Naming Benzene - Online Tutor, Practice Problems & Exam Prep

When naming mono-substituted benzene compounds, the benzene ring serves as the parent chain with a single substituent, eliminating the need for location specification. The nomenclature consists of the substituent name followed by "benzene." For di-substituted benzene, two substituents are present and their locations are indicated numerically or by using the terms ortho (1,2-disubstitution), meta (1,3-disubstitution), and para (1,4-disubstitution). These terms simplify the naming process and can be remembered with the mnemonic "Order More Pizza," corresponding to ortho, meta, and para positions, respectively. This system applies regardless of whether the substituents are identical or different, providing a standardized approach to benzene derivative nomenclature.

Monosubstituted Benzene

Here in this video we're going to take a look at naming mono substituted benzene. Here we're going to say a monosubstituted benzene is a compound where benzene is the parent chain with only one substituent.

Now here, this represents the simplest benzene to name, and because there's only one substituent, the location of that substituent is not necessary. So in terms of our naming convention, we have our substituent name followed by the end of the name as benzene.

Naming Benzene Example

For this example question, it says give a systematic name of the following compound O. Here we have benzene and connected to it is this alkyl group. Now this alkyl group has four carbons involved, which means that it could represent butyl, isobutyl sect, butyl or turf butyl.

Here we'd say based on the way it looks, we have our connection on this carbon here which is connected to three methyl groups. This represents a tert butyl, so the name of the alkyl group would be tert butyl. Remember there's a- there and it's connected to a benzene, so we end a name with benzene.

So this would be the name of our given compound, Tert Butyl Benzene.

Disubstituted Benzene

Hey everyone, so in this video we're going to take a look at dye substituted benzene, which are compounds where benzene is the parent chain and it has two substituents. Now these substituents are numbered in alphabetical order. So if we have for example fluorine and bromine, bromo comes before fluoro, so we'd start numbering at the bromo position.

Now here this would tell us in terms of the naming convention, we'd say the location of each substituent and at the end of the name we'd say benzene. Now benzene itself is pretty unique because we could number where these two substituents are numerically as 1-2, 1-3, or 1-4. Or we could do a brand new way of designating their locations in the form of ortho, meta, and para.

Here in this example, these are all dichlorobenzene. The chlorines are in different locations. Now here they're in positions one and two in this first image. Here when they're in the positions one and two we say 1-2 dichloro or we could say ortho. In the next one they are 1-3 to each other. So instead of saying 1-3 dichloro we could say meta dichloro and then finally their positions one and four here. So we have 1-4 dichlorobenzene or we could say para dichlorobenzene.

Now the two substituents don't have to be the same, they could be the same or they can be different from each other. This ortho, meta, and para convention still would work. Now our memory tool here to help us remember the order is "order more pizza." Now I know in college a lot of us kind of survive on pizza. At least that's the way it was for me when I was in college. So order more pizza gives us the letter designation of 1-2, 1-3, and 1-4: order 1-2 ortho, more 1-3 meta, and pizza 1-4 para right.

So keep that in mind, we can name these two substituents by our traditional numerical method or we could do ortho, meta, and para.

Naming Benzene Example

Here in this example question it says give a systematic name of the following compound. In this compound we have our benzene ring connected to two alkyl groups which happen to be ethyl groups. They're both 2 carbon chains. Now here you could start numbering on either carbon position on benzene because they're both the same. So this could be 1, 2, 3. Or we could go the other way 1, 2, 3, 5 and 6:00.

So we have two apples in positions one and three, so they're numerical. Location is 1/3. There's two of them. They're the same, so it's dye and they are ethyl and we end the name with benzene, so this would be our systematic name. So this would be our answer.

Now if they wanted us to give the common name if we wanted to with the use of ortho, meta or para. Since it's 1, 3, we'd say that the more common way of naming it is meta diethyl benzene. Although the question doesn't ask this, I'm giving it to you just so you can see the differences between the two answers. OK, but our official answer is 1/3 diethyl benzene.

Determine the systematic name of the molecule.

• A. 1-iodo-4-bromobenzene
• B. 1-bromo-4-iodobenzene
• C. 4-bromo-1-iodobenzene
• D. 4-iodo-1-bromobenzene

Determine the systematic name of the molecule.

• A. ortho-fluoroisopropylbenzene
• B. para-fluoroisopropylbenzene
• C. meta-fluoroisopropylbenzene
• D. 1-fluoro-2-tert-butylbenzene

Here’s what students ask on this topic:

What is the IUPAC name of benzene?

The IUPAC name for benzene is simply "benzene." The International Union of Pure and Applied Chemistry (IUPAC) is the organization responsible for establishing the rules for chemical nomenclature. While IUPAC often provides systematic names for organic compounds, in the case of benzene, its common name is also its IUPAC name because of its widespread historical use and recognition.

Benzene is a fundamental structure in organic chemistry, and its ring structure serves as a parent compound for many derivatives. When benzene is a substituent on a larger molecule, it is referred to as a phenyl group. However, when it is the main component of the compound, it retains the name benzene. This is an exception to the IUPAC's systematic naming rules, which typically generate names based on the structure of the molecule to reflect its composition and properties.

What is the IUPAC name for the following substituted benzene?

To provide an accurate IUPAC name for a substituted benzene, I would need the specific details about the substituents attached to the benzene ring. The IUPAC (International Union of Pure and Applied Chemistry) name for a substituted benzene depends on the type and position of the substituents.

Generally, the IUPAC naming follows these rules:

1. Identify the substituents attached to the benzene ring.
2. If there is one substituent, the benzene is named as a derivative of benzene, e.g. chlorobenzene for a chlorine substituent.
3. If there are two substituents, number the ring to give the lowest possible numbers to the substituents, and use prefixes like ortho- (1,2-), meta- (1,3-), and para- (1,4-) for common names, or use the numbers directly in the IUPAC name.
4. For more than two substituents, use numbers to indicate the position of each substituent, listed in alphabetical order in the name.

If you provide the specific substituents and their positions on the benzene ring, I can give you the exact IUPAC name for the compound.

How to name benzene rings?

Naming benzene rings involves identifying the substituents attached to the ring and applying the rules of the International Union of Pure and Applied Chemistry (IUPAC). Here's a simplified guide:

1. Mono-substituted Benzene: When there is only one substituent, name it as a prefix to "benzene." For example, "methylbenzene" for a benzene ring with a methyl group.
2. Disubstituted Benzene: If there are two substituents, you must determine their positions. They can be:
   • Ortho (o-): Substituents are adjacent (1,2-positions).
   • Meta (m-): Substituents are separated by one carbon (1,3-positions).
   • Para (p-): Substituents are opposite each other (1,4-positions).
   Name the substituents in alphabetical order, followed by the position prefix, and end with "benzene."
3. Poly-substituted Benzene: When there are more than two substituents, number the ring to give the lowest possible numbers to the substituents, and list them in alphabetical order before "benzene."
4. Common Names: Some benzene derivatives have common names that are widely accepted.

How to name benzene rings with substituents?

Naming benzene rings with substituents involves a systematic approach:

1. Identify the Substituents: First, you need to identify the groups attached to the benzene ring. These could be simple groups like a methyl (CH₃) or complex functional groups.
2. Number the Positions: If there's only one substituent, you don't need to number it; benzene serves as the parent name (e.g., methylbenzene). However, with multiple substituents, you must number the carbon atoms to which they are attached to minimize the numbers in the name. Start numbering from the substituent of highest priority, according to IUPAC rules, or the one that comes first alphabetically if priority is equal.
3. Use Prefixes: For two substituents, use the prefixes ortho- (1,2-), meta- (1,3-), and para- (1,4-) to indicate their positions. For more than two substituents, use numbers (di-, tri-, etc.) to indicate how many of each substituent there are, and number each position.
4. Assemble the Name: Combine the substituents in alphabetical order (ignoring any prefixes like di-, tri-, etc.) with their position numbers, followed by the parent name 'benzene'. If there are multiple substituents, ensure the name reflects the lowest possible numbers for the substituents. For example, 1-bromo-3-chloro-5-methylbenzene.