Write down the correct priority for citation as principal groups :
`-overset(O)overset(||)(C)-,-COOH,-CHO,-OH,-Br,-`

Answer

To determine the correct priority for citation as principal groups according to IUPAC nomenclature, we need to analyze the functional groups provided in the question: `-C(=O)-`, `-COOH`, `-CHO`, `-OH`, and `-Br`.

Here’s a step-by-step solution:

### Step 1: Identify the Functional Groups
- **-C(=O)-**: This represents a carbonyl group, which is part of a ketone.
- **-COOH**: This is a carboxylic acid group.
- **-CHO**: This is an aldehyde group.
- **-OH**: This is a hydroxyl group, which represents an alcohol.
- **-Br**: This is a bromine atom, which is a halogen.

### Step 2: Determine the Priority of Functional Groups
According to IUPAC nomenclature, the priority of functional groups is determined based on their reactivity and the functional group hierarchy. The general order of priority for the functional groups listed is as follows:

1. **Carboxylic Acid (-COOH)**: This has the highest priority.
2. **Aldehyde (-CHO)**: This comes next in priority.
3. **Ketone (C=O)**: This is the third in line.
4. **Alcohol (-OH)**: This has a lower priority than the above groups.
5. **Halogen (-Br)**: This has the lowest priority among the given groups.

### Step 3: Write the Final Order of Priority
Based on the analysis, the correct order of priority for the given functional groups is:
1. Carboxylic Acid (-COOH)
2. Aldehyde (-CHO)
3. Ketone (C=O)
4. Alcohol (-OH)
5. Halogen (-Br)

### Final Answer
The correct priority for citation as principal groups is:
1. -COOH (Carboxylic Acid)
2. -CHO (Aldehyde)
3. -C(=O)- (Ketone)
4. -OH (Alcohol)
5. -Br (Bromine)

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