Question

its a two part question use the first question to answer the second one

Correctly assign R or S to the carbons labeled a) 2 and b) 5. СНО HO- 2H HOTH H- OH н 5-ОН CH,OH 1. The structure in Q10 is an example of a: a) L-aldohexose b) D-aldohexose c) L-ketohexose d) D-ketohexose e) L-aldopentose f) D-ketopentose

Answer 1

i ? ? i CHO НО-23-н НОЕн НЕОН H5-ОН CH OH E ? І П ? І

Stereochemistry of Carbon 2

give the priority according to the atomic mass of atom directly attach to the chiral carbon, more atomic mass atom will get more priority.

In this case aldehyde carbon get the second priority because there is double bond attach to it. we count this carbon as two carbon

our priorities are in clockwise direction, so it should be R configuration but our 4th priority is in above the plan hence we have to reverse the configuration,

The configuration of carbon 2 is S

HO, HO H1 - Ho 우 포

in case carbon 5 the above carbon get the second priority because it is connected to so many atom.

the priorities are in anticlock wise manner but our 4th priority is in above the plan hence we have to reverse the configuration

The configuration of carbon 5 is R

| 우 2 I 도

B) In this structure the last highlighted OH group is in right side so it should be D type monosaccharide. so option a, c, e are in correct

CHO НО-2-н НО -н НЕОН н 5-ОН CH2OH

this structure do not have ketone hence option f and d is also in correct

D-aldohexose definition ---> Any D-aldose having a chain of six carbon atoms in the molecule.

option b is correct because this compound have aldehyde group in it and have six carbin chain.