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THE EFFECT OF SOLVENT COMPOSITION ON THE KINETICS OF DEACYLATION OF LECITHIN
(1985-02) ABALAKA, IDUH; JOHAH
A back titration technique has been used to follow up the effect of change in the composition of the propan-1-ol/ water solvent on the kinetics of the deacylation of egg yolk lecithin under second order conditions in alkaline media. The lecithin was employed at a concentration of 1.5 x 10-2 molar and the alkali concentration was double that of the lipid. The reaction was investigated in concentrations of propan-1-ol ranging from 10 % v/v to 97 % v/v in water. The work involved the withdrawal of aliquots of 1 cm3 from the reaction solvent which was maintained at a temperature of 30O C under nitrogen reflux and magnetic stiringr Withdrawn aliquots were titrated to phenolphthalein end point using 3 x 10-3 molar hydrochloric acid and a 10 cm3 burette. readable to 0.02 cm3. From the titre values obtained estimations of the rate constants for the deacylation process in the various compositions of the propan-1-ol in v/ater solvents employed were obtained. Association of lecithin in the various solvent systems was examined spoctrophotometrically between 255 and 295 nm using a Pye Unicam SP 30 digital, spectrophotometer using phenolplrthaleln as a probe. The lecithin existed as monomers in 83.33 % v/v propan-1-ol in water while various molecular regates were formed in the other solvent systems. vi ABSTRACT