A kinetic study of the addition reactions of borohydride and sulfite ions and of hydroxylamine to a number of stereospecifically deuterated carbonyl compounds (3,3,5,5-tetramethyl cyclohexanone, 7,7-d2-bicyclo[2,2,1]-2-bornanone) leads to the observation of a distant secondary deuterium isotope effect. The results obtained reveal the intervention of a directional effect in the steric origin of these isotope effects. In particular, this study shows the importance of the orientation of the vibrations brought into play by a C—D bond during the reaction process. (Journal translation)