Name aliphatic hydrocarbons and alcohols with 1 carbon to 10 carbon atoms using the IUPAC system and Chemistry software

Alkanes are saturated hydrocarbons containing only single carbon-carbon bonds. They have the general formula CₙH₂ₙ₊₂, where n is the number of carbon atoms.

IUPAC Rules for Alkanes

1. Identify the longest continuous carbon chain — this determines the parent name.
2. Use the Greek numerical prefix for the number of carbon atoms in the chain.
3. Replace the suffix with "-ane" to indicate an alkane.

Table: Names and Formulas of Alkanes (C₁–C₁₀)

Alkenes contain at least one carbon-carbon double bond (C=C). They have the general formula CₙH₂ₙ.

IUPAC Rules for Alkenes

1. Find the longest chain containing the double bond — this is the parent chain.
2. Use the same prefix based on the number of carbon atoms.
3. Replace the suffix with "-ene" to indicate an alkene.
4. Number the chain so that the double bond gets the lowest possible number. This number becomes part of the name (e.g., but-1-ene, not but-2-ene).

Examples of Alkenes (C₂–C₁₀)

• C₂H₄ → Ethene (eth- + -ene)
• C₃H₆ → Propene (prop- + -ene)
• C₄H₈ → But-1-ene (double bond at carbon 1)
• C₅H₁₀ → Pent-1-ene or Pent-2-ene (depending on double bond position)

Alkynes contain at least one carbon-carbon triple bond (C≡C). They have the general formula CₙH₂ₙ₋₂.

IUPAC Rules for Alkynes

1. Find the longest chain containing the triple bond — this is the parent chain.
2. Use the same numerical prefix for the number of carbon atoms.
3. Replace the suffix with "-yne" to indicate an alkyne.
4. Number the chain so that the triple bond gets the lowest possible number. This number is included in the name (e.g., prop-1-yne).

Examples of Alkynes (C₂–C₁₀)

• C₂H₂ → Ethyne (eth- + -yne)
• C₃H₄ → Propyne (prop- + -yne)
• C₄H₆ → But-1-yne or But-2-yne (depending on triple bond position)

Alcohols contain the hydroxyl functional group (-OH). They can be considered as alkanes where one hydrogen atom is replaced by an -OH group. Their general formula is R-OH, where R is an alkyl group.

IUPAC Rules for Alcohols

1. Find the longest chain containing the -OH group — this is the parent chain.
2. Use the same numerical prefix for the number of carbon atoms.
3. Replace the suffix "-ane" with "-anol" to indicate an alcohol.
4. Number the chain so that the -OH group gets the lowest possible number. This number is included in the name when necessary.

Table: Names and Formulas of Alcohols (C₁–C₁₀)

Example 1: Naming a Straight-Chain Alkane

A compound has the formula C₇H₁₆. Name it using IUPAC.

Solution:

• The carbon chain has 7 carbons.
• The prefix for 7 is "hept-".
• Since it is an alkane (only single bonds), the suffix is "-ane".
• Answer: Heptane

Example 2: Naming an Alkene with a Double Bond

A compound has the formula CH₃-CH=CH-CH₃. Name it using IUPAC.

Solution:

• The longest chain containing the double bond has 4 carbons: but- (prefix for 4).
• The suffix for an alkene is "-ene".
• Numbering from left gives the double bond at carbon 1; from right gives it at carbon 1 as well (the compound is symmetrical). The name is but-2-ene (the double bond is between carbons 2 and 3).
• Answer: But-2-ene

Example 3: Naming an Alcohol

A compound has the formula CH₃-CH₂-CH₂-OH. Name it.

Solution:

• The longest chain containing the -OH group has 3 carbons: prop- (prefix for 3).
• Replacing the alkane suffix with "-anol" gives propanol.
• Numbering from the end closest to -OH gives carbon 1. No number is needed since -OH is at carbon 1.
• Answer: Propanol

Example 4: Identifying a Compound from its Name

What is the molecular formula of Octan-1-ol?

Solution:

• "Octan" indicates 8 carbon atoms in the parent chain.
• "-1-ol" indicates the -OH group is on carbon 1.
• The formula is C₈H₁₇OH, which can also be written as C₈H₁₈O.
• Answer: C₈H₁₇OH (or C₈H₁₈O)

Chemistry software can help visualize molecular structures and verify IUPAC names. Software such as ChemDraw, Avogadro, or online tools like ChemSpider allow you to:

• Draw a molecular structure
• Automatically generate the IUPAC name
• Verify your manual naming is correct

When naming compounds using software, always confirm the name matches the IUPAC rules covered in this note.

In Tanzania, petroleum products like petrol (octane) and diesel are sold at stations such as TOTAL, OILIB, and GPS. Understanding IUPAC names helps you recognize that octane (C₈H₁₈) in petrol is named using the prefix for 8 carbons plus the alkane suffix. Additionally, ethanol (C₂H₅OH) produced locally from cassava or maize at factories like Tanzania Alcohol and Liquor Company is used in hand sanitizers and as a fuel additive — knowing its IUPAC name connects directly to these everyday products found in Tanzanian markets.