Quina

The important role played by the quinicines (rubatoxanones, quina-toxines) in the syntheses of the dihydrocinchona alkaloids and the possibility that such substances might be used for the preparation of products approaching quinine in therapeutical interest, has led to the production of a large number of quinolyl ketones of various types and the corresponding secondary alcohols, and other derivatives obtainable from them, of which mention may be made of Rubtzov s syntheses of several isomerides of dihydroquinine. ... 

The central. CHOH. group in the cinchona alkaloids seems to be essential to anti-malarial activity Conversion into quinicines [quinatoxines (I) — (VII)] destroys activity and so do such changes as. CHOH. — . CHCl. (cinchona chlorides) or. CHOH. — . CHj. (deoxy-cinchona bases) or. CHOH. — . CO. quina-ketones), or acylation of the hydroxyl group except in the case of quinine ethylcarbonate. 

Reaction of 1 -methylene-1,2,3,4-tetrahydro-5//-pyrazino[2,1 -Z)]quina-zoline-3,6-diones (435) with PhLi and MeMgBr in THE at —78°C gave a mixture of 1 l//-pyrido[2,l-Z)]-quinazolin-l 1-ones 435-439 (01T1987). 

Reaction of 8,9-difluoro-5-methyl-6,7-dihydro-5//-pyrido[3,2,l-//]quina-zoline-l,3-dione with 2,4-dinitrophenylhydroxylamine in the presence of NaH in a 1 1 mixture of dioxan and DMF at 60-80 °C afforded 2-amino derivative (01MIP23). 

Tctrahydro-l 1 //-pyrido[2,l - quina/olin-l 1 -one was prepared by cyclization of 2-(4-hydroxybutyl)quinazo-linH(3//)-onc upon treatment with NaH, and TsOH in THF at room temperature <2004T3417>. Cyclization of 4-(4-oxo-3,4-dihydroquinazolin-2-yl)butyric acid and its 2-acetylamino derivative in refluxing AC2O gave 6-acetyl-... 

Specific-ion electrodes are expensive, temperamental and seem to have a depressingly short life when exposed to aqueous surfactants. They are also not sensitive to some mechanistically interesting ions. Other methods do not have these shortcomings, but they too are not applicable to all ions. Most workers have followed the approach developed by Romsted who noted that counterions bind specifically to ionic micelles, and that qualitatively the binding parallels that to ion exchange resins (Romsted 1977, 1984). In considering the development of Romsted s ideas it will be useful to note that many micellar reactions involving hydrophilic ions are carried out in solutions which contain a mixture of anions for example, there will be the chemically inert counterion of the surfactant plus the added reactive ion. Competition between these ions for the micelle is of key importance and merits detailed consideration. In some cases the solution also contains buffers and the effect of buffer ions has to be considered (Quina et al., 1980). 

With these assumptions, ion exchange between a reactive anion, Y , and an inert anion, X , for example, was written in terms of (7).2 It then was relatively straightforward to write the concentration of reactive ion in the micelle in terms of an assumed constancy of fractional micellar charge, a, and the ion exchange parameter, K, and to analyse rates in terms of these parameters, the binding constants of the substrate, Ks, and the second-order rate constants, kw and A M (Romsted, 1977, 1984 Quina and Chaimovich, 1979 Bunton and Romsted, 1979). 

The original ion-exchange treatment was developed for competition between reactive and inert monoanions, but Chaimovich, Quina and their coworkers have extended it to competition between mono and dianions (Cuccovia et al., 1982a Abuin el al., 1983a). The ion-exchange constant for exchange between thiosulfate dianion and bromide monoanion is not dimensionless as in (7) but depends on salt concentration, and the formalism was developed for analysing micellar effects upon reaction of dianionic nucleophiles, e.g. thiosulfate ion. 

The pH of the aqueous pseudophase, but not that at the micellar surface, can be controlled by buffers, although then it may be necessary to allow for exchange of buffer anions between water and micelles (Romsted, 1984). This approach has been used by some workers who have developed equations which include terms for exchange of all ionic species between water and micelles (Quina et al., 1980). 

Freitas, A. A., Quina, F.H., and Carroll, F.A. Eshmahon of water-organic interfacial tensions. A linear free energy relationship analysis of interfacial adhesion, J. Phys. Chem. B, 101 (38) 7488-7493, 1997. 

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