In the IUPAC system, `PhCH_(2)CH_(2)CO_(2)H` is named

Options

A. 3-phenylpropanoic acid
B. benzylacetic acid
C. carboxyethyl benzene
D. 2-phenylpropanoic acid

Explanation

To name the compound `PhCH₂CH₂CO₂H` using the IUPAC system, we will follow these steps:

### Step 1: Identify the longest carbon chain
The compound contains a phenyl group (Ph) attached to a three-carbon chain leading to a carboxylic acid group (CO₂H). The longest carbon chain that includes the carboxylic acid is three carbons long.

### Step 2: Determine the functional group
The functional group present is a carboxylic acid (−COOH). In IUPAC nomenclature, carboxylic acids are given priority in naming.

### Step 3: Number the carbon chain
We will number the carbon chain starting from the end closest to the carboxylic acid group to give it the lowest possible number. In this case, the numbering will be:
1. Carboxylic carbon (C1)
2. Second carbon (C2)
3. Third carbon (C3)

### Step 4: Name the carbon chain
The three-carbon chain with a carboxylic acid is called "propanoic acid."

### Step 5: Identify the substituent
The phenyl group (Ph) is a substituent on the second carbon of the propanoic acid chain.

### Step 6: Combine the names
The full name of the compound is derived by combining the name of the substituent and the main chain. The phenyl group is located at the second carbon, so we name it as "phenyl" followed by the name of the acid.

### Final IUPAC Name
Thus, the IUPAC name for `PhCH₂CH₂CO₂H` is **"Phenylpropanoic acid."**

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