Reaction Cards

The 2° carbocation is more stable than the 1°, so Br ends up on C-2.

Sodium reduces the C-X bond, generating a radical/organosodium that couples.

Ni adsorbs H₂ and the alkene, weakening the H–H and π bonds so hydrogen adds syn across the double bond.

Used industrially to convert vegetable oils (containing C=C double bonds) into solid margarine and cooking fats via catalytic hydrogenation.

Br₂ is polarised by the π electrons; anti addition through a cyclic bromonium ion places Br on both carbons.

1,2-Dibromoethane was historically used as a fuel additive (anti-knock agent) and is still used as a fumigant in soil treatment for nematodes.

The 2° carbocation is more stable than the 1°, so the proton adds to the terminal carbon and Br to the middle carbon.

Alkyl halides like 2-bromopropane are key intermediates in pharmaceutical synthesis — used to introduce isopropyl groups into drug molecules.

The poisoned palladium is too weak to reduce the alkene further, so hydrogenation stops cleanly at ethene.

Lindlar-catalyst reduction is used in the synthesis of natural pheromones and insect attractants where cis-double bond geometry is critical.

Aromatic stability means benzene substitutes rather than adds — and it needs the stronger Br⁺ electrophile from FeBr₃.

Bromobenzene is a reagent in Grignard reactions and is used to manufacture pharmaceuticals, agrochemicals, and flame retardants.

CaO keeps the NaOH dry and active; the carboxylate's C–C bond breaks, expelling carbon dioxide as carbonate.

Decarboxylation is used industrially to produce methane (biogas) from organic acids, and in amino acid metabolism in living cells.

Sodium reduces each C–X bond to a reactive organosodium intermediate, which then couples with a second molecule to form a new C–C bond.

AlCl₃ is a Lewis acid that generates the electrophilic carbocation; the aromatic π cloud then substitutes a ring hydrogen for the alkyl group.

The resonance-stabilised acylium ion (CH₃CO⁺) is the electrophile; unlike alkylation, it can't rearrange, so acylation gives a clean single product.

Phosphorus converts the acid to an acyl bromide, whose enol is far more reactive toward Br₂ at the α-position than the acid itself.

In water, OH⁻ acts as a nucleophile (SN2). In ethanol it acts as a base, favouring elimination — so the solvent decides.

Hydrolysis of haloalkanes is a key step in producing industrial alcohols and in the breakdown of organohalide pollutants in the environment.

In ethanol, KOH behaves as a strong base and removes a β-H (E2), rather than as a nucleophile attacking carbon.

Elimination reactions are used to manufacture alkenes (ethene, propene) that serve as monomers for plastics like polyethylene and polypropylene.

KCN is largely ionic, so the more nucleophilic carbon of CN⁻ attacks, forming a C–C bond (the nitrile).

Nitrile synthesis via haloalkanes is used to make nylon-6,6 precursors (adiponitrile) and pharmaceutical intermediates.

Excess NH₃ ensures the primary amine forms predominantly rather than reacting on to secondary/tertiary amines.

Amines produced this way are used in drug synthesis — antihistamines, local anaesthetics, and neurotransmitter analogues all contain amine groups.

Sodium reduces the C–Cl bond to a reactive organosodium intermediate, which then couples with a second molecule.

The Wurtz reaction was historically used to build carbon chains; today it inspires organolithium and Grignard coupling strategies in fine chemical synthesis.

The C–Cl bond has partial double-bond character from ring resonance, so only forcing conditions drive substitution.

The Dow Process produces phenol at industrial scale — phenol is the starting material for aspirin, bisphenol-A (plastics), and antiseptics like TCP.

The Cu(I) salt catalyses a radical substitution: the C–N₂⁺ bond breaks, N₂ leaves, and the halide takes its place on the ring.

Cuprous salts can't deliver fluoride well, so the dry fluoroborate salt is thermally decomposed instead, releasing F to the aromatic carbon.

In water, OH⁻ acts as a nucleophile rather than a base, so substitution outcompetes elimination.

Hydrolysis of haloalkanes is a key step in producing industrial alcohols and in the breakdown of organohalide pollutants in the environment.

In ethanol, OH⁻ behaves as a base (E2), abstracting the β-H anti to the leaving group.

Dehydrohalogenation is used to manufacture alkenes that serve as monomers for plastics, and in the synthesis of drugs with C=C bonds.

KMnO₄ has Mn in +7. It accepts electrons from the carbon chain, oxidizing -OH all the way to -COOH.

Base generates dichlorocarbene (:CCl₂), an electrophile the phenoxide ring attacks ortho; hydrolysis then unmasks the aldehyde.

The phenoxide ring is electron-rich enough to attack CO₂ as a weak electrophile, carboxylating the ortho carbon.

PCC is anhydrous and mild, so the aldehyde isn't hydrated to the gem-diol that strong oxidisers oxidise further.

This reaction occurs in your liver when you metabolise alcohol — alcohol dehydrogenase converts ethanol to ethanal (acetaldehyde), which causes hangover symptoms.

The acid converts –OH to a better leaving group (–OH₂⁺); E1 elimination then forms the alkene.

Industrial ethanol dehydration over Al₂O₃ produces ethene for making polyethylene — one of the world's most produced plastics.

SOCl₂ converts –OH into a chlorosulfite leaving group, which Cl⁻ then displaces.

Ethyl chloride is used as a local anaesthetic spray (coolant) in sports medicine to numb skin instantly before minor procedures.

The lone pair on oxygen donates into the ring, making it highly reactive to electrophilic Br⁺.

2,4,6-Tribromophenol is a widely used flame retardant added to electronics circuit boards, textiles, and building materials.

Dichlorocarbene (:CCl₂) is the electrophile; the phenoxide directs it ortho, then hydrolysis gives the aldehyde.

Salicylaldehyde is used in perfumery (violet-like scent) and as a chelating agent in analytical chemistry.

The electron-rich phenoxide attacks the electrophilic carbon of CO₂; the ortho product dominates by H-bond stabilisation.

Salicylic acid is converted to aspirin (acetylsalicylic acid) — the world's most widely used painkiller. Also used in acne treatments and skin peels.

The alkoxide is a strong nucleophile; a primary alkyl halide gives clean SN2 ether formation.

Diethyl ether produced via Williamson synthesis was the first general anaesthetic used in surgery (1846) and is still used as a solvent in labs.

Lacking α-H, the only path is a disproportionation — hydride transfers from one carbonyl to another, oxidising one and reducing the other.

Base removes an acidic α-hydrogen to form an enolate nucleophile, which adds to a second carbonyl carbon — a C–C bond-forming addition.

The aldehyde is oxidised to a carboxylate while Ag⁺ is reduced to Ag⁰; ketones can't do this, so the test distinguishes the two.

The aldehyde is oxidised to a carboxylate while Cu²⁺ is reduced to Cu⁺ (as red Cu₂O); aromatic aldehydes and ketones don't respond.

Under strongly acidic conditions the amalgamated zinc supplies electrons that fully reduce C=O to CH₂; basic substrates instead use Wolff-Kishner.

Hydrazine forms the hydrazone; hot base then drives off N₂, reducing C=O to CH₂ without acid — useful for acid-sensitive compounds.

Pd is poisoned with BaSO₄ (and sometimes sulfur/quinoline) to weaken it, halting reduction at –CHO instead of carrying on to –CH₂OH.

SnCl₂/HCl delivers just enough hydride to stop at the imine salt; aqueous workup then hydrolyses it cleanly to –CHO.

The chromyl chloride forms an isolable complex at the benzylic carbon that, on hydrolysis, gives the aldehyde rather than over-oxidising to the acid.

NaBH₄ delivers H⁻ to the electrophilic carbonyl carbon, reducing the ketone to a 2° alcohol.

Propan-2-ol (isopropanol/IPA) is the active ingredient in hand sanitisers, rubbing alcohol, and disinfectant wipes.

Base and Br₂ form an N-bromoamide that rearranges via an isocyanate; the alkyl group migrates to nitrogen, shortening the chain by one carbon.

LiAlH₄ is a powerful reducing agent that reduces –COOH (and esters, amides) to –CH₂OH.

Reduction of carboxylic acids to alcohols is used in the biosynthesis of fatty alcohols found in cosmetics, lotions, and emulsifiers.

SOCl₂ activates the hydroxyl as a leaving group; chloride substitutes to form the acyl chloride.

Ethanoyl chloride (acetyl chloride) is used to introduce acetyl groups in drug synthesis — aspirin and paracetamol are made via acetylation.

Heating the ammonium carboxylate drives off water, forming the C–N amide bond.

Amide bond formation is the basis of peptide (protein) synthesis and the production of paracetamol (acetaminophen) — a common painkiller.

Soda lime supplies the base/heat to cleave the C–COO⁻ bond, releasing CO₂ (as Na₂CO₃) and the alkane.

Decarboxylation of organic acids is exploited in biogas digesters to produce methane fuel from food and agricultural waste.

P converts the acid to an acyl halide whose enol is halogenated at the α-position — the HVZ mechanism.

Chloroacetic acid produced by HVZ reaction is used to make the herbicide 2,4-D, carboxymethylcellulose (food thickener E466), and cosmetic preservatives.

Mn(VII) is a powerful oxidiser; with excess and acid it oxidises 1° alcohols fully to carboxylic acids.

Vinegar is 5–8% ethanoic acid made by oxidising ethanol in fermented liquids — used for centuries as a food preservative and condiment.

Acid protonates the carbonyl; the alcohol adds and water leaves in a reversible equilibrium driven by excess reagent.

Ethyl ethanoate (ethyl acetate) is used as a solvent in nail polish remover, printing inks, adhesives, and as a flavour in confectionery.

Poisoning Pd lowers its activity so the aldehyde isn't reduced on to a primary alcohol.

The Rosenmund reduction is used in pharmaceutical synthesis to make aldehydes selectively — without over-reducing to the alcohol.

Carboxylic acids are Brønsted acids; a base removes the –COOH proton to form the carboxylate.

Sodium ethanoate is used in hand warmers (supersaturated solution that crystallises exothermically), food preservation (E262), and as a buffer in biochemistry labs.