Question

using wedge-dash notation to designate stereochemistry, draw (R)-pentane-1,2-diol

Answer 1

Sol:-

Note :-

(1). Rotate the molecule as I -> II -> III pattern if the lowest priority group (i.e. IV) lies on the dash position.

(2). Rotate the molecule as III -> II -> I pattern if the lowest priority group (i.e. IV) is not lies on the dash position.

(3). If the direction of rotation is clockwise then use R-configuration and

(4). If the direction of rotation is anti-clockwise then use S-configuration and

Cahn-Ingold-Prelog Priority Rules :-

1.See the atomic numbers of each of the atoms or groups bonded to the chiral carbon. The atom or group with the highest atomic number always receives the highest priority number i.e. I and remaining atoms or groups are ordered accordingly based on their atomic numbers as II, III and IV.

2. If very first atoms of the two different groups have same atomic number then we must consider atoms at a two-bond distance from the chiral carbon.

3. If there is still same atomic number, then we must consider atoms at a three-bond distance from the chiral carbon and so on until the similarity in atomic number is broken.