None
15. The hydrogen atoms of the alkyl groups present in the ketones can be replaced by chlorine and bromine. 1 6. Boiling with acid ch'orides, especially benzoyl chloride, converts many ketones into esters of the isomeric a/J-olefine alcohols (p. 124), RC(O.COC6H5) : CHR'. 17. Unlike the lower members of the aldehyde series which easily undergo polymerization, the ketones never do this. Compared with aldehydes the ketones possess a symmetrical structure. Nucleus-synthetic Reactions of the Ketones. — Reactions of this class were ob- served in the action of ammonia and of phosphorus trichloride on acetone in the presence of aluminium chloride (comp. 12 and 13). The following are, however, more important : — (i) Just as two aldehyde molecules condense to aldol, so aldehyde or chloral will unite with acetone, forming hydracetyl acetone and trichlorohydracetyl acetone (q.v.): CH3.C<g +CH,.CO.CH3=CH3.CH<g^ Acetone will also condense with other aldehydes, — e.g., benzaldehyde. But it is impossible to obtain the ketone-alcohols which form at first. There is a loss of water, and unsaturated derivatives are produced, just as in the condensation of two molecules of aldehyde to form crotonaldehyde. Thus, two molecules of acetone, in the presence of ZnCl2,HCl, or H2SO4, unite directly, with the elimination of water, to form mesityl oxide (p. 229), which in turn condenses with a third molecule of acetone to form phorone (p. 229). /PTT \ f*(~\\ C*\l PPi PW ^•*":*-3NSP PW PPl PT-T J_T-I t~\ (\sfij)i\s\j -}-\_/ri8.^^.\^n3 — pi-i ^^* — x*x».VrfV.vx«* J*T*»*»^'« * Mesityl Oxide. X-*TT PT-T *. C^t-f v/n8>vy-> pur rc\ PT-f -L-rT^/PM ^ Vy-l-l3\p PW PO PM p< 3_i_H p» n^.,a^\^=^ri.\^\J.^rl^-f-\^\J(^n.3)t = /->rj ^v^ — L/rl.^w.L/rl=L/\pTT*-t-rljV^. U±18 ^"3 ^na Phorone. (2) Acetone and other ketones, having a suitable constitution, change into symmetrical trialkyl benzenes, under the influence of concentrated sulphuric acid. It is very probable that there is an intermediate formation of alkylated acetylenes (p. 89). Acetone yields mesitylene : CH8 H2S04 3CO > CH, CH Acetone. Allylene. (3) Acetone condenses, in presence of lime or sodium ethylate, to isophorone, a trimethyl cyclo-hexenone (q.v.). A sodium hydroxide solution at o° causes two molecules of acetone to condense to diacetone alcohol, (CH3)2C(OH).CHaCOCH3. (4) The ketones, like the aldehydes, unite with hydrocyanic acid to form hydroxycyanidcs or cyanhydrins, the nitriles of the a-hydroxy-acids. They will 222 ORGANIC CHEMISTRY be described after the a-hydroxy-acids, into which they pass when treated with hydrochloric acid : HNC - HC1 (CH,),CO - - a-Hydroxyisobutyric Acid. (5) Acetone, in the presence of sodium hydroxide, combines with chloroform, yielding acetone chloroform, which is a derivative of a-hydroxyisobutyric acid ; the latter can be obtained from it : (CH3),CO - - -> (CH8),C<» -- > (CH3)2C<' Acetone Chloroform. a-Hydroxyisobutyric Acid. (6) Nascent hydrogen converts the ketones not only into secondary alcohols (p. 1 06), but also into pinacones, or di-tertiary glycols (p. 220) : Acetone, Dimethyl Ketone [Propanone], CH3.CO.CH3, m.p. —94° (B. 33, 638), b.p. 56-5°, D20 = 07920, is isomeric with propion- aldehyde, propylene oxide, trimethylene oxide, and allyl alcohol. It occurs in small quantities in the blood and normal urine, whilst in the urine of those suffering from diabetes it is present in considerable amount, due, apparently, to the breaking down of the acetoacetic acid formed at first. It is also produced in the dry distillation of tartaric acid, citric acid (q.v.), sugar, cellulose (wood), and is, therefore, found in crude wood spirit (p. 109). Technically it is prepared by the distillation of calcium acetate, or from crude wood spirit. It is also formed : by the oxidation of isopropyl alcohol, isobutyric acid, and a-hydroxyisobutyric acid ; by heating chloracetol and bromacetol, CH3CBr2CH3, with water to 160-180° ; and /J-chloro- and /?-bromopropylene, CH3CBr=CH2, with water at 200°. It would naturally be expected that an alcohol, CH3.C(OH) : CH2, would be formed, but a transposition of atoms occurs and acetone results (see p. 36). Acetone is similarly formed from allylene, CH3.C • CH, by action of sulphuric acid or HgBr2 in the presence of water (p. 89). It results, further, in the action of zinc methyl on acetyl chloride ; and, accompanied by diacetyl, by the electrolysis of a solution of pyroracemic acid and potassium acetate (B. 33, 650. Acetone is also formed from a-bromoisobutyric amide by bromine and alkali (C. 1905, I. 1219): zKOH (CH3)2CBr.CONHBr - > (CH3)2CO+NH3+ 2KBr+COa. (See also the general methods of formation of the ketones, pp. 216, 217.) Acetone is a mobile, peculiar-smelling liquid, and is miscible with water, alcohol, and ether. Calcium chloride, or potassium carbonate, throws it out from its aqueous solution. It is an excellent solvent for many carbon compounds, and for many inorganic salts such as potassium permanganate, etc. (B. 37, 4328). Its most important reactions were described under the reactions of the ketones (p. 218), as well as its behaviour towards nascent hydrogen, oxidizing agents, amyl nitrite, hydrogen sulphide, mercaptans and hydrochloric acid, alkali bisulphites, ammonia, hydroxylamine, phenyl- hydrazine, phosphorus pentachloride, halogens, condensation agents, hydrocyanic acid, chloroform, and potassium hydroxide. (See j3-AUyl Alcohol, p. 124, for the action of sodium on acetone.) Acetone is used in the preparation of sulphonal (p. 226), chloroform (p. 245), and iodoform (p. 246) ; the production of the latter serves for its detection (B. 13, 1002 ; 14, 1948 ; 17, R. 503 ; 29, R. 1006). (For KETONES OF THE SATURATED SERIES 223 other such reactions, consult B. 17, R. 503 ; 18, R. 195 ; A. 223, 143.) Acetone can be quantitatively determined by means of mercuric sulphate (B. 32, 986) ; also by heating it with mercuric acetate, whereby acetone-mercury substitution compounds are produced (B. 36, 3699). Mercuric oxide dissolves in a weakly alkaline aqueous solution of acetone, forming the compound 2C3H6O.3HgO which by boiling with alkalis changes to the insoluble Acetone Mercarbide, CH3COCHg3O2H (B. 38, 2677). Homologues of Acetone. — (a) Simple Ketones are usually prepared by the dis- tillation of the calcium or barium salts of the corresponding fatty acids. Name. Formula. M. P. B. P. Diethyl Ketone, Propione [3-Pentanone] Di-n-Propyl Ketone, Butyrone. Di-isopropyl Ketone, Tetramethyl Ace- CO(C2H6), CO(C3H7)2 CO[CH(CH3)2]2 — I03° M4° 124° Di-isobutyl Ketone, Isovalerone CO[CH2CH(CH3)2]2 CCKCiR,.)* 14-6° I65° 226° CO[CH(C2HB)2]. 203° CO(C.H1S), 30° 263° Caprylone CO(C7H15)2 CO(C.H17)2 40° 48° CO(CnH23)a 69°. Myristone . . • . .••• CCKC^Ho,)., 76° Palmitone CO(C,KH,t), *3° Stearone • . • . . .. CO(C,,H,K), 88° _= Diethyl Ketone is produced from carbon monoxide and potassium ethyl (p. 184). Tetramethyl and Tetraethyl Acetone have been obtained as decomposition products of pentamethyl and pentaethyl phloroglucinol, when these bodies were oxidized by air (B. 25, R. 504). (b) Mixed Ketones, Most of the members of this class are made by the distillation of the barium salts of the corresponding fatty acids with barium acetate (p. 217). Name. Formula. M. P. B.P. Methyl Ethyl Ketone [Butanone] .. Methyl Propyl Ketone [2-Pentanone]. Methyl Isopropyl Ketone [Methyl Buta- none] CH3.CO.C2H6 CH3.CO.C3H7 CH3.CO.CH(CH3)2 — 81° 102° 96° Methyl sec. -Butyl Ketone .... Pinacollne, Methyl tert.-Butyl Ketone Methyl (Enanthone Methyl Hexyl Ke~ tone . . ..... CH3.CO.CH2CH(CH3)2 CH3.CO.C(CH3)3 CH3.CO.C6H13 — 116° 1 06° 171° Methyl Heptyl Ketone Methyl Nonyl Ketone CH3.CO.C7H16 CH3.CO.C,H19 -15° + 15° 193° 225° Methyl Decyl Ketone CH3.CO.C10H2] 21° 247° Methyl Undecyl Ketone from Laurie Acid . ... CH3.CO.CnH2, 28° 263° Methyl Dodecvl Ketone CH3.CO.C12H2. 34° (207°) Methyl Tridecyl Ketone from Mvristic Acid CH3.CO.C13H27 39° (224°) Methvl Tetradecvl Ketone .... Methyl Pentadecyl Ketone from Pal- mitic Acid CH,.CO.Cl4Hit CH3.CO.C1SH31 43° 48° (231°) (244°) Methyl Hexadecyl Ketone from Mar- garic Acid CHa.CO.C1BH,, 52° (252°) Methyl Heptadecyl Ketone from Stearic CH3.CO.C17H35 55° (265°) 224 ORGANIC CHEMISTRY The boiling points, inclosed in parentheses, were determined under 100 mm. pressure. Methyl Ethyl Ketone occurs in crude wood spirit. Methyl sec.-Butyl Ketone results from the interaction of methyl-acrylic ester, CH2:C(CH3).CO2R, with two molecules of magnesium methyl iodide (C. 1907, I. 559). Methyl Htxyl Ketone is obtained from cenanthol and diazomethane (mode of formation 13, p. 218). Pinacoline is obtained by the withdrawal of water from the pinacone, tetramethyl ethylene glycol, (CH3)2C(OH).C(OH)(CH3)2, and from trimethyl acetyl chloride and zinc methyl (p. 217). When oxidized with chromic acid, it breaks down into trimethyl acetic and formic acid. Potassium permanganate converts it into trimethyl pyroracemic acid (q.v.}. It is converted by iodomethane and alkali into Pentamethyl Acetone (CHS)3C.COCH(CH3)2, b.p. 134° (A. 310, 325). Reduction produces pinacolyl alcohol (p. 122). For further changes, see C. 1906, II. 496. Homologous pinacones yield homologous pm&colines; thus Methyl Ethyl Pinacone, >C(OU).C(OU)<] . yields Ethyl tert.-Amyl Ketone, >C.CO.C2H6, b.p. 150°. C2H5X Methyl Nonyl Ketone is the chief constituent of oil of rue (from Ruta grave- olens), from which it may be extracted by shaking with concentrated sodium bisulphite solution (C. 1902, I. 744). Methyl Heptyl Ketone occurs in the same oil (C. 1901, I. 1006 ; 1903, I. 29 ; B. 35, 3587). Acetone Peroxide. Two cyclic acetone peroxides are known. Cyclo-diacetone Peroxide (CH3)aC<£^Q>C(CH3)2, m.p. 132°, is prepared by the action of H2SO, (Caro'sacid) on acetone (B. 33, 858). Cyclo-triacetone Peroxide (C3H«O2)3, m.p. 97°, is obtained from acetone and hydrogen peroxide, with special ease when in the presence of hydrochloric acid. It is insoluble in water, but soluble in benzene and in ether. It forms beautiful crystals, and explodes when struck or suddenly heated {B. 28, 2265). Methyl ethyl ketone and H2SO6 produce Methyl Ethyl Ketone Peroxide (C4H8O2)2, a colourless oil, which explodes above 100° (C. 1907, I. 944)- I. HALOGEN SUBSTITUTION PRODUCTS OF THE KETONES, PARTICU- LARLY ACETONE Monochloraeetone, CH3.CO.CH8C1, b.p. 119°, is obtained when chlorine is conducted into cold acetone (A. 279, 313), preferably in the presence of marble (B. 26, 597) ; also by the electrolysis of a mixture of acetone and hydrochloric acid (C. 1902, I. 101). Its vapours provoke tears. a-Dlchloracetone, CH3.CO.CHC12, b.p. 120°, is formed on treating warmed acetone with chlorine, and is also obtained from dichloraceto-acetic ester (B. 15, 1165). 0-DIehloracetone, C1CH2.CO.CH2C1, m.p. 45°, b.p. 172-174°, is obtained by the chlorination of acetone and in the oxidation of a-dichlorhydrin, CH,C1.CH(OH).CH,C1 (q.v.), with potassium dichromate and sulphuric acid. sym.-Tetrachlorac*tone, CHC12.CO.CHC12+2H2O, m.p. 48-49°, is obtained by the action of potassium chlorate and hydrochloric acid on chloranilic acid (B. 21, 318) and triamidophenol (B. 22, R. 666); or of chlorine on phloro- glucinol (B. 22, 1478). unsym.-Tetrachlor acetone, CH2C1.CO.C€12, b.p. 183°, is produced by the action of chlorine on isopropyl alcohol (C. 1897, I. 28). Pentachloraceto'ne, CHC12.CO.CC13, b.p. 193°, is obtained from chlorine and acetone (A. 279, 317). Monobromacetone, CH2Br.CO.CH3, b.p.8 31° (B. 29, 1555 ; 31, 2684). Penta- bromacetone, m.p. 74°, is produced from acetone dicarboxylic acid and bromine (C. 1899, I. 596). Perbromacetone, CBrs.CO.CBr3, m.p. iio-m°, is obtained from triamidophenol (B. 10, 1147), and bromanilic acid (B. 20, 2040 ; 21, 2441) by means of bromine and water. lodoacetone, CH3.CO.CH2I, b.p.^ 58°, is produced when potassium iodide in an aqueous methyl alcohol solution acts on monochloracetone (B. 29, 1557). It is a heavy oil with an intolerable pungent odour. SULPHUR DERIVATIVES OF THE SATURATED KETONES 225 £-Di-iodoacetone, CH2I.CO.CH2I, results when iodine chloride acts on acetone. p-Chlorisobutyl Methyl Ketone, (CH3)2.CC1.CH2.CO.CH3, and Di-B-chloriso- butyl Ketone, (CH3)2CC1.CH2.CO.CH2CC1(CH3)2, are the readily decomposable addition products of mcsityl oxide and phorone with hydrochloric acid. w-Bromo- butyl Methyl Ketone, see Acetobutyl Alcohol. y-Dibromoketones are prepared from the oxetones (q.v.) by the addition of 2HBr, e.g. y-Dibromobutyl Ketone, (CH3CHBr.CH2.CH2)2CO, is formed from dimethyl oxetone and 2HBr, or by the addition of aHBr to diallyl acetone (p. 232) a-Dichloroketones are discussed with the diketones. 2. ALKYL ETHERS OF THE ORTHO-KETONES The ketones may be regarded as the anhydrides of hypothetical glycols, which bear the same relation to the ketones that the orthocarboxylic acids do to the carboxylic acids. In this sense it is then permissible to speak of ortho-ketones. Their alkyl ethers, corresponding with the acetals, are produced by heating the j8-diethoxy-carboxylic acids, and also from acetone by means of orthoformic ester (Claisen, B. 31, 1010) : CH3.C(OC2H5)2CH2.C02H > CH3.C(OC2H6)2.CH3+CO2 CH3.CO.CH3+ HC(OC2H6)3 > CH3.C(OC2H5)2CH3-fHCO2C2H§. Orthoacetone Methyl Ether, (CH3)2C(OCH3)2, b.p. 83°. Orthoacetone Ethyl Ether, b.p. 114°, is a liquid with an odour resembling that of camphor. These substances are stable when pure, but water or a trace of mineral acid causes them to break down into ketones and alcohols. The ortho-ester homologues of orthoformic esters react on ketones like the first member, and the same may be said of the imido-ether hydrochloride and alcohol mixture. Methyl Ethyl Ketone Orthoethyl Ether, b.p. 120° ; Diethyl Ketone Orthoethyl Ether, b.p. 154° ; Dipropyl Ketone Orthoethyl Ether, b.p.12 70°, are prepared from acetimido-ether hydrochloride or phenyl acetimido-ether hydrochloride and alcohol (B. 40, 3020). 3. KETONE HALIDES arc produced, as mentioned on p. 220, by the action of PC15, PCl3Br2, and PBr5 upon ketones. They easily give up the halogen in form of acid, forming halogen olefines (p. 96), which in turn yield acetylene, by the action of alkalis (p. 96). Acetone Chloride, Chloracetol, CH3.CC12.CH3> b.p. 70°; D16=i-827. Brom- acetol, b.p. 114°; D0 = i'8i40. Methyl Ethyl Dichloromethane, CH3.CC12.C2H6, b.p. 96°. Methyl Ethyl Dibromomethane, b.p. 144°. Methyl tert.-Butyl Dichloro- methane, CH3.CC12.C(CH3)3, is produced from pinacoline by PC15 (comp. C. 1906, II. 496). Heptachloropropane, CHC12.CC12.CC13> m.p. 30°, b.p. 150°, is obtained from pentachloracetone (A. 297, 314). 4. KETONE BISULPHITES AND SULPHOXYLATES The addition compounds, which many ketones form with alkali bisulphites, comparably with the aldehydes (p. 207), are probably salts of acid sulphurous esters with ortho-ketones : CH8Xr .OH CH3.r^OH CH3>C<OS02Na C2H6>(X-OS02Na With alkali cyanides they yield hydroxy-acid nitriles (C. 1903, I. 1244). Reduc- tion produces ketone sulphoxylates, (CH3)2C(OH).OSONa, which are also formed, together with bisulphites, from ketones and hydrosulphites (C. 1907, I- 855). 5. SULPHUR DERIVATIVES OF THE SATURATED KETONES A. Thioketones and their Sulphones.— When hydrogen sulphide acts on » cold mixture of acetone and concentrated hydrochloric acid, the first product VOL. I. Q 226 ORGANIC CHEMISTRY is a volatile body with an exceedingly disagreeable odour which spreads with great rapidity. It is probably thioacetone, which has not been further in- vestigated. The final product of the reaction is — /S— /C(CH3)2 Trithioacetone, (CH3)2C< S< , m.p. 24°, b.p.18 130°. Potassium X\ permanganate oxidizes it to — Trisulphone Acetone, [(CH3)2CSO2]3, m.p. 302°. When distilled at the ordinary pressure it is converted into Dithioacetone, (CH3)aC<|>C(CH3)2) b.p. 183-185°. This is also formed in the action of phosphorus trisulphide on acetone. It is converted, by oxida- tion, into — Disulpho-te Acetone, [(CH3)2CSO2]2, m.p. 220-225°. vlet'iyl ;thy\ ketone behaves similarly (C. 1903, II. 281). B. Mercantols and their Sulphones.— Although the ketone derivatives corre- vi ling with the acetals cannot be derived from ketones and alcohols by the it i Irin- il of '.vit^r, it is possible to obtain the mercaptols — the ketone derivatives » T -sponlH" wi'h the mercaptals — in this manner; but best, however, by the action of hydrochloric acid on ketones and mercaptans : HC1 (CH3)2CO+2C2H.SH -- —> (CH3)2C(SC2H5)2 + H20. Like the mercaptals, they are liquids with unpleasant odour. Acetone Ethyl Mercaptol, Dithioethyl Dimethyl Methane, (CH3)2C(SC2H5)2, b.p. 190-191°, may be prepared from mercaptan. However, to avoid the intolerable odour of the latter, sodium ethyl thiosulphate and hydrochloric acid are used (p. 147). It combines with methyl iodide (B. 19, 1787 ; 22, 2592). By this means, from a series of simple and mixed ketones, corresponding mercaptols have been made, and in nearly all instances they have been oxidized to the corresponding sulphones, some of which possess medicinal value. Sulphonal, Acetone Diethyl Sulphone, (CH3)2C(SO2C2H5)2, m.p. 126°, was discovered by Baumann, and was introduced into medicine, as a very active sleep-producing agent, by Kast in 1888. It is prepared by oxidation of acetone mercaptol with potassium permanganate : 4O (CH3)2.C(SC2H5)2 -- > (CH,)1.C(S01CfH8)t. Sodium hydroxide and methyl iodide (A. 253, 147) acting on ethylidene diethyl sulphone (p. 210) produce it: NaOH CH3I CH3CH(SO,C2H6)2 -- >CH3.CNa(S02C2H5)2 -- ^(CH3)2C(SO2C2H6)2. Trional, Methyl Ethyl Ketone Diethyl Sulphone, Diethyl Sulphone Methyl Ethyl Methane, C™3>C(SO2C2H5)2, m.p. 75° ; etronal, Penlane-yy-diethyl Sulphone, (C3H5)2C(SO2CaH5)2, m.p. 85°; Pentane-yy-dimethyl Sulphone,(C2H5)2C(SO2CH3)2, m.p. 132-133°, and other " sulphonals," are prepared similarly to sulphonal. and act in like manner. However, Acetone Dimethyl Sulphone, (CH3)2C(SO2CH8)2, not containing an ethyl group, no longer acts like sulphonal. 6. NITROGEN DERIVATIVES OF THE KETONES A. Nitro-compounds.— Pseudonitroles (p. 153) and Mesodinitroparaffins (p. 154) have already been discussed after the mononitroparamns. B. Ammonia and ketones. — Two bases result from the action of ammonia on acetone : diacetonamine and trlacetonamine (p. 230). From methyl- ethyl ketone, diethyl ketone, and methyl propyl ketone, ammonia produces oils of the formula R2C(N:CRa)2, from which the original ketone is easily recovered (C. 1905, II. 540 ; 1907, I. 810). ^C. Hydroxylamine and ketones. NITROGEN DERIVATIVES OE THE KETONES 227 Ketoximes (V. Meyer). — In general, the ketoximes are formed with greater difficulty than the aldoximes (B. 39, 1452). It is usually best to apply the hydroxylamine in a strongly alkaline solution (B. 22, 605 ; A. 241, 187). They are also produced when the pseudonitroles are reduced by free hydro xylamine or potassium hydrosulphide (B. 28, 1367 ; 29, 87, 98): They are very similar in properties to the aldoximes. Acids resolve them into their components, whilst sodium amalgam and acetic acid convert them into primary amines (p. 158). They are characteristically distinguished from the aldoximes by their behaviour towards acid chlorides or acetic anhydride, yielding in part acid esters ; and by their conversion by the same reagents, as well as by HC1 or H2SO4 in glacial acetic acid, into acid amides (Beckmann's inversion, B. 20, 506, 2580; comp. also B. 24,4018 ; A. 312, 172, note). CH CH CH*>C=NOH ** CH3CO.NHCH2CH.CH3. Methyl Propyl Ketoxime. Acetopropylamide. If the two alkyl groups in a ketone differ only slightly from one another, two isomeric amides are formed. If one alkyl group contains many more carbon atoms than the other, it is usually the group richer in carbon that wanders to the nitrogen atom (C. 1904, I. 355). For the investigation of this change, which is comparable to that undergone by carboxylic bromamides, azides, and hydrox- amic acids (p. 244), see C. 1903. I- 489- Nitrogen tetroxide converts the ketoximes into pseudonitroles (p. 153). Chlorine and sodium hydroxide or bromine and pyridine produce i,i-chloro- and bromo-nitrosoparamns (p. 153). Ketoximes combine with hydrocyanic acid to form nitriles of a-amidoxyl carboxylic acids (B. 29, 62). Acetoxime, (CH3)aC:NOH, m.p. 59-60°, b.p. 135°, smells like chloral. It dissolves readily in water, alcohol, and ether, from which it crystallizes well (B. 20, 1505 ; 39, 876). The hydroxyl hydrogen present in acetoxime may be replaced by acid radicals through the agency of acid chlorides or anydrides (B. 24, 3537). Methyl Ethyl Ketoxime, b.p. 152-153°. Methyl n-Propyl Ketoxime, b.p. 168° (C. 1898, II. 474), is an oil with an agreeable odour. Methyl Isopropyl Ketoxime, b.p. 157°. Methyl n-Butyl Ketoxime, b.p. 185°. Methyl tert.-Butyl Ketoxime, Pinacoline Oxime, m.p. 75°, reacting with PC15 produces aceto-tert.-butyl- amine. Nitrogen tetroxide does not produce pseudonitroles, but a nitrimine, C(CH,),.C(CH8):N.N02( or the desmotrope C(CH3)3C(:CH2).N:NOOH. (Comp. mesityl nitrimine, p. 231, and A. 338, i.) n-Butyrone Oxime, b.p. 193°. Isobutyrone Oxime, m.p. 6-8°, b.p. 181-185°. Methyl Nonyl Ketoxime, m.p. 42°, behaves contrary to the rule (see above) and undergoes internal change under the influence of concentrated sulphuric acid, forming considerable quantities of capric methylamide, C,HltCONHCH8, together with acetononylamine (B. 35, 3592). Capryl Ketoxime, m.p. 20°. Nonyl Ketoxime, m.p. 12°. Laury I Ketoxime, (CnH23)2C:N.OH, m.p. 39° Myristyl Ketoxime, (CJ3 H27C:N.OH, m.p. 51°. Pal- mityl Ketoxime, (C16Hia)2C:N.OH, m.p. 59°. Stearyl Ketoxime, (C17H36)aC:N.OH, m.p. 62°. When a solution of a ketoxime is acted on by iodo-alkyls in the presence of sodium methoxide, a mixture is formed, which on distillation yields alkylated oximes, such as (CH8).C:NOCH8. These pass over, and alkylated isoketoximes (CH3)8C— NCH8.NaI remain behind combined with Nal as \/ . The alkyl iso- O ketoxime cannot be obtained from this compound. Acetoxime Ethyl Ether, (CH3)2C=NOCH3, b.p. 72°. Methyl Isoacetoxime (CH8)aC— N.CH3.NaI Sodium Iodide, \/ , m.p. 206°, with decomposition, and others of this group, see C. 1901, II. 184. 228 ORGANIC CHEMISTRY D. Ketazines (Curtius and Thun). — An excess of hydrazine acting on the ketones produces the unstable, secondary symmetric hydrazines, readily changing even in the cold into ketazines, which are quite stable towards alkalis (B. 25, R. 80). Dimethyl ketazine in contact with maleic acid changes into the isoineric trimethyl pyrazoline (B. 27, 770; C. 1901, II. 1121): (CH3)2C=N N=CCH, (CH,),C=N~ >HN CHa :(CH3)8. The homologues of methyl-alkyl ketazine behave similarly, whilst diethyl ketazine does not undergo the change (C. 1898, II. 1249). Bis-dimethyl Azimethylene, Dimethyl Ketazine, [(CH8)2C:N]2, b.p. 131°; Bis-methyl Ethyl Azimeththylene, b.p. 170°; Bis-methyl Propyl Azimethylene, b.p. 197°; Bis-methyl Hexyl Azimethylene, b.p. 290°; Bis-diethyl Azimethylene, b.p. 193°. E. Ketone Phenylhydrazones (E. Fischer, B. 16, 661 ; 17, 576 ; 20, 513 ; 21, 984). — These compounds result by the action of phenylhydrazine on the ketones. The phenylhydrazine is added to the ketone until a sample of the mixture no longer reduces an alkaline copper solution. They behave like the aldehyde phenylhydrazones (p. 213). Acetone Phenylhydrazone, (CH3)2C:N2HC6H5, m.p. 16°, b.p.,3 165°. Methyl n-Propyl Ketone Phenylhydrazone, b.p.100 206°. p-Nitrophenylhydrazones are specially suitable for identifying ketones on account of the relative insolubility of the compound formed. Acetone p-Nitro- phenylhydrazone, (CH3)2C:NNHC6H4NO2, m.p. 148° (C. 1904, I. 14). Ketone Semicarbazones result when ketones are mixed with semicarbazide, NH2CO.NH.NH2 (q.v.) at ordinary temperatures. Such compounds are particularly suitable for the identification of the ketones, on account of the excellent way they crystallize. Acetone Semicarbazone, (CH3)2C:NNHCONH2, m.p. 187°. Ethyl Methyl Ketone Semicarbazone, m.p. 135°. Diethyl Ketone Semicarbazone, m.p. 139°, and other members, see B. 34, 2123. 3B. Olefine and Diolenne Ketones. Olefine ketones, in which the double bond is situated next to the keto-group, are very easily prepared, and are interesting in their behaviour. (1) (a) ajS-olefine ketones are obtained from the product of condensation of ketones with aldehydes or ketones ; the i,3-keto-alcohols which are formed easily give up water : CH8CHO+CH3COCH3 > CH3CH(OH)CH2COCH8 > CH,CH:CHCOCH8. Condensation of several molecules of the same ketone results in the formation of ajS-olefine ketones and a2/?2-diolefme ketones : acetone yields Mesityl Oxide and Phorone : (CH8)8CO 2CH8COCH3 > (CH3)2C:CHCOCH3 - > (CH^CiCHCOCI^CH^. (b) The haloid esters of the i,3-keto-alcohols, such as j3-chloro- and /?-bromo- ketones, easily give up halogen acids, forming a/3-olefine ketones ; e.g. /S-chloro- ketones (prepared from j8-chloropropionyl chloride and zinc alkyls : mode of formation, p. 217), and diethyl aniline yield vinyl alkyl ketones (C. 1906, I. 650) : Zn(CaH5)a C1CH8CH2COC1 - —>- ClCHaCH2COC2H8 >• CH2:CHCOC2H5. (c) Allyl alkyl ketones, which can be prepared from the acid nitriles, allyl iodide and zinc (comp. mode of formation 9, p. 217) very easily change into propenyl a'Jryl ketones, under the influence of mineral acids (C. 1905, I. 431): C3H.ZnI CH,C;N > CH9COCH2CH:CH, > CH3COCH:CHCH8. (2) defines with any desired position of the double bond can be obtained OLEFINE AND DIOLEFINE KETONES 229 by decomposing olefine-substituted /?-ketone acid esters or j8-diketones (comp. mode of formation 13, p. 218) ; e.g. allyl acetic ester gives allyl acetone ; dimethyl allyl acetyl acetone yields dimethyl heptenone. The ajS-olefine ketones are remarkable for the great additive capacity of their C=C group, which approximates to that of the C=O group. Hydroxylamine produces not only oximes but also fi-Hydroxylamino-oximes, RCH(NHOH).- CH2C(:NOH)R. Ammonia, primary and secondary amines are particularly easily taken up, forming fi-aminoketones. Hydrazines react with the CO and C=C groups, producing cyclic pyrazolines. Mercaptans form not only mercaptols. but also mercapto-mercaptols, even when the C=C group is not contiguous to the CO group ; e.g. CHSCH(SC2H6)CH2C(SC2H6)2CH3, CH3CH(SC1H6)CHaCH2C(SC1H6)aCH3> etc. In phorone, only the two C=C groups react : (CH3)2C(SC2H5).CH2.CO.CH2C(SC2H5)(CH3), (B. 37, 502). Sulphurous and hydrocyanic acids sometimes unite with the C=C group rather than with the CO. Malonic ester, acetoacetic ester, and other such reactive bodies similarly unite with the C=C bond of afl-olefine ketones, forming RCOCH2CR.CH(C02C2H6)2, etc. Addition compounds with the halogen acids are very readily formed. It is a general rule that, when HX becomes attached to these unsaturated substances, the hydrogen atom always takes the a- position to the CO group, and the X group the ^-position. Bromine forms a/J-dibromoparaffms, which readily give up HBr, leaving a-bromo-olefine ketones, which yield a-diketones on hydrolysis (B. 34, 2092). Vinyl Ethyl, Vinyl Propyl, Vinyl Isopropyl Ketone, CH2:CHCOR, b.p.47 31°, b.p.10 24°, and b.p.10 32°, are produced from jS-chloropropyl ethyl ketone, £-chloro- propyl propyl ketone, and j8-chloropropyl isobutyl ketone. They all easily undergo polymerization. Allyl Methyl Ketone, b.p. 108°, AllyltEthyl Ketone, b.p. 127°, and Allyl Propyl Ket&ne, b.p. 147°, CH2:CH.CH2COR, are readily changed by mineral acids into Propenyl Methyl Ketone, b.p. 121°, Propenyl Ethyl Ketone, b.p. 137°, and Propenyl Propyl Ketone, b.p. 157°. Ethylidene Acetone, CH3CH=:CH.CO.CH3, b.p. 122°. It has a penetrating odour like that of crotonaldehyde. It is formed when hydracetyl acetone (q.v.) is boiled with acetic anhydride or anhydrous oxalic acid (B. 25, 3166; 34, 2092). Isobutylidene Acetone, (CH3)2CH.CH:CH.COCH8, b.p.16 51° (C. 1900, 1. 403). Iso- amylidene Acetone (CH3)2CH.CHtCH:CHCOCHs, b.p. 180° (B. 27,R. 121 ; C. 1897, I. 365). Heptachlorethylidene Acetone, CHC12CC1=CC1.CO.CC13, b.p.14 184°, results when trichloracetyl tetrachlorocrotonic acid is heated with water (B. 25, 2695). Mesityl Oxide, (CH3)2C=CH.CO.CH3, b.p. 130°, is a liquid smelling like peppermint. Phorone, (CH3)2C=CH.CO.CH=C(CH3)a, m.p. 28°, b.p. 196°. These are formed simultaneously on treating acetone with dehydrating agents, e.g. ZnCl2, H2SO4, and HC1. Hydrochloric acid is best adapted for this purpose, the acetone being saturated with it, while it is cooled. The addi- tion products which are first formed, (CH3)2CC1.CH2.COCH3 and (CH3)2CC1.- CH2.CO.CH2.CC1(CH3)2, are decomposed by alkali hydroxides, and the mesityl oxide and phorone then separated by distillation. When acetone is condensed by lime or sodium ethylate there is produced along with the mesityl oxide a cyclic ketone isomeric with phorone, called isophorone (Vol. II.). Camphorphorone is also isomeric with these two phorones. Mesityl oxide is also produced when diacetone alcohol (q.v.) and diacetonamine (p. 230) are heated alone; also, together with acetone, when phorone is heated with dilute sulphuric acid, which eventu- ally causes it to break down into two molecules of acetone, as the result of water absorption (A. 180, i) ; also by the action of isobutylene on acetic anhydride in the presence of a little ZnCl2 (B. 27, R. 942). Mesityl oxide combines with ammonia to form diacetonamine (p. 230) and with hydrazine to trimethyl pyrazoline (Vol. II.). Mesityl oxide takes up two and phorone four bromine atoms. Just as acetone condenses to mesityl oxide and phorone, so the homo- logous ketones, and methyl ethyl ketone, methyl propyl ketone, methyl heptyl ketone, and methyl nonyl ketone are condensed by hydrochloric acid (B. 36, 2555) °r zinc chloride, and acetyl chloride (C. 1903, II. 566) to homologues of mesityl oxide and phorone. 230 ORGANIC CHEMISTRY Historical. — Kane discovered mesityl oxide in 1838, when he obtained it, together with mesitylene, by the action of concentrated sulphuric acid on acetone. At that time he regarded acetone as alcohol, and called it mesitalcohol. In mesityl oxide and mesitylene, Kane thought he had discovered bodies which bore the same relation to mesityl alcohol or acetone that ethyl ether or ethyl oxide and ethylene bear to ethyl alcohol. KekuU developed the formula (CH3)2.C=CH.CO.- CH3 for mesityl oxide, which was substantiated later by Claisen. Baeyer discovered phorone, and Claisen assigned to it the formula (CH3)2C=CH.CO.CH=C(CH3)a (A. 180, i). THE ACTION OF AMMONIA ON MESITYL OXIDE AND PHORONE Ammonia unites with these bodies at their double bonds and forms three bases, Diacetonamine. Triacetonamine, and Triacetone Diamine — the same that are formed from ammonia and acetone (Heintz, A. 174 133 ; 198, 42 ; 203, 336). There are two possible courses that the reaction may follow : firstly, that the acetone is condensed to mesityl oxide and phorone by the ammonia which then become converted into the amines, or secondly, the ammonia forms OH a simple addition compound, (CH3)2C<NH , which then condenses, NH3 CH3X /CHpDCH. >C = CHCOCH , ^ * CH/ CH/ XNH2 Mesityl oxide. Diacetonamine. CH3, /CH8.CO.CH8 /CH, CH,, /CH3 /* C ^>C >C=CH.CO.CH=C< — <- CH/ ^-NH^' XCH3 CH/ N:H, Triacetonamine. C,CO.CH XH, / NsTH2 NH/ X:HS Phorone. 4^ Triacetonamine. Triacetone diamine. (A. 203, 336-) Diacetonamine forms a colourless liquid, slightly soluble in water, which is decomposed into mesityl oxide and ammonia by distillation (B. 7, 1387). It shows a strongly alkaline reaction and forms crystalline salts with one equivalent of acid. The hydrochloride, acted on by potassium nitrite, yields Diacetone Alcohol, (CH3)2C(OH)CH2COCH3 (q.v.), which can be considered to be a derivative of diacetonamine. It loses water and changes to mesityl oxide. Urea derivative of diacetonamine, see B. 27, 377. Diacetonamine Oxime, m.p. 55°, b.p.18 121° (B. 34, 300, 792). Oxidation by chromic acid mixture produces amino-isobutyric acid, (CH8)2C(NH2)COOH (propalanine), and amino-isovaleric acid, (CH8)2C(NH2).- CH2COOH. Triacetonamine, m.p. 39'6°; NH2O, m.p. 58°, is prepared from phorone and ammonia, and is an imide base (p. 165). It crystallizes anhydrous in needles, and with one molecule of water in large quadratic tables. It is weakly alkaline. Its hydrochloride with potassium nitrite yields a nitrosamine compound, C,HlflON.NO, m.p. 73°, which regenerates phorone when boiled with sodium hydroxide. The nitroso-body is transformed by hydrochloric acid back into triacetonamine. This substance, with bromine, forms N-Bromotriacetonamine, C9H16ONBr, m.p. 44° (B. 31, 668). For further reactions, see Vol. II. Phorone and primary amines produce n-Methyl Triacetonamine, etc. (B. 28, R. 166). Just as the reaction of diacetonamine with acetone yields triacetonamine, so acetaldehyde produces Vinyl Diacetonamine (B. 17, 1788). (CH3)2C.CH2COCH3 CH3CHO (CH3)2C.CH2CO.CHt NH2 NH - CHCH8 With cyanacetic ester an analogous 8-lactam is formed (B. 26. R. 450). ACTION OF HYDROXYLAMINE ON MESITYL OXIDE 231 ACTION OF HYDROXYLAMINE ON MESITYL OXIDE AND PHORONE According to the conditions of experiment, hydroxylamine becomes added on to the mesityl oxide molecule and gives Diacetone Hydroxylamine, or else oxime formation takes place. In the case of phorone, however, only addition compounds are formed — Triacetone Hydroxylamine and Triacetone Dihydroxylamine, corre- sponding with the two compounds obtained with ammonia. Mesityl Oxide Oxime, (CH3)2C=CH.C(NOH)CH3, a-form, b.p., 83°, £-form, m.p. 49°, b.p. 9 92°, is prepared from mesityl oxide and free hydroxylamine. It is obtained in two modifications. The oily a-oxime is transformed into the solid j8-form by the action of heat on the hydrochloride, or by repeated distillation under reduced pressure. This body, acted on by hydroxylamine hydrochloride and boiled with alkali, regenerates the a-modification. r~*T-T Mesityl Nitrimine, (CH3)2C=CH.C<N j|Q , m.p. 155°, with rapid decomposi- tion, is produced when both modifications of mesityl oxide oxime are treated with amyl nitrite in glacial acetic acid (B. 32, 1336). Reduction changes it to Trimethyl Pyrazoline (Vol. II.). Heated with water it forms an isomeric keto- trimcthyl dihydr o-isoxazole oxime (Vol. II.); oxidation with nitric acid changes it to Nitrilomesityl Dioxime Peroxide. This is converted by aniline in glacial acetic acid solution into Anilonitro-acetone, which, in turn, is changed by sul- phuric acid into nitro-acetone, (A. 319, 230), a derivative of hydroxy-acetone : (CH8)aC.CHaC --- CH CH8C -- CH2NOa CH8CO.CH2NOa. ONO N.O.O.N N.C2H5 MesitylOxide Semicarbazone,>C<^^ ' m'P' l6*° < Diacetone Hydroxylamine, CH3>C<NH2OH3' m>p> 52°' b>ptl« 95°' is formed' together with a-mesityl oxide oxime, by the action of free hydroxylamine on mesityl oxide. Oxidation with chromic acid yields : fi-Nitroso-isopropyl Acetone, cHB>C<NOt~~' '***' dimolecular form. m.p. 75° ; monomolecular form, b.p.u 60°, which is also formed from diacetonamine (p. 230) by oxidation with persulphuric acid. In the dimolecular condition it forms white tabular crystals, which melt to a blue monomolecular liquid. It is easily decomposed (comp. nitrosoparafnns, p. 153, and B. 36, 1069). fi-Nitro-isopropyl Acetone, (CH3)2C(NO2)CH2cqCH8, b.p.17 119°, is produced when diacetone hydroxylamine is oxidized with nitric acid. It can be reduced back to its parent compound by aluminium amalgam (B. 36, 158). Triacetone Hydroxylamine, >C<— — >C< prepared from phorone and hydroxylamine hydrochloride, and yields with hy- droxylamine, an oxime, m.p. 126°. Triacetone Dihydroxylamine, c b.p- 20 I35° (B- 36, 657), results from interaction of phorone and two molecular proportions of free hydroxylamine. Reduced by Zn and HC1, it changes to triacetone diamine. Boiled with alkalis it gives : PTJ Triacetone Dihydroxylamine Anhydride, rS8>c\ CH» \NH pTT _ p PH or ru*>c\ H 2N>C<r58> m-P- IIX'- Reduction by Zn and HC1 STH— 00— HN gives triacetone diamine (see above). Dinitrosodiisopropyl Acetone, CH3>C<NO2~C°~CON>C<CH8' m'P' I32°' is produced from triacetone dihydroxylamine by chromic acid (B. 31, 1379)' On melting it forms a deep blue liquid. The scheme on which this work is based requires that diacetonamine and diacetone hydroxylamine should be discussed as derivatives of diacetone alcohol *& ORGANIC CHEMISTRY \vith the ketoles ; and triacetonamine, triacetone diamine, triacetone hydroxyl- amine, and triacetone dihydroxylamine, etc., as derivatives of the still unknown triacetone dialcohol among the ketodioles. They have, however, been examined before the olefine ketones, on account of their genetic connection with mesityl oxide and phorone. Allyl Acetone, CH2:CH.CH2.CH2COCH3, is obtained from allyl acetoacetic ester. It is isomeric with mesityl oxide (C. 1898, II. 663 ; B. 33, 1472). Methyl Heptenone, (CH3)2C = CH.CH2.CH2COCH3, b.p. 173°, is found in a number of ethereal oils which contain citral, linalool, and geraniol. It results from the distillation of cincolic anhydride (Vol. II.). Synthetically it can be produced by the action of sodium hydroxide .solution on the reaction product of sodium acetyl acetone on amylene dibromide, (CH3)2CBr.CH2CH2Br (B. 29, R- 59°)« It is also prepared from dimethyl allyl acetoacetic ester, the result of the reaction between acetoacetic ester and amylene dibromide, and sodium ethoxide solution (B. 34, 594). It possesses a penetrating odour like amyl acetate. Oxidation with KMnO4 breaks it down to acetone and laevulinic acid ; zinc chloride produces dihydro-m-xylol (A. 258, 323 ; B. 28, 2115, 2126). Sorbic Ethyl Ketone, CH3.CH:CH.CH:CH.CO.C2H5, b.p.M 93°, is prepared from sorbyl chloride and zinc ethyl (B. 34, 2222). Condensation of the respective a/3-olefme aldehydes (p. 214) with acetone leads to the formation of the following diolefine ketones (B. 28, R. 608 ; C. 1906, II. ma): (1) y-Methyl Sorbic Methyl Ketone, CH3CH:C(CH3)CH:CHCOCH2, b.p.12 92°. (2) ye-Dimethyl Sorbic Methyl Ketone, (CH3)CH2CH:C(CH3)CH:CHCO.CH8, b.p.g 97°- (3) yc-Diisopropyl Sorbic Methyl Ketone, (C3H7)CH2CH:C(C3H7)CH:CHCOCH8. Boiling with zinc chloride gives rise to benzene derivatives with varying facility : (i) no condensation ; (2) a bad yield ; (3) a better one (see Vol. II.). Diatlyl Acetone, CH2=CH.CH2.CH2COCH2.CH2.CH=CH1, b.p.70 116°, is prepared from diallyl acetone carboxylic ester (comp. Oxetone). Pseudo-ionone is also a diolefine ketone, and is described in Vol. II., together with the olefine terpenes. 30. Acetylene Ketones. These are obtained by the action of acid chlorides on sodium compounds of alkyl acetylene. Acetyl CEnanthylidene, CH3[CH2]4C^C.COCH3, b.p.18 93°, is obtained from sodium oenanthylidene and acetyl chloride. It possesses an irritating odour. Dilute H2SO 4 con verts it into acetyl caproyl methane, CH3[CH2]4CO.CH2COCH3 (C. 1900, II. 1231, 1262). Hydroxylamine and hydrazines combine with the acetylene ketones, forming isoxazoles and pyrazoles respectively (C. 1903, II- 122 ; 1904, I. 43). 4. MONOBASIC CARBOXYLIC ACIDS The organic acids are characterized by the atomic group, CO.OH, called carboxyl, of which the hydrogen can be replaced by metals and alcohol radicals, forming salts and esters. These organic acids may be compared to the sulphonic acids (p. 146), which contain the sulpho-group, SO2.OH. The number of carboxyl groups present in them determines their basicity, and distinguishes them as mono-, di-, tri-basic, etc., or as mono-, di-, and tri -carboxylic acids : CH8.C02H CH2<2 C,62 UUa±1 \C02H. Acetic Acid Malonic Acid TricarballyUc Acid (Monobasic)- (Dibasic). (Tribasic). MONOBASIC CARBOXYLIC ACIDS 233 The monobasic saturated acids can be looked on as being combina- tions of the carboxyl group with alcohol radicals ; they are ordinarily termed fatty acids. They correspond with the saturated primary alcohols and aldehydes. The unsaturated acids of the acrylic acid and propiolic acid series, corresponding with the unsaturated primary alcohols and aldehydes, are derived from the fatty acids by the loss of two and four hydrogen atoms. They are distinguished as : A. Paraffin monocarboxylic Acids, CnH2nO2, formic acid or acetic acid series. B. Olefme monocarboxylic Acids, CnH2w_2O2, oleicor acrylic acid series. C. Acetylene monocarboxylic Acids, CnH^-^Oo, propiolic acid series. D. Diolefine carboxylic Acids, CnH2n_4O2. Nomenclature. — The " Geneva nomenclature " deduces the names of the carboxylic acids, just like the alcohols (p. 102), the aldehydes (p. 193), and the ketones (p. 218), from the corresponding hydro- carbons ; thus formic acid is [methane acid] and acetic acid is [ethane acid], etc. The radical of the acid is the residue in combination with the hydroxyl group : CH3.CO— CH3.CH2.CO— CH3.CH2.CH2.CO— Acetyl. Propionyl. Butyryl. The names of the trivalent hydrocarbon residues, which in the acid residues are united with oxygen, are indicated by the insertion of the syllable " en " into the names of the corresponding alcohol radicals : CH3.C= CH3.CH,.C= CH,.CH2.CHa.= Ethenyl. Ethylmethenyl. n-Propylmethenyl. The group CH^, however, is not only called the methenyl group, but also the me thine group. Review of the Derivatives of the Monocarboxylic Acids.— Numerous classes of bodies can be derived by changes in the carboxyl group. In connection with the fatty acids mention will only be made of the salts. The other classes of derivatives will be considered as such after the fatty acids. They are : (1) The esters, resulting from the replacement of hydrogen in the carboxyl group by alcohol radicals (p. 265). (2) The chlorides (bromides, iodides, and fluorides), which are com- pounds of the acid radicals with the halogens (p. 269). (3) The acid anhydrides (p. 271), compounds of the acid radicals with oxygen. (4) The acid peroxides (p. 273). (5) The thio-acids (p. 273), compounds of the acid radicals with SH. (6) The carbithionic acids. (7) The acid amides (p. 274), compounds of the acid radicals with NH2. (8) The acid nitriles (p. 278). Hence acetic acid yields the following : i. CH3.C02.C,H6 2. CH3.COC1 3. (CH3.CO)2O 4. (CH,.CO)2Oa Acetic Ethyl Ester. Acetyl Chloride. Acetic Anhydride. Acetyl Peroxide. 5- CH,.COSH 6. CH3.CSSH 7. CH3.CONH2 8. CH3.C=N Thioacetic Acid. Methyl Carbithionic Acetamide. Acetonitrile. Acid. 234 ORGANIC CHEMISTRY Besides the acid halides, amides, and nitriles, there exist the following more complex derivatives : — (9) Hydrazides (p. 278) ; (10) azides (p. 278) ; (n) amide chlorides (p. 281); (12) imide chlorides (p. 281); (13) imido-ethers (p. 281); (14) thio-amides (p. 282); (15) thio-imido-ethers (p. 282); (16) hydroxamic acids (p. 282); (17) hydroxamoximes (p. 283) ; (18) nitrosolic acids (p. 283) ; (19) nitrolic acids (p. 283); (20) hydroxamyl chlorides (p. 283); (21) amidoximes (p. 283); (22) amidines (p. 282); (23) hydrazidines (p. 284); (24) formazyles, and others: — ^° /& /&* 9. CH3C<; 10. CH3C^ /N XNHNH2 XN< || ii. ^XH, Acetohydrazide. 12. CH; Acetimide Chloride. /SC8H$ 15. CH3C^ Thioacetimido Ether. [Acetazide]. X)C2H6 i. CH,C^ Acetimido-ether. ,OH 1 6. CH3Q' Acetohydroxamic Acid. 1 8. CH8C ,NO NO, Acetonitrosolic Acid. 21. NHt 19- 22. Acetamide Chloride. 14. CH8C/s Thioacetamide. /NHOH 17. CH3C^ iyd )xii /C1 Acetohydroxamic Oxime. 20. CH Ethyl Nitrolic Acid. NH, Acetohydroximic Acid Chloride. Acetamiae Oxime. 24. CH Acetamidine. N:NC6H6 / 3C/ ^ 23- etc. Acetohydrazidine. Methyl Formazyl. Aromatic carboxylic acids, especially benzoic acid, are particularly suitable for the preparation of carboxylic acid derivatives, and various classes of substances which actually belong here, have been discovered and more closely studied in that series. Benzoic acid transmits its own facility in crystallization to its derivatives, so that the process of investigation becomes the easier. Similarly, the aromatic amines and hydrazines, such as aniline, toluidine, and phenylhydrazine, are more easily prepared and more convenient to manipulate than the conesponding aliphatic com- pounds, so that in this direction also the benzene derivatives have been more closely investigated than the simple methane compounds. Numerous derivatives are also obtained by the replacement of the hydrogen atoms in the radical combined with hydroxyl by other atoms or groups. Only the halogen substitution products will be de- scribed under the fatty acids, after the discussion of the various classes mentioned in the preceding paragraphs. The fatty acids can be recovered from all of the above classes of derivatives by simple reactions. It has already been indicated under the oxygen derivatives of the methane hydrocarbons, that aldehydes, ketones, and carboxylic acids may be considered to be anhydrides of theoretical, non-existing diacid or triacid alcohols, in which the hydroxyl groups are attached to the MONOBASIC SATURATED ACIDS 235 same carbon atom (p. 99). The aldehydes and ketones were here especially referred to, because there were, among their acetals (p. 205) and the orthoketone alkyl ethers (p. 225), for example, stable ethers of glycols or orthoaldehydes and of orthoketones, ordinarily non- existent in the free state, among which chloral hydrate itself is included. The trihydric alcohols, corresponding with the carboxylic acids, cannot exist, but ethers of them are known. The hypothetical, trihydric alcohols, of which the carbonic acids may be considered anhydrides, have been called ortho acids, comparably to tribasic phosphoric acid being termed orthophosphoric acid (A. 139, 114 ; J. (1859) 152 ; B. 2, 115). This designation has also been applied to the orthoaldehydes and orthoketones. It is customary, therefore, to speak of " hypothetical orthoformic acid " and of " orthoformic esters" (the esters of tribasic formic acid), of formic acid — which, in reference to the relation of orthophosphoric to metaphosphoric acid, PO(OOH), might be termed metaformic acid — and of formic acid esters : /OH /OC,H6 /OH /OCaH6 HC^OH HOH3C2H6 CH< CH< XCH XOC2H6 X) ^O Orthoformic Acid. Ortho formic Ethyl Formic Acid. Formic Ethyl Ester. Ester. The chloride, bromide, and iodide corresponding with orthoformic acid are chloroform, bromoform, and iodoform ; further derivatives are nitroform, orthotrithioformic ester, formyl trisulphonic acid, and others : /Cl /N02 /SC2H6 /S03H HC(-C1 HC(-NO, HC^-SC2H5 HC^SO3H XC1 xNOa XSC2H6 XS03H Chloroform. Nitroform. Orthotrithioformic Formyl Trisulphonic Ester. Acid. It is only in the case of formic acid that the ortho-acid derivatives require a special designation. They will be discussed immediately following the derivatives of the ordinary formic acid. Comparably to the above, substances are known which are derived from orthoacetic acid, CH3C(OH)3 : CH,C(OC2H5)3 CH3CC13 CH3C(N02)8 CH3C(NC6H10), Orthoacetic Ethyl Methyl Methyl Orthoacetic Ester. Chloroform. Nitroforra. Piperidide. A. MONOBASIC SATURATED ACIDS, PARAFFIN MONOCARBOXYLIC ACIDS, CnHiw+1.COaH Formic acid, H.CO.OH, is the first member of this series. The radical HCO, which, here, is united to hydroxyl, is called formyl. This acid is distinguished from all its homologues and the unsaturated monocarboxylic acids, in that it exhibits not only the character of a monobasic acid, but also that of an aldehyde. To express in a name its aldehyde character the acid might be designated hydroxy formaldehyde, HO.C<°. From a chemical standpoint, this acid is more closely connected 236 ORGANIC CHEMISTRY with glyoxylic acid, CHO.CO2H (q.v.) than to acetic acid. Therefore^ formic acid and its derivatives will be treated before acetic acid and its homologues are discussed. FORMIC ACID AND ITS DERIVATIVES It is not only the aldehyde character which distinguishes formicl acid from acetic acid and its homologues, but it is also the absence of I a chloride and anhydride, corresponding with acetyl chloride (q.v.) and| acetic anhydride (q.v.). The withdrawal of water from formic acid^ leads to the formation of carbon monoxide, a reaction which does^ not take place in the case of any of the higher homologues.*] Hydrocyanic acid, the nitrile of formic acid, has an acid nature, andj therein differs from the indifferent nitriles of the homologous acids. I Formic acid is twelve times stronger than acetic acid, as is shown by i the affinity constants derived from the electric conductivity (Ostwald). \ To the section on formic acid will be appended carbon monoxide, \ and its nitrogen-containing derivatives, the isonitriles or carbylamines, C=N — R', andfulminic acid, C=NOH. Formic Acid, H.CO.OH [Methane Acid] (Acidum formicum), m.p. 8*6° (crystallizes at o°), b.p.10o 100 6°, D2o=r22, is found free in ants, in the procession caterpillar, Bombyx processionea, in pine needles, and in various animal secretions (perspiration), from all of which it may be obtained by distillation with water. It is almost certainly not present in stinging nettles [TR.]. It is produced in the laboratory : (1) By the oxidation of methyl alcohol and formaldehyde (B. 36, 3304): H.CHgOH -- > H.CHO - — > H.COaH. (2) By heating hydrocyanic acid, the nitrile of formic acid, with alkalis or acids : HCN+2H2O=HCOOH+NH3. (3) By boiling chloroform with alcoholic potassium hydroxide (Dumas) : CHC13+4KOH=HCOOK+3KC1+2H2O. (4) From chloral (Liebig), (5) from acetaldehyde disulphonic acid (see p. 208), and (6) from propargylic aldehyde (p. 215) and sodium hydroxide : CC13.CHO -f NaOH =HCCl,+HCOONa ; (SO3Na)2CH.CHO+NaOH = (SO,Na)1CH1+HCOONa; Remarkable and of technical importance is (7) the direct production of formates by the action of CO on concentrated potassium hydroxide at 100°, or more easily on soda-lime at 200-220° (Berthelot, A. 97, 125 ; Geuther, A. 202, 317 ; Merz and Tibirifd, B. 13, 718) : CO+NaOH=HCO.ONa. (8) By action of acids on isocyanides or carbylamines (p. 247) : CN.CsH6+2H,0=HCOaH+C,H6NH2. * Comp. Dimethyl Ketene (p. 290), Di-Ketals or Carbon Suboxide (Vol. I.), and Di-Phenyl Ketene. FORMIC ACID AND ITS DERIVATIVES 237 (9) From fulminic acid by means of concentrated hydrochloric acid (see Formyl Chloridoxime, p. 244), hydroxylamine hydrochloride being formed simultaneously : C=N.OH+2H2O + HC1=H.CO2H+NH,OH.HC1. (ioa) By the reduction of moist carbon dioxide (carbonic acid) by potassium (Kolbe and Schmitt, A. 119, 251) : Formates are also produced by the action of sodium amalgam or electrolytic hydrogen (B. 38, 4138) on ammonium carbonate and an aqueous solution of primary carbonates ; likewise on boiling zinc carbonate with potassium hydroxide and zinc dust. (io&) Potassium hydride combines at ordinary temperatures with CO2, forming HCOOK. At higher temperatures (80°) there results a mixture of potassium formate and oxalate (C. 1905, II. 29). Potassium formate is also formed when CO and H2 are passed together over heated potassium (Moissan C. 1902, I. 568): = HC04K+C. (n) Formic acid is best prepared from oxalic acid, by heating it with glycerol. Oxalic acid heated alone decomposes into carbon dioxide and formic acid, or carbon monoxide and water, the latter decomposition preponderating : COOH ^HC02H+COa COOH~ ^CO + HjO+CO,. When, however, the acid is heated with glycerol in a distillation flask to 100-110°, glyceryl monoxalic ester is first formed, and afterwards by loss of carbonic acid, mono-formin, the monoformic ester of glycerol : CH,.OCO.COaH CH2O.COH+CO, CHOH = CHOH CHaOH CH2OH On further addition of crystallized oxalic acid the latter again breaks up into the anhydrous acid and water, which converts the glycerol formic ester into glycerol and formic acid : C3H5O.CHO(OH)2+HaO=C,H6(OH)8+CHO.OH. At first the acid is very dilute, but later it reaches 56 per cent. If anhydrous oxalic acid be employed at the beginning, a 95-98 per cent, formic acid is produced. To obtain anhydrous formic acid, the aqueous product is boiled with lead oxide or lead carbonate. The lead formate is then decomposed, at 100°, by a current of hydrogen sulphide. Or, formic acid of high percentage may be dehydrated by means of boric anhydride (BaOs) (B. 14, 1709) ; or, finally, sodium formate may be decomposed by sulphuric acid (C. 1905. I. 1701). Formic acid is a mobile liquid which possesses a pungent odour and causes blisters on the skin. It mixes in all proportions with water, alcohol and ether, and yields the hydrate 4CLltO2+3H2O, b.p.760 107-1°, with dissociation into formic acid and water. Concentrated hot sulphuric acid decomposes formic acid into carbon monoxide and water. 238 ORGANIC CHEMISTRY A temperature of 160° suffices to break up the acid into carbon dioxide and hydrogen. The same change may occur at ordinary temperatures by the action of finely divided rhodium, iridium, and ruthenium, but less readily when platinum sponge is employed. 