AQA A-Level Chemistry – Introduction to Organic Nomenclature

13 flashcards summarizing key rules, priorities, examples, and common errors in IUPAC organic nomenclature.

What is nomenclature in organic chemistry?

It is the system of naming organic compounds using standardized rules set by IUPAC.

Why is IUPAC nomenclature important?

It gives every compound a unique, universally understood name, preventing confusion in scientific communication.

What are the three main components of an IUPAC name?

Root (longest carbon chain), prefix (substituents/other functional groups), and suffix (main functional group).

How is the root (stem) of an IUPAC name determined?

By counting the number of carbon atoms in the longest continuous chain that contains the highest-priority functional group.

Give the standard root prefixes for 1–6 carbon atoms.

Meth (1), Eth (2), Prop (3), But (4), Pent (5), Hex (6).

Name six common suffixes and the functional groups they represent.

–ane (alkanes), –ene (alkenes), –ol (alcohols), –al (aldehydes), –one (ketones), –oic acid (carboxylic acids).

What is a position number in organic nomenclature?

A numeral indicating the carbon to which a functional group or substituent is attached, chosen to be as low as possible.

State the main rules for naming branched alkanes.

1) Find the longest chain. 2) Identify and number alkyl substituents. 3) List substituents alphabetically with di-, tri-, etc. 4) Use numbers to show positions.

When a molecule has multiple functional groups, how is one chosen for the suffix?

The group with the highest priority in the IUPAC hierarchy becomes the suffix; others are written as prefixes.

Give the IUPAC priority order of these groups (highest to lowest): COOH, COOR, COCl, CHO, CO, OH, NH₂, C=C, C≡C, alkanes/halogens.

1 Carboxylic acids, 2 Esters, 3 Acid chlorides, 4 Aldehydes, 5 Ketones, 6 Alcohols, 7 Amines, 8 Alkenes, 9 Alkynes, 10 Alkanes/halogens.

Using IUPAC rules, name CH₂=CHCH₂OH.

Prop-2-en-1-ol (alkene at C-2, alcohol given higher priority suffix).

How are halogenoalkanes named? Give an example.

Use the prefixes fluoro-, chloro-, bromo-, or iodo- plus position numbers before the alkane name; e.g., CH₃CHClCH₃ is 2-chloropropane.

List five common mistakes students make in organic nomenclature.

Incorrect chain numbering, ignoring longest chain, omitting position numbers, misusing prefixes/suffixes, not alphabetizing substituents.