Carbohydrates

Question 1

where is the carbonyl bond for aldehydes?

Answer 1

C1

Question 2

where is the carbonyl bond for ketones?

Answer 2

C2

Question 3

how do you find out the number of OH groups in a monosaccharide?

Answer 3

OH = N - 1

• N = # of carbons

Question 4

What is a tautomer?

Answer 4

two structures with the same atomic position, which differ only in the position of their H atoms and double bonds

Question 5

what are constitutional isomers?

Answer 5

same molecular formula but different connectivity of their atoms

Question 6

what is a chiral compound?

Answer 6

a mirror image of a structure that is non-superimposable
- carbon with 4 different constituents attached

Question 7

what is a stereoisomer?

Answer 7

molecules that have the same molecular formula and the same connectivity of atoms but differ in the spatial arrangement (3D)

Question 8

what are enantiomers?

Answer 8

a type of stereoisomer that are non-superimposable mirror images of each other

Question 9

what are diastereomers?

Answer 9

Diastereomers are a type of stereoisomer that are not mirror images of each other and cannot be superimposed

Question 10

where is carbon 1 labled from?

Answer 10

the carbon closests to the double bond

Question 11

what classifies if a sugar is D or L?

Answer 11

if the chiral carbon furthest away from from the carbonyl group has it OH group on the right or left

right = D sugar
left = L sugar

Question 12

what is the equation figure out the number of stereoisomers a compound has?

Answer 12

2 ^n

Question 13

what is an empimer?

Answer 13

strucures that differ in configuration only around ONE carbon

Question 14

what compounds form a hemiacetal?

Answer 14

alcohol + aldehyde

Question 15

what is an anomeric carbon?

Answer 15

A carbon that goes from achiral to chiral following the transition to a cyclic structure

Question 16

what kind of sugars will readily form ring structures? (how many carbons do they need)

Answer 16

Aldotetroses (4C) and higher
ketotetoses (4C) and higher

Question 17

will a triose form a ring?

Answer 17

No, it must be at least 4C

Question 18

what compounds form a hemiketal?

Answer 18

Alcohol + Ketone

Question 19

how many C is furan? what type of ring does it form?

Answer 19

4C forming a 5-membered ring including oxygen

Question 20

how many C is pyran? what type of ring does it form?

Answer 20

5C ring forming a 6-membered ring including oxygen

Question 21

For a cyclic hemiacetal of an aldopentose pyranose ring explain:

1) what membered ring
2) where the carbonyl C would be
3) which C will attack the carbonyl

Answer 21

1) 5 C with a 6 membered ring
2) carbonyl on C1
3) C5 will attack

Question 22

For a cyclic hemiacetal of an aldotetrose furanose ring explain:

1) what membered ring
2) where the carbonyl C would be
3) which C will attack the carbonyl

Answer 22

1) 4C - 5 membered ring
2) carbonyl on C1
3) C4 will attack

Question 23

what is an anomer?

Answer 23

isomers that only differ at the anomeric carbon

Question 24

when transposing fisher projections to geometric form, where is C1 / C2 located?

Answer 24

C1 is located on the right for aldoses
C2 is located on the right for ketoses

Question 24

when transposing the fisher projection to geometric form where will the last carbon always be ?

Answer 24

the last carbon will always be a part of a CH2OH group

Question 25

When transposing from the fisher projection to geometric form:

what direction are C numbered?

Answer 25

clockwise

Question 26

When transposing from the fisher projection to geometric form:

where are groups on the right located when in a geometric form? and groups on the left?

Answer 26

below the plane of the ring
-above the plane for groups on the left

Question 27

When transposing from the fisher projection to geometric form:

where is the CH2OH and OH group at C1/C2 for beta anomers?

Answer 27

CH2OH group at C5
OH at C1/C2 on the SAME side of the ring

Question 28

When transposing from the fisher projection to geometric form:

where is the CH2OH and OH group at C1/C2 for alpha anomers?

Answer 28

CH2OH group at C5
OH at C1/C2 on OPPOSITE sides of the ring

Question 29

when naming deoxy sugars, what does the placement of the number indicate? where is it most common to be put?

Answer 29

The number indicates the position where carbon is replaced
-commonly on C2,3 or 4

Question 31

what is an amino sugar?

Answer 31

sugar molecules that have had their hydroxyl replaced by an amino groupx

Question 32

how are alcohols formed from aldoses and ketoses? what sugar would form ribotol?

Answer 32

from the reduction of them to make sugar alcohol
ribotol is formed from the reduction of ribose

Question 33

What major factors classifies a sugar as a reducing agent?

Answer 33

1) being an aldose (or a ketose that has gone through tautomerization to have carbonyl at C1)
2) must have a free anomeric carbon
3) having a linear form

Question 34

what is an O-glycosidic bond?

Answer 34

a bond linking an anomeric carbon to the oxygen atom of a hydroxyl group

Question 35

what are N/O glycosidic bonds?

Answer 35

formation of glycosidic bonds from the reaction of an anomeric carbon with:
1) Hydroxyl to form O-glycosidic
2) Nitrogen to form N-glycosidic

Question 36

what type of bonds are present in glycogen?

Answer 36

alpha 1, 6