Question

Convert each Haworth projection in Problem 28.14 to a three-dimensional representation using a chair pyranose ring.

Short answer

Answer

Step-by-step solution

Haworth projection

A monosaccharide’s cyclic structure can be indicated using structures referred to as the Haworth projection. Fischer projections are frequently transformed into several forms like Haworth projections and chair conformation.

These structures are important in several fields like organic chemistry and biochemistry.

Conversion of Haworth projection to the three-dimensional representation using the chair form

The following rules are considered for converting a projection formula to the chair form.

• The pyranose ring is illustrated with the oxygen atom as the top atom.
• The substituents situated at the top (axial or equatorial) are labeled in the top position in the chair form.
• The substituents situated at the bottom (axial or equatorial) are labeled at the bottom part in the chair form.

Conversion of the Haworth projections in Problem 28.14 to the chair form

The Haworth projection of the first structure can be given as:

The conversion of the Haworth projection to the chair form can be given as:

The Haworth projection of the second structure can be given as:

The conversion of the Haworth projection to the chair form can be given as:

The second structure is less stable than the first structure as it has more axial groups, which contributes to steric hindrance when compared to the first structure.