Kinetics of bromine addition to acrylic acid and methacrylic acid in aqueous solution

Department of Chemistry, Arignar Anna Government Arts College, Karaikal-609 605, Puducherry, India

E-mail : farook.ny@gmail.com

Department of Physical Chemistry, Madras University, Chennai-600 025, India

Manuscript received 17 January 2011, revised 30 June 2011, accepted 12 July 2011

The most important feature of this potentiometric study of bromination of acrylic and methacrylic acids in aqueous medium is the complete solution of rate laws by varying [Br^-] and [H⁺I over an extended concentration range. This observation completely rules out the possibilities of reactions of undissociated acid with Br₂ or Br₃^- and dissociated acid anion with Br₃^- for both acids. Values of rate constants and energy of activation were evaluated and interpreted. The reactivity of methacrylic acid was greater than that of acrylic acid. The enhancement of reactivity by methyl group depends on the nature of the substrate.