Question

Do the following compounds have the R or the S configurations?

Short answer

Here we will find which compound has R and S configuration:

a) R configuration

b) R configuration

c) R configuration

Step-by-step solution

Rules of giving priority.

1. Assign the priority order to the groups on the basis of atomic number. The higher atomic number gets the highest priority.

2. Double bond is considered as carbon is attached to 2 carbons.

3. Triple bond is considered as carbon is attached to 3 carbons.

4. Lowest priority group is always on the dotted line.

5. If the lowest priority group is not on the dotted line, then exchange the group with that group that is on the dotted line to maintain the stability of the compound.

6. Then according to the priority order, determine the configuration. Now, move from the highest priority order to the lowest priority order. If the movement is clockwise then it is an R configuration and if the movement is anticlockwise then it is an S configuration.

Subpart (a)

Here, as the lowest priority group is not on the dotted line, exchange the group with that group that is on the dotted line to maintain the stability of the compound.

Now, moving from the highest priority order to the lowest priority order, the movement is clockwise so it is an R configuration.

Subpart (b)

Here, the rotation is seen in a clockwise direction, therefore it is an R configuration.

Subpart (c)

Here, as the lowest priority group is not on the dotted line, exchange the group with that group that is on the dotted line to maintain the stability of the compound.

Now, the rotation is seen in a clockwise direction, therefore it is an R configuration.