| Selective ester bond cleavage using lithium and zinc halides was attempted in a select group of phospholipids, namely phosphatidylcholine (PC), phosphatidylethanolamine (PE), and phosphatidylserine (PS). Several reaction parameters including catalyst (lithium chloride, lithium bromide, lithium iodide, zinc chloride, zinc bromide and zinc iodide), reaction temperature (21, 30, 50 and 60°C), and reaction time (2 and 4 hours) were varied and the effects on cleavage studied. Reacted phospholipid samples were characterized by attenuated total reflectance (ATR) and transmission FTIR spectroscopy. The FTIR spectra of pure (unreacted) and reacted PC, PE and PE were analyzed qualitatively and quantitatively (Peak Height Ratio). The appearance of asymmetric carboxylate anion stretch (1577 cm-1) and symmetric phosphonyl dianion stretch (1006 cm-1) in the reacted phospholipid spectra reveals cleavage of ester bonds in carbonyl and phosphonyl. Reaction temperature and time did not significantly influence the cleavage results over the temperature and time range tested. |
