Monosaccharides Flashcards
When does an acetal functional group form
when 2 monosaccharides join, they are linked by an acetal functional group. The anomeric carbon becomes fixed in either the alpha/beta position
Hemiacetal functional group is what
C-O-C-O-H
Acetal functional group is what
C-O-C-O-C
when does a hemiacetal functional group form
when the hydrogen is still attached to the oxygen so the oxygen is not bonded C-O-C. OH group can open and close to form either alpha or beta
in the cyclisation of monosaccharides, the former carbonyl carbon becomes what
the anomeric carbon, the new chiral center
The former carbonyl oxygen becomes what in the cyclisation of monosaccharides
A hydroxyl group which determines whether alpha or beta
If the hydroxyl group faces down (or opposite side of the ring as the CH2OH) then what is the config
alpha
Aldehyde and ketones are whatphillic
Electrophillic (positively charged)
The alcohol oxygen atom is whatphilic
Nucleophilic
When aldehydes are attacked by alcohols, what forms?
hemiacetals
formation of a cyclic hemiacteal creates what
anomer (diasteroisomeric)
Anomers freely interconvert between alpha and beta in solution, what is this called?
mutarotation
is the chair or boat form more stable
Chair, owing to less steric hindrance
what are conformers
Can be interconverted without breaking bonds
What are reducing sugars
Saccharides with free anomeric carbons not in a glycosidic bond because the free aldehyde reduces mild oxidizing agents
What test shows the aldehyde can reduce Cu2+ to Cu+
Fehlings’ Test
What test shows the aldehyde being reduced from Ag+ to Ag
Tollens’ Test
Sugars that react with oxidizing agents are called
Reducing sugars
What are the conditions for the Fehlings reaction
Alkaline conditions
The cuprous ion (Cu+) produced forms
a red cuprous oxide preciptate
In the hemiacetal (ring) form, C1 of glucose cannot be oxidized by what. however the open chain form is in equilibrium with the ring form
By the Cu2+
