Page:Encyclopædia Britannica, Ninth Edition, v. 5.djvu/584

572 CHEMISTRY [OKGANIC. Acetyl chloride, when made to act upon potassium hydrosulphide, forms thiacetic acid: C 2 H 3 O.C1 + KHS = (C 2 H 3 O)HS + KC1 . When it is mixed with acetic acid, and acted on by sodium amalgam, the corresponding alcohol is produced : 3CH 3 .CO 2 H 4- (CH 3 .CO)C1 + 2Na 2 = 3CH 3 .CO 2 Na Acetic acid. Acetyl chloride. Sodium acetate. + CH 3 .CH 2 (HO) + NaCl . Ethyl alcohol. Some acid halides can be synthesized from hydrocarbons by the action of carbonyl dichloride (phosgene gas) C 2 H 4 + COC1 2 - (C 3 H 4 0)"C1 2 Ethene. Paralactyl chloride. C 6 H 6 + COC1 2 = C 7 H 5 O.C1 4- HC1. Benzene. Benzoyl chloride. XL ETHEREAL SALTS. These compounds are derived from acids by the substi tution of hydrocarbon radicles for hydrogen, but it is only the hydrogen entering into the composition of hydroxyl that can be thus replaced. Thus, the number of ethereal salts that any acid can form depends upon the number of times it contains HO ; in other words, an ?e-hydric acid can form n ethereal salts. It has been previously men tioned that the basicity of an organic acid depends upon the number of times it contains COOH, hence it follows that monohydric acids must be monobasic, but n-hydric acids may be 1, 2, 3, n-basic. For example, tartaric acid is tetrahydric, but as only two of its hydrogen atoms are replaceable by metals it is dibasic, and consequently contains 2(COOH). But this acid being tetrahydric con tains 4(HO) , and has thus four hydrogen atoms replace able by radicles, giving rise to four ethereal salts : Metallic ) n TT mn x /COOM n mrYk /COOH salts / ^2 il 2l lu ; 2 COOM ^a u a^ ^h COOM Normal salt. Acid salt. Ethereal ) salts, / TT / R O.COOR a n * R O.COOR HO.COOR HO.COOR nTT /HO.COOR U 2 n 2 R O.COOR HO.COOH HO.COOR Ethereal salts are normal or acid according as the carboxyl (basic) hydrogen is entirely or partially replaced by radicles. Every acid, inorganic and organic, can give rise to the formation of ethereal salts, these being in many cases pro duced by the direct action of the acid on the alcohol con taining the necessary radicle : NO 2 HO + C 6 H n .HO = N0 2 (OC 5 H U ) + OH 2 Nitric acid. Ainyl alcohol. Amyl nitrate. PO(HO) 3 + C 2 H 5 .HO = PO OH Phosphoric acid Ethyl alcohol. Mono-ethyl phosphate. CH 3 .COOH + C 2 H 5 .HO = CH 3 .CO(OC 2 H 5 ) + OH 2 Acetic acid. Ethyl alcohol. Ethyl acetate. 3CH 3 .COOH + C 3 H 5 " (HO) 3 = C 3 H 5 "(O.COCH 3 ) 3 + 30H 2 Acetic acid. Propenyl alcohol Propenyl triacetate (glycerin). (triacetin). Other methods of preparing ethereal salts are exemplified by the following reactions: C 5 H n .HS0 4 + CH 3 .COOK = CH 3 .CO(OC 5 H n ) + KHS0 4 . Amyl hydrogen Potassium . . etMe sulphate. acetate. 2C , 2Hs H0 . CA | co(oc A) + 2HC1 Succinyl chloride. Ethyl alcohol. Ethyl succinate. [In practice this reaction is effected by passing HC1 gas into a mixture of the acid and alcohol.] 3C 2 H 5 I = PO(OC 2 H 5 ) 3 + 3AgI Ethyl Triethyl iodide. phosphate. PO(AgO) 3 Triargentic phosphate. CH 3 .K.CO 3 = C 2 H 5 .CH 3 .CO Potassium ethyl Potassium methyl Methyl ethyl carbonate. carbonate. B 2 O 3 = B(OC 2 H 5 ) 3 Triethyl borate. C 2 H 5 .K.S0 4 hyl sulphate. 3C 2 H 5 .HO Ethyl alcohol. Ethyl alcohol. 2^3 Boric anhydride. SiCl 4 = Silicon tetrachloride. K 2 S0 4 B(HO) 3 Boric acid. + 4HC1 Tetrethyl silicate. Most ethereal salts are decomposed on heating with water into an acid and an alcohol. The same reaction is more speedily induced by caustic alkalies: CH 3 .CO(OC 2 H 5 ) + KHO = CH 3 .COOK + C 2 H 5 .HO . Ethyl acetate. ^etete Etn > 1 alcoho1 - The ethereal salts of nitrous acid are metameric with nitre-derivatives of hydrocarbons ; thus H 5 C 2 .NO 2 H 5 C 2 .O(NO) . Nitroethane. is metameric with Ethyl nitrite. Ethyl nitrite is produced by the action of ethyl sulphuric acid on potassium nitrite. Nitroethane is formed when ethyl iodide acts on silver nitrite. By the action of nascent hydrogen the difference in constitution between these two compounds is well brought out : 3H 2 = C 2 H 5 (OH) + NH 3 + OH 2 Alcohol. Ammonia. 3H 9 = C 9 H,.NH, + 2OH 9 . C 2 H 5 .O(NO) Ethyl nitrite. CJL.NO, Nitroethane. Amidocthane (Ethylamine). Many ethereal salts exist ready formed in various animal and vegetable substances. Thus, oil of wintergreen (Gaultherla procumbens) contains methyl salicylate, C 6 H 4 (HO).CO(OCH 3 ). The ethereal salts of glycerin (glycerides) have received special names: Palmitins. C 3 H ? (HO) 2 (C 16 H 31 !! ) , Monopal- mitin. C,H 5 (HO)(C 16 H 81 S ) S> Dipalmi- Oleins. C 3 H 5 (HO) 2 (C 18 H 33 !! ), Monolein. C 3 H 5 (HO)(C 18 H 33 2 ) 2I Diolein. C 3 H 5 (C 18 H 33 2 ) 3 , Triolein. (Triolein exists in animal fats and olire oil.) tin. C 8 H B (C 16 H 81 0,) 3> Tripalmitin. (Tripalmitin exists in palm oil and other | fats.) Stearins. C 3 H 5 (HOyC 18 H 35 2 ), Monosteaiin. 3 H 5 (HO)(C 18 H 35 2 ) ? , Distearin. C 3 H 5 (Cj 8 H 35 O 2 ) 3 , Tristearin. (Stearins occur in suet, tallow, and other fats.) Giucosides are compounds existing in vegetables which by the action of reagents or natural ferments are resolved into glucose and some other compound. Thus amygdalin, a crystalline substance from bitter almonds, <fec., when decomposed by the action of synaptase or emulsin, a ferment existing in the plant, is converted into glucose, benzoic aldehyde, and hydrocyanic acid : C 20 H 27 NO U 4r 20H 2 = C 7 H 6 O 4- HCN 4- 2C 6 H 12 O 6 . Among the more important giucosides are : Gallotannic acid (C 27 H 22 17 ), from oak-galls, sumach, &c. Salicin (C 13 H 18 7 ), from bark and leaves of poplar and willow. sEsculin (C 21 H 24 13 ), from bark of horse-chestnut, &c. Glycyrrhizin (C 24 H 36 9 ), from liquorice root. Quercitrin (C 33 H 30 17 ), from bark of quercitron (Quercus infectoria). Phlorizin (C 21 H 24 Oi . 20H Z ), from root bark of apple, pear, plum, and cherry. Many of the vegetable colouring matters employed in dyeing are giucosides. Thus indican, from woad (Isatis tinctoria), is a colourless substance decomposed by acids into indigo-blue and a glucose-like body (indiglucin) : 2C 26 H 31 N0 17 + 40H 2 = C 16 H 10 N 2 2 + 6C 6 H 10 O 6 . Indican. Indigo blue. Indiglncin.

The most valuable tinctorial constituent of madder-root