// CHEMISTRY L4 — FURTHER ORGANIC
Same backbone, different endings.
Swap a hydrogen on a carbon chain for an –OH and you've made an alcohol; add another twist and you've got acids and the fruity-smelling esters. React an acid with an alcohol below and name the ester you make.
// FIG. 01 — THE ESTERIFICATION BENCH
CARBOXYLIC ACID
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YOU MADE THE ESTER
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{{ smell }} A drop of concentrated sulfuric acid catalyses the reaction, and the water is pulled out from the acid's –OH and the alcohol's –H.
// THE FUNCTIONAL GROUPS
A functional group is the reactive part of a molecule — the bit that decides how it behaves. Molecules sharing a functional group form a homologous series: same general formula, similar reactions, gradually changing physical properties as the chain grows.
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// ALCOHOLS — THE VERSATILE MIDDLE
Alcohols (like ethanol, the one in drinks and hand-sanitiser) contain the –OH group. They burn cleanly as fuels, dissolve things water can't, and — crucially — can be oxidised: gentle oxidation turns a primary alcohol into a carboxylic acid (this is exactly what turns wine into vinegar as it goes off). That makes alcohols a key stepping-stone in building bigger molecules.
// ESTERS — SMELLS & MATERIALS
Esters form when a carboxylic acid reacts with an alcohol (the reaction you ran above). Small esters are volatile and sweet-smelling — they give fruits their scent and are used in perfumes and flavourings. Chain many ester links together and you get polyesters: the plastic in drink bottles and clothing fibres.
// REFERENCES & FURTHER READING
Cross-check against your own exam board's specification (AQA, Edexcel, OCR, SQA).