ORG CHEM | Acyclic Hydrocarbons & Nomenclature of Alkanes

Steps for Drawing Acyclic Alkanes

1. Determine the number of carbon atoms in the alkane.

2. Draw a chain of single bonds between carbon atoms.

3. Attach the correct number of hydrogen atoms to each carbon atom, ensuring that each carbon has four bonds in total.

Drawing Cycloalkane

1. Determine the number of carbon atoms in the ring.

2. Draw a polygon representing the carbon ring (e.g., a triangle for cyclopropane or a hexagon for cyclohexane).

3. Attach the appropriate number of hydrogen atoms to each carbon.

Naming Straight-chain Alkanes

prefix based on no. of C atoms in the longest continuous chain + -ane

Prefix for 1 carbon atom/substituent

meth-

Prefix for 2 carbon atoms/substituents

eth-

Prefix for 3 carbon atoms/substituents

prop-

Prefix for 4 carbon atoms/substituents

but-

Prefix for 5 carbon atoms/substituents

pent-

Prefix for 6 carbon atoms/substituents

hex-

Prefix for 7 carbon atoms/substituents

hept-

Prefix for 8 carbon atoms/substituents

oct-

Prefix for 9 carbon atoms/substituents

non-

Prefix for 10 carbon atoms/substituents

dec-

Steps for Naming Acyclic Branched Alkanes

1. Identify the longest carbon chain.

2. Identify the substituents or branches.

3. Number the carbon atoms in the main chain.

4. Assemble the name.

Identifying the substituents (Alkanes)

These are any branches seen in the structure. They are named based on the number of carbon atoms in one branch. The nomenclature follows the assigned prefixes per number of carbons with an added suffix -yl.

Numbering the carbon atoms (Alkanes)

The numbering must start from the end that is closest to a substituent. If there is an equal distance, then the end nearest to the substituent with more carbons is where you start.

Naming for Multiple Substituents (Alkanes)

If there are multiple identical substituents, use prefixes like “di-”, “tri-”, “tetra-”. When writing the position numbers per branch, write one number per branch and separate the numbers with a comma. (e.g. 2,2-methyl-)

Assembling the Name

• For each substituent number, combine the position number/s with the substituent.

• List them alphabetically, ignoring di-,tri-,tert- etc., for identical substituents.

• Add the base name at the end.

• Separate the (group of) position numbers and substituents with a dash. Do not put a dash between the last substituent and the base name. (e.g. 5-ethyl-3-methyloctane)

Steps in Naming Cycloalkanes

1. Determine the Ring Size.

2. Identify the Substituents.

3. Number the Carbon Atoms in the Ring.

4. Assemble the Name.

Determining the Ring size (Cycloalkanes)

Base this on the number of atoms. This follow the same naming conventions for an acyclic alkane with an added cyclo- prefix before it.

Identifying Substituents (Cycloalkanes)

Identify and name the substituents attached to each carbon in the ring.

Number the Carbon Atoms in the Ring (Cycloalkanes)

Start numbering at the carbon with the substituent that is alphabetically first. Then, continue numbering counterclockwise.

Alphabetical Order of the Branches

butyl (4), decyl (10), ethyl (2), heptyl (7), hexyl (6), methyl (1), nonyl (9), octyl (8), pentyl (5), propyl (3)

International Union of Pure and Applied Chemistry (IUPAC)

they created the naming convention for the nomenclature for the systematic names of chemical compounds

Iso- and neo-

Part of akyl group name and are used for alphabetizing

sec- and tert-

not included in the alphabetical order