Answer
1 - C (Bottom Left)
2 - C (Bottom Right)
3 - C (Top Left)
4 - H
Work Step by Step
1. Identify the stereocenter.
- And draw the missing hydrogen.
2. List all atoms connected to the stereocenter, and rank them by the atomic number.
- C, H, C, C
Ranked by atomic number:
- C, C, C, H
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:
- Top left chain: No variations
- Bottom left chain: Double bond on the first carbon.
- Bottom right chain: Double bond on the fourth carbon.
Therefore, the bottom left chain gets first priority, and the bottom right gets second 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: H, H, H
- Bottom right carbon: C, H, H
- Bottom left carbon: C, C, H.
Since (C>H), the bottom left gets first priority, and the bottom right gets second.
** Double bond: We count the connected atom two times.
4. Put the numbers on the stereocenter atoms:
1 - C (Bottom Left)
2 - C (Bottom Right)
3 - C (Top Left)
4 - H
