The IUPAC name of given compound is :-
`CH_(3)CH = undersetunderset(COOH)(|)C-CHCH_(3)`

Options

A. 3-Carboxy-2-pentene
B. 2-Ethylidene butanoic acid
C. 2-Ethyl-2-butenoic acid
D. 3-Ethyl-2-buten-4-oic acid

Answer

To determine the IUPAC name of the given compound, we will follow these steps:

### Step 1: Identify the Longest Carbon Chain
First, we need to find the longest continuous carbon chain in the compound. The compound has a carboxylic acid group (-COOH), which will influence our numbering.

### Step 2: Number the Carbon Chain
We will start numbering from the end of the chain that is closest to the carboxylic acid group to give it the lowest possible number.

1. Start from the carbon of the carboxylic acid group:
- Carbon 1: COOH
- Carbon 2: Double bond (C=C)
- Carbon 3: CH
- Carbon 4: CH3

### Step 3: Determine the Parent Chain
From our numbering, we see that we have a total of 4 carbon atoms in the longest chain. The name for a 4-carbon alkane is "butane". However, since there is a double bond, we will modify this name.

### Step 4: Identify the Type of Hydrocarbon
Since there is a double bond between the second and third carbon atoms, we will replace the "ane" ending of butane with "ene". Thus, we have "butene".

### Step 5: Indicate the Position of the Double Bond
The double bond is located between the second and third carbon atoms, so we will indicate this by adding the number 2 before "butene". This gives us "2-butene".

### Step 6: Include the Functional Group
Since the compound is a carboxylic acid, we replace the "e" in "butene" with "oic acid". Therefore, "2-butene" becomes "2-butenoic acid".

### Step 7: Identify and Name Substituents
Now we need to look for any substituents. There is an ethyl group (C2H5) attached to the second carbon of the main chain.

### Step 8: Combine the Names
The substituent is named "ethyl" and is located on the second carbon. Therefore, we will write the full name as "2-ethyl-2-butenoic acid".

### Final IUPAC Name
The final IUPAC name of the compound is **2-ethyl-2-butenoic acid**.

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