A DTA study of phenols

Abstract

A comprehensive DTA study is reported of 17 halophenols and of the corresponding pnitrobenzoylchloride 3,5-dinitrobenzoylehloride and p-phenylazobenzoylchloride derivatives, prepared ~in-situ'by heating intimate mixtures of phenol and acid chloride in the DTA system. The thermal analysis data, in particular, the derivative formation temperatures, are interpreted in terms of the inductive, mesomeric and sterie effects associated with the ring substituents of the phenol and acid chloride and the extent of inter-and intramolecular hydrogen-bonding existing in these systems. The DTA data collectively provide a reference base for the identification and characterization of halophenols via thermal analysis.

A DTA study of phenols

“…Interpretation of the various peaks in the DTA profiles of these phenols is generally in accordance with the sequence: mp of phenol, mp of acid chloride, derivative formation (TD), derivative mp and derivative decomposition [2]. Such an interpretation was facifitated in all cases, by confirmation of derivative mp by Thermal Optical Analysis.…”

“…The source of phenols and acid chlorides, the DTA system used, the sample presentation procedures and the data analysis procedures with respect to DTA curve analysis and peak assignments, have been fully described in Part I [2]. The Hot Stage Microscopy system, used to confirm derivative melting points, has also been described [2].…”

A DTA Study of phenols

“…These data collectively constitute a comprehensive data bank for the subsequent characterisation of these phenols in the solid-state by DTA. It has been well documented [1,2] that the case of derivative formation, as reflected in the magnitude of TD, is dependent on the relative acidic and basic strengths of the acid chloride and phenoxide ion respectively, although it appears that phenol acidity is the dominant effect in this synergistic interaction. The peak definition temperature data (Tables 1 and 2), as related to the initial decomposition of the parent phenols, give a quantitative indication of the relative thermal stability of these compounds.…”

“…The source of phenols and acid chlorides, the DTA system used, the sample presentation procedures and the data analysis procedures with respect to DTA curve analysis and peak assignments, have been fully described in Part 1 [1]. The ThermaI Optical Analysis System, used separately to confirm derivative melting points, has also been described [1].…”

“…Parts 1 [1] and 2 [2] in this series of papers have reported a detailed DTA study of halo-, methyl-, and methyl-halo-phenols together with the 'in situ' formation in a DTA of the corresponding p-nitrobenzoylchloride (p-NBC), 3,5-dinitrobenzoylehloride (3,5-dNBC) and p-phenylazobenzoylchloride (p-PABC) derivatives. It was conclusively shown that these groups of phenols can be eharacterised in the solid state by DTA and that such characterisation is augmented by a DTA study of the 'in situ' phenol/acid chloride derivative formation process -a proposal which had earlier been suggested by Crandall and Pennington [3].…”