The rates of exchange of the C1-acetoxy group of a variety of 1,2-trans-sugar acetates with acetate from stannic trichloride acetate labelled with carbon-14 were determined in chloroform containing stannic chloride. A correlation was found to exist between reactivity and configuration with the configuration at C3 playing a dominating role. The greater reactivity of the 2,3-trans-sugar compounds is attributed to steric inhibition to the formation of the resonance stabilized intermediate 1,2-cyclic carboxonium ion in the case of the 2,3-cis-compounds.