Question

The absolute configuration of the compound is:

Answer 1

To solve this question, first we need to understand the concept of absolute configuration. From absolute configuration we can understand that it refers to the spatial arrangement of the atoms of a chiral molecular entity or a group and its stereochemical compound.

Complete step by step answer:
In case of an absolute configuration, we have to draw an arrow which starts from the priority one and moves towards priority two. Then, it again moves towards priority 3. We also need to understand that if the arrow moves in clockwise direction like in the case of the absolute configuration, it is R. And opposed to this, if the arrow moves in a counterclockwise direction then the absolute configuration will be S.
Based on this rule we will solve the above question.
In the given compound, we will start numbering from the atom which has the highest atomic number. So, OH has the highest atomic number which is numbered as 1. Then, following it we will number Cl as 2. COOH as 3 and H as 4.
Now, the arrow will move in clockwise direction from 1-2 so here, the absolute configuration is R. So, 2 carbon have 2S configuration. It is opposed by anticlockwise direction where absolute configuration is S. Here,
3 Carbon configurations are 3R. Therefore, the given compound has (2S , 3R) as absolute configuration .

As H is in front, S→R and S→R as H is in front, then we will reverse the configuration obtained.

Note:
After solving this question, we need to understand the meaning of optical activity. It is the ability of a chiral molecule to rotate the plane of a plane-polarized light that is measured using a polarimeter. We know that a simple polarimeter comprises a light source, polarizing lens, sample tube and analyzing lens.