Page:Encyclopædia Britannica, Ninth Edition, v. 5.djvu/590

Rh 578 All the known amides are white crystalline solids, many of them possessing both acid and basic properties ?&amp;gt;&amp;lt;_ iled with acids or alkalies the primary amides regenerate their parent acids : CH 3 .CO(NH 2 ) + HC1 + OH 2 = CH 3 .COOH + NH 4 C1 Acetamlde. Acetic acid. CH 3 .CO(NH 2 ) + KHO = CH 3 .COOK + NH 3. Acetamide Potassium acetate. Distilled with P 2 O 5 primary amides are converted into nitriks : CH 3 .CO(NH 2 ) - OH, = CH 3 .CN Acetamide. Acctonitvile. C C H 5 .CO(NH 2 ) - OH 2 = C 6 H 5 .CN Benzamide. Benzonitrile. C 2 2 (NH 2 ) 2 - 20H 2 = (CN),. &quot;Oxamide. &quot; Cyanogen. Amic adds are intermediate between the amides and their parent acids, from which they are produced by sub mitting the acid ammonium salts to dry distillation : CO(ONH,) _ / CO(NH ) COOH : COOH &quot; &quot;* Oxamic acid. Acid ammonium oxalate / CO(ONH 4 ) 1 COOH _ ( CO(NH 2 7t Acid ammonium succinate. Succinamic acid. Diamides of dibasic acids must be distinguished from secondary monamides containing dyad acid radicles. The latter are termed imides. Thus, - 20H 3 - [C 2 H 4 (CO) 2 ]&quot;(NH)&quot;. Succinimide. Ethereal salts of amic acids have been obtained by various methods. The following are a few examples : CO&quot;(NH 2 )(OC 2 H 6 ) (&amp;lt;&quot;&amp;lt; &quot; V/IIA i Ethvl carbamate. Acid ammonium fuccinate. V fHOl ) 10) Etliyl malamate. CO [NH(C 6 H B )](HO)(C S H,)&quot; (OC 6 IT B ) { CO(NH.) ( CO(OC,H 8 ) Ethyl oxamate. fCO(NH.C,H ) I ^w^&amp;lt;_/j.l .11 j Ethyloxomlc acid. Phe nylcarbamic acid. : Ammoaium phenylmalamate. The salts formulated above, containing the radicle in the carboxyl group, are neutral; those in which the radicle replaces amido-hydrogen are acid. The ammonium salt of carbamic acid is formed by the direct action of carbon dioxide on ammonia: CO 2 + 2NH 3 = CO&quot;(ONH 4 )(NH ). The neutral ethereal salts of carbamic acid are known as urethanes. Alkalamides are compounds intermediate between amines and amides, that is, containing both positive and negative radicles. The following are examples : C 2 H S N&amp;lt;jC 2 H 5 (H Ethyl acetamide. f C 2 H N J CoH o l.l..j_/ ( C 2 H 3 Ethyl diacetamide. ( C-H..O i { C T H:O I c &, Phenyl dibenzamide X Diethyl It has been previously mentioned that cyanic acid forms T hvo classes of compounds analogous to the nitriles and carbamines. Sulphocyanic acid forms two analogous series. The ethereal salts of the iso-series derived from these acids can be formulated as alkali mides : X CO&quot; H X CO&quot; CH, CS&quot; Cyanic acid, Methyl isocvanate. Ethyl isosulpho- Phenyl isosulpho- or carbimide. or methyl carbimide c &amp;gt; anate - . et iy cyanate, or phenyl sulphocarbimide sulphocarbimide Allyl isosulphocyanate, N(CS)&quot;(C 3 H 5 ), is interesting as being obtained from oil of mustard. Carbamide and Urea CO (NIL,) . These compounds [ORGANIC. are the neutral amides of carbonic acid. Urea is the chief solid constituent of human urine, and is interesting as being the first organic compound synthesized (Wohler, 182S). It was first produced artificially by heating a solution of ammonium cyanate : CNO(NH 4 ) = CO(NH 2 ) 2 . Urea may also be obtained by the action of ammonia on carbon oxydichloride : COC1 2 + 4NH 3 = CO(NH 2 ) 2 + 2NH 4 C1 ; by the action of ammonia on ethyl carbonate : CO(OC 2 H 5 ) 2 + 2NH 3 = CO(NH 2 ) 2 + 2C 2 H 5 .HO ; and by the action of heat on ammonium carbamate and carbonate i 2CO(NH 2 )(ONH 4 ) = CO(NH ) 9 + (NH 4 ) 2 C0 3, and (NH 4 ) 2 CO, - 2OH 2 = CO(NH 2 ) 2 . Urea crystallizes in long white 4-sided prisms, very soluble in water and alcohol. It combines with acids, form ing compounds like CO(NH 2 ) 2 .HC1, CO(NH 2 ). 2 .HNO 3 , and with metallic oxides, forming such compounds as CO(NH 2 ) 2 .2HgO . Heated with water to a very high- temperature, it decomposes into carbon dioxide and am monia : CO(NH 2 ) 2 + OH 2 = CO., + 2NH 3 ; by the action of nitrous acid it is decomposed into carbon dioxide, nitrogen, and water: CO(NH 2 ) 2 + N,O 3 = CO 2 + 2OH 2 + 2N 2. Urea is also decomposed by chlorine with the for mation of cyanuric acid, &c. : 6CO(NH 2 ) 2 + 3C1.&amp;gt; = 2H 3 C 3 N 3 O 3 + 4NH 4 C1 + N 2 + 2HC1. Urea combines with aldehydes, with the elimination of water, giving rise to a series of compounds termed ureides. By the action of heat on ammonium sulphocyanate, sidpho- urea, CS(NH 2 ) 2, is obtained. Compound ureas are derived from urea by the replace ment of amido hydrogen by hydrocarbon radicles. Some of the methods employed in their production are shown, by the following equations : HCNO + N(C 2 H 5 )H 2 = C Cyanic acid Ethvlamlnc. HCNO + N(C 2 H 5 ),H Cyanic acid. Diethylamine. 2N(C e H 5 )H 2 + CS 2 = Ani-e. dl ^ c Diethyl Diphenyl sulpha men. urea. - +SH 2. Uric Acid (C 5 N 4 H 4 O 3 ) is contained in human urine^ serpents excrement, guano, &c. It is a dibasic acid yield ing a large number of derivatives by oxidation, tire. It has never been obtained artificially. UNCLASSIFIED ORGANIC COMPOUNDS. These are substances of which the formulae have not yet been satisfactorily determined, owing to their com plexity of composition and to the difficulty of obtaining them in a state of purity. The names and sources of some of these compounds are given below. Mucilage, abundant in linseed., mallow root, &c.; allied to starch and gum ; soluble in cold water. Gum-tragacanth, a kind of mucilage, insoluble in water, but becoming soft and gelatinous. Pectin (C 32 H 4S O 32 f), a transparent jelly contained in most ripe fruits ; soluble in water, precipitated by alcohol. It is probably allied to the carbohydrates (p. 564). Justus, allied to theterpenes. Common resin (colophony), from pine, contains two acids, abietic acid (C 44 H 6t O 5 ) and pinic acid (C 20 H 30 O 2 ), the former crystalline, the latter amorphous. Other well-known resins are lac, mastic, copal, sandarac, dragon s blood, &c. Amber is probably a fossil resin. Caoutchouc (India-rubier) and gutta-percha are the hardened juices of species of Ficus, Euphorbia, Isojiandra^ &c. These substances appear to consist of a mixture of terpenes (p. 559)
 * (C 2 H,) 2.