Chapter 24, Problem 83IP

Interpretation Introduction

Interpretation:

The compound A should be identified.

Concept introduction:

The Fischer projection: Fischer projection is a two-dimensional representation of a three-dimensional organic molecule by projection. It is mainly proposed for the representation of carbohydrate chemistry.

The orientation of the carbon atoms in a molecule is arranged vertically from top to bottom.

The C1 carbon is at the top of the orientation, the hydrogen and hydroxyl groups are placed in right and left side of the orientation. D and L form are depends on the arrangement of the hydroxyl group. If the hydroxyl group is in the right side of the molecule in the penultimate (next-to-last) carbon is called as D sugar, if the If the hydroxyl group is in the left side of the molecule in the penultimate (next-to-last) carbon is called as L sugar.

Reducing sugar: Sugars that contain aldehyde or a free ketone groups that are oxidized to carboxylic acids are classified as reducing sugars.

Epimer: Epimer is one of a pair of stereoisomers. The two isomers differ in configuration at only one stereogenic center.

The Wohl degradation: D-glucose is reaction with hydroxylamine and sodium methoxide which yields oxime then resultant oxime is reaction with acetic anhydride in acetic acid with sodium acetate which afforded pentaacetyl glycononitrile. In this reaction step the oxime is converted into the nitrile with simultaneous conversion of all the alcohol groups to acetate groups. Finally, sodium methoxide in methanol is added to the reaction which yields the final degradation compound.

Cahn–Ingold–Prelog system: The first priority goes to the atom in a molecule whose atomic number is higher. After assigning the priorities to each of the substituents, rotate the molecule so that the number-four priority substituent is oriented in the back.

Draw a curve from the first-priority substituent through the second-priority substituent and then through the third.

If the curve goes clockwise, the chiral center is designated R; if the curve goes counterclockwise, the chiral center is designated S.

Ethylation: carbohydrates ethylated by using ethyl iodide and silver oxide.

To find: The structure of compound A.