What is the IUPAC name for CH3-CH2-COOH?

The compound CH3-CH2-COOH is a carboxylic acid characterized by the presence of the -COOH functional group, which is the hallmark of this class of organic compounds. To determine its IUPAC name, one must first identify the longest carbon chain that includes the carboxylic acid functional group.

In this structure, there are three carbon atoms in the longest continuous chain: two carbon atoms are part of the alkane (CH3-CH2, which is ethane), and the third carbon is part of the carboxylic acid group (COOH). The presence of three carbon atoms indicates that the base name is derived from propane. As the compound is a carboxylic acid, the suffix "-oic acid" is added to the base name.

Thus, the three-carbon chain leads to the name "propanoic acid" because the chain has three carbons and the -COOH group is present. Therefore, the correct IUPAC name for CH3-CH2-COOH is propanoic acid.

The other options do not apply because butanoic acid would imply a four-carbon chain, propanal would be an aldehyde with a three-carbon structure instead of