Quinoline-pyridines

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. 

In this process, catalysts, such as boric acid, molybdenum oxide, zirconium, and titanium tetrachloride or ammonium molybdate, are used to accelerate the reaction. The synthesis is either carried out in a solvent (aUphatic hydrocarbon, trichlorobenzene, quinoline, pyridine, glycols, or alcohols) at approximately 200°C or without a solvent at 300°C (51,52). 

The Nitrogen Availability Assay [376] consists of growth tests under defined conditions using mineral salts medium and organonitrogen compounds as sources of carbon and/or nitrogen. Probe molecules include quinoline, pyridine, carbazole, and porphyrin. Growth tests are performed using six conditions ... 

Since the early work dealing with Zeise s salt, many complexes have been prepared with the formula [PtL(C2H4)X2], where L = quinoline, pyridine, or ammonia and X=C1 , Br , I, or N()2. Similar compounds have been prepared that contain other alkenes than C2H4. Many of the complexes containing dienes, trienes, and tetraenes as ligands also contain carbonyl ligands. In fact, metal carbonyls are frequently starting complexes from which alkene complexes are obtained by substitution reactions. 

V,Af-Dimethylaniline A A,A, AT-Tetramethyl-p-phenylenediamine Cyclic amines 4,4 -Bipyridyl Quinoline Pyridine A-oxide Pyridinium chloride Hydroxides CsOH LiOH NaOH Triton B6 Alkylamines Ammonia Methylamine Ethylamine Propylamine Butylamine Decylamine Dodecylamine Tridecylamine Tetradecylamine Pentadecylamine Hexadecylamine Heptadecylamine Octadecylamine Tributylamine Miscellaneous Ammonium acetate Hydrazine Potassium formate Guanidine... 

This form of selenium can also be produced from amorphous selenium by heating with quinoline, pyridine, aniline or other basic organic solvent,7 and also by sublimation. In this latter case the sublimate also contains the amorphous form.8 Atmospheric oxidation of solutions of alkali selenides gives this variety of selenium as a granular deposit. When produced by these last three methods, leafy crystals may be obtained, and Muthmann (1890) discovered that crystals which he obtained by the sublimation method were of the trigonal (rhombohedral) system and isomorphous with those of tellurium. 

The decreasing reactivity of the most familiar aromatic heterocyclic compounds with nucleophilic reagents may be illustrated by the following sequence quinoxaline > acridine > phenanthridine > isoquinoline > quinoline > pyridine. Acridine is alkylated in the 4-position, phenanthridine and quinoxaline in the a-position, isoquinoline in the 1-position, and quinoline and pyridine in the 2- or 4-positions. Weaker nucleophilic reagents seem to enter the 4-position of the pyridine and quinoline rings. If the addition occurs readily and in good yield, the intermediate dihydro derivative may sometimes be isolated otherwise, the product of the subsequent oxidation results. In synthetic work the dihydro derivative is usually directly oxidized. 

The deactivation of a lanthanum exchanged zeolite Y catalyst for isopropyl benzene (cumene) cracking was studied using a thermobalance. The kinetics of the main reaction and the coking reaction were determined. The effects of catalyst coke content and poisoning by nitrogen compounds, quinoline, pyridine, and aniline, were evaluated. The Froment-Bischoff approach to modeling catalyst deactivation was used. 

This agrees with the relative ease of polarographic reduction of the same heterocycles. However, there is no strict dependence between 7r-deficiency and -acceptor strength of the compounds. -Acceptor properties of azines also increases on transition to benzo derivatives, e.g., acridine > quinoline > pyridine. 

Substituent effects follow the general pattern of substituted benzene derivatives in that nitro, sulfonic acid, and carboxyalkyl groups deactivate the ring to further substitution, whereas amino and methoxy groups strongly activate, and methyl and chloro groups have little effect. Ridd383 has recently reviewed electrophilic substitutions on quinoline, pyridine, and imidazole. 

Alternating copolymers are, of course, formed also by other than radical copropagations. Soga et al. obtained an alternating copolymer from oxirane and S02 in the presence of aromatic amines (quinoline, pyridine) [254] and Koinuma and Hirai did so with C02 in the presence of Et2Zn/H20 (1 1) [255], Many similar studies have been published [256],... 

The submitters have also prepared 2,2 -dithienyl sulfide in 34% yield by condensation of 2-thiophenethiol with 2-bromothiophene in the presence of cuprous oxide in a quinoline-pyridine mixture. Challenger and Harrison6 have obtained 2,2 -dithienyl sulfide in 50-55% yield by treatment of 2-thienyl-magnesium bromide with excess sulfur. This sulfide may also be obtained in 20% yield by condensation of thiophene with sulfur monochloride, followed by pyrolysis of the resultant disulfide.7... 

Chloro-3-fonnylquinolines 161 (Scheme 31) were transformed in the presence of acetic acid to 3-formylquinolones which upon reaction with acetophenones provided the intermediate a,p unsaturated Knoevenagel adducts. Subsequent Krohnke reaction of these adducts with pyridinium salts 162 and ammonium acetate provided the final quinoline-pyridines 163 in excellent yields [68]. All the compounds were tested... 

In heterocyclic aromatic compounds, the ring containing electron-withdrawing substituents is more resistant to oxidative degradation. Both quinoline and 8-hydroxyquinoline give quinolinic (pyridine-2,3-dicarbox-ylic) acid (equation 160) [117, 459]. 

Reactions of highly electrophilic fluoro-containing compounds with cyclic enamines, isoquinoline, quinoline, pyridine and indole derivatives 01MI77. 

The constants for quinoline, pyridine, and cumene hydroperoxide were obtained in these studies with both types of reactors and afford a check for the validity of the methods and for the kinetics scheme. The values for quinoline and pyridine for the differential reactor are given in Fig. 2 as a nKp vs. 1/ T plot to facilitate the comparison. The agreement is fair and is considered to support the scheme, since the value of Kp obtained is very sensitive to small effects. 

In addition to a number of inorganic polychromates, R. Weinland and H. Staelin prepared dichromates of quinoline and guanidine and trichromates of quinoline, pyridine and guanidine. A. Werner represented dichromic acid as a derivative... 

It is well established that low molecular weight modifiers such as quinoline, pyridine, etc. [51] increase the selectivity of the hydrogenation of acetylene alcohols, but often the modifiers leach and selectivity deteriorates. In the case of pyridine units of the P4VP block, the modification is fairly permanent. The stability of modification, which governs the stability of catalytic properties and high selectivity, is one of the important advantages of catalytic nanoparticles stabilized in the polymeric media [47]. 

The question of the rate-determining step in the Chichibabin reaction is still open. Clearly, it is difficult to expect that such a complex process can be controlled by any single parameter. On the basis of the rate of hydrogen gas evolution, the following sequence of the reactivity of aza-heterocyclic compounds has been established 1-R-benzimidazoles > isoquinoline > 1-R-perimidines > benzo[/]quinoline > pyridine acridine. Evidently, this raw indicates that sodamide amination depends on number of factors, involving electron deficiency of the substrate C(a)-atom, ease of the adduct aromatization, substrate basicity, etc. Evidently, acridine s position in this raw reflects the difficulty of the y-amination. 

---