Stereochemical Impacts on Acyclic Mechanochemical Carbon‐Carbon Bond Activation.

The influence of stereochemistry on the mechanochemistry rate is studied using a new mechanophore based on a benzopinacol (BP) skeleton. Two sets of BP diastereomers, the meso R,S and the R,R/S,S were isolated, incorporated into the center of a poly(methyl acrylate), and their mechanical activation rate was measured in solution. Under mechanical stress, the central C−C bond in BP is cleaved, providing two independent benzophenone molecules with higher UV‐absorption coefficient at 254 nm. Monitoring the reaction rate spectroscopically indicates that the chiral R,R/S,S enantiomers react ~1.4 fold faster compared to the meso R,S diastereomer. <italic>In‐silico</italic> modeling indicates that a hydrogen bond between the <italic>syn</italic> hydroxyls in the R,R diastereomer becomes shorter with stress, reducing the maximal force required for C−C bond scission, while this bond is inexistent in the meso diastereomer, as the hydroxyl are <italic>anti</italic> to each other. Our results indicate that in polymer where free rotation around bonds is possible, non‐covalent interactions between backbone substituents, which are affected by relative stereochemistry, can play a fundamental role in the mechanochemical stability of the polymer. [ABSTRACT FROM AUTHOR]