.

11

3

(1349) Propionamide (Є,H,NO), Butyramide (EH ̧N→), and Valeramide (EH1NO) may all be obtained by the action of ammonia, aided by heat, upon their respective ethers. They are fusible, volatile compounds, which may be sublimed without decomposition; they are soluble in water, alcohol, and ether. When distilled with phosphoric anhydride, they lose the elements of one atom of water, and yield the nitriles of the acid, or the hydrocyanic ether of the alcohol below them :

(1350) Benzamide [E,H,NO; Fusing pt. 239° (115° C.)] is a white solid, which may be sublimed without undergoing decomposition. It is sparingly soluble in cold water; boiling water dissolves it easily, and deposits it, on cooling, in acicular crystals. It is still more readily dissolved by alcohol and by ether, from which it crystallizes in right rhombic prisms. When boiled with free acid or alkali, it is quickly converted into ammonium benzoate. Benzamide is most easily obtained by the action of dry ammoniacal gas upon benzoyl chloride; in which case the change is accompanied by the formation of benzonitrile. It may also be procured by heating an alcoholic solution of ammonia with benzoic ether for some hours in a sealed tube. When boiled with mercuric oxide, water is separated, and hydrargo-benzamide is obtained; 2 €,H,NO + HgO= €12H12HgÑ‚Ð2 + H ̧Ð. Hydrargo(Є,H,O)2)

14 12

benzamide may be viewed as a diamide Hg" N, or two

H2

atoms of benzamide in which half the remaining typical hydrogen has been displaced by mercury. Benzamide, when heated with potassium, loses oxygen; hydrogen is eliminated, and benzonitrile is formed:

2 €‚H‚NO+K ̧= 2 €,H ̧N + H2+ 2 KIIO.

NITRILES-DIAMIDES-OXAMIDE.

(b) Nitriles.

485

(1351) Benzonitrile (E,H,N); Sp. gr. of liquid 1007; of vapour 370; Rel. wt. 515; Boiling pt. 376° (191° C.).—This substance is a colourless oil, with a powerful odour of bitter almonds. It is sparingly soluble in water, but is miscible with alcohol and ether in all proportions. When heated it emits an inflammable vapour, which burns with a smoky flame. Benzonitrile may be obtained by the dry distillation of benzoate of ammonium, or of benzamide; and still more readily by mixing either of these bodies with phosphoric anhydride in excess before proceeding to the distillation; the distillate when washed with hydrochloric acid, and redistilled, is pure benzonitrile. Benzamide also yields benzonitrile when treated with benzoyl chloride :

Benzonitrile, when boiled with alkalies, or with concentrated acids, is converted into benzoic acid and ammonia, with assimilation of the elements of water.

Cumonitrile [E10H11N; Sp. gr. of liquid 0765; Boiling pt. 462° (239° C.)] may be obtained by similar methods from ammonium cuminate, as a liquid with a fragrant odour.

The nitriles of the fatty acids are identical with the hydrocyanic ethers of the alcohol in the series immediately below that of the acid from which they are obtained (1149).

(c) Diamides-Amides of Dibasic Acids.

(1352) The dibasic acids give rise to the formation of diamides; that is to say, to amides, each atom of which is formed from 2 atoms of ammonia. We shall examine those of two acids only, viz., the amides of oxalic acid and those of succinic acid. The latter afford an instructive illustration of the preparation and properties of primary, secondary, and tertiary diamides, from the same acid.

(1353) Oxamide [(H,N),,,, or H2 N.]-This interest

2

ing compound is most readily obtained by decomposing oxalic ether by an aqueous or an alcoholic solution of ammonia. It may also be procured, though less advantageously, by distilling ammonium oxalate, when it condenses in the neck of the retort and in the receiver in the form of white flocculi. Oxamide is a

light tasteless powder, which is insoluble in cold water, but soluble to a small extent in boiling water, from which it is deposited on cooling in crystalline flakes, The solution is neutral, and gives no precipitate with salts of calcium. It is insoluble in alcohol. It may be sublimed in an open tube, though with difficulty. When its vapour is transmitted through a red-hot tube, it is decomposed, according to Liebig, into bicarbonate of ammonia, hydrocyanic acid, carbonic oxide, and urea :

€0

Urea.

2 [(H2N) ̧¤ ̧Ð ̧] = H ̧Ñ‚Є0, + HЄN + ¤Ð + H ̧‚N ̧¤Ð.

When oxamide is heated to 436° (224°5 C.), in a sealed tube with water, it becomes transformed into ammonium oxalate. The same change is effected by boiling oxamide with dilute acids or alkalies. If heated alone in closed vessels to 590° (310° C.), it is converted into a mixture of cyanogen, carbonic oxide, and ammonium carbonate. Oxamide, in fact, contains the elements of cyanogen and water; (H,N),¤ ̧Ð ̧=(EN), +2 H2O; but the water reacting upon a portion of oxamide, converts it into ammonium oxalate, and this, by the action of heat, is resolved into ammonium carbonate and carbonic oxide:

When oxamide is boiled with mercuric oxide, the two bodies enter into combination, and form a white heavy powder Hg [(HN),¤ ̧Ð2]2.

If oxalic ether be decomposed by the alcohol alkalies, such as ethylia, methylia, and amylia, or by other bases, such as aniline, compounds are obtained corresponding to oxamide: for example, ethylia, when made to act upon oxalic ether, yields diethylox

amide, (¤¿H12N ̧Ð1⁄2), or (¤ ̧H ̧), N ̧; and aniline, under similar

12 2 2/9

H2

2

2

circumstances, if heated in a closed tube to 320° (160° C.), produces diphenyloxamide (oxanilide), 1H12N,,:

141 121 2 2 Oxanilide.

Alcohol.

Ꮎ, + 2

H2

H2