Give the formal (IUPAC) names for the following:
a. CH3CH2Cl
b. CH3CHClCH3
c.(CH3)2CHCH2Cl
The correct answer and explanation is :
Here are the formal IUPAC names for the given compounds:
a. CH3CH2Cl:
IUPAC Name: Chloroethane
Explanation:
- The compound consists of an ethane backbone (C2H5) with a chlorine atom (Cl) attached to one of the carbon atoms.
- Ethane is a two-carbon alkane, and when a chlorine atom substitutes one of the hydrogen atoms on the carbon chain, the compound becomes chloroethane.
- The IUPAC naming system follows this approach by naming the parent chain (ethane) and adding the substituent (chloro) to indicate the presence of the chlorine atom. There is no need for further specifications because the chlorine is attached to the second carbon in this straight-chain molecule, making it chloroethane.
b. CH3CHClCH3:
IUPAC Name: 1-Chloropropane
Explanation:
- This compound consists of three carbon atoms (propane) with a chlorine atom attached to the first carbon.
- Propane is the parent chain, and a chlorine atom is attached to the first carbon in the chain. The number “1” indicates the position of the chlorine atom on the carbon chain.
- In this case, the chlorine is attached to the first carbon, making the name “1-chloro” followed by “propane,” which is the parent chain.
- The IUPAC rules dictate that when there are no other substituents, the smallest number (in this case, 1) is assigned to the position of the substituent.
c. (CH3)2CHCH2Cl:
IUPAC Name: 1-Chloro-2-methylpropane
Explanation:
- The compound has a three-carbon chain (propane), but one of the carbons is attached to two methyl groups (CH3).
- The structure indicates that the chlorine atom (Cl) is attached to the first carbon of the chain, and the methyl group is attached to the second carbon of the parent chain.
- The parent chain is propane, and the number “1” indicates that the chlorine atom is on the first carbon. The “2-methyl” part indicates that a methyl group is attached to the second carbon.
- The IUPAC naming convention uses the lowest number for the position of the substituent (the chlorine), and then it identifies the side chain (methyl) as a substituent on the second carbon.
These names are determined by following IUPAC rules for naming alkanes and their derivatives, including correct numbering and assigning the appropriate prefixes for substituents.