Naming Amides - Online Tutor, Practice Problems & Exam Prep

Amides are derivatives of carboxylic acids, formed by replacing the -oic acid suffix with -amide. Unlike esters, amides can have multiple R groups attached to the nitrogen atom, allowing for up to three substituents. Naming involves identifying these substituents as N- or N,N- prefixes, followed by the parent chain's name. Understanding the structure and nomenclature of amides is crucial for grasping their chemical behavior and reactivity in organic synthesis, particularly in nucleophilic acyl substitution reactions.

Amide Nomenclature

Time to learn how to name amides. Amides are carboxylic acid derivatives. Again, pretty much everything that applies from a carboxylic acid derivative applies to an amide. We're going to replace the E ending of the parent chain with the suffix amide. That's pretty straightforward. The only thing that complicates an amide is that you've got the possibility for multiple R groups on the N. It's not like an ester, for example. Remember that in an ester, you can only have 1 R group on an O, and that's it. It's easy. But for nitrogen compounds, you can form 3 bonds. That means you could have up to 3 things coming off of that N. You're going to name them as substituents either on the N or N’ positions. It's just easier if I show you an example. This general structure would be N,N-dimethyl. Notice because I have methyl groups coming off of it. And then it would be alkanamide. Of course, I'm waiting to know what the identity of that R group is to figure out what I put here. You could use common names or IUPAC names. Remember to change your locations and descriptions with numbers or Greek letters depending on which one you're using. You guys are all set to start this example. Go ahead and try to name it, and then I'll help out.

Name the molecule

Let's do the IUPAC name first. The IUPAC name would be 4 carbons. I would have a butanoic acid. Wow, that is not butanoic. Butanoic, but I'm going to change it to butanamide. Awesome. This becomes a butanamide. What substituents do I have? Because of the fact that this is IUPAC, I can just use numbers. It would be 2, 3. This is looking like a dimethyl anhydroxy. H comes before M. It's going to be in terms of the root name, it's going to be 2, comma oops, just a second. Hydroxy comes first. It's be 3-hydroxy, 2,3-dimethylbutanamide. But we're not done. We need to name the alkyl group on the N, and that always comes first. Did you guys have any problems naming this? This is called a vinyl group. That's just a common substituent you should know. This would be N-vinyl and then the rest of the name. N-vinyl and then you've got your root. Let's do common. Common is going to be a butyric acid. Instead of butyric acid, it would be butramide. We know that the substituents are going to be named using Greek symbols. Pretty much I'm actually going to move this over because I drew it too far out. I want to move it back in so I can have space for everything else. The N-vinyl doesn't change, guys. N-vinyl stays the same. But now I'm going to have all these substituents with Greek symbols and the Greek symbols I'm going to be using are alpha and beta. In alphabetical order, it would be beta-hydroxy and then alpha, beta-dimethylbutyramide. All right, guys. Awesome. Not so bad. Let's move on to the next problem.

Draw the amide

For this one, maybe the most challenging thing was that you might have forgotten what a benzyl group looks like. Remember that's not a phenyl. Phenyl is a benzene ring directly attached. You're like, "Oh shoot, I forgot. Benzyl is a phenyl with an extra CH2." Let's draw our amide. Our amide looks like this. It's our general formula. Now in terms of the root, acetamide, that's just a 2 carbon chain. This is drawn correctly. I'm just going to keep it like this, CH3. That's my acetamide. Now I just need the N-alkyl groups and that's going to be 2 benzyl groups. It's going to be 1, 2 like this and 12 like this. Awesome. That's my compound. One thing that actually didn't come up in any of these examples but I want to make sure you know it is just what happens if you have 2 different substituents? Then you'd put those in alphabetical order on the end. If I had let's say an ethyl and a methyl, then that would turn into an ethyl N-methyl. You would not put N,N-ethyl methyl. That's wrong. You have to put the N before every substituent. Other than that, you should be good to go. Let's move on to the next topic.

Here’s what students ask on this topic:

How do you name amides in organic chemistry?

To name amides in organic chemistry, start by identifying the parent chain and replacing the -oic acid suffix of the corresponding carboxylic acid with -amide. If there are substituents attached to the nitrogen atom, denote them with N- or N,N- prefixes. For example, if there are two methyl groups attached to the nitrogen, the name would be N,N-dimethyl followed by the parent chain name ending in -amide. Ensure to use IUPAC naming conventions for clarity and consistency.

What is the difference between naming esters and amides?

The main difference between naming esters and amides lies in the substituents and suffixes used. Esters are named by replacing the -oic acid suffix of the parent carboxylic acid with -oate and naming the alkyl group attached to the oxygen first. In contrast, amides are named by replacing the -oic acid suffix with -amide and using N- or N,N- prefixes to denote substituents attached to the nitrogen atom. Esters can only have one R group on the oxygen, while amides can have up to three substituents on the nitrogen.

What are the rules for naming substituents on the nitrogen atom in amides?

When naming substituents on the nitrogen atom in amides, use the prefix N- for each substituent. If there are multiple substituents, use N,N- to indicate that both are attached to the nitrogen. For example, if there are two methyl groups attached to the nitrogen, the name would be N,N-dimethyl. List the substituents in alphabetical order if there are different groups. This helps in clearly identifying the structure and ensuring consistency in naming.

Can you provide an example of naming an amide with multiple substituents?

Sure! Let's consider an amide with the structure CH₃-CONH-CH₃. The parent chain is derived from acetic acid (ethanoic acid), so the base name is ethanamide. Since there is a methyl group attached to the nitrogen, the name would be N-methyl ethanamide. If there were two methyl groups attached to the nitrogen, it would be N,N-dimethyl ethanamide.

What is the IUPAC naming convention for amides?

The IUPAC naming convention for amides involves identifying the parent carboxylic acid and replacing the -oic acid suffix with -amide. If there are substituents on the nitrogen atom, use the prefixes N- or N,N- to denote their presence. For example, the IUPAC name for CH₃-CONH₂ is ethanamide. If there are substituents like methyl groups on the nitrogen, the name would be N-methyl ethanamide or N,N-dimethyl ethanamide, depending on the number of substituents.