Question

Identify the indicated faces in the following molecules as Re or Si:

(a)

(b)

Short answer

(b)

Step-by-step solution

Re or Si face

There are two planar faces in a compound, with a prochiral hybridized group designated Re and Si faces.The ‘Re’ face is clockwise, and the ‘Si’ face is anticlockwise. The Si face can be obtained by flipping the molecule.

The faces in the crotonate molecule

(b) According to C.I.P. sequence order, ‘Re’ face is given to the lower planar face, which is clockwise. ‘Si’ face is given to the upper planar face, which is anticlockwise.

Re and Si faces in crotonate