Racemic Mixtures? (Achiral product+Achiral reagent= chiral product =Racemic mixture?) ?

Question

I have learned that if you have achiral starting material, an achiral reagent, and get a chiral product, then you will have a racemic mixture.

Would it also be a racemic mixture if you had chiral starting material, chiral reagent, and achiral product?

Also is BH3 chiral?

Thank you

Answer 1

achiral products are, well, achiral therefore they cannot be racemic.

BH3 is achiral, but there are many chiral borane derivatives that can be used to perform asymmetric reductions.

Answer 2

A racemic mixture is an optically inactive mixture of equal amounts of two enantiomers.

If your product is achiral, then there are no enantiomers present - only a single molecule. In this case, it would be a mistake to call the product racemic, even though it has no optical activity.

BH3 is not chiral, and BRR'R'' is also not chiral if R, R', and R'' are achiral groups. This is because a planar trigonal geometry exists around the boron atom. However, a substituted borane can be chiral if at least one of its substitutents is chiral