Naming Carboxylic Acids - Online Tutor, Practice Problems & Exam Prep

Carboxylic acids are characterized by a carbonyl group (C=O) attached to a hydroxyl group (OH), making the carbon in the carbonyl group the number one carbon in naming conventions. When naming carboxylic acids, the 'e' at the end of the corresponding alkane name is replaced with 'oic acid'. It is essential to locate and name any substituents present, ensuring the parent chain reflects the carboxylic acid functional group. This nomenclature is crucial for the correct identification and classification of carboxylic acids in organic chemistry.

Rules for Naming Carboxylic Acids

Now recall that carbosilic acids possess a carbonyl carbon connected to a hydroxyl group. So your hydroxyl group is an OH group, so we have a carbonyl connected to OH. Now, the set of rules for naming carbosilic acids are similar to aldehydes. That's because just like an aldehyde, the carbonyl carbon in this case of a carbacillic acid is always numbered 1.

Now here we're going to modify the E ending of the original alkane to OIC acid because it's no, it's not an alkane, it's a carbosolic acid. So E becomes OIC acid, our naming convention. We still have to give the locations of our different substituent. Our parent chain would be modified from an E ending to OIC acid. So keep this in mind as we start naming different types of carbosolic acids.

Naming Carboxylic Acids Example

Provide the systematic name for the following carbacillic acid here. To do that, we're going to utilize these steps in terms of naming the molecule before us. O Here's step one. Find the longest carbon chain. This will represent our parent chain and assign name according to the prefixes and modifier. The parent change should include the carbosilic acid group and greater number of carbons. Now if a tie between longest chain, choose chain with more substituents.

All right, so we're going to find the longest carbon chain we got to make sure that the carbon silic acid group is part of it. So if we look, this would be the longest carbon chain. So we can go this way, or you can go this way. Both would give us the same length for the carbon chain and the same number of substituents. So here I'm just going to go by the original way. This way.

Now assign name to all the substituents for Step 2. So here we have a bromine group as a substituent, so this will be bromo. And then here we have a three carbon alkyl group, which is ethyl. Start numbering the chain at the carbon of the carbasilic acid group, so COOH group. So this would be 12345 and six, and then steps four to six. We repeat steps from previous naming topics. Mainly, we give numerical locations to the substituents, we make sure that they're named alphabetically in a relation to each other, and we make sure we use commas to separate numbers and dashes or hyphens to separate letters from numbers.

O here alphabetically B comes before E though bromo is on carbon 3, so 3 bromo and then we have the ethylene carbon 4/4 ethyl. Since the carbosillic acid carbonyl carbon is carbon number one, we don't have to give it a number of designation. So we have a six carbon chain which is hexane. But we changed the E ending to hexanoic acid, here it becomes OIC acid. So the name of our carbosolic acid here will be 3 bromo 4 ethyl hexanoic acid.

If the substituent name of the OH group is hydroxy in the presence of a carboxylic acid, provide the systematic name for the following compound.

• A. 5-ethyl-4-hydroxyoctanoic acid
• B. 4-ethyl-5-hydroxyoctanoic acid
• C. 5- isopropyl-4-hydroxyoctanoic acid
• D. 4-isopropyl-5-hydroxyoctanoic acid

Here’s what students ask on this topic:

How do you name a carboxylic acid?

To name a carboxylic acid using the IUPAC system, follow these steps:

1. Identify the longest carbon chain that includes the carboxyl group (-COOH). The number of carbon atoms in this chain determines the base name of the acid.
2. Number the carbon atoms starting from the end nearest to the carboxyl group, which always receives the number 1.
3. Replace the '-e' ending of the corresponding alkane name with '-oic acid' to denote the presence of the carboxyl group. For example, a one-carbon chain is methane, so the carboxylic acid is methanoic acid (commonly known as formic acid).
4. If there are substituents (other groups or atoms attached to the main chain), name them and give their position numbers based on the numbering of the carbon chain. Prefix the substituent names to the front of the carboxylic acid name.
5. If there is more than one carboxyl group, use the suffixes '-dioic acid', '-trioic acid', etc., and number each carboxyl group.

For example, a four-carbon chain with a carboxyl group at the end is butanoic acid. If there is a chlorine substituent on the second carbon, it becomes 2-chlorobutanoic acid.

How is the name of a carboxylic acid derived from the corresponding alkane?

The name of a carboxylic acid is derived from the corresponding alkane by changing the '-ane' suffix to '-anoic acid.' Here's the step-by-step process:

1. Identify the longest carbon chain that includes the carboxyl group (COOH). This chain determines the base name of the alkane.
2. Number the carbon atoms in the chain starting from the end nearest to the carboxyl group, ensuring that this group has the lowest possible number (which will be 1, as the carboxyl group must be at the end of the chain).
3. Replace the '-ane' suffix of the alkane with '-anoic acid' to indicate the presence of the carboxyl group. For example, if the longest chain has four carbons and is butane, the corresponding carboxylic acid is butanoic acid.
4. If there are substituents or branches on the carbon chain, indicate their position using the appropriate numbers and names before the base name of the acid.

Remember that the carboxyl group has the highest priority, so it defines the numbering of the carbon chain and the resulting name of the acid.

What is the IUPAC name for carboxylic acid?

The IUPAC (International Union of Pure and Applied Chemistry) name for a carboxylic acid is derived from a systematic approach to naming organic compounds. The general formula for a carboxylic acid is $R-\mathrm{COOH}$, where R represents the hydrocarbon part of the molecule. To name a carboxylic acid using IUPAC rules, you follow these steps:

1. Identify the longest carbon chain that contains the carboxyl group (COOH). This chain determines the base name of the acid.
2. Number the carbon atoms in the chain starting from the end nearest the carboxyl group, which always receives the number 1.
3. Replace the 'e' at the end of the alkane name (corresponding to the carbon chain length) with the suffix 'oic acid'. For example, a one-carbon chain with a carboxyl group is called methanoic acid (common name: formic acid), and a two-carbon chain is called ethanoic acid (common name: acetic acid).
4. If there are substituents or branches on the carbon chain, their positions are indicated by the appropriate numbers, and their names are prefixed to the base name.

Remember, the carboxyl group has the highest priority when numbering the carbon chain in IUPAC nomenclature for carboxylic acids.

How do you name a carboxylic acid as a substituent?

When a carboxylic acid group is a substituent on a larger molecule, it is named using the prefix "carboxy-" followed by the name of the parent hydrocarbon chain. The carbon of the carboxylic acid group is not included in the numbering of the parent chain; instead, it is considered as a substituent.

For example, if you have a benzene ring with a carboxylic acid group attached, the compound would be named as "carboxybenzene." If the parent chain is a longer alkane, you would name the compound by identifying the number of the carbon to which the carboxylic acid is attached, followed by the prefix "carboxy-" and the name of the alkane. For instance, if a carboxylic acid group is attached to the third carbon of a pentane chain, it would be named "3-carboxypentane."

Remember that the carboxylic acid group has priority in the naming process, so it often dictates the numbering of the carbon atoms in the parent chain to give it the lowest possible number.