Phenols cycloalkylation

Oxygen is one of the five (C, H, N, O, and S) major elements in resids and asphalt, although the level rarely exceeds 1.5% by weight. Many petroleum products do not specify a particular oxygen content, but if the oxygen compounds are present as acidic compounds such a phenols (Ar-OH) and naphthenic acids (cycloalkyl-COOH), they are controlled in different specifications by a variety of tests. 

Several chromans have been synthesized using the Parham cycloalkylation technique (76JOC1184). l-Bromo-3-(2-bromophenoxy)propane, prepared from phenol and 1,3-dibromopropane, is treated with n-butyllithium at — 100 °C. Halogen-lithium exchange yields the aryllithium (278) which cyclizes either at — 100°C or in some instances only at an acceptable rate at higher temperatures. This method offers the advantage of regio-specificity since cyclization is controlled by the location of the o-bromine atom (Scheme 72). 

II can be observed that a fair variety of classes of substrates is represented in the table. In addition to the most frequently employed alkyl ketones, particularly cycloalkyl ketones, quinonic, phenolic, and alkync subsn-ates have been subjected to Mannich... 

The last example that deserves to be highlighted in this section on spirocyclization is the DIB-induced domino reaction described by Fujioka, Kita, and co-workers [99] (Fig. 38), who utilized phenolic cyclobutanols of type 151 in aqueous HFIP with the aim of producing spiroketonic cyclohexadienones of type 153 through a 1,2-cycloalkyl shift analogous to the DIB-mediated Wagner-... 

The magnitude of the dipole moment of phenol is also slightly less than that of cyclohexa-nol, its cycloalkyl counterpart, but in the opposite direction. The oxygen atom is the positive end of the dipole in phenol. 

Matisova-Rychla, L., Ambrovic, P., Kulickova, N. and Rychl, J., J. Polym. Sci., Symposium No. 57, 181 (1976). This paper describes the influence of 2,4,6-trisubsti-tuted phenols (e.g. 2,6-di (t-butyl)-4-alkyl- or -cycloalkyl phenols on the autoxidation chemiluminescence of polypropylene... 

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