1370 cm-l strong and 1395 cm-I moderate (t-butyl).
There are no peaks at all at the following wavenumbers:
1640-1680 cm-l (alkenes), 2100-2260 cm-l (alkynes), 1690-1760 cm-l (aldehydes, ketones, carboxylic acids, esters), 1455-1460 cm-l (CHz), and 718-727 cm-l ((CH&).
The spectrum of the compound correlates exactly with the spectrum of 2,6-di-t-butyl-4 methylphenol'.
This compound has a molecular weight of 220.36 and a melting point of 69-7 1Β°C 7.
It is worth noting that all the work done on vacuum pyrolysis of coal has been performed at temperatures greater than 150Β°C ', whereas in this work 2,6-d&tbutyl-4methylphenol was obtained at the very low temperature of 35'C. This might indicate that the compound is present free in the brown coal and not formed by decomposition of a larger molecule.
The fact that the removal of this compound and water greatly affects the oxidation of the coal indicates that this removal significantly changes the chemical nature of the coal surface. Investigations are being carried out to determine the precise relation between compound removal, water removal and oxidation.
The drying method used by most authors in oxidation and hydration studies on brown coal is such that the compound would be removed from the coal Letters to the Editor during drying. The experimental results show the importance of the compound in oxidation.
The compound removal may be of importance in hydration studies since its removal may significantly affect the coal-water relation.
The melting-point difference suggests the possibility that more than one compound is removed from the coal during drying, and consequently a more suitable apparatus for vacuum drying of coal is being built; further work is proceeding.