Page:Encyclopædia Britannica, Ninth Edition, v. 5.djvu/582

Rh 570 CHEMISTRY [ORGANIC. with water. Ketones containing CJrlgn+i radicles, when heated with HCN, HC1, and water, produce acids of this group : CO(CH 3 ) 2 + HCN + 20H 2 + HC1 = C(CH 3 ) 2. HO. C0 2 H + NH 4 C1. Oxybutyric acid. QQ OH Produced the J OTT 2 3. Primary Olefine Adds, CH 2n oxidation of glycols of the form C n H 2n 4. Secondary Olefine Adds, C n H 2n j c^ ( o^- n+l) R Produced by the action of nascent hydrogen on certain compounds formed by the action of sodium on ethyl acetate, CH 3 .CO(C 2 H 5 0). (See p. 573.) The following is a list of the acids of the lactic series : Carbonic acid 1 ........................ HO.CCXH Glycollic ......................... CH 8 (HO).C0 1 H Ethylidene lactic acid Ethylene ............ C,H 4 (HO).CO S H Paralactic, , Hydracrylic, , Oxybutyric acids ..................... C 3 H fi (HO).C0 2 H Oxyvaleric ...................... C 4 H 8 (HO).C0 2 H Oxycaproic ...................... C 5 H ]0 (HO).C0 2 H Oxyheptylic acid ...................... C 6 H 12 (HO).C0 2 H Oxydodecatylic ,, .................. C U H 22 (HO).C0 2 H Ethylidene lactic acid is the first product of the butyric fermentation of sugar ; ethylene and paralactic acids are contained in the juice of flesh. Lactide and dilactic acid (C 3 II 4 O 2 and C 6 H 10 6 ) are produced by the elimination of water from one and two molecules of lactic acid by heat. Series C n H 9n _ 1 O.CO 2 H, Pyruvic Series. These acids may be regarded as derived from those of the lactic series by the abstraction of H 2. The following are known : Pyruvic or pyroracemic acid ........... C 2 H 3 O.C0 2 H Epihydric ........... C 3 H 5 O.C0 2 H Acetopropionic ............ C 4 H 7 0. C0 2 H Convol vulinoleic ............ C 12 H 23 0. C0 2 H Jalapiuoleic ............ C 15 H 29 0. C0 2 H Ricinoleic ............ C 17 H 33 O.C0 2 H Series C n H 2n+1 2 .C0 2 H comprises qlyoxylic and glyceric acids, CH 3 2 .C0 2 H and C 2 H 5 O 2 .C0 2 H. Series C n H. 2n _ l .CO 2 R, Acrylic Series. The acids known in this series are the following : Acrylic acid .................................... C 2 H 3 .C0 2 H Crotonic and methacrylic acids ............ C 3 H 5 .C0 2 H Angelic and methylcrotonic acids ......... C 4 H 7 .C0 2 H Pyroterebic, hydrosorbic, and ethylcro- tonic acids ................................... C 5 H 9 .C0 2 H Moringic and cimicic acids .................. C 14 H 27 .C0 2 H Hypogceic, gaiidic, and pliysetcleic acids C 15 H 29. C0 2 H Oleic and elaidic acids ...................... C 17 H 33. C0 2 H Doeglicacid .................................... Ci 8 H 35 .C 0, 2 H Brassic and erucic acids ..................... C 21 H 41. C0 2 H These acids are produced by the oxidation of the corre sponding aldehydes, and also by the dehydration of secondary lactic acids. They may be arranged in two iso- meric series: primary adds of the form CHR&quot;.CO 2 H,a7id secondary acids, CR R&quot;.CO 2 H. These acids combine directly with 7/a 2, H//a, and are raised to the C,,H 2n+1 .CO 2 H type. On fusion with KHO they yield potassium salts of two fatty acids. Series C n H 2n _ 3 .CO 2 H contains tetroleic (C 3 H 3 .C0 2 H), sorbic (C 5 H 7 .CO 2 H), and stearolic (C 17 H 31 .C0 2 H) acids. Series C n H 2n _ 7 .C0 2 H, Benzoic or Aromatic Series. The following are known : Benzoic acid ................................. C fi H g .C0 2 H Toluic acids ................................. C 7 H 7 .C0 2 H Xylic, hydrocinnamic, mesitylenic, ) Q jj ^Q jj and ethylbenzoic acids ............. ) Cumic and cumylic acids .................. C 9 H U .C0 2 H Homocumic acid ............................. C 10 H 13. C0 2 H These acids are prepared by the general methods of oxidizing the corresponding alcohols and aldehydes, and by the action of KHO en the cyanides of the C n H 2n _ 7 radicles. Benzoic acid exists in gum-benzoin, from which it sublimes, This acid (the hydroxyl derivative of formic acid) is unknown in the free state, and is dibasic. on heating, in white feathery crystals, having a fragrant odour. By the action of Cl, HNO 3, &c., these acids yield substitution derivatives, such as C 6 H 4 C1.CO 2 H and C 6 H 4 (NO 2 ).CO 2 H, chlorobenzoic and nitrobenzoic acids. The latter, by the action of nascent hydrogen, is con verted into C 6 H 4 (NH 2 ).CO 2 H,amidobenzoic acid. Hippuric acid, the potassium salt of which occurs in the urine of many herbivorous animals, is benzamido-acetic acid CH 2 (NH.COC 6 H 5 ).C0 2 H. The aromatic acids can be arranged in two metameric series corresponding to the benzylic alcohols and the phenols. Series C n H 2n _ s (HO).CO 2 H, Oxybenzoic Series. This bears to the preceding series the same relationship as the lactic to the fatty series : and Salicylic (ortho-), oxybenzoic (meta-), paraoxybenzoic acids Anisic (or oxymethyl-benzoic), cresotic, and mandelic (or formo-benzoic) acids Phloretic, hydrocourrmric, hydroparacou- rnaric and phenyl-lactic acids Thymotic and thymyl-carbonic acids C 6 H 4 (HO).C0 2 H C 7 H 6 (HO).C0 2 H C 8 H 8 (HO).C0 2 H C 10 H 12 (HO).COJI Series C n H 2 ,,_ 9 (HO) 2 .C0 2 H, Dioxybenzoic Series, contains oxysalicylic, hypogallic, protocatecJudc, and carbolujdro- quiiionic acids C 6 H 3 (HO) 2 .CO 2 H. Allied to this series are piperic (C 12 H 10 O 4 ) and eugetic (C n H 12 O 4 ) acids. (SmesC,,H 2n _ 10 (HO) 3 .C0 2 H, Gallic Series. Gallic acid, C G H 2 (HO) 3 .CO 2 H, exists ready formed in many plants, such as sumach, hellebore, &c. Tannins are the astringent vegetable principles made use of in tanning. They all contain some form of tannic acid, C 27 H 22 O 17, a compound resolved by the action of acids into gallic acid and glucose (see p. 572). Gallic acid is generally prepared from the gallotannic acid extracted from gall-nuts. Series C n H 0n _ 9 .CO 2 H : Cinnamic, atropic, and isatropic acids, C 8 H 7 .CO 2 H. Series C,,H&amp;lt;, n _ 10 (HO).C0 2 H : Coumaric and paracouma/ ric acids, C 8 H (HO).C0 2 H. Series C n H 2n _ n .C0 2 H : Phenyl-propiolic acid, C 8 H 5 .C0 2 H. Series C n H 2n _ 13 .C0 2 H, comprising two narjhthoic acids, C 10 H 7 .C0 2 H. Series C n H 0n _ 14 (HO).C0 2 H, containing oxynaphthoic acids, C 10 H 6 (HO).CO 2 H. Series C n H 2n _ 16 (HO).C0 2 H, containing benzilic acid, C 13 H 10 (HO).C0 2 H. Series C n H 2n _ 19 .C0 2 H : Anthracenecarlonic acid, C 14 H 9 .C0 2 H. Dibasic Acids. Series C n H. 2n (CO 2 H.) 2 ,Succinic Series. The following are known : Oxalic acid (C0 2 I1) 2 Malonicacid ... CH n (C0 2 H) 2 Succinicacid ... C 2 H 4 (C0 2 H) 2 Pyrotartaric acid C 3 H 6 (C0 2 H) 2 Adipic acid C 4 H 8 (C0 2 H) 2 Pimelic acid ., Suberic acid. Anchoic acid Sebacic acid. Eoccellicacid. C 5 H 10 (C0 2 H) 4 C 6 H 12 (C0 2 H) 2 C 7 H 14 (C0 2 H) 2 C 8 H ]r ,(CO,H) 2 C 15 H 80 (CO,11) 2 These acids may be prepared by the general methods of oxidizing the corresponding alcohols (glycols), and from the cyano-olefine compounds, C n H 2n (CN) 2, by the usual reactions. Oxalic acid (sodium salt) may be synthesized by heating sodium in dry CO 2, and is manufactured on the large scale by fusing sawdust with caustic alkalies. This acid, free or combined, is found in many plants, hence the name (from Oxalis, wood-sorrel). Succinic acid exists in amber. Many of these acids are produced by oxidizing various organic substances with nitric acid. The acids of the present series are crystalline solids, forming, like all