Hydrolysis and transesterification of parabens in a aqueous solution in the presence of glycerol and boric acid

  • Old?ich Farsa University of Veterinary and Pharmaceutical Sciences, Faculty of Pharmacy, Institute of Pharmaceutical Chemistry, Brno
  • Jan Šubert Pharmaceutical Consulting, Dušínova 1522, Ku?im
  • Marie Mare?ková Institute of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Veterinary and Pharmaceutical Sciences, Brno

Abstract

In a solution containing 0.067 % methylparaben, 0.033 % propylparaben, 3.4 % glycerol and 2.0 % boric acid, concentrations of both parabens, 4-hydroxybenzoic acid and 2,3-dihydroxypropyl 4-hydroxybenzoate were monitored after up to 68 months storage. 4-hydroxybenzoic acid is the main hydrolysis product of parabens, while 2,3-dihydroxypropyl 4-hydroxybenzoate was proposed as the main product of transesterification of parabens with glycerol. Results of an HPLC evaluation of parabens, 4-hydroxybenzoic acid and 2,3-dihydroxypropyl 4-hydroxybenzoate showed that the decomposition of 68 months old samples stored at the room temperature did not exceed 2.0 %. The stability of both parabens in a medicinal preparation of the stated composition has thus been satisfactorily demonstrated after more than 5 years storage under ambient conditions. The transesterification reaction was shown to influence the chemical stability of parabens to an extent comparable to hydrolysis. Moreover, the presence of 2,3-dihydroxypropyl 4-hydroxybenzoate in the solution containing glycerol and boric acid was confirmed by 1H-NMR spectroscopy.
Published
2011-06-28
How to Cite
FARSA, Old?ich; ?UBERT, Jan; MARE?KOV, Marie. Hydrolysis and transesterification of parabens in a aqueous solution in the presence of glycerol and boric acid. Journal of Excipients and Food Chemicals, [S.l.], v. 2, n. 2, p. 41-49, june 2011. ISSN 21502668. Available at: <https://ojs.abo.fi/ojs/index.php/jefc/article/view/87>. Date accessed: 27 oct. 2021.
Section
Original Research Articles

Keywords

Parabens; glycerol; boric acid; transesterification; hydrolysis; 2,3-dihydroxypropyl 4-hydroxybenzoate; 1H-NMR