3. Naming organic compounds

Substituent

A part of an organic compound that is not part of the longest carbon chain.

Structural Isomer

A compound with the same molecular formula as another but a different structure.

Alkane Naming Rule

Identify the longest chain, name substituents, and assign lowest possible locants.

Alkene Naming Rule

The longest chain must include the double bond, which takes priority in numbering.

Halogenoalkane Naming Rule

Halogens are listed in alphabetical order, and double bonds take priority over halogens.

Alcohol Naming Rule

The hydroxyl (-OH) group gets the lowest locant, and the suffix changes to "-anol."

Aldehyde Naming Rule

The carbonyl (-C=O) group is at the terminal position, and the suffix "-al" is used.

Ketone Naming Rule

The carbonyl (-C=O) gets the lowest locant, and the suffix "-one" is used.

Carboxylic Acid Naming Rule

The functional group (-COOH) is always at the terminal position, and the suffix "-oic acid" is used.

How do you determine the root name of an alkane?

By identifying the longest continuous carbon chain in the molecule.

How are alkyl substituents named?

The suffix “-ane” changes to “-yl” (e.g., methane → methyl).

How should the carbon chain be numbered when naming alkanes?

It should be numbered so that the substituent gets the lowest possible locant

How are multiple substituents arranged in the name of an alkane?

They are listed in alphabetical order before the root name.

When naming alkenes, what takes priority in numbering?

The position of the carbon-carbon double bond gets the lowest possible locant.

What happens when both a halogen and a double bond are present in a molecule?

The double bond takes priority in numbering over the halogen.

What are some common pharmaceutical compounds and their IUPAC names?

• Paracetamol: N-(4-hydroxyphenyl)ethanamide

• Cetirizine: [2-[4-[(4-Chlorophenyl)phenylmethyl]-1-piperazinyl]ethoxy]acetic acid dihydrochloride

• Vitamin D (Drisdol): (3β,5Z,7E,22E)-9,10-secoergosta-5,7,10(19),22-tetraen-3-ol

What does "monosubstituted" mean in the context of alkenes?

A monosubstituted alkene has only one alkyl group attached to the doubly bonded carbon atoms.

How does alkene substitution affect stability?

The more substituted an alkene is, the more stable it becomes due to hyperconjugation and electron-donating effects of alkyl groups.

Why is a tetrasubstituted alkene the most stable?

A tetrasubstituted alkene has four alkyl groups that provide maximum hyperconjugation and inductive effects, stabilizing the π-bond.

How does the number of substituents on a double bond relate to stability?

Stability increases as the number of alkyl substituents on the double bond increases.