title: The sulfophosphovanillin reaction for serum lipids: a reappraisal.
abstract: New evidence is presented for the mechanism of this reaction, which is used in estimating lipids. The reaction occurs in two stages: (a) Stage 1 evidently involves an oxidation step, forming a specific type of carbonium ion called an alkenyl cation of the general formula R--C+--C==C--R' (previous evidence had indicated that a carbonium ion of general formula R--C+--R' was formed by protonation only.) (b) Stage 2 of the reaction was examined by nuclear magnetic resonance studies and by partition experiments, which have indicated that a vanillin phosphate ester is not formed as previously suggested. Comparative data from other acid-aldehyde reactions indicate that in this reaction 1,1-di(4-hydroxy-3-methoxy phenyl)ethylene ion is formed, a product compatible with the formation of an alkenyl cation at stage 1.
mesh_terms: D001547:Benzaldehydes; D055598:Chemical Phenomena; D002621:Chemistry; D005421:Flavoring Agents / Q000031:analogs & derivatives*; D006801:Humans; D007202:Indicators and Reagents; D008055:Lipids / Q000097:blood*; D009682:Magnetic Resonance Spectroscopy; D009946:Organothiophosphorus Compounds; D013053:Spectrophotometry / Q000379:methods
chemical_list: D001547:Benzaldehydes; D005421:Flavoring Agents; D007202:Indicators and Reagents; D008055:Lipids; D009946:Organothiophosphorus Compounds; C015519:sulfophosphovanillin