Homolytic Aromatic Substitution

Abstract

No. 4253 May 5. 1951 NATURE 725 graphy (Figs. 1-4), 20 µgm. protein being detectable. Protein degradation products do not cause a 'protein error' with the above indicators and, therefore, are not recorded on the chromatogram. Since neither bromothymol blue nor tetrabromophenolphthalein ethyl ester contains nitrogen, we are exploring the possibility that quantitative analysis of protein mixtures may be ach,ieved by nitrogen determinations of the spots. We should like to thank Dr. T. H. H. Quibell of the Chemistry Department, University of Manchester, for kindly preparing a specimen of tetrabromophenolphthalein ethyl ester.

Visible‐Light Promoted Catalyst‐Free Imidation of Arenes and Heteroarenes

“…The observed regioselectivity is generally para ‐ and ortho ‐ directing, consistent with substitute effect typically observed in radical aromatic substitution reactions (Figure 3). 12 The steric effect would also contribute in the regioselective control as reflected by the generally favored para ‐selectivity. In the cases with tert ‐butylbenzenes, the sterically controlled process becomes dominant with the major imidation site remote to the bulky tert ‐butyl group ( 3 f and 3 j ).…”

Quantitative Investigation of Homolytic Arylation

“…Some examples of this procedure are given in Table 4-5. Hey, Shingleton and Williams (unpublished observations); 10 Cadogan, Hey and Williams (1954a); 11 idem (1954b); 12 Augood (1952); 13 Rondestvedt and Blanchard (1956); 14 Augood, Hey, Nechvatal, Robinson and Williams (1951); 15 Davies (1958); 16 Augood, Hey and Williams (1953). The benzoyl peroxide was allowed to decompose in dilute solution (usually about 6 g. per 200 g. mixed solvent; mole fraction ^0-01) at 80° for 72 hr.…”

Degradation of 2-hydroxybenzoic acid by advanced oxidation processes

“…The exclusive hydroxylation in the positions ortho and para to the phenol group is an evident characteristic of the ring substituents (Augood et al, 1959). Thus, hydroxylation of a phenol, like 2-HBA, leads to substitution in the positions ortho and para to the hydroxyl groups only (Loebl et al, 1951).…”