Naming Esters - Online Tutor, Practice Problems & Exam Prep

Esters are organic compounds characterized by an oxygen atom bonded to an alkyl group and a carbon chain with a carbonyl group. When naming esters, the carbon chain connected to the carbonyl is named as if it were a carboxylic acid, but the ending is altered from 'oic acid' to 'oate' to reflect its ester status. The naming convention also includes identifying substituents on the parent chain. Understanding the structure and nomenclature of esters is crucial for students studying organic chemistry, as it aids in the identification and discussion of different ester compounds.

Rules for Naming Esters

Now recall Esther's possess an oxygen atom connected to an alkyl group, so a carbon group, and a carbon chain containing a carbonyl group. So esters have this as the portion that indicates what they are. Now esters have a unique naming system.

The carbon chain with the carbonyl group is named as though it was a carbacillic acid, but it's not a carbacillic acid anymore, it's an Ester. So we have to modify the ending. So we're going to modify the ending from OIC acid, which is the ending of a carbosolic acid, to 8, which is now the end of the name for an Ester.

In terms of our naming convention, we still talk about our substituents and we'll see how that works. In terms of esters, we'll have our parent chain where we modify the ending to 8. So keep this in mind as we start naming different types of esters.

Naming Esters Example

Provide the systematic name for the following Esther. To do that we're going to utilize the following steps. Step one, we have to identify the alkyl group connected to the oxygen atom, and we're going to name the alkyl group as a substituent. Now when it comes to this alkyl group connected to our oxygen, no numerical location for the alkyl group is needed.

So if we take a look here, I've highlighted the portion that's the alkyl group O. Here it's a 2 carbon alkyl group. So that's ethyl. Step three, we identify the carbonyl chain connected to the carbonyl group. So here our carbonyl group is highlighted in yellow here. Step 4. Figure out the length of the carbon chain starting from the carbonyl group. So here I've already numbered it for us, so we start here 1, 2, 3, 4. The carbonyl group is carbon number 1 as carbon #1 is implied.

Now here we have to assign numbers for the location of each substituent on the carbon chain with the carbonyl group. So here we have as our substituent this methyl group. Down here, when more than one identical substituent, we use the prefixes of di for two, tri for three, and tetra for four. So here we have a methyl group, and remember this is our original 1, the alkyl group which is ethyl. We name all substituents in alphabetical order. Prefixes do not count, and here we're going to use commas to separate numbers from numbers, and we're going to use dashes to separate letters from numbers.

Now letters are not separated from letters, and this is important here. This is an additional step we have to take in mind where we write the alkyl group name with spaces. OK, so when it comes to writing this alkyl group that's connected to the oxygen, we write it with spaces. So let's put all this together. So E comes before M, so it's going to be ethyl. Remember this. We write it with spaces. Then we're going to have what on carbon #3 of the carbon chain? We're going to have a methyl. So 3-methyl and then here it's a 4 carbon chain which is butane and as a carboxylic acid it would have been butanoic acid.

But remember, we're changing this to oate so it becomes butanoate. So we end the name with butanoate. So it'd be ethyl 3-methylbutanoate. That'd be the name of this particular ester.

Provide the systematic name for the following ester.

• A. propyl butanoate
• B. butyl propanoate
• C. isopropyl butanoate
• D. isobutyl propanoate

Provide the systematic name for the following ester.

• A. tert-butyl 3,3-dimethylpentanoate
• B. sec-butyl 3,3-dimethylpentanoate
• C. tert-butyl 4,4-dimethylpentanoate
• D. isopropyl 3,3-dimethylpentanoate

If the substituent name of benzene is phenyl, which structure represents phenyl propanoate?

• A.
• B.
• C.
• D.

Here’s what students ask on this topic:

How do you name an ester?

To name an ester, which is an organic compound made from an acid where the hydrogen in the acid's hydroxyl group is replaced with an alkyl or aryl group, you follow a specific nomenclature system:

1. Identify the alkyl or aryl group that comes from the alcohol. This group is named first and uses the common alkyl names, such as methyl, ethyl, propyl, etc.
2. Next, determine the acid part of the ester. Name this part after the acid from which it is derived, but replace the "-ic acid" ending with "-ate." For example, if the acid is acetic acid, the corresponding part of the ester name would be "acetate."

So, the full name of an ester is the alkyl group name followed by the modified acid name. For example, if you have an ester formed from methanol and acetic acid, the name would be methyl acetate. If the ester is formed from ethanol and butyric acid, it would be named ethyl butanoate. Remember to also consider any other substituents or double bonds when naming complex esters, following the rules of IUPAC nomenclature for organic compounds.

How do you name an ester as a substituent?

When naming an ester as a substituent in organic chemistry, you follow a specific nomenclature system. Esters are compounds where an organic group replaces a hydrogen atom in a carboxylic acid. When an ester group is a substituent, it is often referred to as an "alkoxy carbonyl" group.

To name it:

1. Identify the alkyl group (the part of the ester that comes from the alcohol) attached to the oxygen atom.
2. Use the name of this alkyl group followed by the term "oxycarbonyl" as a prefix to the name of the main molecule.

For example, if the ester substituent is derived from methyl alcohol (methanol), it would be named "methoxycarbonyl" as a substituent.

Remember, the ester's naming priority is lower than that of functional groups like carboxylic acids, aldehydes, and ketones, so it will often be named as a substituent in the presence of these higher priority groups.

How do you name an ester using IUPAC?

To name an ester using the IUPAC system, you need to identify the two parts that make up the ester: the alkyl group and the acid part. The alkyl group comes from the alcohol, and the acid part comes from the carboxylic acid.

1. Start by naming the alkyl group (the part of the molecule that comes from the alcohol). This is the "R" group attached to the oxygen atom. Use the standard alkane nomenclature, dropping the "-e" and adding "-yl" (for example, "methyl" for a one-carbon alkyl group).
2. Next, name the acid part. This involves identifying the carboxylic acid that has been esterified. Replace the "-ic acid" ending of the carboxylic acid name with "-ate." For example, if the acid part is derived from ethanoic acid (acetic acid), the corresponding ester part would be named "ethanoate."
3. Combine the names of the alkyl group and the acid part, placing the alkyl group name first, followed by the acid part name. For instance, if the alkyl group is methyl and the acid part is ethanoate, the ester is named "methyl ethanoate."

Remember that there are no spaces in the IUPAC names.