None
On the phenomenon of the " double melting-point " of palmitin and stearin, see C. 1902, I. 1196. Triolein, or Olein, C3H5(O.C18H33O)3, solidifies at —6°. It is found in oils, like olive oil. It is oxidized on exposure to the air. Nitrous acid converts it into the isomeric elaidin, m.p. 36° (p. 301). Lecithins are widely distributed in the animal organism and occur especially in the brain, in the nerves, the blood corpuscles, and the yolk of egg, from which stearin-palmitic lecithin is most easily prepared. Lecithin occurs in the seeds of plants (B. 29, 2761). It is a wax-like mass, easily soluble in alcohol and ether, and crystallizes in fine needles. It swells up in water and forms an opalescent solution, from which it is reprecipitated by various salts. It units with bases and acids to salts, forming a sparingly soluble double salt, (C42H84NPO8.HC1)2.- PtCl4, with platinic chloride. Lecithin is decomposed into choline, glycero- phosphoric acid (see above), stearic acid, and palmitic acid, when it is boiled with acids or barium hydroxide solution. Therefore we assume it to be an ethereal compound of choline with glycerophosphoric acid, combined as glyceride with stearic and palmitic acids : CH2— O.COC17H,. CH— O.COC16H31 CHa— O.PO(OH).O.CH2CH2>N'OH Lecithin is optically active — dextro-rotatory. When heated in alcoholic solution to 90-100° it is racemized, and from this i-lecithin, l-lecithin can be separated by lipase (C. 1901, II. 193 ; 1906, II. 493). The distearin and dioleo- compounds are also known. Protagon, a substance obtained from the brain, appears to be closely related to the lecithins. Glycerol Ethers : i . Alkyl Ethers. Mixed ethers of glycerol with alcohol radicals are obtained by heating the mono- and dichlorhydrins with sodium alcoholates. Epichlorhydrin, sodium hydroxide solution, and an alcohol form glycerol dialkyl ether (C. 1898, I. 237). Monoethylin, CHaOH.CHOH.CH2OC2H6, b.p. 230°, is soluble in water. rlycerol Dimethyl Ether, b.p. 169°. Diethylin, CH2OH.CH(OC2H6)CH2OC2H6, b.p. 191°, dissolves with difficulty in water, and has an odour resembling that of peppermint. Triethylin, C3H6(OC2H5)3, b.p. 185°, is insoluble in water. Allylin, CH2OH.CHOH.CH2C3H6, b.p. 225-240°, is produced by heating glycerol with oxalic acid (B. 14, 1946, 2270), and is present in the residue from the preparation of allyl alcohol (p. 123). It is a thick liquid. DiallyUn, HO.C3H5(OC3H6)2, b.p. 225°-227, is produced when sodium allylate acts on epichlorhydrin (B. 25, R. 506). Dialkyl Ethers of Homologous Glycerols. Fatty acid esters are condensed with chloromethyl alkyl ethers to form dialkyl ethers of homologous glycerols by means of magnesium, which can be rendered more active by means of HgCl2 (C. 1907, I. 871) : RCOOC2H6+2ClMgCHaOC2H6 > RC(OH)(CH2OC2H6)2. These diethylines yield acroleins, similarly to glycerol itself, when treated 532 ORGANIC CHEMISTRY with oxalic acid : two molecules of alcohol are eliminated and o-alkyl acroleins result (comp. p. 214). Ethyl Glycerol Diethyl Ether, C2HBC(OH)(CH2OC2H6)2, b.p. 195°, is prepared from propionic ester, chloromethyl ethyl ether and magnesium. Propyl Glycerol Diethylin, b.p. 210°; the Isobutyl, b.p. 215°; n-Amyl, b.p.13 119°; Hexyl, b-P-i5 I36° I Octyl, b.p.16 160° ; Decenyl Glycerol Dimethylin, b.p.12 180°. 1, 7 -Dimcthoxy heptane- $-ol, HC(OH)[CH2CH2CH2OCH3]2, b.p. 247°, is pre- pared from formic ester, y-methoxypropyl iodide and magnesium. It is a liquid possessing a very bitter taste (C. 1906, I. 332). 2. Cyclic Ethers : /CH,— O.CH2 /CH2.O.CH2\ / Glycerol Ether, CH^ O ^CH or CH, /OCH, b.p. 171°, is \CH2.O.CH/ \ / | \CH — OCH± formed when glycerol is heated to 270-330°, with a little ammonium chloride (A. 335, 209) ; also, together with diallylin, from epichlorhydrin and sodium allylate (see above). It is readily soluble in water, and is hydrolyzed with difficulty. An isomeric substance, m.p. 124°, has been obtained as a by-product of the preparation of pyridine bases from glycerol and ammonium phosphate (comp. p. 528) (C. 1897, I. 583). Glycerol derivatives resemblingthe acetalsare formed when formaldehyde, acet- aldehyde, acrolem, benzaldehyde, or acetone act on glycerol hot, or in presence of /O.CH, /O. hydrochloric acid. Formal Glycerol, CH2< orCH2< xO.CH.CHaOH XXCH b.p. 193° (A. 289, 29 ; 335, 209). Acetal Glycerol, HOC8H6O2>CHCH3, b.p.18 86°. a-Acrolein Glycerol, HO.C3H6O2>CH.CH:CH2, is isomeric with glycerol ether or /S-acrolem glycerol (g.v.). Benzal Glycerol, HOC3H5O2>CHC6H6, m.p. 66°. Acetone Glycerol, HOC3H6O2>C(CH3)2, b.p.n 83° (B. 27, 1536 ; 28, 1169). XCH.CH2OH Glycide Compounds: Glycide, Epihydrin Alcohol, Oc | , b.p. 162°, XCH? D0 = i-i65, is isomeric with acetyl carbinol (p. 341). This body shows the properties both of ethylene oxide and of ethyl alcohol. It is obtained from its acetate by the action of sodium hydroxide or barium hydroxide. Glycide and its acetate reduce ammoniacal silver solutions at ordinary temperatures. Glycerol also forms polyglycerols. Thus glycerol yields Diglycerol, (HO)?.C3 H 6OC3H 6 (OH) 2, when it is treated with chlorhydrin or aqueous hydrochloric acid a f^TT — j(~\ f^T-T f^TT O TT 130'. The polymer of glycide, " results from the action of sodium acetate on epichlorhydrin in absolute alcohol and the subsequent hydrolysis of diglycide acetate with sodium hydroxide. /CH.CH2C1. Epichlorhydrin, O< b.p. 117°, Df = 1*203, is isomeric with mom NCH, chloracetone, and constitutes the parent substance for the preparation of th< glycide compounds. It is obtained from both dichlorhydrins by the actior of alkali hydroxides (analogous to the formation of ethylene oxide from gly chlorhydrin) (p. 319) : C1CH2.CHOH C1CH2.CH v C1CH.CH2C1 CH2C1 CHj/ HOCH, It is a very mobile liquid, insoluble in water. Its odour resembles that chloroform, and its taste is sweetish and burning. It forms a-dichlorhydrin wit concentrated hydrochloric acid. PC16 converts it into trichlorhydrin. Coi tinued heating with water to 180° changes it to a-monochlorhydrin. centrated nitric acid oxidizes it to j8-chlorolactic acid. Metallic sodium co it into sodium allylate, CHa=CH.CH,ONa. DIHYDROXY-ALDEHYDES 533 Like ethylene oxide, epichlorhydrin combines with HNC to the hydroxy- cyanide, C3H6Cl/°^. Epibromhydrin, C8H6OBr, b.p. 130-140°, is prepared from the dibrom- hydrin. Epi-iodohydrin, C8H6OI, b.p.,a 62°, is prepared from epichlorhydrin by the action of KI and alcohol, and subsequent treatment with aqueous alkali hydroxides. Epihydrin-ether, [O<C3H6]aO, b.p.22 103°, is produced from the above by means of silver oxide; and Nitroglycide, NO2.OC3H5>O, b.p.,, 63°, by silver nitrate. It also results when alkali acts on either of the two dinitroglycerols (p. 530) (A. 335,238; B. 41, 1117). Di-epi-iodohydrin, ICHa.CH/£~^*«\CH.CH2I, m.p. 160°, is formed when iodine acts on mercury allyl alcohol iodide, (C3H5O.HgI)2. This body, as well as mercury propylene-glycol iodide, IHg.CH8CH(OH)CH2OH, is also obtained from allyl alcohol and mercury salts (comp. Mercury Ethanol Iodide, p. 326) (B. 34, 1385. 2911). Epiethylin, Ethyl Glycide Ether, O<C3H6.OCaH8, b.p. 129°, and Amyl Glycide Ether, b.p. 188°, are produced from the respective ethers of chlorhydrin by distillation with potassium hydroxide (A. 335, 231). Glycide Acetate, O<X3H6.OCOCH3, b.p. 169°, is formed from epichlorhydrin and anhydrous potassium acetate. Nitrogen Derivatives of the Glycerols. Nitroisobutyl Glycol, CH3C.(NOa)(CHaOH)a> b.p. 140°, is formed from nitro- ethane and formaldehyde (B. 28, R. 774). i-Aminopropane Diol, NH,.CHaCH(OH)CH2OH, b.p.m 238°, is formed from glycide and aqueous ammonia. Similarly, the i-alkyl aminopropane diols can be prepared ; tertiary amines react with glycerol a-chlorhydrin to form quarternary ammonium chlorides, e.g. (CaH,)8N(Cl)CH2CHOH.CH2OH (B. 33, 3500). 2- Aminopropane Diol, HOCHa.CH(NHa).CHaOH, is formed when dihydroxyacetone oxime is reduced (B. 32, 751). 2- Amino-tert. -butane Diol, CH8C(NH2)(CHaOH)a (C. 1908, I. 816). From i,3~Diamino-2-propanol is derived the local anaesthetic Alypin, C6H5CO.OCHrCH2N(CH8)a]a (C. 1905, II. 1551); also i.^-Dianilinopropanol, (C6H5NHCHa)aCHOH, from aniline and epichlorhydrin (B. 37, 3034); also, finally, Trimethylene-imino-2-sulphonic acid. This substance is obtained from bromomethyl taurine, a decomposition product of the thiazoline derivative obtained from allyl-mustard oil dibromide (B. 39, 2891). BrCHa.CH— Sx O BrCH2.CHSO8H — HBr CHa— CHSO8H i > I i CHa.NH, NH— CHa Triaminopropane, CHaNH2.CHNHa,CHaNHa, b.p.9 93°, is prepared from Glycerol Triurethane, C3H6(NHCO2CaH6)8, m.p. 92°, which is formed from the action of absolute alcohol on the triazide of tricarballylic acid (J. pr. Ch. [2] 62, 240). i,3-Tetramethyl-diamino-2-nitropropane, [(CH8)aN.CHa]2.CHNOa, or [(CH8)2- NCH2]2C : NOOH, m.p. 58°, is prepared from 2 molecules of methanol- dimethylamine, (CH3)2NCH2OH, and nitromethane. It forms salts both with acids and alkalis (comp. Nitromethane, p. 151). When boiled with water it is decomposed to formaldehyde ; with aqueous aniline it forms Dianilinonitro- propane, (C,H?NHCHa)aCHNOa ; by reduction with tin chloride it yields Tetra- methyl-j.,-$,2-triamino-propane, [(CH8)2NCHa]aCHNH2, b.p. 175° (B. 38, 2037). 2. DIHYDROXY-ALDEHYDES. Glycerol Aldehyde [Propane Diolat], CH2OH.CHOH.CHO, m.p. 138°, is pre- pared in the pure state by hydrolysis of its acetal (see below) with dilute sulphuric acid. When treated with alcohol and hydrochloric acid, it is reconverted into the parent substance. It crystalizes in needles from dilute methyl alcohol, and is almost insoluble in alcohol and ether. It reduces Fehling's solution in the cold, and forms a characteristic compound with phloroglucinol (Vol. II.) with 534 ORGANIC CHEMISTRY loss of water. The Glycerol Acetal, CH2OH.CHOH.CH(OC2H6)2, b.p.21 130*, is best obtained by oxidation of acrolein acetal (p. 215) with permanganate. Glycerol Aldehyde Oxime, CH2OH.CHOH.CH : NOH, is an oil. When warmed with alkalis it loses water and hydrocyanic acid, forming glycol aldehyde (p. 337) (comp. the carbohydrates). In the solid form both giycol aldehyde and glycerol aldehyde are apparently to be looked on as dimolecular polymers (B. 33, 3095). 2-Chloro-^-hydroxy-propionacetal, CH2(OHVCHC1.CH(OCH3)2, b.p.n 98°, is formed from acrolein acetal and HC1O. Oxidation converts it into 2-chloro- 3-dimethoxy-propionic acid, (CH3O)2CH.CHC1COOH ; reaction with ammonia produces 2-Hydroxy-^-amino-propionacetal, CH2(NH2).CH(OH)CH(OCH3)2, m.p. 55-58°,. b.p.u in0, with intermediate formation of open ethylenoxy-com- pound. This acetal gives rise to the hydrochloride of fi-Aminolactic Aldehyde, NH2CH2CH(OH)CHO, which, on oxidation yields isoserine (p. 541) (B. 40, 92). A mixture of a little glycerol aldehyde with glycerol ketone or dihydroxy- acetone (see below) is formed by the oxidation of glycerol with dilute nitric acid, bromine or hydrogen peroxide in presence of a little ferrous sulphate (C. 1888, II. 104 ; B. 33, 3098). It is known as glycerose, and is condensed by sodium hydroxide to inactive acrose. This compound is related to dextrose, which can also be formed from each of the two separate compounds above mentioned. Methyl Glycerol Aldehyde, CH3CH(OH).CH(OH)CHO, is a syrupy body formed, analogously to glycerol aldehyde, from its acetal, CH3CH(OH)CH(OH)- CH(OC2H5)2, the oxidation product of croton aldehyde acetal (B. 35, 1914). Pentaglycerol Aldehyde, CH3C(CH2OH)2CHO, is prepared by condensing propionaldehyde with two molecules of formaldehyde. Hexyl Glycerol Aldehyde, (CH3)2C(OH)CH(OH)CH2CHO, is obtained by condensation of rf-hydroxy- isobutyric aldehyde with acetaldehyde (M. 22, 443, 527). Chloral Aldol, CCl3.CH(OH).CH(CHO).CHOH.CHs. and Butyl Chloral Aldol, CH3.CHC1.CC12.CH(OH).CH(CHO).CHOH.CH8, are thick oils. They result from the condensation of chloral or butyl chloral with paraldehyde and glacial acetic acid (B. 25, 798). 3. DIHYDROXY-KETONES (OXETONES) Dihydroxy acetone, Glycerol Ketone [Propane Diolone], CH2OH.CO.CH2OH, m.p. 68-75°, is prepared from its oxime by the action of bromine (p. 527). It tastes sweet and cooling. Water, alcohol, and acetone dissolve it easily, ether with difficulty. Reduction (p. 527) and the action of the sorbose bacterium (C. 1898, I. 985) convert it into glycerol (see also Glycerose, above). It reduces Fehling's solution in the cold. The oxime, CH2OH.C=N(OH).CH2OH, m.p. 84°, is produced from hydroxylamino-tert.-butyl-glycerol by HgO (B. 30, 3161). Chloracetyl Carbinol, C1CH3.CO.CH2OH, m.p. 74°, is formed from allene (p. 90) and HC1O, together with some dichloracetone (C. 1904, I. 576). Diethoxy- acetone, (C2H6O)CH2.CO.CH2(OC2H6), b.p. 195°, is prepared from ay-diethoxy- acetoacetic ester, and by distillation of calcium ethyl glycollate (B. 28, R. 295). Diamino acetone, NH2CH2.CO.CHaNH2, is obtained by the reduction of di- isonitroso-acetone (B. 28, 1519). 2,2-Nitro-bromo-trimethylene Glycol [2,2-Nitro- bromo-propane-diol\, HO.CHaCBr(NO2).CH2OH, m.p. 106°, is prepared from bromonitromethane and formaldehyde (C. 1899, I. 179). Homologous Dihydroxyketones. Trimethyl Triose, (CH3)2C(OH).CH(OH)COCH3, b.p.j, 109°, is obtained by the oxidation of mesityl oxide, (CH3)2C : CHCOCH3 (p. 229), by permanganate, and appears to decompose rapidly into acetone and acetol. Dihydroxy-dihydro- methyl-heptenone, (CH3)2C(OH)CH(OH)CH2CH2COCH3, m.p. 67°, is similarly prepared from methyl heptenone (p. 232) and permanganate (B. 34, 2979 ; 35, 1181). y%-Dihydroxy-butyl-methyl Ketone, CH2(OH)CH(OH)CH2CH2COCH3, b.p. 22 190°, results from the splitting up of a-acetyl-8-chloro-y-valerol acetone (the condensation product of epichlorhydrin and acetoacetic ester) by means of potassium carbonate (B. 34, 1981). It is similarly prepared from epichlorhydrin and sodium acetyl acetone (C. 1904, I. 356). Derivatives of Triacetone Dialcohol, 8f is as yet unknown) are compounds, discussed in connection with phorone (p. 229), HYDROXY-DIALDEHYDES 535 such as triacetonamine, triacetone diamine, triacetone hydroxylamine, triacetone dihydroxylamine, their anhydrides and dinitroso-di-isopropyl-acetone. Similar compounds when treated with ammonia, also yield, in part, methyl ethyl ketone p. 224). Trimsthyl Diethyl Ketopiperidine, m.p. 247°, corresponding with triacetonamine (B. 41^ 777). The oxetones, discovered by Fittig, may be considered as the anhydrides of the yy-dihydroxyketones. Their constitution is indicated by the formation of dimethyl oxetone by treatment of the addition product of dialkyl acetone with two molcules of HBr with potash solution (Volhard, A. 267, 90) : Br Br HaO CH3CHCHaCH2.CO.CH2CH8CHCH3 > CH3CHCHaCHa.C.CH8CH2CHCH3 The oxetones are obtained from the condensation products of the y-lactones with sodium ethoxide in consequence of the elimination of carbon dioxide (see P- 374)- Oxetone, C7H12O2, b.p. 159-4°. Dimethyl Oxetone, C,H16O2, b.p. 169-5°, D0 = o-978. Diethyl Oxetone, CnH2oO2, b.p. 209°. These oxetones are mobile liquids, and possess an agreeable odour. They are not very soluble in water, reduce an ammoniacal silver solution, and combine with 2 HBr to y-dibromo- ketones. y-Pyrone, CO<5;J ZpS!>O> may be considered the anhydride of an unsatu- rated dihydroxyketone. 4. HYDROXY-DIALDEHYDES Nitromalonic Dialdehyde, NO2CH(CHO)a, or HO2N : C(CHO)2, m.p. 50*, is a derivative of the dialdehyde of tartronic or hydroxymalonic acid . Its sodium salt is prepared from mucobromic acid (p. 402) and sodium nitrite (comp. C. 1900, II. 1262). The free aldehyde is obtained from the silver salt by hydro- chloric acid, in ethereal solution. In aqueous solution it changes into formic acid and sym.-trinitrobenzene (Vol. II.). It condenses with acetone in alkaline solution to form ^-nitrophenol, and behaves similarly with a series of other ketones, ketonic acid esters, etc. (C. 1899, II. 609; 1900, II. 560). Hydroxyl- amine converts nitromalonic aldehyde into mtro-isoxazole, NO2C(^ j , and salts of the unstable nitromalonic aldehyde dioxime, MeO2N.C(CH : NOH)2, which can be converted into nitromalonic aldoxime nitrile, NO2HC(CN)CH : NOH, and fulminuric acid, NO2HC(CN)CONH2 (C. 1903, I. 957). Chloromalonic Dialdehyde, C1CH(CHO)Z or CHO.CC1 : CHOH, m.p. 144°, with decomposition, and - Bromomalonic Dialdehyde, BrC3H3O2, m.p. 140°, with decomposition, are prepared from nitromalonic aldehyde and mucochloric and mucobromic acids. Aniline causes the loss of CO2 and converts them into dianils of the dialdehydes, which are liberated by hydrolysis : CC1CHO -coa CC1.CH:N,CH6 2H2O CC1CHO HO2CCC1 HCNHC,H6 HCOH The two dialdehydes are also formed from ethoxyacrolein acetal (C2H5O)CH : CH.CH(OC2H5)a (see Malonic Dialdehyde, p. 347), by chlorine and bromine. The ewof-connguration (see above) gives rise to strongly acid bodies giving a reddish-violet coloration with ferric chloride. Their stability towards alkalis is remarkable. Hydrazines give rise to pyrazolcs (B. 87, 4638). 536 ORGANIC CHEMISTRY 5. HYDROXY-ALDEHYDE KETONES Hydroxypyroracemic Aldehyde, CHO.CO.CH2OH, m.p. 134°, is the simplest hydroxyaldehyde ketone. It is only known in the form of its osazone, and is produced by the interaction of phenylhydrazine and dihydroxyacetone (B. 28, 1522). Propanone Trisulphomc Acid, (SO3H)2CHCOCH2(SO3H), is a derivative of hydroxypyroracemic acid, prepared by the action of fuming sulphuric acid on acetone. It is decomposed by alkalis into methionic and sulphoacetic acid (C. 1902, I. 101). 6. HYDROXY-DI KETONES afi-Diketo-butyl Alcohol, CH3CO.COCH2OH, is the simplest hypothetical hydroxydiketone. A derivative is a-Dibromethyl Ketol, CH3CBr2.CO.CH2OH, m.p. 85°, prepared from bromotetrinic acid (p. 544) and bromine. Derivatives of a body, (CH3)2C(OH)COCOCH3, are found among the reaction products of nitrous or nitric acid on mesityl oxide oxime (p. 231). •L-Ethoxy acetyl Acetone, (C2H6O)CH2COCH2COCH3, b.p.13 84°, is prepared from ethoxyacetic ester, sodium, and acetone (comp. p. 350) (C. 1907, I. 871). 3-Aminoacetyl Acetone, (CH3CO)2CHNH2, is formed when isomtroso-acetyl acetone is reduced. Nitrous acid converts it into Dimethyl Diacetyl Pyrazine (i ), m.p. 99°, and a diazo-anhydride or furo\B.\>\diazole (2), of which the connecting oxygen is easily replaceable by NR and S (see Vol. II. ; Pyrro[ab]diazoles and Thio[<ib]diazoles) (A. 325, 129) : CH3C— N— C.COCH3 CHSC— Ov (I) II I II (2) II >N CH3COC— N— CCHS CH3COC— N^ Hydroxymethylene Acetyl Acetone, (CH3CO)2C=CHOH, m.p. 47°, b.p. 199°, which is the aci- or enol-iorm. of sym.-Formyl Acetyl Acetone, Formyl Diacetyl Methane, (CH3CO)2CH.CHO, is a stronger acid than acetic acid, and soluble in aqueous alkali acetates. It readily absorbs oxygen from the air, and is decom- posed by gentle heating with water and HgO into COa and acetyl acetone ; copper salt, m.p. 214°. Ethoxymethylene Acetyl Acetone, (CH3CO)2C=CH(OC2H5), b.p.ie 141°, is formed by condensation of acetyl acetone with orthoformic ether by acetic anhydride. It decomposes with water into alcohol and the previous substance. It combines with acetyl acetone to form Methenyl-bis-acetyl Acetone, (CH3COX2C = CH — CH(COCH3)2, m.p. 118°, which is easily changed by ammonia into di- acetyl lutidine (Vol. II.), and by abstraction of water into diacetyl tw-cresol. Aminomethylene Acetyl Acetone, (CH3CO)2C : CHNH2, m.p. 144°, is formed frcm ethoxymethylene acetyl acetone and ammonia. Anilinomethylene Acetyl Acetone, (CH3CO)2C : CHNHC6H5, m.p. 90°, results when diphenyl formamidine, C6H5N : CH.NHCGH5, is heated with acetyl acetone (B. 35, 2505). Hydroxymethylene acetyl acetone, as well as the corresponding derivatives of acetoacetic ester and malonic ester, can be considered as being formic acid in which the intra-radical oxygen has been replaced by a carbon atom carrying two negative groups (X) : 0=CH.OH *>C=CH.OH. Formic Acid. Hydroxymethylene Compounds.' As these bodies are strong monobasic acids, the group X2C= would seem to exert an influence on the carbon atom combined with it, or on the hydroxyl in union with the carbon atom, just as is done by oxygen that is joined with two bonds, but the influence may not be as great as in the latter case. The com- pounds just described are the first of the complex substances, containing only C, H, and O, which, without carboxyl, still approach the monocarboxylic acids in acidity. Indeed, in some instances they surpass them in this respect (B. 26, 2731 ; L. Claisen, A. 297, i). TRIKETONES 537 7. DIALDEHYDE KETONES Mesoxalic Dialdehyde, CHO.CO.CHO, is formed, together with acetone peroxide, when phorone ozonide (p. 229), (CH3)2C(O3)CHCOCH(O3)C(CH3)2, is shaken with water, and the aqueous solution concentrated. It may be in the form of a syrup, the hydrate, solidifying to a glass-like substance, or a loose light yellow powder (a polymerized body), which, in aqueous solution, is strongly reducing in its action. The diphenylhydrazone, CO[CH : NNHCaH6]a, m.p. 175° with decomposition, is formed by the action of phenylhydrazine, and also from acetone dicarboxylic acid (p. 568) with diazobenzene ; the triphenylhydrazone C8H5NHN : C[CH : NNHC6H6la, m.p. 166°, may be prepared (B. 38, 1634). The Dioxime, Di-isonitroso-acetone, CO[CH:NOH]2, m.p. 144°, with decom- position, is formed from acetone dicarboxylic acid and nitric acid ; further action of N,O3 produces mesoxalic dialdehyde. The trioxime, trioximidopropane, HON : C[CH : NOH]2, m.p. 171°, is formed by means of hydroxylamine (B. 38, 1372). 8. ALDEHYDE DIKETONES See above, under hydroxymethylene acetyl acetone or zci-formyl diacetyl methane (p. 536). 9. TRIKETONES Related Triketones are obtained from the i,3-diketones by means of nitroso- dimethyl-aniline, followed by decomposition of the resulting dimethyl amido-acid by dilute sulphuric acid (B. 40, 2714) : NOC6H4N(CH3)a HaO (CH3CO)2CH2 - — >• (CH3CO)2C : NC6H4N(CH3)2 — -> (CH,CO)2CO. These tri-ketones are orange-red oils which form colourless hydrates with water. They are very strongly reducing bodies, and indicate a relationship with animal hairs. Triketopentane [Pentane-2,3,4-trione], CH3Cp.CO.COCH3> b.p.30 65-70°, is formed by decomposing the reaction product of nitroso-dimethyl-aniline (Vol. II.) and acetyl acetone. It is an orange-yellow oil, which unites with water to form a colourless crystalline hydrate, C6H6O8-fH2O. The phenylhydrazone, benzene azo-acetyl acetone, C6H6NHN : C(COCH3)2, and the oxime, isonitroso-acetyl acetone, HON : C(COCH3)2, m.p. 75°, are prepared from sodium acetyl acetone and diazo- benzene salts or nitrous acid (A. 325, 139, 193). Triketopentane and phenyl- hydrazine form a bis-phenylhydrazone ; with semicarbazide a bis-semicarbazone, m.p. 221° ; with hydrazine hydrate, dimethyl-hydroxy-pyrazole (comp. i,3-diketone, P- 35°) i with o-phenylene diamine, a quinoxaline-deriv&tive (comp. i,2-diketone, p. 348). Alkalis decompose triketopentane into 2 molecules of acetic acid and formaldehyde. 2,1,4-Triketohexane, CH3CO.CO.COC2H6, b.p.18 70°, is obtained, analogously to triketopentane, from acetyl methyl ethyl ketone, CH3COCH2.COC2H6 (B. 40, 2728). 2,1,5-Triketohexane. The trioxime, CH3C(NOH)CHaC(NOH)C(NOH)CH3, m.p. I59°i is formed, similarly to succinic dialdoxime from pyrrole (p. 355), and from /J-nitroso-aa, -dimethyl-pyrrole and hydroxylamine (C. 1908, I. 1630). Diacetyl Acetone, 2,^,6-Triketoheptane, [2,4,6-Heptane Trione], CO(CHaCO- CH3)2, m.p. 49°, is produced from 2,6-dimethyl pyrone, CO^H^cfcH8)^0' gnd concentrated barium hydroxide solution, from which it is separated by hydro- chloric acid. It decomposes spontaneously into water and dimethyl pyrone (A. 25?, 276). Ferric chloride produces a deep red colour with it. The oxime, m.p. 6h°, easily turns into an anhydride (B. 28, 1817). With sodium and iodomethane it is converted into a Dimethyl Diacetyl Acetone, m.p. 87° (C. 1900, II. 625). Acetonyl Acetyl Acetone, CH3COCHa.CH(COCH3)2, b.p.S5 156°, is formed from sodium acetyl acetone and chloracetone (C. 1902, II. 346). 53$ ORGANIC CHEMISTRY 10. DIHYDROXY-MONOCARBOXYLIC ACIDS The acids of this series bear the same relation to the glycerols that the lactic acids sustain to the glycols, and may also be looked on as being dihydroxy-derivatives of the fatty acids. They may be arti- ficially prepared by means of the general methods used in the pro- duction of hydroxacids, and also by the oxidation of unsaturated acids with potassium permanganate (p. 293) (B. 21, R. 660 ; A. 283, 109). Glyceric Acid, C3H6O4, Dihydroxypropionic Acid, [Propanediol Acid], is formed : (i) By the careful oxidation of glycerol with nitric acid (method of preparation, B. 9, 1902, 10, 267 ; 15, 2071) ; or by oxidizing glycerol with mercuric oxide and barium hydroxide solu- tion (B. 18, 3357), or with silver chloride and sodium hydroxide (B. 29, R. 545), or with red lead and nitric acid (C. 1898, I. 26). The calcium salt is decomposed with oxalic acid (B. 24, R. 653) : CH2(OH).CH(OH).CH2.OH+O2=CH2(OH).CH(OH).CO.OH+H2O. (2) By the action of silver oxide on /J-chlorolactic acid, CH2C1.- CH(OH).CO2H, and a-chlorohydracrylic acid, CH2(OH).CHC1.CO2H (p. 368). (3) By heating glycidic acid with water (p. 539). Glyceric acid forms a syrup which cannot be crystallized. It is easily soluble in water, alcohol, and acetone. It is optically inactive, but as it contains an asymmetric carbon atom (p. 29), it may be changed to active laevo-rotatory glyceric acid by the fermentation of its ammonium salt, through the agency of Penicillium glaucum. Bacillus ethaceticus, on the other hand, decomposes inactive g.yceric acid so that the laevo-rotatory glyceric acid is destroyed and the dextro-rotatory acid remains (B. 24, R. 635, 673). This glyceric acid is also formed by reduction of hydroxypyroracemic acid (p. 543), whilst the 1-glyceric acid is obtained by the action of milk of lime on glycuronic acid. Further, both forms can be separated by means of brucine (B. 37, 339 ; C. 1905, I. 1085, 1089). Reactions. — When the acid is heated above 140° it decomposes into water, pyroracemic and pyrotartaric acids. When fused with potassium hydroxide it forms acetic and formic acids, and when boiled with it, yields oxalic and lactic acids. Phosphorus iodide converts it into j8-iodopropionic acid. Heated with hydrochloric acid, it yields a-chlorohydracrylic acid and a)3-dichloropropionic acid. (See also j3-chlorolactic acid (p. 368).) When glyceric acid is kept, it probably forms a lactide or anhydride. This is sparingly soluble in water, and crystallizes in fine needles. Salts and Esters. — Its calcium salt, (C3H5O4)2Ca+2H2O, dissolves readily in water ; lead salt, (C3H5O4)2Pb, is not very soluble in water ; ethyl ester is formed on heating glyceric acid with absolute alcohol. The rotatory power of the optically active glyceric esters increases with the molecular weight (B. 26, R. 540), and attains its maximum with the butyl ester (B. 27, R. 137, 138 ; C. 1897, I. 970). The homologues of glyceric acid (Dihydroxy-acids with adjacent hydroxyl groups) have been obtained (i) from the corresponding dibromo-fatty acids ; (2) from the corresponding glycidic acids on heating them with water (A. 234, 197) ; and (3) by oxidizing the corresponding unsaturated carboxylic acids (p. 293) with potassium permanganate or persulphuric acid, which at the same time occasion DIHYDROXY-MONOCARBOXYLTC ACIDS 539 stereoisomeric transformation (comp. Dihydroxystearic Acid) (A. 268, 8 ; B. 22, R. 743 ; C. 1903, I. 319). afc-Dihydroxybutyric Acid, ^-Methyl Gly eerie Acid, CH3CH(OH)CH(OH)CO2H, in.p. 75°, is resolved from the mixture of its optically active components by quinidine. Also, the a-form appears to result from oxycellulose by the action of milk of lime (B. 32, 2598 ; C. 1904, I. 933). ap-Dihydroxyisobutyric Acid, a-Methyl Glyceric Acid, CH2OH.C(CH3)(OH)CO2H, m.p. 100°. Triglyceric Acid, m.p. 88°. Anglyceric Acid, m.p. 111° (A. 283, 109). a-Ethyl Glycenc Acid, m.p. 99°. a-Propyl Gly eerie Acid, m.p. 94°. a-Isopropyl Gly eerie Acid, m.p. 102° (C. 1899, I. 1071). a-Ethyl fi-Methyl Glyceric Acid, Isohexeric Acid, CH3CH(OH)C(C2H6)(OH)COOH, m.p. 145°, is formed from a-ethyl crotonic acid (A. 334, 68), apDihydroxyiso-octylic Acid, (CH3)2CHCH2CH2CH(OH)CH(OH)CO2H, m.p. % 106° (A. 283,291). a-Isopropyl p-Isobutyl Glyceric Acid, m.p. 154° (B. 29, 508). Py-Dihydroxybutyric Acid, Butyl Glyceric Acid, CH2(OH).CH(OH)CH2CO2H, is a thick oil. The Py-dihalogen and hydroxy-halogen-butyric acids corresponding with these, are obtained from vinyl acetic acid (p. 297), or from epihalogen hydrins (p. 532), and hydrocyanic acid ; y-Ethoxy-d-hydroxy-butyric Acid is a syrup ; ethyl ester, b.p.l3 121° ; nitrile, b.p. 245°, is prepared from epiethylin (p. 533) and hydrocyanic acid (C. 1903, II. 106 ; 1905, I. 1586). y§-Dihydroxyvaleric Acid, CH2(OH)CH(OH)CH2CH2CO2H, rapidly decom- poses into water and forms hydroxy lac tone. Dihydroxyundecylic Acid, C11HS8(OH)2O2, m.p. 85°, is prepared from unde- cylenic acid (p. 299). Dihydroxystearic Acid, C18H34(OH)2O2 (see Oleic and Elaidic Acids, p. 300) (C. 1902, I. 179 ; 1903, I. 319). Dihydroxybehenic Acid, C22H42(OH)2O2, m.p. 127°, is formed from erucic acid, C22H42O2. Glycidic Acids are formed (i) by the action of alcoholic potassium hydroxide on the addition product of hypochlorous and olefine carboxylic acids (A. 266, 204) ; (2) by condensation of ketones and a-halogen fatty esters by sodium ethoxide or sodium amide, whereby the glycidic esters are formed : (CH3)C20 +NaNH r(CH3)2C.ONa-, CO2R.CH2c CO2R.CHC1 The acids obtained from these esters easily lose CO2 and change into aldehydes or ketones (C. 1906, I. 669 ; B. 38, 699). In general, the glycidic acids, like ethylene oxide, form addition products with the halogen acids, water and ammonia, whereby chloro-hydroxy fatty acids, dihydroxy, and amino-hydroxy-fatty acids can be prepared. Many add sodium malonic ester, etc. (C. 1906, II. 421). yCHC02H Glycidic Acid, Epihydrinic Acid, O< , is isomeric with pyroracemic acid. It is produced, like epichlorhydrin (p. 532), from a-chlorhydracrylic acid and /?-chlorolactic acid by means of alcoholic potassium hydroxide. Glycidic acid, separated from its salts by means of sulphuric acid, is a mobile liquid miscible with water, alcohol, and ether. It is very volatile and has a penetrating odour. The free acid and its salts are not coloured red by iron sulphate solutions (dis- tinction from isomeric pyroracemic acid). It combines with the halogen acids to /J-halogen lactic acids, and with water, either on boiling or on standing, it yields glyceric acid. Its ethyl ester, m.p. 162°, obtained from the silver salt with ethyl iodide, resembles malonic ester in its odour (B. 21, 2053). p-M ethyl Glycidic Acid, CH3CH.OCHCOOH, is known in two modifications. The one, m.p. 84°, unites with water to qjS-dihydroxybutyric acid. The other modification is a liquid. Epihydrin Carboxylic Acid, CH2.O.CHCH2COOH, m.p. 225°, is obtained from its nitrile, which results from the action of KCN on epichlorhydrin (p. 532). a-Methyl Glycidic Acid, CH2.O.C(CH3)COOH, consists of shining leaflets. The ethyl ester, b.p. 162-164° (B. 21, 2054). afi-Dimethyl Glycidic Acid, CH,CH.O.C(CH,)COOH, m.p. 62° (A. 257, 128). 540 ORGANIC CHEMISTRY pf}-Dimethyl Glycidic Acid, (CH3)2C.O.CHCOOH, is formed as a syrup, from a-chloro-^-hydroxy-isovaleric acid (A. 292,282); ethyl ester, b.p. iS\°, is obtained in good yield from acetone, chloracetic ester and sodium amide (see above) (B. 38, 707). pp-Methyl Ethyl Glycidic Ester, b.p. 198° ; ffi-Diethyl Glycidic Ester, b.p. 212° ; and fifi-Trimethyl Glycidic Ester, b.p.ao 81°, etc., are formed according to method 2. Hydroxylaetones are formed from those dihydroxy acids in which the hydroxyl group stands in the y-position to the carboxyl group. Thus, a-hydroxy-y-lactones are obtained by hydrolysis of cyanhydrins of the aldols (p. 338) : CH8CH(OH)CH2CHOH CHSCH.CH2CHOH O CN O CO HOCH2C(CH3)2CHOH CH2C(CH3)2CHOH CN O— —CO These hydro xylactones are readily caused by acids to undergo isomeric transformation accompanied by wandering of the OH-group ; in the case of a,-hydroxyualerolactone (see above), the OH-group apparently migrates first to the /?- and finally to the y-position, forming laevulinic acid (p. 421) (A. 334, 68 ; C. 1914, I. 217). On the other hand, the cyanhydrin of fi-chloro-diethyl-ketone (p. 228) and alkali yield salts of Ethyl Trimethylene Oxide Carboxyhc Acid: C2H6C(COOH).CH2.CH20, b.p.16 136° (C. 1908, I. 1615). HO.CH2CH- — O §-Hydroxyvalerolactone, \ , b.p. 300-301°, results from CH2CH2— CO the action of potassium permanganate on allyl acetic acid (A. 268, 61). Hydroxycaprolactone and Hydroxyisocaprolactone, C6H10O3, are colourless liquids, into which the oxidation products of hydrosorbic acid by means of KMnO4 rapidly pass on liberation from their barium salts (A. 268, 34). Hydroxyiso- heptolactone, (CH3)2CH.CH.CH(OH).CH2.COO, m.p. 112°. Hydroxyiso-octolactone, (CH3)2CH.CH2.CH.CH(OH)CH2CO.O, m.p. 33° (A. 283, 278, 291). The following section of the hydroxy-amino, thio-amino, and diamino-carboxylic acids embraces a number of substances which, with the simple amino-acids (pp. 381, 390), commands the greatest interest, as constituting the decomposi- tion products of the proteins — serine, cystine, ornithine, arginine, proline, lysine. Monoamino-hydroxy-earboxylie Acids. a-Aminohydracrylic Acid, a-Amino-fi-hydroxy-propionic Acid, HO.CH2CH- (NH2)COOH, m.p. 246° with decomposition, has been named serine, because it was first obtained from sericin (silk-gum). It is also obtained from silk-fibroin, horn, gelatin, casein, etc., by hydrolysis with dilute acids. It was first synthesized from glycolyl aldehyde (p. 337), ammonia, hydrocyanic acid, and hydrochloric acid (B. 35, 3794) ; also, by the following steps : formic ester and hippuric ester were condensed by sodium ethoxide to formyl hippuric ester, CHO.CH(NHCOC6H5)- COOC2H5 (p. 543), which, on reduction, yields benzoyl serine ester, HOCH2CH- (NHCOC6H6)COOC2H6, m.p. 80°; this, on hydrolysis, gives serine (A. 337, 222). The best synthesis consists in preparing fi-ethoxy-cL-amino-propionic acid C2H6OCH2.CH(NH2)COOH, m.p. 256° with decomposition, from ethoxyacetal- dehyde (p. 338), NH3, HCN, and HC1, and decomposing this with hydrobromic acid (B. 39, 2644). Serine forms hard crystals, soluble in 24 parts of water at 20°, but insoluble in alcohol and ether. As an amino-acid it reacts neutral, but forms salts with bases and acids. The taste is sweet, like glycocoll. Both synthetic and natural serine are optically inactive on account of racemiza- tion ; resolution can be effected through the quinine salts of the p-nitrobenzoyl- derivative into d- and \-serine, [a]p20=-j-6-8°, m.p. 228° with decomposition, soluble in 3-4 parts of water. d-Serine tastes sweeter than 1-serine (B. 38, 2942) MONAMINOTHIOCARBOXYLIC ACIDS 541 Serine Methyl Ester, a syrup, loses alcohol spontaneously and passes into a di-aci-piperazine (p. 391 ) : ot which the 1-form [a]D2s= — 67*46° appears to be identical with a decomposition product of silk-fibroin. Nitrous acid converts serine into glyceric acid. PC16 changes serine ester into fi-chloro-a-amino-propionic acid, which, on reduction, yields alanine ; 1-serine gives d-alanine (p. 388). ^-Naphthaline Sulphoserine, m.p. 214°. Serine (3-Phenyl Cyanate, m.p. 169°. fl-Amino-lactic Acid, a.-Hydroxy-f$-amino-propionic Acid, Isoserine, H2NCH2- CH(OH)COOH, m.p. 248° with decomposition, is prepared from fi-chlorolactic acid (p. 368) or from glycidic acid (p. 539), and NH3 ; from ap-diaminopro- pionic acid, hydrochloride, and silver nitrite (B. 37, 336, 343, 1278) ; also by reduc- tion of the addition product of acrylic acid and nitrous acid (C. 1903, II. 343) ; Isoserine ethyl ester, m.p. 78° ; methyl ester, a syrup, passes easily into isoseryl isoserine ester, and dipeptide. Isoserine ester hydrochloride yields glyceric ester with sodium nitrite. Reduction produces /J-alanine (p. 393) (B. 37, 1277; 38, 4171). a-Amino-p-hydroxy-butyric Acid, CH3CH(OH).CH(NH2)COOH, m.p. 230° with decomposition, is obtained by reduction of the addition product of crotonic acid and nitrous acid. HI and phosphorus yield a-aminobutyric acid (C. 1903, 11.554). a-Amino-y-hydroxy-butyric Acid, HOCH2.CH8CH(NH2)COOH, m.p. 207° (indefinite), is obtained by the decomposition of j3-hydroxy-ethyl-phthalimido- malonic mono-ester lactone, a product of ethylene bromide and sodium phtha- limidomalonic ester (C. 1908, II. 683). The hydrobromide of the lactone (formula, see below) is obtained by heating together hydrobromic acid and y-Phenoxy-a-amino-butyric acid, m.p. 233° with decomposition. This substance is prepared by acting with ammonia on phenoxybromobutyric acid, the result of brominating and then decomposing phenoxyethylmalonic acid. The oily lactone changes spontaneously into di-fi-hydroxy ethyl diketopiperazine, m.p. 192° (B. 40, 106) : 20CH2CH2CH< NH a-Amino-y-hydroxy-valeric Acid, CH3CH(OH)CH2CH(NH2)COOH, m.p. 212° with decomposition, is prepared from aldol, NH3, HCN, and HC1. Like the previous substance, it readily passes into the aminolactone, b.p.,3 124°, which spontaneously changes into the dipeptide anhydride, m.p. 224°. Reduction with HI yields a-amino-n-valeric acid (B. 35, 3797). 8-Amino-y-hydroxy-valeric Acid, NH2CH2CH(OH)CH2CH2COOH, is formed from alkyl acetic acid dibromide (B. 32, 2682). a-Amino-S-hydroxy-valeric Acid, HOCHa.CH2CH2CH(NH2)COOH, m.p. 224° with decomposition, is prepared from phthalimidobromopropyl malonic ester, BrCH2CH2CH2C(C02R)2N(CO)2C6H4 (C. 1905, II. 398). Monaminothiocarboxylic Acids. a-Amino-B-thiolactic Acid, Cysteine, HSCH2.CH(NH2)COOH, is easily oxidized by the air to the disulphide. Cystine, HOOC.CH(NH2)CH2S.SCH2CH(NH2)COpH, decomposes at 258-261°. The laevo-rotatory form of this substance is obtained from many proteins, especially from hair, horn, egg-shells. It is the chief sulphur compound of the proteins. It occurs also in the crystallites of those suffering from cystinuria (C. 1905, II. 1237). The action of nitrous and hydro- chloric acids changes cystine into a-chlorodithiolactic acid, (SCH2CHC1.COOH)2, which yields p-dithiopropionic acid, (SCH2CH2COOH)2, on reduction. Hydro- bromic acid produces cysteinic acid, SO3H.CH2CH(NH2)COOH, which loses CO2 and changes into taurine, SO3H.CH2CH2NH2 (p. 326) (C. 1902, II. 1360). Cysteine and cystine are closely connected with serine : (i) when j8-chloro-a- amino-propionic acid (above) is heated with Ba(SH)2, it yields first cysteine and then cystine ; (2) the syntheic benzoyl serine ester (p. 540), treated with P2S6 gives benzoyl cysteine ester, HSCHaCH(NHCOCaH5)COOC2HB, m.p. 158°, which 542 ORGANIC CHEMISTRY on hydrolysis is changed to i-cystei'ne and i-cystine (A. 337, 222 ; B. 40, 3717). l-Serine produces the natural laevo-rotatory cystine [<x]D22 = —224°. Cystine forms crystals which dissolve with difficulty in water. Salts (C. 1905, II. 220) ; dimethyl ester, is a syrup ; hydrochloride, m.p. 173°, with decomposition (C. 1905, II. 1237)- a-Thio-p-amino-propionic Acid, Isocysteine, NH2CH2CH(SH)COOH, hydro- chloride, m.p. 141° with decomposition, is obtained from jS-alanine (p. 39^) by gradual transformation of its ure'ide, hydrouracil (p. 444) — into bromohydrb- uracil, then into cyanohydrouracil, and decomposing the latter with hydrochloric acid, CO NH.CH2 NH2CH2 NH— CO— CH.SCN COOH.CH.SH Isocysteine is oxidized by iodine to Isocystine, [SCH(CH2NH2)COOH]2, m.p. 155°, with decomposition ; and by hydrobromic acid into Isocysteine acid, HO3S CH- (CH2NH2)COOH (B. 38, 630). a-Thio-y-amino-butyric Acid and y-Amino-a-butyro-sulphonic Acid, NH.CH2- CHaCH(S03H)COOH (B. 41, 513). Diaminomonocarboxylic Acids. Diaminopropionic Acid, CH2NH2.CHNH2.CO2H, is obtained from a£- dibromopropionic acid by means of aqueous ammonia ; also by the decompo- sition of hippuryl asparaginic acid (p. 554). Optical resolution has been per- formed by means of its salts with d-camphor sulphonic acid (Vol. II.) ; and through the quinidine salts of dibenzoyl diaminopropionic acid (C. 1906, II. 1119; B. 39, 2950). The dextro-rotatory compound reacts with i molecule of HNO2 to form isoserine (p. 541), and with 2 molecules of HNO2 to produce 1-glyceric acid. Diaminopropionic methyl ester is changed by heat into the ester of di- aminopropionyl diaminopropionic ester, one of the dipeptides (B. 38, 4173). afi-Diaminobutyric Acid, CH3CH(NH2).CH(NH2)COOH, is formed from ajS-dibromocrotonic acid and ammonia, together with a hydroxyaminobutyric acid (C. 1906, II. 764). ay-Diaminobutyric Acid, NH2CH2CH2CH(NH2)COOH, is obtained from phthalimido-ethyl-malonic ester by bromination, hydrolysis of the phthalimido- a-bromobutyric acid formed, treatment with NH3> and final decomposition ; dibenzoyl derivative, m.p. 201° (B. 34, 2900). a&-Diaminovaleric Acid, NH2CH2CH2CH3CH(NH2)COOH, is synthetically prepared from 8-phthalimido-a-bromovaleric acid, and from the condensation product of phthalimidopropyl bromide with sodium phthalimidomalonic ester (C. 1903, II. 34). It is the optically inactive form of the dextro-rotatory Ornithine. This body is produced, together with urea by the action of barium hydroxide solution, on Arginine, a-Amino-o'-guanidino-valeric Acid, NH2(NH)C.NHCH2- CH2CH2CH(NH2)COOH, a substance found among the decomposition products of many animal and vegetable proteins (B. 34, 3236 ; 38, 4187). Permanganate converts arginine into y-guanidinobutyric acid (C. 1902, II. 200). It is prepared synthetically from cyanamide, CN.NH2, and ornithine (B. 34, 454; C. 1902, I. 300). The dibenzoyl derivative of ornithine, Ornithuric Acid, m.p. 185°, occurs in the urine of hens when fed with benzoic acid (B. 31, 3183). CH2.CH(COOH)X a-Pyrrolidine Carboxylic Acid, Proline, | -^NH, is the imine CH2.< _.CH2 of 08 -diamino valeric acid. It results when casein, gelatin, and other proteins are treated with hydrochloric acid. It can be synthetically prepared in several ways, more particularly from a8-dibromo valeric acid and ammonia ; and from 8-bromo-a-amino-valeric acid, the decomposition product of bromo- propyl phthalimidomalonic ester (C. 1908, II. 680; B. 33, 1160; 34, 3071; 37, 3071 ; C. 1902, II. 284). It is connected with the coca-alkaloids. ae-Diaminocaproic Acid, NH2CH2CH2CH2CH2CH(NH2)COOH, is prepared synthetically by the reduction of a-hydroximido-y-cyano-valeric acid by means of sodium and alcohol. This product is the inactive form of the optically active lysine, which is formed in the decomposition of casein and other proteins. Pan- creatic decomposition converts lysine into pentamethylene diamine (cadaverine, DIHYDROXYOLEFINE MONOCARBOXYLIC ACIDS 543 P- 334) • and ornithine into tetramethylene diamine (putresce'ine, p. 333) (B. 32, 3542 ; C. 1902, I. 985). Permanganate oxidizes lysine into glutaric acid, together with hydrocyanic and oxalic acids (B. 35, 3401). Like the simple amino-acids, the hydroxyamino-, thioamino-, and diamino-carboxylic acids are connected with one another and with the mono-amino acids in so far that through their amides they go to form protein-like bodies, such as di- and poly-peptides and dipeptide anhy- drides (diazopiperazines, p. 391) . Therefore, in general, similar methods of formation can be employed in both cases : Diglycl Cystine, [NH2- CH2CONHCH(COOH)CH2S]2, is prepared from bischloracetyl cystine and ammonia ; Leucyl Proline from bromisocaproyl proline ; anhydride, m.p. 126-129°. Prolyl Alanine, from aS-dibromo-valeryl-alanine ; anhy- XCH2.N— CO.CH2 dride, m.p. 171-121°. Prolvl Glycine Anhydride, CH2^ \ , NCHa.CH— CO.NH m.p. 183°, is obtained by tryptic digestion of gelatin (comp. B. 37, 3071, 4575 ; 38, 4173 ; 39, 2060, etc.). Dihydroxyolefine Monocarboxylic Acids. The y-lactones of these bodies are the tetronic acid and mono-alkyl tetronic acids. These substances can also be looked on as being the aci-iorms of $-Keto-y- lactones. They are, therefore, considered under the heading of hydroxy-ketone- carboxylic acids (below) according to the principle set down on p. 398. ii, 12. Aldo-hydroxy-carboxylic Acids and Hydroxy-keto-earboxylic Acids. Hydroxypyroracemic Acid, CH2OH.CO.COOH, or Formyl Hydroxyacetic Acid, Tartronic Acid Semi- Aldehyde, CHO.CH(OH)COOH, is formed when nitrocellulose (collodion cotton) is treated with sodium hydroxide solution. Reduction converts it into /-glyceric acid ; hydrocyanic and hydrochloric acids produce /- and some meso-tartaric acid (C. 1905, I. 1088). Formyl- or Hydroxy- methyleneHippuric Ester, OCH.CH(NHCOC6H5)CO2R, or HOCH : C(NHCOC6H6)- CO2R, m.p. 128° (comp. p. 540), is a derivative of formyl hydroxyacetic acid. Tribromomethyl Ketol, CH2OH.CO.CBra, decomposes at 174° (see Bromotetronic Acid, p. 544). The following substances are derived from the enol- or aci-iorm of a-Hydroxyacetoacetic Acid, CH3COCH(OH)COOH, and y-Hydroxy- acetoacetic Acid, HOCH2.COCH2COOH, both of which are unknown in the simple form. a-Thioacetoacetic Ester, S[CH(COCH3)CO2C2H5]2, keto-iorm, m.p. 76°, is prepared by the action of sulphur chloride or thionyl chloride on acetoacetic ester. The solid keto-iorm is converted into the oily enol- or aci-iorm. by the influence of solvents (alcohol, benzene), or a trace of alkali ; soda causes the re-production of the keto-body (B. 39, 3255). Benzene-sulphone-thioacetoacetic Ester, CeH6- SO2.SCH(COCH8)CO2C2H6, m.p. 55°, is prepared from a-chloracetoacetic ester and benzene thiosulphonate (J. pr. Ch. [2] 70, 375)- a-Nitro-methyl-isoxazolone, ON:C(CH8).CH(NO2)CO, decomposes at 123°, is formed when isonitroso-methyl-isoxazolone is oxidized by nitric acid (B. 28, 2093). a-Amino-acetoacetic Acid, CH8CO.CH(NHa)COOC2H5, is obtained by the reduction of isonitroso-aceto-acetic ester (p. 546) by zinc and sulphuric acid, together with dimethyl pyrazine dicarboxylic ester (Vol. II.). Amino-acetoacetic acid reacts with nitrous acid to form Diazo-acetoacetic Ester Anhydride, /O Nsv /N CH,C/ >N, or CH8COC(COaR)<( ||, an oil, b.p.ia 102-104°. Acids ^C(COtRK XN and alkalis convert it into acetic and diazo-acetic acids (p. 402). When boiled with water or superheated to above no0, it breaks down into nitrogen and methyl 544 ORGANIC CHEMISTRY malonic mono-ester (L. Wolff, A. 325, 129), a decomposition which may be explained as follows (Schroeter) : /N CH8COC(C02R)< || > N2+CH3COC(C02R)< > \N CH3C(C02R)=CO — ^-> CH3CH(C02R)C02H. Ammonia or amines convert the diazo-anhydride into pyrro[a,b]diazole ; H2S produces thio[a.b]diazole (Vol. II.). /?-Diketones react with it as with aromatic diazo-bodies (Vol. II.), forming azo-compounds, such as hydrazones, which easily condense further to pyrazoles. a-Isonitramine Acetoacetic Acid; sodium salt, CH3COCNa(NaO2Na)CO2C2H8 (PP- 397. 4l6)- Lactones of the y-Hydroxy-acetoaeetie Acids (pp. 420, 543) are tetronic acid and the alkyl tetronic acids. Substances of this class were obtained by Demar$ay from y-mono-bromo-substituted mono-alkyl acetoacetic esters by alcoholic potassium hydroxide, and were named by him tetrinic acid, pentinic acid, etc. Michael recognized in tetrinic acid a keto-lactone (formula i). L. Wolff examined the parent substance of these compounds and called it tetronic acid, and derived Demarcay's acids from it under the names of a-methyl-, a-ethyl tetronic acid, etc. (A. 291, 226). The keto- and enol-formulae (I. and II.) are applicable to tetronic acid and a-methyl tetronic acid (tetrinic acid) : CO.CH2X C(OH).CH2X I. | \0 II. || \0 CH3CH.CO/ CH3.C CO/ but Conrad and Cast favour the hydroxyl formula, through indirect evidence, namely : that they prepared the lactone of y-hydroxy-dialkyl-acetoacetic acids from dialkyl acetoacetic esters and y-bromo-dialkyl-acetoacetic ester, and they showed that these true keto-lactones differ throughout in boiling-point and chemical behaviour from tetronic acid and the a-alkyl tetronic acids. C(OH)CHav Tetronic Acid. || }O (i) is prepared from synthetic tetronic ester, CH— CO/ by hydrolysis, and elimination of CO2 (B. 36, 471) ; also by reduction by sodium C(OH)CH2X amalgam of a-Brontotetronic acid, [\ >O (2) the decomposition product CBr CO/ CO— CH2, of ay-dibromacetoacetic ester. Dibromotetronic acid, I /O (3) is CBr2— CO/ obtained from bromotetronic acid and bromine. It slowly decomposes into bromotetronic acid and tribromo-methyl-ketol (p. 543), with elimination of CO2. C(OH)CH8X C(OH)CH2X CO— CH2X (i) II >0 * (2) || \0 > (3) I >0. CH CO/ CBr O/ CBr2-CCK C(OH).CH2X Tetrinic Acid, a-Methyl Tetronic Acid, \\ >O, m.p. 189°, b.p. CH3C.CO / 292°, with partial decomposition, results on heating y-bromo-methyl-aceto- acetic ester or by treating it with alcoholic potassium hydroxide. Heated with water to 200°, it breaks down into ethyl ketol (p. 341) and CO2, and when it is boiled with barium hydroxide it yields glycollic acid and propionic acid. Chromic acid oxidizes it to diacetyl and CO2 (A. 288, i). Pentinie Acid, a-Ethyl Tetronic Acid, m.p. 128°. Hexinie Acid, a-Propyl Tetronic Acid, m.p. 126°. Heptinic Acid, a-Isobutyl Tetronic Acid, m.p. 150°. It is the tertiary methinic group of the tetronic acid (formula i, above) and the methylene group in the diketone formula (I., above) that react most actively with other substances : iodine produces directly iodotetronic acid ; fuming sulphuric gives rise to sulphotetronic acid. Nitrous acid gives oximidotetronic acid, Oximido-ketobutyrolactone, (C4H2O3) : NOH, m.p. 136°, with decomposi- tion, which on oxidation yields Nitrotetronic acid, (C4H2O3) : NOOH, m.p. 195°, with decomposition ; this substance can also be prepared directly from tetronic acid and nitric acid. Reduction results in the formation of aminotetronic acid, ALDEHYDOKETONE CARBOXYLIC ACIDS 545 from which nitrous acid produces (i) Diazotetronic anhydride, m.p. 93°. It is stable towards acids, but with alkalis generates nitrogen and forms (2) glycollo- glycollic Acid, m.p. 100° (p. 367) : /CH2.C(OH) /CHa.C— Ov /CH2COOH (i) O/ || - >• (2) 0< || >N - -> 0< XCO.C(NH2) XCO.C— H^ XCO.CH2OH Tetronic acid reacts with diazobenzene salts to form diketobutyrolactone phenylhydrazone, (C4H2O3) : NNHC6H8, which is isomerized by alkalis to salts of benzene azotetronic acid. a-M ethyl Tetronic acid is converted by rupture of the ring into glycolyl pyroracemic acid phenylhydrazone, CQ XH2COOH *<CO.C(CH3) : NNHC.Hj by diazobenzene salts. Aldehydes and ketones unite very readily with two molecules of tetronic acid to form alkylidene bis-tctronic acids, (C4H8O3)2CRR,, substances from which further condensation produces a series of interesting cyclic compounds (see Vol. IT.) (A. 312, 119; 322.351). Ethoxyl Acetoacetic Ester, (C2H6O)CH2COCH2COOC2H6, or CH3.CO.CH- (OC2H5).CO2C2H5, b.p.44 105°, is formed by reduction of ethoxyl chloraceto- acetic ester, the condensation product of chloracetic ester and sodium (A. 269, 15). y-M ethoxyl Dimethyl Acetoacetic Ester, (CH8O)CH2.CO.C(CH3)2CO2C2H6, m.p. 70°, b.p. 241°, is prepared from y-bromo-dimethyl-acetoacetic ester and sodium mcthoxide in methyl alcohol (B. 30, 856). y-Acetoxyla-Acetyl Butyric Ester, CaH3O.OCH2.CHaCH(COCH8)CO2CH3, b.p.,2 15°- 1 53°, is formed from glycol bromacetin (p. 230) and sodium acetoacetic ester (C. 1904, II. 586). a-HydroxyknuKnic Acid, CH3CO.CH2CH(OH)CO2H, m.p. 103°, and £- Hydroxylcevulinic Acid, CH3COCH(OH)CH2CO2H, an oil, are prepared from the corresponding bromolaevulinic acids (A. 264, 259). Chloral acetone (p. 342) may be considered as being the orthotri chloride of the first of these acids. a-Amino-a-methyl-lfBvulinic Acid; the nitrile (formula, see below), b.p.,7 108°, is formed from acetonyl acetone (p. 351) and ammonium cyanide. It readily loses water and passes into a cyclic imine or pyrroline derivative (B. 40, 2886): CHaCOCH3 CH2.C(CH3)(NHa)CN CHa— C(CH3k CN - > | - >- | />NH CHaCOCH3 CH2COCH8 CH = C(CU&Y Ketohydroxystearic Acid, CH3[CHa],jCH(OH)CH3CH2CO[CH2]7COOIJ, m.p. 84°, is obtained from ricinostearolic acid (p. 302). An isomenc ketohydroxy- stearic acid, m.p. 64°, is obtained by oxidizing oleic acid with permanganate in neutral solution (B. 36, 2657). Hydroxy-olefine Ketocarfcoxylic Acids include Hydroxymethylene Acetoacetic Ester, HOCH:C(COCH3)CO2R, which can also be looked on as being the ad- form of J or my I acetoacetic ester among the aldehydoketone carboxylic acids (below). 13. ALDEHYDOKETONE CARBOXYLIC ACIDS Glyoxyl Carboxylic Acid, CHO.CO.CO2H, is formed by the oxidation of tartaric acid by chlorine in the presence of ferrous salts ; also from dihydroxy- maleic acid (q.v.) and ferric sulphate (C. 1902, I. 857, 978). Uric Acid may be looked upon as the diure'ide of this half-aldehyde of mesoxalic acid. Di-isonitroso- propionic Acid, HON:CH.C:N(OH).COaH, is the dioxime of glyoxyl carboxylic acid. It is obtained from dibromopyroracemic acid. It is known in two modi- fications, the one m.p. 143°, the other m.p. 172° (B. 25, 909). Furaza^i Carboxylic Acid, o^-*, m.p. I07°, is the anhydride of this dioxime. It results N:CH from the oxidation of furazan propionic acid with KMnO4. Sodium hydroxide causes it to rearrange its. If into cyanoximido-acetic acid (A. 260, 79 ; B. 24, noy). Osazone of glyoxyl carboxylic acid, CH(NNHC.H6)C(NNHC,H6)COOri, m.p. 223°. VOL. I. 2 N 546 ORGANIC CHEMISTRY Glyoxyl Propionic Acid, HCO.CO.CH2CH2CO2H, results, together with diacetyl, when /JS-dibromolaevulinic acid is boiled with water. It forms a yellow varnish. It passes into succinic acid upon oxidation. Its oxime is •yB-dioximido- valeric acid, HC(:NOH).C(:NOH).CH2.CH2.CO2H, m.p. 136°. Concentrated sulphuric acid changes it into the anhydride, Furazan- Propionic Acid, 0<N-CHHaCHaCOaH' m'p' 86°' Sodium hydroxide converts this acid into cyanoximidobutyric acid (p. 568), whilst with potassium permanganate it yields furazan carboxylic acid. In the form of a keto-aldehyde (see pp. 346, 3.19), glyoxyl propionic acid condenses with ammonia and formaldehyde to a sly ox aline ,N-CH propionic acid, CH^f , which is also produced from histidine, XNH.CCH2CH2CO2H one of the protein decomposition bodies (C. 1905, II. 830 ; 1908, II. 606). Gloxyl Isobutyric Acid, CHO.CO.C(CH3)2COOH, m.p. 138°. is obtained from the I | isomeric Dihydroxyacetyl Dimethyl Acetic Acid Lactone, (HO)CH.CO.C(CH3)2COO, m.p. 1 68°, by solution in soda and subsequent precipitation by hydrochloric acid. The lactone was obtained on treating y-methoxy-dimethyl-acetoacelic ester with bromine, and then decomposing the monobromosubstitution product with water (B. 30, 856). Derivatives of an aldehydo-keto-carboxylic acid, CHO.CH2CO.CO2H (or an unsaturated hydroxy-aldehydic acid, CHO.CH:C(OH)CO2H), are probably exemplified by muco-hydroxy-chloric acid and muco-hydroxy-bromic acid (p. 402) (Am. 9, 148 ; 160). Formyl Acetoacetic Acid, CHO.CH(COCH3)COOH, and in its desmotropic enol-torms, HOCH:C(COCH3)COOH, and CH3C(OH):C(CHO)CO2H, is the hypothetical acid from which may, perhaps, be derived Hydroxymethylene Acetoacetic Ester, HOCH^CX^Q^11*, b.p.21 95°, which is formed by the action of water on Ethoxymethylene Acetoacetic Ester, C2H6O.CH=C<^2C|H5, b.p.16 150°. The substances are also obtained from orthoformic ester and acetoacetic ester by heating them with acetic anhydride (B. 26, 2730). Hydroxymethylene acetoacetic ester is a strong acid (see Hydroxy- methylene Acetyl Acetone, p. 536) ; it is readily soluble in alkali acetates, but is insoluble in water ; copper salt, m.p. 156°. Ethoxymethylene acetoacetic ester is converted by ammonia into Aminomethylene Acetoacetic Ester (C6H8O3)- =CH.NH2, m.p. 55°, and combines with acetoacetic ester to form Methenyl Bis-acetoacetic Ester, (C6H8O3):CH(C6H9O3), m.p. 96°. The latter is converted by ammonia into lutidine dicarboxylic ester (Vol. II.) ; and by sodium ethoxide into m-hydroxyuvitic acid (L. Claisen, A. 297, 14). When alkoxymethylene acetoacetic acid is melted with sodium acetoacetic ester, two dyes of undeter- mined structure are formed — xanthophanic acid and glaucophanic acid (B. 39, 2071 ). 14. DIKETOCARBOXYLIC ACIDS Paraffin Diketooarboxylic Acids. 