Quinoline interactions

The presence of certain substituents e.g., the amino group) may markedly affect the solubibty and other properties of the sulphonic acid or carboxylic acid. Thus such sulphonic acids as the aminobenzenesul-phonic acids, pyridine- and quinoline-sulphonic acids exist in the form of inner salts or zwitter-ions that result from the interaction of the basic amino group and the acidic sulphonic acid. Sulphanilic acid, for example, is more accurately represented by formula (I) than by formula (II) ... 

A series of 2-aryloxazolo[4,5-/i]quinoline-5-arylidines was prepared by the reaction of 5,7-diamino-8-hydroxyquinoline with aromatic or aliphatic aldehydes in the presence of a basic catalyst such as piperidine. On the other hand, 2-styryl-5-diacetylamino-oxazolo[4,5-/i]quinolines were prepared by interaction of 2-methyl-5-diacetylamino-oxazolo[4,5-/i]quinoline with aromatic aldehydes (77MI1, 82MI2) (Scheme 6). 

Interaction of 6,7-dichloroquinoline-5,8-dione with amides in ethylene glycol afforded oxazolo[4,5-g]quinoline-4,9-dione, a compound with activity against Gram-positive bacteria (no data) (90MI2). 

Bond orders, charges on the atoms in 1 l//-pyrido[2,l-Z)]quinazolin-l 1-one and its protonated form were calculated by quantum chemical calculations by the semiempirical AMI method. According to the results, the equilibrium conformation of the ring in 1 l//-pyrido[2,l-Z)]quinazolin-l 1-one is planar, while l//-pyrimido[l,2-u]quinolin-1-one adopts a conformation close to a half-chair due to the unfavorable interactions between the oxygen atom of the carbonyl group and the ring C-10 atom in the pen-position (97MI22). 

It would be expected that the stabilization of the adsorbed species by an extended conjugated system should increase with the number of aromatic rings in the adsorbed azahydrocarbon. However, data suitable for comparison are available only for phenanthridine, benzo-[/]quinoline, and benzo[h] quinoline. The large difference in the yields of biaryl obtained from the last two bases could be caused by steric interaction of the 7,8-benz-ring with the catalyst, which would lower the concentration of the adsorbed species relative to that with benzo[/]quinoline. The failure of phenanthridine to yield any biaryl is also noteworthy since some 5,6-dihydrophenanthridine was formed. This suggests that adsorption on the catalyst via the nitrogen atom is possible, but that steric inhibition to the combination of the activated species is involved. The same effect could be responsible for the exclusive formation of 5,5 -disubstituted 2,2 -dipyridines from 3-substi-tuted pyridines, as well as for the low yields of 3,3, 5,5 -tetramethyl-2,2 -bipyridines obtained from 3,5-lutidine and of 3,3 -dimethyl-2,2 -... 

Several products other than 2,2 -biaryls have been isolated following reaction of pyridines with metal catalysts. From the reaction of a-picoline with nickel-alumina, Willink and Wibaut isolated three dimethylbipyridines in addition to the 6,6 -dimethyl-2,2 -bipyridine but their structures have not been elucidated. From the reaction of quinaldine with palladium-on-carbon, Rapoport and his co-workers " obtained a by-product which they regarded as l,2-di(2-quinolyl)-ethane. From the reactions of pyridines and quinolines with degassed Raney nickel several different types of by-product have been identified. The structures and modes of formation of these compounds are of interest as they lead to a better insight into the processes occurring when pyridines interact with metal catalysts. 

Blocking of reaction sites The interaction of adsorbed inhibitors with surface metal atoms may prevent these metal atoms from participating in either the anodic or cathodic reactions of corrosion. This simple blocking effect decreases the number of surface metal atoms at which these reactions can occur, and hence the rates of these reactions, in proportion to the extent of adsorption. The mechanisms of the reactions are not affected and the Tafel slopes of the polarisation curves remain unchanged. Behaviour of this type has been observed for iron in sulphuric acid solutions containing 2,6-dimethyl quinoline, /3-naphthoquinoline , or aliphatic sulphides . 

Wallis and Dunitz (1984a) also investigated another type of sterically induced interaction of a donor group with a diazonio group. Quinoline-8-diazonium-l-oxide tetrafluoroborate (4.14) was analyzed at 95 K (R = 0.034). 

The first approach applied for [cinchonidine (CD) - a-keto ester] complex was also unsuccessful. In the open conformation CD cannot provide the required steric shielding. In open form either the quinuclidine or the quinoline moiety of CD will interact with the substrate. It has already been demonstrated that the quinuclidine moiety has a crucial role both in the rate acceleration and the induction of ED [13]. 

As an example of this nonlinear character we may consider two pairs of compounds, naphthalene versus quinoline and indole versus benzimidazole (Fig. 11.5). In both pairs of compounds the second differs from the first by a mutahon of an aromahc -CH group to an aromahc nitrogen, which introduces a strong H-bond acceptor into the molecule. In quinoline, which has no H-bond donor, the acceptor has no favorable interaction partner in the supercooled liquid or crystalline state, while it can make strong H-bonds with the solvent in water. Therefore, log Sw of quinoline is about 2 log units higher [35, 36] than that of naphthalene, i.e. the introduction of the H-bond acceptor strongly increases solubility in this... 

In pyridine- X-C interactions, the C - X moiety is roughly coplanar with the pyridine and the two C-N- X angles are approximately 120° [129,143, 144]. The same holds for other nitrogen heteroaromatics (e.g. pyrazine, quinoline, etc.) [145-147]. A carbonyl group pins the donors after a trigonal planar geometry and works either as a mono- [148,149] or bidentate XB acceptor [150]. Sulfoxides behave similarly [151,152] and imines form XB along the expected axis of the lone pair [153]. 

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