Question

A student has isolated a chiral alkyl halide (shown below) with a specific rotation of [alpha] = +22.1 degrees. The student decided to store the compound in the solvent MeOH overnight. However, reanalysis of the alkyl halide showed a new chemical formula of C11H16O with a specific rotation of [alpha] = 0 degrees. Suggest a mechanism to justify these results.

Answer 1

Here product formed is enantiomeric pair and they are present in equal amount and it is known fact that optical rotation of one enantiomer is equal in magnitude but opposite in sign . So in solution if both pair is present in equal amount then effective optical rotation will be zero . Analysis of optical rotation indicates that product formed is enantiomeric pair and they are in equal amount . The reason behind the equal amount is planar shape of intermediate carbocation. Since nucleophile can attack from both side of the plane that's why two spatially differently oriented product is formed.

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