lecture 12 - carbohydrate structure Flashcards
what is an aldose?
If there is sugar which also has an aldehyde group on it
what is a ketose?
if there is sugar which also has an ketone group attached to it
What type of sugar is glucose and galactose?
aldoses
What type of sugar is fructose?
ketose
What is another name for glucose?
aldohexose
What is the Fisher convention?
D sugars have the absolute configuration at the asymmetric centre farthest removed from there carbonyl group as doe D - Glyceraldehyde
What does erythrose mean?
The same groups are on the same side as the Fisher projection
What does threo mean?
The groups are on opposite sides of the Fisher projection
What is an epimer?
sugars that differ by only the configuration around one atom
What is a method for determining D and L isomers?
Optical rotation , if they rotate the light to the right its D (Dextro) . If the light rotates left the its L (levy)
How to determine the number of isomers a compound has?
2^n . n = number of chiral centres
How to form a hemiacetal?
Alcohol and aldehyde
What is ring glucose?
hemiacetal
How to form a hemiketal?
alcohol and ketone
what is ring fructose?
hemiketal
What is the name of a 6 membered ring with an oxygen in it?
pyranose
what is the name of a 5 membered ring with an oxygen in it?
fruanose
What are the 4 different forms of glucose ?
a-D- Glucopyranose
B-D - Glucopyranose
a-D-glucofuranose
B-D- Glucofuranose
What are diastereomers?
Contain chiral centres which are non-superimposable but are NOT mirror images
what type of epimer is galactose in relation to glucose ?
C4 epimer
What type of epimer is Mannose in relation to Glucose?
C2 epimer
What is another definition of an epimer?
chorally opposite centre
which conformation isomer stable, the chair or the boat?
chair
which from of glucose is more common In solution Furanose or pyranose?
pyranose (99%)
which anomer is more common , a or B?
B (63%)
What is an anomer?
An anomer is an epimer at the hemiacetal/acetal carbon in a cyclic saccharide,
Which form Is fructose most commonly in ?
B -pyranose form (70%)
What is the parent sugar for the aldose series?
3 carbon , glyceraldehyde
What is the parent sugar for the ketose series?
dihydroxyacetone
