IUPAC name of allyl chloride is - Identify.
3-chloro-prop-1-ene
Understanding the IUPAC Name of Allyl Chloride
The question asks for the IUPAC (International Union of Pure and Applied Chemistry) name of allyl chloride. Allyl chloride is an organic compound with the chemical formula \(\text{CH}_2=\text{CH-CH}_2\text{Cl}\). To find its IUPAC name, we need to follow the standard IUPAC nomenclature rules for organic compounds containing a double bond and a halogen substituent.
Identifying the Structure of Allyl Chloride
Let's look at the structure:
\(\text{CH}_2=\text{CH-CH}_2\text{Cl}\)
This molecule contains:
- A carbon-carbon double bond (\(\text{C}=\text{C}\)), which indicates it's an alkene.
- A chlorine atom (\(\text{Cl}\)) as a substituent.
- A chain of three carbon atoms.
Applying IUPAC Nomenclature Rules for Alkenes
The key rules for naming alkenes with substituents are:
- Identify the longest carbon chain containing the double bond. In this case, the longest chain containing the double bond has three carbon atoms. A three-carbon alkane is propane, so the corresponding alkene base name is propene.
- Number the carbon chain starting from the end that gives the carbons involved in the double bond the lowest possible numbers. In \(\text{CH}_2=\text{CH-CH}_2\text{Cl}\), the double bond is at one end of the three-carbon chain. If we number from the left: C1 (\(\text{CH}_2\)) = C2 (\(\text{CH}\)) - C3 (\(\text{CH}_2\)). The double bond is between C1 and C2. If we numbered from the right: C3 (\(\text{CH}_2\text{Cl}\)) - C2 (\(\text{CH}\)) = C1 (\(\text{CH}_2\)). The double bond is between C1 and C2. Numbering from the left gives the double bond carbons positions 1 and 2. Numbering from the right also gives the double bond carbons positions 1 and 2. In cases where the double bond gets the same numbers from either end, we look at the substituents. However, the primary rule is to give the double bond the lowest possible numbers. So, numbering from the left (C1=C2) is correct, placing the double bond starting at position 1.
- Identify any substituents and their positions on the numbered chain. The chlorine atom is attached to the carbon atom at position 3 in our numbering (C1=C2-C3-Cl).
- Write the name: substituent position - substituent name - base chain name - double bond position - 'ene'. The substituent is chloro at position 3. The base chain is propene. The double bond starts at position 1.
Step-by-Step Naming of Allyl Chloride
- Chain length with double bond: 3 carbons (prop-).
- Double bond location: Between C1 and C2. Position is 1-ene.
- Substituent: Chlorine at C3. Position is 3-chloro.
- Combining them: 3-chloro + prop + 1-ene = 3-chloroprop-1-ene.
So the IUPAC name of allyl chloride is 3-chloroprop-1-ene.
Comparing with the Options
Let's evaluate the given options based on our derived IUPAC name:
| Option | Name | Analysis |
|---|---|---|
| 1 | 3-chloro-prop-2-ene | Prop-2-ene would mean the double bond is between C2 and C3. If the chain is 1-2-3, double bond 2-3 means numbering is 1-2=3. Chlorine at 3 means C3 has Cl. This doesn't match the structure CH2=CH-CH2Cl where the double bond is at the end. Incorrect numbering. |
| 2 | 1-chloro-prop-2-ene | Prop-2-ene means double bond between C2 and C3. 1-chloro means chlorine at C1. Structure would be Cl-CH2-CH=CH2. This is not allyl chloride. Incorrect. |
| 3 | 1-chloro-prop-3-ene | Prop-3-ene is incorrect numbering for a 3-carbon chain. The double bond position cannot be 3. Incorrect. |
| 4 | 3-chloro-prop-1-ene | Prop-1-ene means double bond between C1 and C2 (CH2=CH-). 3-chloro means chlorine at C3 (-CH2Cl). Putting it together: CH2=CH-CH2Cl. This matches the structure of allyl chloride. Correct. |
Based on the IUPAC nomenclature rules and our step-by-step process, the correct IUPAC name for allyl chloride is 3-chloroprop-1-ene.
Revision Table: Key IUPAC Rules for Haloalkenes
| Rule | Description | Example (Allyl Chloride) |
|---|---|---|
| Parent Chain | Longest chain containing the double bond. | 3 carbons (propene) |
| Numbering | Give double bond carbons lowest possible numbers. | Numbering starts from the end of the double bond (1, 2). |
| Substituents | Identify and locate substituents. | Chlorine at position 3. |
| Naming Order | Substituent(s) with position(s) precede parent alkene name with double bond position. | 3-chloro + prop-1-ene |
Additional Information: Allyl Group and Vinyl Group
The term 'allyl' refers to the functional group \(\text{CH}_2=\text{CH-CH}_2-\). When a chlorine atom is attached to this group, it forms allyl chloride, \(\text{CH}_2=\text{CH-CH}_2\text{Cl}\).
Another common related group is the 'vinyl' group, which is \(\text{CH}_2=\text{CH}-\). Vinyl chloride is \(\text{CH}_2=\text{CHCl}\). Following IUPAC rules, vinyl chloride is named chloroethene.
Understanding these common names can help in recognizing structures, but for systematic naming, IUPAC rules must be applied.
Important Questions from Organic Chemistry
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1. Carbon forms the basis for all living organisms and many things we use
2. Carbon shows tetra-valency and the property of catenation
3. Carbon forms covalent bonds with itself and other elements
4. Carbon forms compounds containing triple and tetra bonds between carbon atoms
Select the correct answer using the code given below:
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