A nuclear magnetic resonance study of molecular motion in (2,4,5-Trichlorophenoxy)acetic acid

Abstract

Proton magnetic resonance data in polycrystalline (2,4,5-trichlorophenoxy)acetic acid in the temperature range 77-400 K are reported in this communication. After a correction is made for the H-H distance in the methylene group the rigid lattice second moment (S₂) coincides with the experimental value in the temperature range 77-170 K. The observed fall in S₂ in the temperature range 170- 208 K is interpreted as the result of the CH₂COOH group reorientation. The barrier height associated with the reorientation is found to be 8.728 kJ mol^- which indicates non-cleavage of hydrogen-bonding in the dimeric unit during reorientation.