carbohydrates Flashcards
(35 cards)
empirical formula of carbohydrates
(CH2O)n
chirally active carbon
carbon is attached to 4 different groups
aldehyde carbon in aldoses
C1
carbonyl carbon in ketoses
C2
aldehyde
carbon is attached to hydrogen, r group and double bonded to oxygen
ketone
carbon attached to 2 r groups and double bonded to oxygen
3 carbon molecule
trioses
4 carbon molecule
tetroses
5 carbon molecule
pentoses
6 carbon molecule
hexoses
aldehyde + alcohol
hemiacetal
ring forms because r is part of same molecule as aldehyde
ketone + alcohol
hemiketal
ring forms because r is part of same molecule as the ketone
ring form of pyranose sugar structure
planar chair configuration
axial orientation
substituent points up or down
equatorial orientation
substituent is on the same plane as the ring
anomer
an epimer at the hemiketal/hemiacetal carbon = the anomeric carbon
when the stereochemical isomer is at c1, is it a new sugar?
no, just an alpha or beta form of the sugar
alpha and beta sugars
configuration (a or e) of anomeric carbon compared to anomeric reference atom.
eg in alpha it could be axial and beta it could be equatorial
anomeric carbon in aldoses
C1
anomeric carbon in ketoses
C2
how are D and L sugars determined
configuaration of chirally active carbon furthest away from aldehyde or ketone groups
enantiomer
mirror image molecules
epimer
molecules are different sugars, asymmetric carbon 2,3,4 different configuration to glucose
you say epimers AT C_
eg glucose and mannose epimers at C4
maltose
major product of starch digestion
hydrolysed by maltase