Synthesis of N-(5-vinyl-1,3-thiazolidin-2-ylidene)phenylamine and analysis of oils implicated in the spanish toxic oil syndrome for its presence

Previous reports have implicated 1-phenyl-5-vinyl imidazolidine-2-thione (PVIZT), a cyclic reaction product of aniline and naturally occurring rapeseed oil isothiocyanates, as the potential causative agent of the Spanish toxic oil syndrome (TOS). This report describes the synthesis, preliminary characterization and analysis of that reaction product, which has been identified as N-(5-vinyl-1,3-thiazolidin-2-ylidene)phenylamine (5-VTPA) rather than PVIZT. Oil samples (n = 21) that contained fatty acid anilides and were epidemiologically linked to TOS were analysed for the presence of 5-VTPA by extraction of the oil with methanol and clean-up on an ion-exchange column, followed by capillary gas chromatography mass spectrometry using selected ion detection. A limit of detection of less than 500 ppb was established for these analyses. No 5-VTPA could be detected, however, in any of the TOS oils. As 5-VTPA was shown to be unstable in both heated and unheated food oils, it is possible that the compound had been lost from the oils since the time of the epidemic in 1981. However, no direct evidence for the involvement of 5-VTPA in TOS could be obtained in this study.