Quinolines, methyl

Quinoline, 4-methyl-5,6,7,8-tetrahydro-synthesis, 2, 471 Quinoline, 2-methylthio-3-nitro-3-substituted... 

Lepidine Quinoline, 4-methyl- Phenetole Benzene, ethoxy-... 

Friedel-Crafts acylation, 2, 322 Quinoline, methyl-basicity, 2, 172 NMR, 2, 120 radical cations... 

Long-chain halides undergo this reaction at 100°, no C-dialkylated products being formed. In alkylations with aryl-substituted alkyl halides, Ar(CH,) X, n= 1 to 3, yields are improved by performing the reaction rapidly in liquid ammonia (56-9S>%). Also, quinoline methylated in the 2-or 4-position reacts in the same way. A methyl group in the 3-position of pyridine or quinoline is unreactive. 

Quinoline, dimethyl-(5 isomers) Quinoline, ethyl-(2 isomers) Quinoline, methyl-(6 isomers) Quinoline, (1-methylethyl)-... 

Quinoline, methyl-1,2,3,4-tetrahydro- several isomers present in MSS 1587 ... 

A number of azaarenes have also been detected in cigarette smoke (/7, 28, 56). These have included quinoline, methyl- and dimethylquinolines, isoquinoline, and alkylisoquinolines, benzo[/i]quinoline, acridine, phenan-thridine, benzo[/]quinoline, 4-azafluorenes, 1-azafluoranthenes, 4-azapyrenes, 9-methylcarbazoles, indole, alkylindoles, alkylcarbazoles, benzo[Z>]carbazole, dibenzo[c,g]carbazole, and benz[c]acridine. 

Thiazol 2-ones, 49-50, 62, 254 Thiazol-4- and -5-ones, 51-52 Thiazolo-[4,5-6]- and -[5,4-6]-quinolines, methylation of, 259 Thiocoumarin-3,4-diols, methylation of, 276... 

INaJninoi80iuootinic methyl ester 2.6- Dibeiizamidoisonicotiiuc methyl ester 2-Hydrazmo-6-chlorotsonioo-tinyl hydrazide 2,4T-Dihydroxy-6-hydrazino-nicotinyl hydrazide Quinolinic methyl ester Quinolinic anhydride -(106) — (106), 2,5-Dia-minoisoniootinyl hydrazide - (106) t - (119) t — (420) 0% (S6) 0% (106)... 

Doebner-von Miller reaction Condensation of an aromatic amine with an aldehyde or ketone in the presence of hydrochloric acid to form a quinoline derivative. A general method, thus aniline and ethanal give 2-methyl-quinoline (quinaldine) and p-phenetidine. 

B) Methiodi s. Members of Classes (i), (ii) and (iv) combine wdth methyl iodide (some very vigorously) to form quaternary methiodides. It is best to add the amine to an excess of methyl iodide dissolved in about twice its volume of methanol, allow any spontaneous reaction to subside, and then boil under reflux for 30 minutes (extend to 1 hour for Class (iv) except pyridine and quinoline). The methiodide may crystallise when the reaction-mixture cools if not, evaporate the latter to small bulk or to dryness, and recrystallise, (M.ps., pp. 553-554 )... 

This method is exemplified by its application to quinoline, isoquinoline, cinnoline, and isoquinoline 2-oxide, which are nitrated as their conjugate acids. The rate profiles for these compounds and their N- or O-methyl perchlorates show closely parallel dependences upon acidity (fig. 2.4). Quaternisation had in each case only a small effect upon the rate, making the criterion a very reliable one. It has the additional advantage of being applicable at any temperature for which kinetic measurements can be made (table 8.1, sections B and D). 

The first quantitative studies of the nitration of quinoline, isoquinoline, and cinnoline were made by Dewar and Maitlis, who measured isomer proportions and also, by competition, the relative rates of nitration of quinoline and isoquinoline (1 24-5). Subsequently, extensive kinetic studies were reported for all three of these heterocycles and their methyl quaternary derivatives (table 10.3). The usual criteria established that over the range 77-99 % sulphuric acid at 25 °C quinoline reacts as its cation (i), and the same is true for isoquinoline in 71-84% sulphuric acid at 25 °C and 67-73 % sulphuric acid at 80 °C ( 8.2 tables 8.1, 8.3). Cinnoline reacts as the 2-cinnolinium cation (nia) in 76-83% sulphuric acid at 80 °C (see table 8.1). All of these cations are strongly deactivated. Approximate partial rate factors of /j = 9-ox io and /g = i-o X io have been estimated for isoquinolinium. The unproto-nated nitrogen atom of the 2-cinnolinium (ina) and 2-methylcinno-linium (iiiA) cations causes them to react 287 and 200 more slowly than the related 2-isoquinolinium (iia) and 2-methylisoquinolinium (iii)... 

Recently kinetic data have become available for the nitration in sulphuric acid of some of these hydroxy compounds (table 10.3). For 4-hydroxyquinoline and 4-methoxyquinoline the results verify the early conclusions regarding the nature of the substrate being nitrated in sulphuric acid. Plots of log Q against — (Lf + logioflHao) fo " these compounds and for i-methyl-4-quinolone have slopes of i-o, i-o and 0-97 at 25 C respectively, in accord with nitration via the majority species ( 8.2) which is in each case the corresponding cation of the type (iv). At a given acidity the similarity of the observed second-order rate constants for the nitrations of the quinolones and 4-methoxy-quinoline at 25 °C supports the view that similarly constructed cations are involved. Application of the encounter criterion eliminates the possibilities of a... 

The 7V-methylbenzo[( e]quinoline 426 was prepared by trapping the insertion product of an internal alkyne with a tertiary dimethylamine. One methyl group is eliminated. The dimethylaminonaphthalene-Pd complex 427 is an active catalyst and other Pd compounds are inactive[290a]. 

The easier elimination of pyridine compared to quinoline-4 may be related to the pK value of 4-methylthiazole, which is between those of lepidine and 2-picoline (25. 55). This reaction explains also why a neutrodimethine cyanine is obtained with such good yields when reacting together a quaternary salt, ketomethylene, and o-ester in a basic medium. As the reaction proceeds, the trimethine cyanine is attacked by the ketomethylene. The resulting 2-methyl quaternary salt is transformed into trimethine cyanine, consuming the totality of the ketomethylene (1, p. 512 661). The mesosubstituted neutrodimethine cyanine is practically pure. 

As early as 1889 Walker (320), using samples of thiazole, 2,4-dimethylthiazoie, pyridine, and 2,6-dimethylpyridine obtained from Hantzsch s laboratory, measured the electrical conductivity of their chlorhydrates and compared them with those of salts of other weak bases, especially quinoline and 2-methylquinoline. He observed the following order of decreasing proton affinity (basicity) quinaldine>2,6-dimethyl-pyridine>quinoline>pyridine>2,4-dimethylthiazole> thiazole, and concluded that the replacement of a nuclear H-atom by a methyl group enhanced the basicity of the aza-aromatic substrates. 

Among the aromatics, it was found that 4-nitroquinoline N-oxide [56-57-5] is a powerful carcinogen producing malignant tumors when painted on the skin of mice (80). It was further estabUshed that the 2-methyl, 2-ethyl, and 6-chloro derivatives of 4-nitro quinoline oxide are also carcinogens (81). 

Excellent yields of the former product are also obtained with quinoline N-oxide. Improved yields of Reissert compounds are found under phase-transfer conditions (29). The regiochemistry of the method changes dramatically with /V-alkyl quin olinium salts, eg, /V-methy1quino1inium iodide [3947-76-0] (12), which form 4-cyanoquinoline [23395-72-4] (13) (30), through the intermediary in this example of A[-methyl-4-cyano-l,4-dihydroquinoline... 

Derivatives. Small amounts of alkyl quiaolines are present ia the tars resulting from the carbonization and Hquefaction of coal (111). Good yields of 4-methyl quinoline, 4,6-dimethyl quinoline [826-77-7], and 4,8-dimethyl quinoline [13362-80-6] are obtained from 4-(diethylamino)-2-butanone and the appropriate aniline. This approach is a promising addition to the traditional syntheses discussed eadier (112). Vlaylacetylene reacts with mercuric chloride and either aniline or -toluidine to yield 4-methyl- and 4,6-dimethyl quinoline, respectively (113). 

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