Chapter 22, Problem 40P

Interpretation Introduction

Interpretation:

Based on the given information, the structures of compounds A-F are to be proposed.

Concept introduction:

A carbohydrate is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1.

The Ruff degradation reaction is used for decreasing the number of carbon atoms of the respective aldoses, thereby shortening the carbon chain of the compound. It works in two steps:

Using bromine water to oxidize an aldose to the respective aldonic acid.

Using ${\text{H}}_{\text{2}}{\text{O}}_{\text{2}}$ and ${\text{Fe}}_2{{\text{(SO}}_{\text{4}}\text{)}}_{\text{3}}$ to carry out oxidative decarboxylation of the aldonic acid to a lower aldose.

The Kiliani-Fischer reaction is used for producing epimers of higher aldoses from a lower aldose.

Alditols are sugar alcohols formed by the addition of hydrogen to the monosaccharide. Reduction of monosaccharides (carbohydrates containing single units of sugar molecules) results in the formation of alditols.

${}^{13}\text{CNMR}$, or the carbon-13 nuclear magnetic resonance, is an analytical technique in chemistry to identify the carbon atoms in the structure of a compound. It is an important tool in structure elucidation of organic compounds. However, it can only detect the ${\text{C}}^{13}$ isotope, and not ${\text{C}}^{12}$, as the latter has zero net spin.

The molecules that are non-superimposable or not identical with their mirror images are known as chiral molecules.

A pair of two mirror images that are non-identical are known as enantiomers, which are optically active.

The stereoisomers that are non-superimposable on each other and not mirror images of each other are known as diastereomers.

The achiral compounds in which plane of symmetry is present internally and consists of chiral centres are known as meso compounds, but they are optically inactive.

Compounds that have a plane of symmetry tend to exist in meso forms. A meso form arises when the two stereoisomers produce superimposable images, and hence, compounds having meso forms are optically inactive.