Online Encyclopedia
Search over 40,000 articles from the original, classic Encyclopedia Britannica, 11th Edition.
CH8
Online EncyclopediaEncyclopedia Home :: CAU-CHA
del.icio.us it!
|
CH8 .CO + NH3 + CO•CH3 CH3•C-NH-G.See also:CH3 The resulting dihydro-See also:compound is then oxidized with nitrous See also:acid, the ester hydrolysed and the resulting acid heated with See also:lime; See also:carbon dioxide is eliminated and a trisubstituted See also:pyridine of the type CH C(CHI) is obtained. The reaction is apparently a R•C' \N See also:general one for all See also:aldehydes. On the course \CH :C(CH3)/ of the reaction see also C. Beyer, Ber., 1891, 24, p. 1662, and E. Knoevenagel, Ber., 1898, 31, p. 738. In this reaction the proportions of aldehyde and acetoacetic ester may be interchanged and ay disubstituted pyridines are then obtained. Of the other methods for preparing pyridine homologues mention may be made of the See also:discovery by A. Ladenburg that the pyridinium alkyl iodides rearrange themselves when strongly heated and yield a and y alkyl pyridines (Ber., 1883, 16, p. 1410 seq. ; See also:Ann., 1888, 247, p. I). S. Ruhemann prepared 7-substituted dioxypyridines by condensing alkyl-dicarboxy-glutaconic See also:esters with See also:ammonia. R'02C)2C:CR•CH(CO2R')2-,R'02Co.c CRH•NC•COH•CO2R'-HHOC:CRNC. On Of •C OH M. Scholtz (Ber., 1895, 28, p. 1726) prepared aa- methylphenylpyridine by distilling cinnamenylidene acetoxime, CSHSCH:CH•CH:CH•C(:N•OH).CH3= H C•CHc See also:H2O CeHs•c•N :C•CHs-- The 1.5 See also:diketones of the type inset, when heated with ammonia, also yield pyridine derivatives. Alkyl pyridines -CO\ /CO- are also obtained by See also:heating aldehyde >C:CH•CH< ammonias alone or with aldehydes and -CO CO- See also:ketones (A. v. See also:Baeyer, Ann., 187o, 155, pp. 281, 294; J. Pldchl, Ber., 1S87, 20, p. subjoined table shows the See also:chief homologues of pyridine: Name. See also:Formula. Position Remarks. of Sub- stituent. Picolines See also:C5H4(CHa)N a Liqquid, b.p. 129°. Oxi- Lutidines CSH4(C2H5)N y dizes to picolinic acid. a, /3, y, Condenses readily with aldehydes. Liquid, b.p. 143°. Oxi- dizes to nicotinic acid. Does not condense with aldehydes. Liquid, b.p. 144-145°. Three isomers. All liquids. The /3 com- See also:pound is a decompo- sition product of cinchonine, See also:quinine, See also:strychnine and bru- cine. CSH3(CHa)2N aa', ay, a,B' Five isomers. All /3l3', /37. liquids. Collidines C5H4(CaH1)N a, P. Liquids. The a com- C5H3(CH3)(C2H5)N a, y. pound is a decomposi- CSH2(CHa)3N a'a, y(3, tionproductof See also:conine. ay, a/3' Both contain the nor- aya' mal propyl See also:group. ay/3' Containing the isopro- Lis.rou p. qu1id Liquid, b. . 171-172°. Prepared by the Hantzsch See also:synthesis. Found in See also:coal-See also:tar. Pyridine carboxylic acids are usually prepared by oxidizing the homologues of the See also:base; they also result as decomposition products of various alkaloids. The more important are shown in the table. Name. Formula. Position Remarks. of Sub- stituent. Picolinic C5H4(See also:CO2H)N a M.p. 137°. Easily solu- acid. ble in See also:water. Yellow coloration with FeSO4. Position of carboxyl group deter- See also:mined by synthesis from a-naphthyl- amine (Z. Skraup and A. Cobenzl, Monals., Nicotinic C5H4(CO2H)N p 1883, 4, p. X36). acid. M.p. 228—229 . An oxi- dation product of See also:nicotine, See also:hydrastine Quinolinic C6H3(CO2H)2N a$ and See also:berberine. See also:Con- acid. C5H3(CO2H)2N py stitution determined Cincho- C6H2(CO2H)2N apy by synthesis from meronic C6H2(CO2H)3N ayf3' p-naphthylamine acid. (Skraup). a-See also:Carbo- M.p. 192—195° with de- cincho- See also:composition into nico- meronic tinic acid. Formed acid. by oxidation of Berbero- See also:quinoline. nic M.p. 258—2590. Formed acid. by oxidation of See also:quin- See also:ine, cinchonine, and of isoquinoline. M.p. 249-250°. Crystal- hies with IIH2O. An oxidation product of cinchonine, quinine and papaverine. M.p. 243°. An oxida- tion product of ber- berine. Gives a red coloration with FeSO4. Boiling with glacial acetic acid gives cinchomeronic acid. Trigonelline, C7H7NO2, the methyl betaine of nicotinic acid, was discovered in 1885 by E. Jahns (Ber., 1885, 18, p. 2518), and is found in the seeds of Trigonella and See also:Strophanthus hispidus. It is very soluble in water. With baryta it yields methylamine, and when heated with concentrated hydrochloric acid, to 26o° C. it yields methyl chloride and nicotinic acid. It was synthesized by A. Hantzsch (Ber., 1886, 19, p. 31) by condensing methyl iodide and See also:potassium nicotinate at 150° C. the resulting iodide being then decomposed by moist See also:silver See also:oxide. A. Pictet (Ber., 1897, 30, p. 2117) obtained it by oxidizing nicotine methyl hydroxide with potassium permanganate. Apophyllenic acid, C8H7NO4•H20, the methyl betaine of cinchomeronic acid, was synthesized by W. Roser (Ann., 1886, 234, p. 118). Piperidine or hexa-hydropyridine, C6H21N, was first obtained in 1848 by distilling See also:piperine with lime. It is formed in the See also:hydrolysis of piperine by alcoholic potash, by the reduction of trimethylene See also:cyanide (A. Ladenburg) and by the See also:action of alkalis on e-chloramylamine, Cl(See also:CH2)s•NH2 (S. See also:Gabriel, Ber., 1892, 25, p. 42I). It is also produced in the electrolytic oxidation of N-nitroso piperidine in sulphuric acid See also:solution (F. B. See also:Ahrens, Ber., 1898, 31, p. 2275). It is a liquid which boils at 105—106° C., and possesses an ammoniacal See also:smell. It is readily soluble in water, See also:alcohol and See also:ether, and is a very powerful base. It is oxidized to pyridine by heating with concentrated sulphuric acid to 300° C., or with See also:nitrobenzene to 250° C., or with silver acetate to 180° C. Being an imide it readily yields a nitroso derivative, and N-alkyl and acidyl derivatives. The piperidine See also:ring is easily split. When heated with fuming hydriodic acid to 300° C. it yields normal pentane and ammonia, and See also:hydrogen peroxide oxidizes it to glutarimide and to a piperidinium oxide or oxime (R. Wolffenstein, Ber., 1904, 37, p. 3228). A. W. See also:Hofmann (Ber.. 1881, 14, p. 66o), by a See also:process of exhaustive methylation and See also:distillation, obtained the unsaturated See also:hydrocarbon piperylene, C H2: C H • C H2 • CH : CH2, from piperidine (see also A. Ladenburg, Ann., 1894, 279, P. 344)- C6HnN(+CH3I) — C5HI0N(CH3)2I (+AgOH) —j See also:C6H,6N(CH3)2.OH (distil) 1 CiH9N(CH3)3.OHE--(+AgOH)C5H9N(CH3)3I<—(-}CHsI)C6H9N(CHs)2 (distil) C1H2+N(CH3)3+H20 J. v. Braun (See also:Bee., 1904, 37, p. 2915) showed that benzoyl piperidine, when heated with See also:phosphorus pentachloride to 20o° C. in sealed tubes, yields benzonitrile, and pentamethylene dichloride, thus leading to a See also:simple method of preparing pentamethylene compounds. At 125—130° C. the compound C6H2C•Cl:N(C112)s•G is obtained; this with water yields benzoylamidochloramylamine C6H5CONH(CH2)5Cl, which when heated with hydrochloric acid tc 17o—18o° C. furnishes e-chloramylamine, See also:NH2(CH2)SCI. a-Propyl, piperidine is the See also:alkaloid conine (q.v.). Additional information and CommentsThere are no comments yet for this article.
» Add information or comments to this article.
Please link directly to this article:
Highlight the code below, right click, and select "copy." Then paste it into your website, email, or other HTML. Site content, images, and layout Copyright © 2006 - Net Industries, worldwide. |
|
|
[back] CH5 |
[next] CHABAZITE |