How do you determine whether a molecule has R or S configuration? Watch

Fyodor Bingoffsky
Badges: 0
Rep:
?
#1
Report Thread starter 8 years ago
#1
I'm a biochemistry student and my lecturer's really confusing. How do you tell whether a molecule has R or S configuration? Please use organic molecules (big ones like amino acids are appreciated) as examples. Thanks!
0
reply
gingerbreadman85
Badges: 9
Rep:
?
#2
Report 8 years ago
#2
It's the Cahn-Ingold-Prelog notational system.

1) Identify the four different atoms or groups attached to the stereogenic center.

2) Rank the atoms or groups based on the priority rules:

The priority rules rank atoms and groups based on atomic mass. The following list summarizes these rules.

a) For the four atoms directly attached to the stereogenic center, the higher the atomic mass, the higher the rank.

b) If two or more atoms directly attached to the stereogenic center have the same mass, work outward along the chains of the groups they are in, atom by atom, until a point of difference is reached. The rank is assigned at this point of difference, based on the difference in atomic mass.

c) If a group contains multiple bonds, the doubly or triply bonded atoms are counted as two or three of those atoms, respectively. Thus the carbonyl group is considered to have two carbon-oxygen bonds, one actual and one theoretical.
3) Orient a projection of the molecule in space so that the group or atom of lowest rank is eclipsed by the stereogenic center.

4) If the ranking declines in a clockwise direction, the configuration is R; if the ranking declines in a counterclockwise direction, the configuration is S.

Oh, and big up the 'ol IC!
0
reply
X

Quick Reply

Attached files
Write a reply...
Reply
new posts
Back
to top
Latest
My Feed

See more of what you like on
The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

Personalise

University open days

  • Cardiff Metropolitan University
    Undergraduate Open Day - Llandaff Campus Undergraduate
    Sat, 19 Oct '19
  • Coventry University
    Undergraduate Open Day Undergraduate
    Sat, 19 Oct '19
  • University of Birmingham
    Undergraduate Open Day Undergraduate
    Sat, 19 Oct '19

Why wouldn't you turn to teachers if you were being bullied?

They might tell my parents (11)
6.04%
They might tell the bully (18)
9.89%
I don't think they'd understand (32)
17.58%
It might lead to more bullying (69)
37.91%
There's nothing they could do (52)
28.57%

Watched Threads

View All