Learn about IUPAC naming for organic compounds and molecules. Understand functional groups tables, use IUPAC name charts, and see IUPAC name examples.
Updated: 05/11/2022
IUPAC Naming of Organic Compounds
The IUPAC Name
IUPAC is an acronym which stands for the International Union of Pure and Applied Chemistry. IUPAC is an international body representing researchers in chemistry and other related sciences and technologies. The overarching goal of IUPAC is to unite the worldwide community of chemists and offer a place for advancement, collaboration and the exchange of scientific research and information.
To further efficient scientific communication, IUPAC has developed an international standardized system of nomenclature to provide names to compounds. The IUPAC naming system functions to give each organic compound a unique and unambiguous name and to correlate easily with other compounds named in the system. Find below an example of an IUPAC name chart which shows how some compounds are named:
IUPAC Name Examples
Below are some common organic molecules in the category alkanes, with examples of the IUPAC naming of organic molecules:
- ethane — has 2 carbon atoms and 6 hydrogen atoms, with the molecular formula of = {eq}C_2H_6 {/eq}
- propane — has 3 carbon atoms and 8 hydrogen atoms, with the molecular formula of = {eq}C_3H_8 {/eq}
- butane — has 4 carbon atoms and 10 hydrogen atoms, with the molecular formula of = {eq}C_4H_10 {/eq}
Note the similarity in the structure of their IUPAC names.
Carbon Is the Key
In organic chemistry there is an atom named carbon. Carbon is one unique atom given the fact that it can form very stable molecules that range in size. Also, carbon can bond with other atoms to create a somewhat endless possibility of organic compounds. How is this possible?
Well, by definition, organic compounds contain a carbon atom. It's good to keep in mind that almost all organic compounds also contain a hydrogen atom.
How does the carbon atom relate to the process of naming organic compounds? Well, by understanding the meaning of the term, organic compound, we can easily crack the code of naming organic compounds. Let's take a look.
Naming Organic Compounds
To better understand the naming system of various compounds, general rules apply. A molecule is often defined by scientists to be organic when it contains not only carbon, but at least one other element, which is often hydrogen. According to the terms provided by IUPAC naming system, three parts are required: a root word, a chemistry prefix, and a suffix, when naming organic compounds to help scientists quickly and efficiently differentiate between molecule types, structure, components and chain length.
- The root word denotes the number of carbon atoms present in the primary chain (or the longest possible chain of carbon atoms). For example, 'Oct' in 'Octane', refers to an 8 carbon atom chain length.
- The prefix is the part of the IUPAC name which appears before the root word. For example, 'cyclo' is the prefix for the compound of 'cyclopropane', and is used to differentiate between a cyclic compound from an acyclic compound.
- The suffix refers to the main functional group and the multiple bonds present within an organic compound. For example, 'ol' in 'alcohol', refers to the specific class of the organic compound.
How to Name Organic Compounds
The step-by-step IUPAC naming process can be followed in order to name organic compounds. There are five steps and associated functional groups tables used for guidance following the IUPAC naming rules. The tables are:
Root Word Table:
| Number of carbon atoms | Root Word |
|---|---|
| 1 | Meth |
| 2 | Eth |
| 3 | Prop |
| 4 | But |
| 5 | Pent |
| 6 | Hex |
| 7 | Hept |
| 8 | Oct |
| 9 | Non |
| 10 | Dec |
Primary Suffix Table:
| Type of Carbon Chain | Primary Suffix |
|---|---|
| Saturated (all C-C bonds) | -ane |
| Unsaturated: one C=C | -ene |
| Unsaturated: two C=C | -diene |
| Unsaturated: one triple C-C bonds | -yne |
| Unsaturated: two triple C-C bonds | -diyne |
| Unsaturated: one C=C and one quad C-C bond | -enyne |
Secondary Suffix Table:
| Name of Functional Group | Suffix When Carbon of the Functional Group is Part of Parent Chain | Suffix When Carbon of the Functional Group is NOT Part of Parent Chain | Prefix |
|---|---|---|---|
| Carboxylic Acid | -oic acid | -carboxylic acid | carboxy- |
| Acid Anhydride | -oic anhydride | -carboxylic anhydride | - |
| Ester | alkyl -oate | -alkyl -carboxylate | alkoxycarbonyl- |
| Ketone | -one | - | oxo- |
| Alcohol | -OH | -ol | hydroxy |
Prefix Table:
| Side Chain or Substituent | Prefix |
|---|---|
| -CH3 | methyl- |
| -CH2CH3 (or) -C2H5 | ethyl- |
| -CH2CH2CH3 | propyl- |
| H3C-CH-CH3 | isopropyl- |
| -CH2CH2CH2CH3 | butyl |
| -X | halo- |
| -OR | alkoxy- |
| -NO2 | -nitro |
Follow the 5 step guide to give the IUPAC name to the following organic compound, sec-isoamyl alcohol (which is used as a solvent and intermediate in manufacturing other chemicals):
Organic compound: sec-isoamyl alcohol
Formula: C_5H_12O
Structure:
IUPAC Naming Process:
- First, select the parent chain and assign a root word. How many carbons are in the parent chain? In this example there are 4, therefore select the root word but.
- Next, select the appropriate primary suffix and add this to the root word to indicate if the compound is saturated or unsaturated. This example is saturated, therefore apply the primary suffix ane.
- Then, determine if the molecule contains a functional group or a number of groups where a secondary suffix is required to indicate the main functional group, if there is no functional group, disregard this step. In this example, there is an alcohol (OH) group on the 2nd carbon, therefore add the secondary suffix of 2-ol.
- If the parent chain is cyclic then prefix the root word with cyclo, if the chain is a spiro compound, use spiro, or if it is a bicyclic compound, use bicyclo. In this example there are no changes to be made.
- Finally, add the chemistry prefixes to the IUPAC name, if there are side chains or substituents on the parent chain. In this example, there is a methyl group on the third carbon, so add the secondary prefix of 3-methyl. Side chains should be alphabetized from A to Z.
Following the above steps produces the full name: 3-methyl (secondary prefix) + but (root word) + ane (primary suffix) + 2-ol (secondary suffix). The IUPAC name is 3-methylbutan-2-ol.
Lesson Summary
IUPAC is an acronym which stands for the International Union of Pure and Applied Chemistry. IUPAC is an international body representing chemistry and other related sciences and technologies. To promote effective scientific communication, IUPAC has developed an international standardized system of nomenclature to provide names to compounds. The IUPAC naming system was created in order to give each organic compound a unique and unambiguous name, and to correlate easily between the structure itself. One common example of an organic compound is ethane, which has 2 carbon atoms and 6 hydrogen atoms, with the molecular formula of = {eq}C_2H_6 {/eq}.
According to the terms provided by the IUPAC naming system, three parts are required when naming organic compounds: a root word, a prefix, and a suffix. For example, when naming an organic compound with 5 carbon atoms, you would use the root word 'pent'. These parts help scientists quickly and efficiently differentiate between molecule types, structure, components and chain length. To account for side chains on a structure when giving it a name, alphabetize them from A to Z. Using functional group tables as a guide, there are 5 steps to follow to efficiently name an organic compound. Keep in mind, carbon atoms are always present in an organic compound.
Naming Organic Compounds
At the most basic level there are three key words to remember when naming organic compounds: prefix, suffix, and the root. Find these, and you are well on your way towards naming an organic compound.
Naming gets complicated, but we can start by applying six steps to all compounds that need to be named. These rules follow a guideline known in organic chemistry as set by the International Union of Pure and Applied Chemistry (IUPAC), which is an authority that creates standards used for naming compounds. Following the IUPAC rules ensures you name every organic structure correctly.
Compound Naming Steps
Step 1: Locate the longest carbon chain in our compound
We will use this compound as our example for naming. As you can see, the longest chain is 7 carbon atoms long.
Step 2: Name that longest carbon chain
Those 7 carbon atoms are equal to a root word. We can find the root word by looking at the table that shows what number of carbon atoms corresponds to what root word. The number 7 corresponds to 'hept-.' Now you know that the root word is the base that lets you know how many carbon atoms are in your compound.
Step 3: Figure out what the ending (suffix) should be
If there is a functional group in your compound, you will need to find the suffix that goes with it and put it at the end of your name. A functional group is a specific group of molecules you can easily spot in a compound. For this compound the functional group alkane (C-H atom) is present, so take a look at the table of suffix endings.
You can see that the ending for alkane is '-ane.' When we take our base name of hept- and add -ane, we get that the name for the parent chain (longest carbon-carbon chain) is heptane.
Step 4: Number your carbon atoms
First, notice any side groups, or any molecule or atom that hangs from your longest (or parent) chain. Okay, now locate the two ends of your carbon chain. Begin numbering each carbon atom (1,2, and so on) on the parent chain from left to right, then do it again but from right to left. Which way approaches a side group first? Then that end is considered to be the #1 carbon end.
Hmm, you'll notice that the carbon attached to our side chain would be numbered 4 no matter which side you come from. Well then, 4 it is! Our side chain will be associated with the number 4, so 4 will come at the very start of our compound's name.
Step 5: Name the side groups
When you see any endings hanging from the longest carbon chain, circle them. By identifying these you will not forget to include them in the chemical name of your compound. In our compound we have one side chain: a bromine atom that is attached to two carbon atoms. This is a special molecule called bromomethyl.
Step 6: Put the side groups in alphabetical order
After you have circled the side chains, you can include them alphabetically in your final chemical name. Luckily we do not have to alphabetize our side chains as there is only one, called bromomethyl. But keep in mind that when you have multiple side chains, the names must be alphabetized and go before the parent name they are attached to.
Putting all of the steps together what is the name of this compound?
- Side chain location: 4
- Side chain names: bromomethyl
- Root name: hept-
- Functional group name: -ane
That's right! It is 4-bromomethylheptane. Note that the number 4 refers to the location of the side groups in this compound. When naming, side groups must be assigned the lowest possible number on your parent chain.
Another Example
Let's take a look at an example. Okay, you've counted six carbons on the parent chain, which means the root is 'hex-'. Look, a functional group! Alcohol (or OH) is present, so our ending is '-ol.'
Now, there's two side chains, alcohol (OH) and a methyl group (CH3). As we number our carbons, we see that both ends come to a side group at the same time (it takes 3 carbons to get to OH and 3 carbons to get to CH3). When this happens, pick whichever side group is the more complex (has the most atoms) to be the carbon #1 group. CH3 has 4 atoms, and OH only has 2. Therefore CH3 will be the carbon #1 group.
The correct name is 4-methyl-3-hexanol.
Did you notice that the word 'alcohol' was not included in our final compound name? If we did then the name would be 4-methyl-3-alcohol-hexanol. This is not correct as alcohol is a functional group. For functional groups we only need two things: (1) the suffix ending '-ol' and (2) its location number.
Lesson Summary
Organic compounds contain carbon atoms. When naming compunds, remember the terms root, suffix, and prefix. Each of these terms are essential when naming an organic compound. The governing standard that creates the rules for naming compound is called IUPAC (International Union of Pure and Applied Chemistry). These rules get complicated, but we've tried to simplify them using 6 steps:
- Locate the longest carbon chain in our compound
- Name that parent chain (find the root word)
- Figure out the ending
- Number your carbon atoms
- Name the side groups
- Put the side groups in alphabetical order
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Video Transcript
Carbon Is the Key
In organic chemistry there is an atom named carbon. Carbon is one unique atom given the fact that it can form very stable molecules that range in size. Also, carbon can bond with other atoms to create a somewhat endless possibility of organic compounds. How is this possible?
Well, by definition, organic compounds contain a carbon atom. It's good to keep in mind that almost all organic compounds also contain a hydrogen atom.
How does the carbon atom relate to the process of naming organic compounds? Well, by understanding the meaning of the term, organic compound, we can easily crack the code of naming organic compounds. Let's take a look.
Naming Organic Compounds
At the most basic level there are three key words to remember when naming organic compounds: prefix, suffix, and the root. Find these, and you are well on your way towards naming an organic compound.
Naming gets complicated, but we can start by applying six steps to all compounds that need to be named. These rules follow a guideline known in organic chemistry as set by the International Union of Pure and Applied Chemistry (IUPAC), which is an authority that creates standards used for naming compounds. Following the IUPAC rules ensures you name every organic structure correctly.
Compound Naming Steps
Step 1: Locate the longest carbon chain in our compound
We will use this compound as our example for naming. As you can see, the longest chain is 7 carbon atoms long.
Step 2: Name that longest carbon chain
Those 7 carbon atoms are equal to a root word. We can find the root word by looking at the table that shows what number of carbon atoms corresponds to what root word. The number 7 corresponds to 'hept-.' Now you know that the root word is the base that lets you know how many carbon atoms are in your compound.
Step 3: Figure out what the ending (suffix) should be
If there is a functional group in your compound, you will need to find the suffix that goes with it and put it at the end of your name. A functional group is a specific group of molecules you can easily spot in a compound. For this compound the functional group alkane (C-H atom) is present, so take a look at the table of suffix endings.
You can see that the ending for alkane is '-ane.' When we take our base name of hept- and add -ane, we get that the name for the parent chain (longest carbon-carbon chain) is heptane.
Step 4: Number your carbon atoms
First, notice any side groups, or any molecule or atom that hangs from your longest (or parent) chain. Okay, now locate the two ends of your carbon chain. Begin numbering each carbon atom (1,2, and so on) on the parent chain from left to right, then do it again but from right to left. Which way approaches a side group first? Then that end is considered to be the #1 carbon end.
Hmm, you'll notice that the carbon attached to our side chain would be numbered 4 no matter which side you come from. Well then, 4 it is! Our side chain will be associated with the number 4, so 4 will come at the very start of our compound's name.
Step 5: Name the side groups
When you see any endings hanging from the longest carbon chain, circle them. By identifying these you will not forget to include them in the chemical name of your compound. In our compound we have one side chain: a bromine atom that is attached to two carbon atoms. This is a special molecule called bromomethyl.
Step 6: Put the side groups in alphabetical order
After you have circled the side chains, you can include them alphabetically in your final chemical name. Luckily we do not have to alphabetize our side chains as there is only one, called bromomethyl. But keep in mind that when you have multiple side chains, the names must be alphabetized and go before the parent name they are attached to.
Putting all of the steps together what is the name of this compound?
- Side chain location: 4
- Side chain names: bromomethyl
- Root name: hept-
- Functional group name: -ane
That's right! It is 4-bromomethylheptane. Note that the number 4 refers to the location of the side groups in this compound. When naming, side groups must be assigned the lowest possible number on your parent chain.
Another Example
Let's take a look at an example. Okay, you've counted six carbons on the parent chain, which means the root is 'hex-'. Look, a functional group! Alcohol (or OH) is present, so our ending is '-ol.'
Now, there's two side chains, alcohol (OH) and a methyl group (CH3). As we number our carbons, we see that both ends come to a side group at the same time (it takes 3 carbons to get to OH and 3 carbons to get to CH3). When this happens, pick whichever side group is the more complex (has the most atoms) to be the carbon #1 group. CH3 has 4 atoms, and OH only has 2. Therefore CH3 will be the carbon #1 group.
The correct name is 4-methyl-3-hexanol.
Did you notice that the word 'alcohol' was not included in our final compound name? If we did then the name would be 4-methyl-3-alcohol-hexanol. This is not correct as alcohol is a functional group. For functional groups we only need two things: (1) the suffix ending '-ol' and (2) its location number.
Lesson Summary
Organic compounds contain carbon atoms. When naming compunds, remember the terms root, suffix, and prefix. Each of these terms are essential when naming an organic compound. The governing standard that creates the rules for naming compound is called IUPAC (International Union of Pure and Applied Chemistry). These rules get complicated, but we've tried to simplify them using 6 steps:
- Locate the longest carbon chain in our compound
- Name that parent chain (find the root word)
- Figure out the ending
- Number your carbon atoms
- Name the side groups
- Put the side groups in alphabetical order
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Frequently Asked Questions
How do you find the IUPAC name?
The IUPAC name can be determined by using the standard steps of nomenclature in chemistry. The IUPAC name will use a root word, prefix and suffix to name an organic compound according to its bond and structure.
What is meant by IUPAC name?
IUPAC names were developed by the International Union of Pure and Applied Chemistry (IUPAC) to create an international standardized system of nomenclature to provide names for chemical compounds. The system allows for more efficient communication among scientists. The IUPAC name gives each organic compound a unique and unambiguous name, and correlates easily to other IUPAC names.
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Naming Organic Compounds | IUPAC Rules, Significance & Examples
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