`CH_(3)CH_(2)-CH_(2)-COOH overset("Red P" +Br_(2))toCH_(3)-CH_(2)-underset(Br)underset(|)(CH)-COOH`
This reaction is called

Answer

To solve the question, we need to analyze the given reaction step by step.

### Step 1: Identify the Reactants
The reactant provided is CH₃CH₂CH₂COOH, which is butanoic acid (a carboxylic acid).

**Hint**: Look for the functional group in the compound to identify its class (in this case, a carboxylic acid).

### Step 2: Understand the Reaction Conditions
The reaction is carried out in the presence of red phosphorus and bromine (Br₂). Red phosphorus is often used to facilitate halogenation reactions.

**Hint**: Remember that red phosphorus can help in the halogenation of compounds, especially in the presence of halogens.

### Step 3: Identify the Alpha Carbon
In the structure of butanoic acid, the carbon adjacent to the carboxylic acid group (COOH) is known as the alpha carbon. In this case, the alpha carbon is the third carbon in the chain.

**Hint**: The alpha carbon is always the one directly next to the functional group in carboxylic acids.

### Step 4: Determine the Reaction Mechanism
In this reaction, the hydrogen atom attached to the alpha carbon is replaced by a bromine atom (Br). This process is known as halogenation, specifically alpha halogenation because it occurs at the alpha carbon.

**Hint**: Look for the substitution of hydrogen with a halogen at the alpha position to identify the type of reaction.

### Step 5: Identify the Product
The product formed is CH₃CH₂CHBrCOOH, which is an alpha-bromobutanoic acid.

**Hint**: The presence of the bromine atom at the alpha position indicates that the reaction has successfully occurred.

### Step 6: Name the Reaction
The reaction described is known as the Hell-Volhard-Zelinsky reaction. This reaction specifically refers to the halogenation of carboxylic acids at the alpha position.

**Hint**: Remember that specific reactions involving halogenation of carboxylic acids often have distinct names, like the Hell-Volhard-Zelinsky reaction.

### Final Answer
The reaction is called the **Hell-Volhard-Zelinsky reaction**.