How many enantiomeric forms are possible for `2,3,4-`tri-hydroxypentanedioic acid?

Options

A. Eight
B. Four
C. Six
D. Two

Answer

B

Explanation

`underset(("Trihydroxyg lutaric acid"))(HO_(2)Coverset(**)CH(OH)overset(**)CH(OH)overset(**)CH(OH)CO_(2)H)`
The molecule contains three chiral carbons. Thus, we can write eight Fischer projections:

It exists on four enantiomers forms: `III` and `IV,V` and `VI` (combined appropriately into two racements) and in two different meso forms: `I` or `II` and `VII` or `VIII`.[ Each pair represents two equivalent Fischer projections which can be interconverted by rotation through `180^(@)`in the plane of the paper. Notice that each meso-compounds contains a plane of symmetry.]