ACID-AMIDES, chemical compounds which may be considered as derived from ammonia by replacement of its hydrogen with acidyl residues, the substances produced being known as, primary, secondary or tertiary amides, according to the number of hydrogen atoms replaced.
Of these compounds, the primary amides of the type Rï¿½COï¿½NH 2 are the most important.
By the action of bromine and alcoholic potash on the amides,, they are converted into amines containing one carbon atom less than the original amide, a reaction which possesses great.
On the preparation of the substituted amides from the corresponding sodamides see A.
The secondary and tertiary amides of the types (RCO) 2 NH and (RCO) 3 N may be prepared by heating the primary amides or the nitriles with acids or acid anhydrides to 200° C. Thiamides of the type R.
The fate of these inorganiccompounds has not been certainly traced, but they give rise later on to the presence in the plant of various amino acid amides, such as leucin, glycin, asparagin, &c. That these are stages on the way to proteids has been inferred from the fact that when proteids are split up by various means, and especially by the digestive secretions, these nitrogen-containing acids are among the products which result.
Taking as types hydrogen, hydrochloric acid, water and ammonia, he postulated that all organic compounds were referable to these four forms: the hydrogen type included hydrocarbons, aldehydes and ketones; the hydrochloric acid type, the chlorides, bromides and iodides; the water type, the alcohols, ethers, monobasic acids, acid anhydrides, and the analogous sulphur compounds; and the ammonia type, the amines, acid-amides, and the analogous phosphorus and arsenic compounds.
Considering derivatives primarily concerned with transformations of the hydroxyl group, we may regard our typical acid as a fusion of a radical R CO - (named acetyl, propionyl, butyl, &c., generally according to the name of the hydrocarbon containing the same number of carbon atoms) and a hydroxyl group. By replacing the hydroxyl group by a halogen, acid-haloids result; by the elimination of the elements of water between two molecules, acid-anhydrides, which may be oxidized to acid-peroxides; by replacing the hydroxyl group by the group. SH, thio-acids; by replacing it by the amino group, acid-amides (q.v.); by replacing it by the group - NH NH2, acid-hydrazides.
It is necessary clearly to distinguish such compounds as the amino- (or amido-) acids and acid-amides; in the first case the amino group is substituted in the hydrocarbon residue, in the second it is substituted in the carboxyl group.
Thus from the acid-amides, which we have seen to be closely related to the acids themselves, we obtain, by replacing the carbonyl oxygen by chlorine, the acidamido-chlorides, R CC1 2 NH 2, from which are derived the imido-chlorides, R CC1:NH, by loss of one molecule of hydrochloric acid.
The carbonyl oxygen may also be replaced by the oxime group,: N OH; thus the acids yield the hydroxamic acids, R C(OH): NOH, and the acid-amides the amidoximes, R C(NH 2): NOH.
The first class includes those substances which require no preliminary treatment, and comprises the amides and ammonium compounds, pyridines, quinolines, alkaloids, albumens and related bodies; the second class requires preliminary treatment and comprises, with few exceptions, the nitro-, nitroso-, azo-, diazoand amidoazo-compounds, hydrazines, derivatives of nitric and nitrous acids, and probably cyanogen compounds.
Oxazoles are produced on condensing phenacyl bromide with acid-amides (M.
They are prepared by condensing thio-amides with a-haloid ketones or aldehydes, the thio-amide reacting as the tautomeric thio-imino acid.
Dihydrothiazoles, or thiazolines, are obtained by condensing ethylene dibromides with thio-amides; by the action of a-haloid alkylamines on thio-amides (S.
Freund, Ber., 1896, 29, p. 2483); by the condensation of hydrazides with acid amides; and by the distillation of the triazolones (see below) with phosphorus pentasulphide.
C H 6h4< >Nr - > C 6 1-14ï¿½ +Nh2r]]; CO > CO COOH by distilling the amino-acids with baryta; by the action of bromine and caustic potash on the acid-amides (A.
Other reactions which introduce carboxyl groups into aromatic groups are: the action of carbonyl chloride on aromatic hydrocarbons in the presence of aluminium chloride, acid-chlorides being formed which are readily decomposed by water to give the acid; the action of urea chloride Clï¿½COï¿½NH 2, cyanuric acid (CONH) 3, nascent cyanic acid, or carbanile on hydrocarbons in the presence of aluminium chloride, acid-amides being obtained which are readily decomposed to give the acid.
The ammonium salts when heated lose one molecule of water and are converted into acid-amides, R.
3, p. 319.) Ammonia finds a wide application in organic chemistry as a synthetic reagent; it reacts with alkyl iodides to form amines, with esters to form acid amides, with halogen fatty acids to form amino-acids; while it also combines with isocyanic esters to form alkyl ureas and with the mustard oils to form alkyl thioureas.
They may be prepared by heating the alkyl iodides with potassium cyanide; by heating sulphuric acid esters with potassium cyanide; by distilling the acid-amides with phosphorus pentoxide; and by distilling amines (containing more than five atoms of carbon) with bromine and potash (A.
They behave in most respects as unsaturated compounds; they combine with hydrogen to form amines; with water to form acidamides; with sulphuretted hydrogen to form thio-amides; with alcohols, in the presence of acids, to form imido-ethers R C(:NH) OR'; with ammonia and primary amines to form amidines R C(:NH) NH 2 i and with hydroxylamine to form amidoximes, R C(:NOH) NH 2.
Acid amides also react to form ketones (C. Beis, ibid., 1903, 1 37, 575): R Conh 2 - E Rr' :C(OMgX) NHMgX R'H--R CO.
The latter readily undergo the " Beckmann " transformation on treatment with acid chlorides, yielding substituted acid amides, RR' C:NOH -› RC(NR') OH - R CO NHR' (see OxIMES, also A.
] Hydrogen peroxide behaves very frequently as a powerful oxidizing agent; thus lead sulphide is converted into lead sulphate in presence of a dilute aqueous solution of the peroxide, the hydroxides of the alkaline earth metals are converted into peroxides of the type MO 2.8H 2 0, titanium dioxide is converted into the trioxide, iodine is liberated from potassium iodide, and nitriles (in alkaline solution) are converted into acid-amides (B.
NH 2, which may be considered as derived from the acid-amides by replacement of oxygen by the divalent imino (= NH) group. They may be prepared by the action of ammonia or amines on imide chorides, or on thiamides (0.
Bernthsen); by the action of ammonium chloride or hydrochlorides of amines on nitriles; by condensing amines and amides in presence of phosphorus trichloride; by the action of hydrochloric acid on acid-amides (0.
They are monacid bases, which are not very stable; they readily take up the elements of water (when boiled with acids or alkalies), yielding amides and ammonia.
Gattermann, Ann., 1888, 244, p. 30), melts at 50° C. and boils at 61-62° C. In the presence of anhydrous aluminium chloride it reacts with aromatic hydrocarbons to form the amides of aromatic acids.
Those containing more than one acyl group are formed by the action of carbonyl chloride on acid amides: COC1 2 +2CH 3 Conh 2 = Co(NHCOCH3)2+2HC1.
They are obtained by condensing a halogen derivatives of ketones with acid-amides (M.
The dihydro-oxazoles or oxazolines are similarly formed when 13-halogen alkyl amides are condensed with alkali (S.
It also acts in an opposite manner in certain cases, adding the elements of water to compounds; thus, nitriles are converted into acid-amides, and various acetylene derivatives may be caused to yield ketonic derivatives.