HYDROGEN-BONDING IN CARBOXYLIC-ACID ADLAYERS ON PD(111) - EVIDENCE FOR CATEMER FORMATION Academic Article uri icon

abstract

  • The adsorption of acetic acid and propanoic acid was studied on the Pd(lll) surface in order to gain insights into the extent of hydrogen bonding present in carboxylic acid adlayers. In the solid phase, acetic acid is known to crystallize in hydrogen-bonded catemers of the form (CH3COOH)n, while propanoic acid crystallizes as dimers of the form (CH3CH2COOH)2. However, on the clean Pd(lll) surface both of these adsorbates formed hydrogen-bonded catemers as indicated by the reduction of the v(OH) vibration frequency to ca. 2550 cm-1. Acetic acid catemers decomposed near 200 K to produce molecular acetic acid which either desorbed or dissociated to form surface acetates. These acetates reacted via two parallel pathways: hydrogenation to acetic acid and decarboxylation. The decomposition of propanoic acid catemers occurred via sequences analogous to those observed for acetic acid. Propanoates derived from the propanoic acid adlayer underwent either hydrogenation to propanoic acid at 280 K or decarboxylation at 355 K. The observation of catemer formation from both acetic and propanoic acids suggests that adsorbed monolayers may differ from crystalline solids in their hydrogen-bonding characteristics. 1989, American Chemical Society. All rights reserved.

published proceedings

  • LANGMUIR

author list (cited authors)

  • DAVIS, J. L., & BARTEAU, M. A.

citation count

  • 65

complete list of authors

  • DAVIS, JL||BARTEAU, MA

publication date

  • November 1989