Content

• Steps
• Method 1 of 5: Alkanes
• Method 2 of 5: Alkenes
• Method 3 of 5: Alkyne
• Method 4 of 5: Cyclic hydrocarbons
• Method 5 of 5: Benzene derivatives
• Tips
• Warnings

Hydrocarbons, or compounds based on a chain of hydrogen and carbon, are the backbone of organic chemistry. You need to learn to name them according to IUPAC, or the International Union of Theoretical and Applied Chemistry, which is now the accepted method for naming hydrocarbon chains.

Steps

1. 1 Find out why there are rules. The IUPAC rules were created to phase out old names (such as toluene) and replace them with a system that is consistent and also provides information on the location of substituents (atoms or molecules attached to a hydrocarbon chain).
2. 2 Keep a list of prefixes handy. These prefixes will help you name your hydrocarbon. They are based on the amount of carbon in the main circuit(and not all the amount of carbon in the compound). For example, CH₃-CH₃is called ethane. Perhaps your teacher will not require you to know more than 10 prefixes; but be prepared if he or she does require more knowledge.
   • 1: met-
   • 2: this
   • 3: prop-
   • 4: but-
   • 5: pent-
   • 6: hex
   • 7: hept-
   • 8: Oct-
   • 9: non-
   • 10: Dec-
3. 3 Practice. Learning the IUPAC system takes practice. Read about the following methods for a few examples, and then find links to practical problems in the Sources and References section at the bottom of the page.

Method 1 of 5: Alkanes

1. 1 Find out what alkanes are. Alkanes are hydrocarbon chains that do not contain a double or triple bond between molecules. The name of alkanes must always have a suffix -an.
2. 2 Draw a molecule. You can draw all the symbols of the molecule or use the skeleton structure. Find out which way your instructor wants to draw and stick to it.
3. 3 Count the amount of carbon in the main chain. The main chain is the longest continuous carbon chain in a molecule. Count the carbon starting with the closest substituent in the group. Each substitute should be recorded by the number of its location in the chain.
4. 4 Write the title in alphabetical order. Substituents must be named in alphabetical order (excluding prefixes such as “di-”, “three-” or “tetra-”), but not numerically.
   • If there are two identical substituents in the hydrocarbon chain, use the prefix "di-" before its name. Even if they are attached to the same carbon, write that number twice.

Method 2 of 5: Alkenes

1. 1 Find out what alkenes are. Alkenes are hydrocarbon chains that contain one or more double bonds between carbon molecules, but do not contain a triple bond. Alkenes must always be named with a suffix -en.
2. 2 Draw a molecule.
3. 3 Find the main circuit. The main chain of alkenes must contain some kind of double bond between carbon. In addition, it should be numbered from the closest carbon-carbon double bond from the end.
4. 4 Note where the double bond is located. In addition to noting the location of the substituents, you should also note where the double bond is. Do this in such a way that the smallest number in the double bond numbering is used.
5. 5 Change the suffix based on the number of double bonds in the main chain. If there are two double bonds in the main chain, the name will end with "-diene", if three - then with "-triene" and so on.
6. 6 Name the substituents in alphabetical order. As with alkanes, you must list the substituents in alphabetical order in the final name. Exceptions are prefixes such as "di-", "tri-" or "tetra-".

Method 3 of 5: Alkyne

1. 1 Find out what alkynes are. Alkines are hydrocarbon chains that contain one or more triple bonds. The name must always contain a suffix -in.
2. 2 Draw a molecule.
3. 3 Find the main circuit. The main chain of alkynes must contain any triple bond carbon atom. Start numbering with the closest triple bond at the end of the chain.
   • If you are working with a molecule that has both a double and a triple bond, start numbering with the closest multiple bond at the end of the chain.
4. 4 Note the location of the triple bond. In addition to marking the location of the substitutes, you must also mark the location of the triple bond. Do this in such a way that the smallest number on the triple bond is used when numbering.
   • If your molecule also contains double bonds, you must mark them.
5. 5 Change the suffix based on the number of triple bonds in the main chain. If there are two triple bonds in the main chain, then the name will end in "-diin", three bonds - "triin" and so on.
6. 6 Name the substituents in alphabetical order. As with alkanes and alkenes, you must list the substituents in alphabetical order in the final name. Exceptions are prefixes such as "di-", "tri-" or "delta-".
   • If the molecule also contains double bonds, name them first.

Method 4 of 5: Cyclic hydrocarbons

1. 1 Find out what kind of cyclic hydrocarbon you are considering. The process of naming cyclic hydrocarbons works like non-cyclic ones - those that do not contain multiple bonds are cycloalkanes, with double bonds - cycloalkenes, with triple bonds - cycloalkenes. For example, a six-carbon ring without multiple bonds is called cyclohexane.
2. 2 Distinguish the names of cyclic hydrocarbons. There are several notable differences between the names of cyclic and non-cyclic hydrocarbons:
   • Since all carbon atoms in a cyclic hydrocarbon ring are equal, you do not need to number them if your cyclic hydrocarbon has only one constituent.
   • If the cyclic hydrocarbon contains an alkyl group larger and more complex than the ring itself, then the cyclic hydrocarbon may become a substituent rather than the main chain.
   • If there are two substituents on the ring, number them in alphabetical order. First (in alphabetical order) Deputy 1; then the numbering is counterclockwise or clockwise, whichever gives the lower number for the second substituent.
   • If there are more than two substituents on the ring, then it must be indicated that the first is alphabetically attached to the first carbon atom. Others are numbered counterclockwise or clockwise, whichever results in fewer numbers.
   • Like non-cyclic hydrocarbons, the final name of the molecule is given in alphabetical order, with the exception of such prefixes as "di-", "tri-" and "tetra-".

Method 5 of 5: Benzene derivatives

1. 1 Find out what benzene derivatives are. Benzene derivatives are based on the benzene molecule, C₆H₆, in which three double bonds are evenly located.
2. 2 Do not number carbon if there is only one substituent. As with other cyclic hydrocarbons, numbering is not required if there is only one substituent on the ring.
3. 3 Learn about the names of benzene. You can name your benzene molecule like any other cyclic hydrocarbon, starting in alphabetical order with the first substituent and assigning numbers in a circle. However, there are some special designations for the location of substituents in the benzene molecule:
   • Ortho or o-: two substituents are located at 1 and 2.
   • Meta or m-: two substituents are located at 1 and 3.
   • Pair or p-: two substituents are located at 1 and 4.
4. 4 If your benzene molecule has three substituents, name it like a regular cyclic hydrocarbon.

Tips

• If there are two candidates for a long chain, choose the one with more ramifications. If you have two nets with the same number of taps, choose the one with the taps closer. If the two nets are identical in branching terms, simply select one of them.
• If a hydrocarbon has an OH (hydroxyl group) anywhere in the bond, it is an alcohol and the suffix "-ol" appears in the name instead of "-an".
• Keep practicing! When you run into these problems on a test, know that the instructor has probably framed the questions so that there is only one correct answer. Memorize the rules and then follow them step by step.

Warnings

• Many compounds are referred to by common names instead of using the IUPAC system. For example, a side chain that will be referred to by the IUPAC system as 1-methylethyl is also known as an isopropyl group. Be careful not to mix up naming systems.