Polar monocyclic compounds

The results in Figure 1 can be interpreted in terms of general ring structures with the hydrocarbon classes. The peak for the polypolar aromatic fraction at 160° C probably is caused by polar-monocyclic compounds and the peak at 240° C is probably the result of polar dicyclic compounds. The broad curve in the monoaromatics centering at 275°C is probably mainly caused by alkyl-substituted tetralins while the peaks... 

Basically, the catalytic site of MAOs is thought to consist of two distinct parts, namely a polar-binding site for the amino group and a hydrophobic entrance cavity [64]. Several 2-aminoethylcarboxamides are potent MAO inhibitors. The monocyclic compounds Ro 19-6327 (14a) and Ro 19-6491 (14b) have been shown to be highly selective for MAO B and the fluorinated dicyclic Ro 41-1049 (15) is a potent MAO A inhibitor, while Ro 41-0770 (16) was found to be quite nonselective [65]. 

The principal nonpolar-type adsorbent is activated carbon. Kquilihrium data have been reported on hydrocarbon systems, various organic compounds in water, and mixtures of organic compounds (11,15,16,46,47). With some exceptions, the least polar component of a mixture is selectively adsorbed eg, paraffins are adsorbed selectively relative to olefins of the same carbon number, but dicycUc aromatics are adsorbed selectively relative to monocyclic aromatics of the same carbon number (see Carbon, activated carbon). 

A number of studies have now been made, notably by Buchanan and coworkers, with the object of determining the position of the equilibrium between the various pairs of interconvertible epoxides the findings are summarized in Chart I. For the dianhydro compounds, the epoxides that contain the free hydroxyl group quasi-axial, and that also have the possibility of a polar interaction between the epoxide ring and the 1,6-anhydro bridge, are clearly less stable than those in which it is quasi-equatorial, although the relative importance of these two factors is uncertain. The situation is less clear for the monocyclic epoxides. The half-chair conformations indicated are considered to be favored on the basis that the alkyl... 

The enhanced nucleophilicity of weakly solvated fluoride ions, solubilized in non-polar solvents as their alkali metal salts by [18]crown-6, has been studied. The wide range of SN2 reactions possible with this system is illustrated in Table 3. Under equivalent conditions in the absence of crown ether no substitution occurs. Similar effects are seen with many nucleophiles which, even if soluble in the solvent employed, show increased nucleophilic substitution rates in the presence of crown ethers (B-78MI52104). However, the monocyclic crown compound exposes the cation on two sides to approach by the counteranion (see Figures lb, c and d for illustrations of this effect in the crystalline state). The resultant ion pairs that form in non-polar solvents reduce the reactivity of the anion. 

Layers of silica gel and alumina have been employed for the separation and identification of 126 monocyclic phenols eluted with 3 solvents of increasing polarity (benzene, diisopropylether, and ethanol) [2]. Alumina is more basic than silica gel and strongly retains phenolic compounds, particularly those with more acidic properties such as chlorophenols and nitrophenols, even when eluting with a medium-polarity solvent. 

Reactives of Side-Chains of Monocyclic Thiophens. - The rate constants for the esterification of some 3-, 4-, and 5-substituted thiophen-2-carboxylic acids and of some 2- and 4-substituted thiophen-3-carboxylic acids with diazodiphenylmethane in methanol solution have been measured, and linear correlations gave information about the transmission of substituent effects. The rates of alkaline hydrolysis of ethyl thiophen-2-carboxylate in ethanol-water and DMSO-water media have been measured and compared with those of other heterocyclic esters. The kinetics of iodination of 2-acetylthiophen in methanol-water, using different carboxylate buffers, have been studied.Basicity constants have been measured for j3-(2-thienyl)-acrylamides and compared with those of the corresponding benzene and furan derivatives. The acidity constants of ( )-a-phenyl-j3-(2-thienyl)-acrylic acids and analogous furan-, selenophen-, and pyridine-substituted compounds have been measured, and have been rationalized by an equation involving separate contributions of polar, conjugative, and steric effects of the heterocycles. ... 

The putative polar transition structure finds supporting evidence in the easily ascertainable acceleration of the reaction (see Figs. 16 and 17, and Table 7 in [72e]) with increasing solvent polarity [68], as well as by the structure of monocyclic five-membered ring compounds of type 71 that appear via dipolar intermediates of type W as side-products Scheme 31). 

The many compounds of each group are differentiated by the type of cyclisation (open-chain, monocyclic, bicyclic etc.), the number and position of double bonds, the centres of asymmetry and the nature and number of functional groups. The individual terpene derivatives are most conveniently treated in the order of increasing polarity hydrocarbons first, then esters and lactones, carbonyl compounds, alcohols and finally phenols and acids. 

Various heterocyclic compounds (borazarenes) have been made in which the B—N grouping forms part of an arene system. The following monocyclic species polymerized so rapidly that it could be identified only by its infrared and mass spectra. It behaved like a polarized butadiene. Other oligocyclic compounds,... 

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