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The kinetics of the inhibited oxidation of tetralin are compared with use of two types of initiator and two types of antioxidant. It is established that radical chain-breaking antioxidants (phenols) give an induction period with azodi-isobutyronitrile but a linear rate curve with tetralin hydroperoxide. Peroxide decomposers (e.g., zinc diethyldithiocarbamate) are almost ineffective in a system initiated by azodi-isobutyronitrile but are autoinhibitive in the presence of tetralin hydroperoxide. These data are consistent with the view that sulphur-containing peroxide decomposers are converted into an effective catalytic non-radical forming hydroperoxide decomposer (probably sulphur dioxide) in a radical-generating reaction.CONSIDERABLE attention has been devoted recently to the study of the radical-deactivating mechanisms of antioxidant action. In particular the removal of alkylperoxy-radicals by hydrogen (or electron) transfer (3) and (4) has been recognised as the primary function of amines and phen~ls.l-~ ( I ) } Chain reaction

Two processes are being developed by the National Coal Board for producing liquids from coal. Both involve extraction of the coal to produce an extract, freed from mineral matter, which is then catalytically hydrocracked. This approach is particularly suitable for producing transport fuels and chemical feedstocks. One process uses as solvent a process-derived liquid. The other uses a compressed supercritical gas to extract the more hydrogen-rich parts of the coal, leaving a reactive char which can provide the necessary hydrogen, heat and power for the process. As part of the development programme, extracts have been prepared by gas extraction over a range of conditions, and their chemical structures investigated by elemental and spectroscopic analysis. The average structures so derived consist of small aromatic clusters joined by methylene, ether and diphenyl linkages. Extracts produced by the liquid solvent route contain larger aromatic clusters.