Advices For Studying Organic Chemistry

1. Convention: The carbon chain is drawn along the vertical line of the Fischer
   projection, usually with the most highly oxidized end carbon atom at the top.

1. Vertical lines: bonds going into the page.


2. Horizontal lines: bonds coming out of the page

CH 3

C

HO

H

COOH

=

(R)-Lactic acid

=

Fischer projection

Bonds out of page

H OH

Bonds into page COOH

HOH

CH 3

C

COOH

CH 3

5.12B ALLOWED MOTIONS FOR FISCHER PROJECTION:

1. 180° rotation (not 90° or 270°):

COOH

HOH

CH (^3)
Same as
COOH
HO H
CH 3
–COOH and –CH 3 go into plane of paper in both projections;
–H and –OH come out of plane of paper in both projections.

2. 90° rotation: Rotation of a Fischer projection by 90° inverts its meaning.

COOH

HO

CH 3

H

Not same as

COOH

H

OH

H 3 C

–COOH and –CH 3 go into plane of paper in one projection

but come out of plane of paper in other projection.