Question

Testbank Question 111 Which of these is a correct Fischer projection formula of the (S) form of 3-bromo-1,1-dichloro-2-propanol? OH CHCl2 CH2Br ‘3-1 CHCl2 2 O II TM

Answer 1

The groups attached to the carbon of the given compounds are, OH, CHCl₂, CH₂Br, and H.

Now, the priority number is, 1) OH 2) CHCl₂ 3) CH₂Br 4) H

If the fourth priority group is on the vertical line and the rotation is clockwise then R configuration.

If the fourth priority group is on the vertical line and the rotation is anticlockwise then S configuration.

If the fourth priority group is on the horizontal line and the rotation is clockwise then R changes S.

If the fourth priority group is on the horizontal line and the rotation is anticlockwise then S changes to R.

Thus, the answer is an option (IV) with (S) form.

2 3 4 1 снCL CH2Br он H 4 1 1 2 4 4 H 3 2 -снCk H- но OH H ClЬНС -CH2Br 3 CH2Br СHCIL 2 Он1 3 CH2Br I II II IV (R)-form (R)- form (R)- form (S)- form 1 он 3 2 -CHCI BrH2C На V (R)- form