Chapter 24, Problem 89CP

(a)

Interpretation Introduction

Interpretation:

The structure of Compound A has to be determined.

Concept introduction:

Wohl degradation: The reverse process of Kiliani-Fischer synthesis and involves the removal of a Carbon atom from an aldose. The aldehyde is first converted to a cyanohydrin, followed by loss of HCN in the presence of a base. This chain reduction only gives only one product, in contrast with the chain lengthening (Kiliani-synthesis) gives two products.

(b)

Interpretation Introduction

Interpretation:

The structure of Compound D and E has to be determined and has to explain how the compounds are distinguished.

Concept introduction:

The ${}^{\text{13}}\text{C}\text{NMR}$ spectrum gives information on the different electronic environments of carbon. As like ${}^{\text{1}}\text{H}\text{NMR}$, the number of signals generated in ${}^{\text{13}}\text{C}\text{NMR}$ are predicted by performing symmetry operations (rotation or reflection symmetry). Only chemical shift values are reported in the spectrum but not the multiplicity and integration values because the coupling between two neighboring ${}^{\text{13}}\text{C}{-}^{\text{13}}\text{C}$ nuclei are weakly involved due to the low abundance of ${}^{\text{13}}\text{C}$ isotopes of carbon atom.