How would I assign priority to 1,2-dimethylcyclopropane?
To assign priority to the substituents on a molecule, you need to follow the sequence rules provided by the Cahn-Ingold-Prelog (CIP) system. In this system, each substituent is assigned a priority based on the atomic number of the atoms bonded to the central carbon.
Here's the step-by-step process to assign priority to the substituents in 1,2-dimethylcyclopropane:
Step 1: Identify the substituents
In 1,2-dimethylcyclopropane, there are three substituents - two methyl (CH3) groups and one hydrogen (H) attached to the cyclopropane ring.
Step 2: Determine the atomic number
Compare the atomic number of the atoms directly bonded to the central carbon atom. Hydrogen (H) has an atomic number of 1, while carbon (C) has an atomic number of 6.
Step 3: Assign priority
The substituent with the higher atomic number is assigned a higher priority. In this case, both methyl groups (CH3) have the same atomic number since they are both made up of carbon (atomic number 6) and hydrogen (atomic number 1). So, the methyl groups are considered equivalent and have the same priority.
The hydrogen (H) substituent has the lowest atomic number (1), so it is assigned the lowest priority.
Since all the substituents have the same priority, 1,2-dimethylcyclopropane is considered an achiral molecule.
Remember, assigning priority is based on the atomic number, and if there is a tie, you continue comparing the atoms attached to the substituent until a difference is found.