Advices For Studying Organic Chemistry

HC

OH OH

CH 3

CH 2 CH 3

1

2

3

CH 2 CH 3

H 3 C

C

H^1

2

(^34)
(R)-(−)-2-Butanol
O HO
CH 2 CH 3
CH 3
C
(^1) H
2
4 3
HC
CH 3
H
CH 2 CH 3
3
2
1
(S)-(+)-2-Butanol

4. The sign of optical rotation is not related to the R,S designation.


5. Absolute configuration:


6. Groups containing double or triple bonds are assigned priority as if both atoms
   were duplicated or triplicated.

C Y Y

Y

Y

Y)

Y

Y)(

C

( )(C)

as if it were C C

(

( C)

as if it were

(C)

H 2 N

COOH

CH 3

C

(^1) H
2
4 3
(S)-Alanine [(S)-(+)-2-Aminopropionic acid], [α]D = +8.5°
HO
CHO
CH 2 OH
C
(^1) H
2
4 3
(S)-Glyceraldehyde [(S)-(–)-2,3-dihydroxypropanal], [α]D = –8.7°
Assignment of configuration to (+)-alanine and (–)-glyceraldehyde:
Both happen to have the S configuration