Explain RS notation of isomers?




Answers were Sorted based on User's Feedback



Answer / tanveer anjam

in rs notation we first give priorty no1,2,3,4 ,rules are,
the atom is given hiest priorty with hihgest atomic no ,
let there are 4 atoms H , O , C , F attatched to chiral
carbon then F gets highest priorty 1 & similarly we give
priorty to others

Is This Answer Correct ?    22 Yes 7 No

Answer / akash

The R S notation of isomers were introduced by robert
cahen, vladimir prelog.
It is more useful for defining the asymmetry of
biomolecules because it accounts for all asymmetric carbons
in an isomer.
if any atom or group on the asymmetric carbon is on the
right side that asymmetric carbon is called as "R"(Rectus)
if any atom or group is on the left side the asymmetric
carbon is designated as "S"(sinister).
isoleucine will have 4 stereo isomers.

Is This Answer Correct ?    20 Yes 11 No

Answer / lisa

First you give priorities as Tanveer Anjam said. Then the
molecule is turned, so that the atom with the lowest
priority is in the back and we face prioritys 1,2 and 3 (In
our case H is in the back because its atomic number is the
lowest). Now you check if the sequence of the prioritys
from 1 to 3 are clockwise, then it's R. If the sequence is
counter clockwise it's S.

Is This Answer Correct ?    10 Yes 1 No




Answer / vijay

As said by Tanveer and Lisa they r correct.But the RS notation depends on CIP rules
The rules r
1.To attain RS notation it should be chiral carbon, means all the four groups attached to the carbon should be different.
2.The lowest priority should be taken backside in wedge method and vertically in fisher method. For example in H,O,C and methyl group, 'H' is taken as lowest priority.
3.The atoms attached to the chiral carbon should be given priority 1 2 3 4 based on highest atomic number.As example given by Tanveer.
4.In case of methyl and ethyl the priority should be given to ethyl first.
5.In case of single,double and triple bonds the priority should be given in this manner triple>double>single.
For example methyl and COOH , COOH is given as first priority.
6.RS notation doesn't accounts on optical activites of a compound.

Is This Answer Correct ?    5 Yes 3 No

Post New Answer



More Bio Chemistry Interview Questions

explain about hyperglycemic agent?

1 Answers  


Name the 3 hormones present in urine of pregnant women?

1 Answers   Apollo,


bane the by products when crude oil is refined by distillation

0 Answers  


Calculate the molar extinction coefficient of a solution containing 5 *10-4 g litre-1 of a biomolecule, molecular weight 275 g mol-1, and absorbance 0.75 in a 1.2 cm cuvette.

0 Answers  


How the pure culture can be produced?

1 Answers  






Autoanalyser is used for[tick your right choice} 1.Analysing heart defect 2.Imaging various internal body parts 3.Estimating requirement of surgical removal or correction 4.Estimating quantity of various biochemicals in body fluids

4 Answers  


Cloning is a process where the nucleus of one egg is taken and it's coated with the membrane of other individual, to get a duplicate of a person. so my question is:when we use egg of some individual and membrane of some other how will we get a duplicate of a particular individual?

3 Answers  


How do hydrophobic and hydrophilic residues arrange themselves in globular proteins?

0 Answers  


What are adjuvants?

1 Answers   Reddy Labs,


What is the difference between myoglobin and haemoglobin in the sequence of poly peptides?

1 Answers  


A principal difference between prokaryotic and eukaryotic DNA replication is a) completely different proteins/enzymes in eukaryotes b) multiple origins in eukaryotes c) no requirement for topoisomerase activity in prokaryotes d) the absence of a nucleus in prokaryotes

9 Answers  


what is ninhydrin reaction?how it is useful?

3 Answers   Jubilant, Aurobindo,






Categories