AS Organic Chemistry

What are the products of complete combustion of alkanes?

Excess O₂ and heat → CO₂ + H₂O

What are the products of incomplete combustion of alkanes?

Limited O₂ and heat → CO + H₂O or C + H₂O

What are the conditions and products of the free-radical substitution of alkanes?

Cl₂ or Br₂ and UV light → haloalkane + HCl or HBr

What is the mechanism of free-radical substitution in alkanes?

Initiation: homolytic fission; Propagation: radical chain reaction; Termination: radicals combine

Why are alkanes generally unreactive?

Strong non-polar C–H bonds and low polarity → low reactivity with polar reagents

What are the conditions and products of electrophilic addition of H₂ to alkenes?

H₂(g) with Pt or Ni catalyst and heat → alkane

What are the conditions and products of electrophilic addition of steam to alkenes?

H₂O(g) with H₃PO₄ catalyst → alcohol

What are the conditions and products of electrophilic addition of HX to alkenes?

HX(g) at room temperature → haloalkane

What are the conditions and products of electrophilic addition of halogens to alkenes?

X₂ at room temperature → dihaloalkane

What is formed when alkenes are oxidised by cold dilute KMnO₄?

A diol

What happens when alkenes are oxidised by hot concentrated KMnO₄?

C=C bond breaks → ketones in secondary, carboxylic acids in primary, and CO2 in zero-th carbons.

What is the product of addition polymerisation of ethene or propene?

Long-chain polymer

What is the mechanism of electrophilic addition in alkenes?

π bond attacks electrophile → carbocation → nucleophile adds

How do inductive effects explain rich-get-richer rule in alkenes?

More electron-donating alkyl groups stabilise the carbocation (tertiary > secondary > primary).

What is the reaction of halogenoalkanes with aqueous NaOH?

Heat → alcohol + NaX

What is the reaction of halogenoalkanes with KCN in ethanol?

Heat → nitrile + KX

What is the reaction of halogenoalkanes with NH₃ in ethanol?

Heated under pressure → amine + HX

How are halogenoalkanes identified using AgNO₃ in ethanol?

Forms AgX precipitate depending on halogen

What is the SN2 mechanism for halogenoalkanes?

Primary halogenoalkanes (one-step)

What is the SN1 mechanism for halogenoalkanes?

Tertiary halogenoalkanes (two-step with carbocation intermediate)

How do secondary halogenoalkanes react?

Via a mixture of SN1 and SN2 depending on structure

What are the products of alcohol combustion?

Reacts with O₂ → CO₂ + H₂O

How are alcohols converted to halogenoalkanes?

React with HX or KBr + H₂SO₄ or SOCl2 or PCl5 or PCl3 with heat

What is the reaction of alcohols with sodium metal?

Forms alkoxide + H₂(g)

How are alcohols oxidised to carbonyl compounds?

Acidified K₂Cr₂O₇ or KMnO₄ and distillation → aldehyde or ketone

How are alcohols oxidised to carboxylic acids?

Acidified K₂Cr₂O₇ or KMnO₄ and reflux → carboxylic acid

How are alkenes formed from alcohols?

Dehydration using heated Al₂O₃ or conc. H₂SO₄ → alkene + H₂O

How are esters formed from alcohols and carboxylic acids?

Reacts with H₂SO₄ or H₃PO₄ catalyst → ester + H₂O

What is the colour change for acidified K₂Cr₂O₇?

Orange to green

What is the colour change for acidified KMnO₄?

Purple to colourless

What is the strength of LiAlH₄ as a reducing agent?

Strong reducing agent (can reduce carboxylic acids)

What is the strength of NaBH₄ as a reducing agent?

Weaker reducing agent

How does alcohol acidity compare to water?

Less acidic than water

How are carbonyl compounds reduced to alcohols?

Using NaBH₄ or LiAlH₄

What is the reaction of carbonyl compounds with HCN?

KCN catalyst and heat → hydroxynitrile

What is the mechanism for nucleophilic addition of HCN to carbonyls?

Nucleophile attacks C=O → tetrahedral intermediate → product

How does 2,4-DNPH test for carbonyl compounds?

Forms orange precipitate

What does Fehling’s test indicate?

Oxidation. Aldehyde/Alcohol gives brick-red precipitate.

What does Tollens’ test indicate?

Oxidation. Aldehyde/Alcohol gives brick-red precipitate.

What is the iodoform test?

Methyl Ketones and Methyl Alcohols + Alkali I₂ (aq) → yellow precipitate of CHI₃ and RCO₂⁻

What is the reaction of carboxylic acids with reactive metals?

Forms salt + H₂(g)

What is the reaction of carboxylic acids with alkalis?

Forms salt + H₂O

What is the reaction of carboxylic acids with carbonates?

Forms salt + H₂O + CO₂(g)

What is esterification of carboxylic acids?

Reacts with alcohol + conc. H₂SO₄ → ester + H₂O

How are carboxylic acids reduced?

LiAlH₄ → primary alcohol

How are esters hydrolysed in acidic conditions?

Dilute acid + heat → carboxylic acid + alcohol

How are esters hydrolysed in alkaline conditions?

Dilute alkali + heat → carboxylate salt + alcohol

How are nitriles hydrolysed to carboxylic acids?

Dilute acid, or alkali + heat + acidify (H+)