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.

thats how its supposed to be

substituting a hydrogen atom with a halogen in a hydrocarbon:

- the single bond remains single. a is wrong.

- the bond with hydrogen is as strong as with a halogen. c is wrong

- a hydrocarbon is saturated if there is no double bond. we do not know that so d is wrong.

- carbon will always have four valence electrons. e is wrong.

by elimination, the correct answer is b. the boiling point of the new compound increases.