Answer
1 - Cl
2 - C (Top Left)
3 - C (Bottom Right)
4 - C (Bottom Left)
Work Step by Step
1. Identify the stereocenter.
2. List all atoms connected to the stereocenter, and rank them by the atomic number.
- C, Cl, C, C
Ranked by atomic number:
- Cl, C, C, C
3. As we can see, there are 3 equal atoms, there are two methods for finding their order.
First Method (Faster):
- Find the closest variation on the chains (Double bond, Substituent).
- The chain with the closer variation gets priority.
In this case:
- The top left chain has a (-OH) on the second carbon.
- The bottom right chain has a double bond on the second carbon.
- The bottom left chain has no variations.
** The top left and the bottom right have variations on the second carbon, but, since (O>C), the top left chain gets first priority.
** Since the bottom left doesn't have variations, it will get last priority.
Second Method:
- Compare the atoms connected to each carbon, and if you don't get the answer, them look at the atoms connected to them.
In this case:
Top left carbon: C, H, H
Bottom right carbon: C, H, H
Bottom left carbon: C, H, H
** Since they are equal, we will have to compare the next carbon on the chains.
Second top left carbon: O, H, H
Second bottom right carbon: C, C, H
Second bottom left carbon: C, H, H
** First priority : Top left carbon (O > C)
** Second priority: Bottom right carbon (C > H)
4. Put the numbers on the stereocenter atoms:
1 - Cl
2 - C (Top Left)
3 - C (Bottom Right)
4 - C (Bottom Left)
