Organic reactions

What is the reaction mechanism for hydrogenation?

Electrophilic addition.

What is the reagent and product in hydrogenation?

Hydrogen is the reagent; the product is an alkane.

What are the conditions for hydrogenation?

Nickel catalyst and 150°C.

What are traditional uses of hydrogenation?

Used to make margarine, but less common due to trans fats.

What is the reaction mechanism for adding a halogen to an alkene?

Electrophilic addition.

What is the product of reacting alkenes with halogens?

Dihaloalkanes.

What are the conditions for reacting alkenes with halogens?

Room temperature.

What happens when bromine water is added to alkenes?

Forms a bromoalcohol; orange to colourless.

What is the reaction mechanism for adding hydrogen halides to alkenes?

Electrophilic addition.

What are the reagents and products for adding hydrogen halides to alkenes?

Reagents: HCl, HBr, HI. Products: haloalkanes.

What are the conditions for reacting hydrogen halides with alkenes?

Room temperature.

What is the reaction mechanism for hydration of alkenes?

Electrophilic addition.

What are the reagents and products for hydration of alkenes?

Reagent: steam. Product: alcohol.

What are the conditions for hydration of alkenes?

300–600°C, phosphoric acid catalyst, 70 atm.

What is the reaction mechanism for reacting haloalkanes with aqueous alkali?

Nucleophilic substitution.

What are the reagents and products for reacting haloalkanes with aqueous alkali?

50/50 ethanol and water; products: alcohol + halide ion.

What are the conditions for reacting haloalkanes with aqueous alkali?

Warm.

What is the reaction mechanism for reacting haloalkanes with water?

Nucleophilic substitution.

What are the reagents and products for reacting haloalkanes with water?

Water in ethanol; products: alcohol + hydrogen halide.

What are the conditions for reacting haloalkanes with water?

Heat under reflux.

How can you test for halides using this reaction?

Add aqueous silver nitrate; silver halide precipitate forms.

What is a nucleophile?

A negative or slightly negative species that donates an electron pair.

What is an electrophile?

An electron-deficient species that accepts an electron pair.

What is the reaction mechanism for reacting ammonia with a haloalkane?

Nucleophilic substitution.

What are the reagents and products for reacting excess ammonia with haloalkanes?

Ethanolic ammonia; forms amines + ammonium salt.

What are the conditions for reacting ammonia with haloalkanes?

Heat in a sealed tube.

What is the reaction mechanism for reacting alcoholic alkali with haloalkanes?

Elimination.

What are the reagents and products for reacting alcoholic alkali with haloalkanes?

Ethanolic NaOH or KOH; produces an alkene + water.

What are the conditions for reacting alcoholic alkali with haloalkanes?

Heat under reflux.

What is the reaction mechanism between potassium cyanide and a haloalkane?

Nucleophilic substitution.

What are the reagents and products for reacting potassium cyanide with haloalkanes?

KCN in ethanol; produces a nitrile + halide ion.

What are the conditions for reacting potassium cyanide with haloalkanes?

Heat under reflux.

What is the reaction mechanism between alkanes and halogens?

Free radical substitution.

What are the reagents and products when reacting alkanes with halogens?

Halogens; products: haloalkanes + hydrogen halides.

What are the conditions for reacting alkanes with halogens?

UV light.

What happens when alcohols combust?

They form carbon dioxide and water.

What are the reagents and products for bromination of alcohols?

NaBr or KBr + conc H₂SO₄ → HBr; forms bromoalkane + water.

What are the reagents and products for bromination or iodination using phosphorus halides?

Halogen + red phosphorus → phosphorus halide; reacts to form haloalkane + phosphoric acid.

How do you purify a bromoalkane?

Use a separating funnel; remove aqueous layer; wash with hydrogen carbonate.

What are the reactants and products when reacting phosphorus chlorides with alcohols?

PCl₃ reacts to form chloroalkanes + phosphoric acid.

What are the reactants and products for the test for alcohols with PCl₅?

PCl₅ reacts violently to form chloroalkanes, HCl gas, and POCl₃.

What are the conditions for the test for alcohols with PCl₅?

Remove substances that react with PCl₅; room temperature.

What are the conditions for chlorination of alcohols?

Room temperature.

What are the reactants and products during chlorination of alcohols?

Alcohol + conc HCl → chloroalkane + water.

What are the reactants and products for partial oxidation of primary alcohols?

K₂Cr₂O₇ + dilute H₂SO₄ + excess alcohol → aldehyde + water.

What are the conditions for partial oxidation of primary alcohols?

Distil aldehyde as it forms; heat.

What is the functional group of an aldehyde?

C=O bonded to H.

What are the reactants and products for full oxidation of primary alcohols?

Excess oxidising agent + dilute H₂SO₄ → carboxylic acid + water.

What are the conditions for full oxidation of primary alcohols?

Heat under reflux; distil acid after reaction.

What happens when tertiary alcohols are oxidised?

No reaction.

What are the reactants and products for oxidising secondary alcohols?

Acidified potassium dichromate; forms a ketone.

What is the functional group of a ketone?

C=O (carbonyl).

What is the colour change when acidified potassium dichromate reacts with alcohols?

Orange to green.

What is the reaction mechanism between potassium manganate and alkenes?

Nucleophilic substitution.

What are the reactants and products when adding potassium manganate to alkenes?

Acidified or alkaline KMnO₄; forms a diol.

What is the positive colour change with acidified potassium manganate (VII)?

Purple to colourless.

What is the positive colour change with alkaline potassium manganate?

Purple → dark green → brown precipitate.