Chemistry - STEREO ISOMERISM Question with Solution | TestHub
Assign R / S configuration at each stereogenic centre in the following molecules :
(a) 
(b) 
(c) 
(d) 
(e) 
(f) 
(g) 
(h) 
Options:
Answer:
Solution:
Assign CIP priorities at each stereogenic centre, then trace 1 2 3 with the lowest-priority group pointing away (invert the result when it points towards you).
(a) (S)-pentan-2-ol : OH CH2CH2CH3 CH3 H : S.
(b) (R)-alanine : NH2 COOH CH3 H : R.
(c) (S)-2-chloropropanoic acid : Cl COOH CH3 H : S.
(d) (2S,3S)-3-bromobutan-2-ol : both centres S.
(e) (R)-2-fluoropropanoic acid : F COOH CH3 H : R.
(f) (2R,3S)-2-bromo-3-chlorobutane : C-2 is R, C-3 is S.
(g) (R)-glyceraldehyde : OH CHO CH2OH H : R.
(h) (S)-1-fluoro-1-iodoethane : I F CH3 H : S.
Ans. (a) S (b) R (c) S (d) 2S,3S (e) R (f) 2R,3S (g) R (h) S
