Sugar Alcohols In the monosaccharide derivatives known as sugar alcohols, the carbonyl oxygen is reduced to a hydroxyl group. For example, D-glyceraldehyde can be reduced to glycerol. However, this sugar alcohol is no longer designated D or L. Why?

Because with reduction of the carbonyl oxygen to a hydroxyl group, the stereochemistry at C-1 and C-3 are the same; the glycerol molecule is not chiral .

This is due to total synthesis of the D or L derivatives

Explanation: In the case of D-glyceraldehyde,the D and L-glyceraldehyde derivatives are chirons that have been exploited extensively in the total synthesis of monosaccharides and analogs. The acetonide of d-glyceraldehyde ((R)-37, (R)-2,3-O-isopropylidene-d-glyceraldehyde) is most simply obtained from d-mannitol. d-Glyceraldehyde has been derived also from d-fructose, l-glyceraldehyde from l-sorbose.

vanderwaal's forces of attraction are the electrostatic intermolecular forces that exist in a molecule due to the temporary or permanent dipoles that are developed in a molecule. in , the major intermolecular forces are dipole-dipole interactions as the molecule is polar (bent structure). so the vanderwaal's forces of interaction in between molecules are the permanent dipole-dipole interactions that develop due to the dipole that exists in between the polar h - s bond. the positively charged hydrogen atom is attracted towards the negative end of the dipole that is sulfur of the adjacent molecule. therefore, these forces of attraction are relatively stronger than that of london dispersion forces that exist in non polar molecules.