New oxidation pathway of 3,5‐di‐ tert ‐butyl‐4‐hydroxytoluene: An ionspray tandem mass spectrometric and gas chromatographic/mass spectrometric study

The autoxidation of 3,5‐di‐ tert ‐butyl‐4‐hydroxytoluene (BHT, 1 ) in bar soap was investigated with ionspray tandem mass spectrometric and on‐line gas chromatographic/mass spectrometric methods. The oxidation products of BHT were extracted from the bar soap surface, concentrated, and fractionated with open‐column chromatography to remove the impurities. New oxidation products of BHT (BHT phenol‐type dimer 7 and others) were identified with the two mass spectrometric methods. The results suggested that oxidation of BHT in bar soap occurred in a way different from that in the previous studies. In the new pathway, oxidation of BHT first generates an excited state of phenol‐type dimer 4 , and then this species decomposes, due to its high energy, to form dimer 7 . The mechanism of oxidation is discussed.