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C2H 4Br2+2NaCH (CO2R)2->(See also:CH2)2C (CO2R)2 +CH2 (CO2R)2 ; See also:ethyl butane tetracarboxylate is also formed which may be converted into a tetramethylene carboxylic ester by the See also:action of See also:bromine on its disodium derivative (W. H. See also:Perkin and See also:Sinclair, ibid., 1829, 61, p. 36). The See also:esters of the acids may also be obtained by condensing sodio-malonic ester with a-halogen derivatives of unsaturated acids: CH•CO2R CH8•CH: CBr•CO2R+NaCH(CO2R),_ CH3•CH~ \C(CO2R)2 ; by the action of diazomethane or diazoacetic ester on the esters of unsaturated acids, the pyrazoline carboxylic esters so formed losing See also:nitrogen when heated and yielding acids of the cyclopropane See also:series (E. See also:Buchner, Ber., 189o, 23, p. 703; See also:Ann., 1895, 284, p. 212; H. v. Pechmann, Ber., 1894, 27, p. 1890: CH2N2+ C!I. I H•CO2R N:N i H•CO2R See also:H2C/CHCO2R CH•CO,R H2C—CH•CO2R \CHCO,R; and by the Grignard reaction (S. Malmgren, Ber., 1903, 36, pp. 668, 2622; N. Zelinsky, ibid., 1902, 35, p. 2687). Cyclo-propane See also:Group. Trimethylene, See also:C3H6, obtained by A. See also:Freund (Monats., 1882, 3, p. 625) by See also:heating trimethylene bromide with See also:sodium, is a See also:gas, which may be liquefied, the liquid boiling at -35° C. (749 mm.). It dissolves gradually in concentrated sulphuric See also:acid, forming propyl sulphate. Hydriodic acid converts it into n-propyl iodide. It is decomposed by See also:chlorine in the presence of sunlight, with explosive violence. It is See also:stable to See also:cold See also:potassium permanganate. Cyclo-propane carboxylic acid, C3H6•CO2H, is prepared by heating the 1.1-dicarboxylic acid; and by the See also:hydrolysis of its nitrile, formed by heating y-chlorbutyro-nitrile with potash (L. See also: Cyclo-butane Group. Cyclo-butane, C4H8, was obtained by R. Willstatter (Ber., 1907, 40, p. 3979) by the reduction of cyclobutene by the See also:Sabatier and Senderens method. It is a colourless liquid which boils at 11-12° C,, and its vapour See also:burns with a luminous See also:flame. Reduction at 18o-2oo° C. by the above method gives n-butane. Cyclo-butene, C4H6, formed by distilling trimethyl-cyclo-butyl. ammonium hydroxide, boils at 1.5-2.0° C. (see N. Zelinsky, ibid., p. 4744; G. Schweter, ibid., p. 1604). When sodio-malonic ester is condensed with trimethylene bromide the See also:chief product is ethyl pentane tetracarboxylate, tetramethylene I.I-dicarboxylic ester being also formed, and from this the See also:free acid may be obtained on hydrolysis. It melts at 154-156° C., losing carbon dioxide and passing into cyclo-butane carboxylic acid, C4H7CO2H. This basic acid yields a monobrom derivative which, by the action of aqueous potash, gives the corresponding hydroxycyclo-butane carboxylic acid, C4H6(OH)•CO2H. Attempts to eliminate water from this acid and so produce an unsaturated acid were unsuccessful; on warming with sulphuric acid, carbon monoxide is eliminated and cyclo-butanone (keto-tetramethylene) is probably formed. The truxillic acids, C18H,604, which result by the hydrolytic splitting of truxilline, Ca8H46N2O8, are phenyl derivatives of cyclo-butane. Their constitution was determined by C. See also:Liebermann (See also:Bee., 1888, 21, p. 2342; 1889, 22, p. 124 seq.). They are polymers of cinnamic acid, into which they readily pass on See also:distillation. The a-acid on oxidation yields benzoic acid, whilst the fl-acid yields benzil in addition. The a-acid is See also:diphenyl-2.4-cyclo-butane dicarboxylic acid -1.3; and the l3-acid diphenyl-3.4-cyclo-butane dicarboxylic acid -1.2. By alkalis they are transformed into stereo-isomers, the a-acid giving y-truxillic acid, and the (3-acid S-truxillic acid. The a-acid was synthesized by C. N. Riiber (Ber., 1902, 35, p. 2411; 1904, 37, p. 2274), by oxidizing diphenyl-2.4-cyclo-butane-bismethylene malonic acid (fron cinnamic aldehyde and malonic acid in the presence of See also:quinoline) with potassium permanganate. Cyclo-pentane Group. Derivatives may be prepared in many cases by the breaking down of the See also:benzene ring when it contains an See also:accumulation of negative atoms (T. Zincke, Ber., 1886-1894; A. Hantzsch, Ber., 1887, 2o, p. 2780; 1889, 22, p. 1238), this type of reaction being generally brought about by the action of chlorine on phenols in the presence of alkalis (see See also:CHEMISTRY: Organic). A somewhat related example is seen in the See also:case of croconic acid, which is formed by the action of alkaline oxidizing agents on heixa-oxybenzene: HO•C•C(OH) : C(OH) HO•C•CO•CO HO•C•CO II HO•C•C(OH) ; C(OH) HO.C•CO•CO HO•C•CO'CO Hexa-oxybenzene. Rhodizonic acid. Croconic acid. Cyclo-pentane, C5H1o, is obtained from cyclo-pentanone by reducing it to the corresponding secondary See also:alcohol, converting this into the iodo-See also:compound, which is finally reduced to the See also:hydrocarbon (J. See also:Wislicenus, Ann., 1893, 275, p. 327). It is a colourless liquid which boils at 50-51 ° C. Methyl-cyclo-pentane, C6HOCH3, first obtained by F. Wreden (Ann., 1877, 187, p. 163) by the action of hydriodic acid and red See also:phosphorus on benzene, and considered to be hexahydrobenzene, is obtained synthetically by the action of sodium on 1.5 dibromhexane; and by the action of See also:magnesium on acetylbutyl iodide (N. Zelinsky, Ber., 1902, 35, p. 2684). It is a liquid boiling at 72° C. Nitric acid (sp. gr. 1.42) oxidizes it to succinic and acetic acids. Cyclo-pentene, C5H8, a liquid obtained by the action of alcoholic potash on iodo-cyclo-pentane, boils at 45° C. Cyclopentadiene, C5H6, is found in the first runnings from crude benzene distillations. It is a liquid which boils at 410 C. It rapidly polymerizes to di-cyclo ,pentadiene. The .CH2. group is very reactive and behaves in a similar manner to the grouping .CO•CH2.CO• in open See also:chain compounds, e.g. with See also:aldehydes and See also:ketones it gives the fulvenes, substances characterized by their intense See also:orange-red colour HC: CH (J. Thiele, Ber., 1900, 33, p. 669). Phenylfulven, '>C:CHPh, HC: CH/ obtained from See also:benzaldehyde and cyclo-pentadiene, forms dark red plates. Diphenylfulven, from See also:benzophenone and cyclo-pentadiene, crystallizes in deep red prisms. Dimethylfulven is an orange-coloured oil which oxidizes rapidly on exposure. Concentrated sulphuric acid converts it into a deep red See also:tar. Cyclo-pentanone, C6H80, first prepared pure by the distillation of See also:calcium adipate (J. Wislicenus, Ann., 1893, 275, p. 312), is also obtained by the action of sodium on the esters of pimelic acid; by the distillation of ,calcium succinate; and by hydrolysis of the cyclopentanone carboxylic acid, obtained by condensing adipic and oxalic esters in the presence of sodium ethylate. Reduction gives cyclo-pentanol, C6H9OH. Croconic acid (dioxy–cyclo-pentene-trione), C6H206, is formed when triquinoyl is boiled with water, or by the oxidation of hexa-oxybenzene or dioxydiquinoyl in alkaline See also:solution (T. Zincke, Ber., 1887, 20, p. 1267). It has the See also:character of a quinone. On oxidation it yields cyclo-pentane-pentanone (leuconic acid). Derivatives of the cyclo-pentane group are met with in the breaking-down products of the See also:terpenes (q.v.). See also:Cam pholactone, C9H1402, is the lactone of trimethyl-2.2.3-cyclopentanol-5-carboxylic acid-3. For an isomer, isocampholactone (the lactone of trimethyl-2.2.3-cyclo-pentanol-3-carboxylic acid-,) see W. H. Perkin, jun., Proc. Chem. See also:Soc., 1903, 19, p. 61. Lauronolic acid, C9H1402, is trimethyl-2.2.3-cyclo-pentene-4-acid-I. Isolauronolic acid, C9H14O2, is trimethyl-2.2.3-cyclo-pentene-3-acid-4. Campholic acid, C1oH18O2, is tetramethyl-1.2.2.3-cyclo-pentane acid-3. Camphononic acid, C9H1403, is trimethyl-2.2.3-cyclo-pentanone-i-carboxylic acid-3. Camphorphorone, C9H140, is methyl-2-isobuty-lene-5-cyclo-pentanone-1. Isothujone, C10H160, is dimethyl-i.2-isopropyl-3-cyclo-pentene-I-one-5. (F. W. Semmler, Ber., 1909, 33, Bou eault and G. See also:Blanc (Comptes rendus, 1903, 136, p. 1460), prepared See also:hydrocarbons of the cyclo-pentane series from cyclohexane compounds by the exhaustive methylation See also:process of A. W. See also:Hofmann (see See also:PYRIDINE). For phenyl derivatives of the cyclopentane group see F. R. Japp, Jour. Chem. Soc., 1897, 71, pp. 139, 144; H. Stobbe, Ann., 1901, 314, p. III; 315, p. 219 seq.; 1903, 326, p. 347. Cyclo-hexane Group. Hydrocarbons.—Cyclo-hexane, or hexahydro benzene, C6H12r is obtained by the action of sodium on a boiling alcoholic solution of i•6-dibromhexane, and by passing the vapour of benzene, mixed with See also:hydrogen, over finely divided See also:nickel. It is a liquid with an odour like that of benzene. It boils at 8o–81 ° C. Nitric acid oxidizes it to adipic acid. When heated with bromine in a sealed See also:tube for some days at 150–200° C., it yields 1.2.4.5–tetrabrombenzene (N. Zelinsky, Ber., 1901, 34, p. 2803). It is stable towards See also:halogens at See also:ordinary temperature. Benzene hexachloride, C0H6C16r is formed by the action of chlorine on benzene in sunlight. By recrystallization from hot benzene, the a See also:form is obtained in large prisms which melt at 157° C., and at their boiling-point. decompose into hydrochloric acid and trichlorbenzene. The l3 form results by chlorinating boiling benzene in sunlight, and may be separated from the a variety by distillation in a current of See also:steam. It sublimes at about 31o° C Similar varieties of benzene hexabromide are known. IZexahydrocymene (methyl-I-isopropyl-4-cyclo-hexane), C10H26, is important since it is the See also:parent substance of many terpenes (q.v.). It is obtained by the reduction of 1.4 dibrommenthane with sodium (J. de Montgolfier, Ann. chim. phys., 1880 [5], 19, p. 158), or of cyrnene, limonene, &c., by Sabatier and Senderens's method. It is a colourless liquid which boils at 18o° C. Cyclo-hexene (tetrahydrobenzene), C6H19r was obtained by A. v. See also:Baeyer by removing the elements of hydriodic acid from iodocyclo-hexane on boiling it with quinoline. It is a liquid which boils at 82° C. Hypochlorous acid converts it into 2-chlor-cyclo-hexanol-I, whilst potassium permanganate oxidizes it to cyclo-hexandi-ol. Cyclo-hexadiene (dihydrobenzene), C6H8.—Two isomers are possible, namely cyclo-hexadiene-i•3 and cyclo-hexadiene-1.4. A. v. Baeyer obtained what was probably a mixture of the two by heating 1.4 dibrom-cyclo-hexane with quinoline. C. Harries (Ann., 1903, 328, p. 88) obtained them tolerably pure by the dry distillation of the See also:phosphates of I.3-diamino and I.4-diamino-cyclo-hexane. The 1.3 compound boils at 81-82° C. and on oxidation yields succinic and oxalic acids. The I.4 compound also boils at 81-82° C. and on oxidation gives succinic and malonic acids. See also:Alcohols.—Cyclo-hexanol, C6H11OH, is produced by the reduction of the corresponding ketone, or of the iodhydrin of quinite. Nitric acid oxidizes it to adipic acid, and chromic acid to cyclo-hexanone. Quinite (cyclo-hexanediol-1.4) is prepared by reducing the corresponding ketone with sodium See also:amalgam, cis-, and trans-modifications being obtained which may be separated by their acetyl derivatives. Phloroglucite (cyclo-hexane-triol-i•3.5) is obtained by reducing an aqueous solution of phloroglucin with sodium (W. Wislicenus, Ber., 1894, 27, p. 357). Quercite (cyclo-hexane-pentol-I.2.3'4'5), isolated from acorns in 1849 by H. Braconnot (Ann. chim. phys. [3], 27,p. 392), crystallizes in colourless prisms which melt at 234° C. When heated in vacuo to 24o° C. it yields hydroquinone, quinone and See also:pyrogallol. It is dextro-rotatory. A laevo-form occurs in the leaves of Gymnema sylvestre (F. B. See also:Power, Journ. Chem. Soc., 1904, 85, p. 624). Inosite (cyclo-hexane-hexol), See also:C6H6(OH)6.—The inactive form occurs in the muscles of the See also:heart and in other parts of the human See also:body. The d-form is found as a methyl See also:ether in pinite (from the juice of Pinus lambertina, and of caoutchouc from Mateza roritina of See also:Madagascar), from which it may be obtained by heating with hydriodic acid. The 1-form is also found as a methyl ether in quebrachite. By mixing the d- and 1- forms, a racemic variety melting at 253° C. Is obtained. A dimethyl ether of inactive inosite is dambonite which occurs in caoutchouc from Gabon. Ketones.—Cyclo-hexanone, C6H16O, is obtained by the distillation of calcium pimelate, and by the electrolytic reduction of phenol, using an alternating current. It is a colourless liquid, possessing a See also:peppermint odour and boiling at 155° C. Nitric acid oxidizes it to adipic acid. It condenses under the See also:influence of sulphuric acid to form dodecahydrotriphenylene, C18H24, and a mixture of ketones (C. Mannul, Ber., 1907, 40, p. 153). Methyl-I-cyclo-hexanone-3, CH6.C6H90, is prepared by the hydrolysis of pulegone. It is an optically active liquid which boils at 168–169° C. Homologues of menthone may be obtained from the ketone by successive treatment with sodium See also:amide and alkyl halides (A. See also:Haller, Comptes rendus, 1905, 140, p. 127). On oxidation with nitric acid (sp. gr. 1.4) at 6o-7o° C., a mixture of —and- -methyl adipic acids is obtained (W. Markownikoff, Ann., 1905, 336, p. 299). It can be transformed into the isomeric methyl-I-cyclo-hexanone-2 (O. Wallach, Ann., 1904, 329, p. 368). For methyl-I-cyclo-hexanone-4, obtained by distilling y-methyl pimelate with See also:lime, see O. Wallach, Ber., 1906, 39, P. 1492. Cyclo-hexane-See also:dione-1.3 (dihydroresorcin), C6H802, was obtained by G. Merling (Ann., 1894, 278, p. 28) by reducing See also:resorcin in hot alcoholic solution with sodium amalgam. Cyclo-hexane-dione-i•4 is obtained by the hydrolysis of succino-succinic ester. On reduction it yields quinite. It combines with benzaldehyde, in the presence of hydrochloric acid, to form 2-benzyl-hydroquinone. Cyclohexane-trione-1.3.5 (phloroglucin) is obtained by the See also:fusion of many resins and of resorcin with See also:caustic See also:alkali. It may be prepared synthetically by fusing its dicarboxylic ester (from malonic ester and sodio malonic ester at 145° C.) with potash (C. W. See also:Moore, Journ. Chem. Soc., 1904, 85, p. 165). It crystallizes in prisms, which melt at 218° C. With ferric chloride it gives a dark See also:violet coloration. It exhibits tautomerization, since in many of its reactions it shows the properties of a hydroxylic substance. Rhodizonic acid (dioxydiquinoyl), C6H206, is probably the enolic form of an oxypentaketo-cyclo-hexane. It is formed by the reduction of triquinoyl by aqueous sulphurous acid, or in the form of its potassium See also:salt by washing potassium hexa-oxybenzene with alcohol (R. Nietzki, Ber., 1885, 18, pp. 513, 1838). Triquinoyl (hexaketo-cyclo-hexane) C6O6.8H2O, is formed on oxidizing rhodizonic acid or hexa-oxybenzene. Stannous chloride reduces it to hexa-oxybenzene, and when boiled with water it yields croconic acid (dioxy-cyclo-pentene-trione). 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