← Organic compounds

1 Reading the notation

Organic chemistry has its own shorthand for structures, reactions and mechanisms. Each convention below is used on this page. All the functional groups, in one go Recommended: walks through every functional group you need — the fastest way to get the whole set straight before naming or spectra make sense.

📖 Symbols and conventions in organic chemistry

10 terms

Cover the right column and check you can say what each one means.

R (as in R–OH)
A stand-in for “any carbon chain”. R–OH means any alcohol. The reaction works whatever the chain is. R and R′ (R-prime) in the same equation mean two chains that may be different.
→ vs ⇌
A single arrow means the reaction goes essentially to completion. A double half-arrow (⇌) means it reaches an equilibrium. Esterification is the one you meet.
Conditions above/below the arrow
Written above the arrow: the reagent. Written below: the conditions (solvent, heat, catalyst). Both are needed for full marks.
Curly arrow (double-headed, ⤻)
Shows the movement of a PAIR of electrons. The TAIL starts at the electron source (a lone pair or a bond); the HEAD points where the pair ends up. A single-headed “fish-hook” arrow means one electron, not needed at Level 3.
δ⁺ and δ⁻ (lower-case delta)
A partial charge caused by unequal electron sharing in a polar bond: much smaller than a full + or −. Not the same δ as NMR chemical shift; same Greek letter, different job.
SN1 / SN2
Substitution, Nucleophilic. The number is the molecularity: how many species are in the rate-determining step (1 = just the haloalkane; 2 = haloalkane and nucleophile together).
1°, 2°, 3° (primary, secondary, tertiary)
How many carbon atoms are attached to the carbon bearing the functional group. 1° = one, 2° = two, 3° = three. This single classification decides oxidation products, SN1 vs SN2, and carbocation stability.
E / Z
Geometric isomer labels using Cahn–Ingold–Prelog priority. Z = higher priorities on the same side (zusammen, together); E = opposite sides (entgegen). Z does not always mean cis: assign priorities explicitly.
Prefixes and suffixes
The suffix names the highest-priority group (…-ol, …-one, …-oic acid). A prefix names lower-priority groups (hydroxy-, oxo-, amino-).
Δ (over a reaction arrow)
Means heat is applied. Often written “reflux” or “warm” instead.
✓

Curly arrows in one line

Tail = where the electrons come FROM, head = where they go TO. Always from negative/electron-rich to positive/electron-poor: never the other way round.

Practise just this