Carbohydrates Flashcards
1
Q
The same sugars in different optical families, are enantiomers.
A
2
Q
Two sugars that are in the same family (both are eithe rketoses or aldoses and have the same number of carbons) that are not identical and are not mirror images of each other are diastereomers.
A
3
Q
A special subtype of diastereomers that differ in configuration at exactly on chiral center are epimers.
A
4
Q
ketoses
A
- contain a ketone i.e. glucose
- can undergo intramolecular rxns to form hemiketals
5
Q
aldoses
A
- contain an aldehyde i.e fructose
- can undergo intramolecular rxns to form cyclic hemiacetals
6
Q
Alpha and Beta glucose
A
7
Q
Monosaccharides
A
- monomer of carbohydrates
- contain alcohols and either aldehydes or ketones
- can undergo oxidation and reduction, esterification, and nucleophilic attack (creating glycosides)
8
Q
Mutarotation
A
- spontaneous change of configuration about C1
- occurs more rapidly when rxn is catalyzed with an acid
Products: mixture of both alpha and beta anomers in equilibrium concentrations
9
Q
Carbohydrate oxidation
A
- Oxidized aldoses are aldonic acids
- any monosaccharide with a hemiacetal ring is considered a reducing sugar
- When aldose in question is in ring form, oxidation yields a lactone instead.
- Tollen’s reagent and Benedict’s reagent are used to detect presence of reducing sugars
10
Q
Tautomerization
A
- the rearrangement of bonds in a compound, usually by moving a hydrogen and forming a double bond.
- Ketones can tautomerize under basic conditions to form aldoses (give + Tollen’s/Benedict’s tests)
11
Q
Esterification
A
- carbohydrates react with -COOHs to form esters
- similar to phosphorylation of glucose
12
Q
Glycoside formation
A
- Hemiacetals + ROH + acid = acetals
- nonspecific; the anomeric carbon of a cyclic sugar can react with any hydroxyl group on any other sugar
13
Q
Sucrose
A
glucose-a-1,2-fructose
14
Q
Lactose
A
galactose-B-1,4-glucose
15
Q
maltose
A
glucose-a-1,4-glucose
