Quinolinium salts

As a whole, 2 moles of quinolinium react with one of thiazolium together with 2 moles of base. This explains the traditional interest of making the condensation with an excess of quinolinium salt in order to get the maximum yield (50. 51). 

Finally, the importance of quinolinium salts to dye chemistry accounts for the long, productive history of their synthesis. The reaction of A/-methylformanihde with ketones, aldehydes, ketone enamines, or enol acetates in phosphoryl chloride leads to high yields of /V-methylquinolinium salts (60). 

The 5-chloro in 5-deazaflavins is reactive (7SJHC181), but not the 8-chloro, in contrast to the flavin case (79LA1802), and 4-chloropyrimido[4,5-Z>]quinolinium salts are readily hydrolyzed (76JCS(Pl)l3l). 

Pyrimido[4,5-6]quinolinium salts pseudo bases - ring opening, 3, 208 Pyrimido[4,5-6]quinolinium salts, 4-chloro-hydrolysis, 3, 214 Pyrimido[4,5-6]quinolinones synthesis, 3, 228 Pyrimido[4,5 -6]quinolin-5-ones synthesis, 3, 221-222 Pyrimidothiadi azoles reactions, 6, 533 Pyrimidothiazines synthesis, 4, 527 Pyrimidothiazinones mass spectra, 2, 23... 

Quinolinium 2-dicyanomethylene-1,1,3,3-tetracyanopropanediide dimensions, 2, 110 Quinolinium iodide, 1-alkyl-Ladenburg rearrangement, 2, 300 Quinolinium iodide, 1-methyl-Ladenburg rearrangement, 2, 300, 335 Quinolinium iodide, [l-methyl-4-[3(5)-pyrazolyl]-blood sugar level and, 5, 291 Quinolinium perchlorate, 1-ethoxy-hydroxymethylation, 2, 300 Quinolinium perchlorate, 1-methyl-nitration, 2, 318 Quinolinium salts alkylation, 2, 293 Beyer synthesis, 2, 474 electrophilic substitution, 2, 317 free radical alkylation, 2, 45 nitration, 2, 188 reactions... 

Quinolinium salts, l-(4-alkoxyphenyl)-2-methyl-synthesis, 2, 475 Quinolinium salts, aryl-Skraup synthesis, 2, 467 Quinolinium salts, 4-chloro-synthesis... 

Quinolinium salts, 2-ethoxycarbonyl-3-hydroxy-acetylation, 2, 544 Quinolinium salts, 1-methoxy-reactions... 

Tn general, quinolinium salts (21) give produets from addition at the 2 position (22) and isoquinolinium salts (23) give products from addition at the 1 position (24). 

The Reverse Vilsmeier Approach to the synthesis of quinolinium salts is discussed in Meth-Cohn, O. Taylor, D.L. Tetrahedron 1995, 51, 12869. 

Analogously, 2-(3,4-dihydroxyphenyl)ethylamine hydrobromide (dopamine) with 4-methoxybut-3-en-2-one (warm acetic acid) forms pyridinium salt 238 (yield 31 %) and quinolinium salt 239 (yield 40%) (64AG534 65AG224 80MI2). In aqueous solution at 20°C, only 239 is obtained (yield 13%). 

The mechanism suggested earlier for the similar isomerization 34 35 involving the reaction of a 1,2-dihydroquinoline molecule with the starting quinolinium salt 33 (Scheme 11) is analogous to that of 4//-thiopyran isomerization discussed above (cf. Scheme 3) and is supported by deuterated substrate studies (85CJC412). Further support for this mechanism is the absence of such isomerization for 4-substituted derivatives such as 1,4-dimethyl-1,2-dihydroquinoline [94JCS(CC)287]. 

Quinoline-5-sulfonic acid, 8-hydroxy-7-iodo-metal complexes absorptiometry, 1,549 Quinolinium salts in gravimetry, 1, 535 Quinolinol metal complexes color photography, 6,107 8-Quinolinol biological activity, 6, 771 gallium and indium complexes radiopharmacology, 6, 971 radionuclide complexes radiopharmacology, 6,994 8-Quinolyl sulfate hydrolysis metal catalysis, 6,465 Quinones... 

Quinolinium salts, in Mills reaction, 37.40 2.2 -Quinoline rnonomethine cyanine. 

Aliphatic pyridinium salts or aliphatic quinolinium salts in the presence of a sulfur-containing compound have been claimed to be active as corrosion inhibitors [952]. 

Heteroanalogues of spirodibenzopyran, such as spiroquinolinonaph-thopyran 18 and spirobenzothiopyranonaphthopyran 19, are similarly prepared from the corresponding quinolinium salts and benzothiopyrylium salts, respectively (Scheme 12)51,52 Spirobenzothiopyranonaphthopyran 19 has an extended 71-conjugation in 4 -position, and its photomerocyanine... 

Dihydro-1-methyIquinoline can be prepared by brief treatment of 1-methyl-quinolinium salts with sodium amalgam in water under alkaline conditions [87]. Reduction of quinolimum salts in acid solution gives dimeric compounds with structures analogous to 22, but with N-alkyl substituents [83]. 

Scheme 6.83 Product range of the 65-catalyzed asymmetric Petasis-type 2-vinylation of N-phenoxycarbonyl quinolinium salts.

Acids and Lewis acids react with quinoline at the basic nitrogen atom to form quinolinium salts, and there is a question over the nature of the substrate for electrophilic attack, i.e. is it quinoline or the quinolinium cation The answer is not a simple one and appears to depend upon the reagents and reaction conditions. Thus, whereas acetyl nitrate at 20 °C gives mainly 3-nitroquinoline (Scheme 3.2), fuming nitric acid in concentrated sulfuric acid containing sulfur trioxide at 15-20 °C yields a mixture of 5-nitroquinoline (35%) and 8-nitroquinoline (43%) (Scheme 3.3). In the case of acetyl nitrate, the reaction may proceed by the 1,4-addition of the reagent to quinoline, followed by electrophilic attack upon the 1,4-dihydro derivative. 

A By reacting quinoline with benzyl bromide in an inert solvent, such as diethyl ether, the corresponding quinolinium salt is obtained (Scheme 3,12), Treatment of this product with sodium... 

In a study concerning the kinetics and mechanism of osmium tetroxide-catalyzed ferricyanide oxidation of pyridinium and quinolinium salts it was found that the rates of reaction are first order with respect to substrate, alkali, and catalyst, but zero order with respect to ferricyanide concentration (82IJC(A)517). 

Quinolinium salts react similarly to pyridinium compounds when oxidized. N-Alkylated salts 142, for example, yield only 2-quinolones 143 after Decker oxidation. 4-Quinolones 144 cannot be isolated (1892CB443 70HCA1903). 

Oxidative imination of quinolinium salts and aza analogues with subsequent hydrolysis to cyclic amides occurs as in the pyridine series (85JHC765). 

Phosphamethin-cyanines, like methin-cyanines, can be protonated by strong acids, forming colorless dications. These can be converted back to the original phosphamethin-cyanines by careful addition of weak bases such as tert.-butanol. This acid-base reaction is least successful in the case of the weakly basic bis-benzthiazole-phosphamethin-cyanine 6. For bis-quinoline-phosphamethin-cyanine 7 b, we obtained vnth perchloric acid in glacial acetic acid the absorption spectrum of the N-ethyl-quinolinium salt. 

A variety of merocyanine dyes (36) have been generated (Scheme 17) by interaction of suitable oxazolium or thiazolium salts with 4-hydroxythiocoumarin. Similar use of quinolinium salts is also reported. 

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