AS Organic Reactions and Conditions

Reagent and Conditions Required:

Limited Supply of Oxygen

Explanation:

CO is formed rather than CO₂ due to limited availability of O₂

Reagent and Conditions Required:

High temperature

Explanation:

O₂ and N₂ are present in air, only high temperature provided by car engines is able to break apart the stable N-triple-bond-N

Reagent and Conditions Required:

High temperature and high pressure

Explanation:

Produces high % of alkenes

Energetic conditions are required as no catalyst = high activation energy

Reagent and Conditions Required:

Zeolite catalyst and high temperature

Explanation:

Produces cycloalkanes and aromatic alkanes

High temperature still required (but not as high as thermal cracking)

Memory trick = ‘C’s… catalytic cracking= cyclo…

FREE RADICAL SUBSTITUTION

Reagent and Conditions Required:

Reagent = Halogen

Condition = UV light

Explanation:

Alkane is very unreactive due to strong C-C and C-H bonds (bonding pair is held close to nuclei) and non-polar bonds. Reactive free-radicals must be formed for reaction to initiate

ELIMINATION

Reagent and Conditions Required:

Reagent = KOH

Conditions = aqueous ethanol (alcoholic) for solvent AND high temperature

Explanation:

Aqueous (water) splits the KOH to K⁺ and OH^-

Ethanol acts as a solvent: mixes polar OH^- with relatively non-polar haloalkane.

Hotter temperature causes elimination

OH^- acts as a base – accepts H⁺

Memory trick: ‘E’s Elimination – ethanolic

NUCLEOPHILIC SUBSTITUTION

Reagent and Conditions Required:

NH₂

Explanation:

Remember x2 NH₂ required:

1st NH₂ produces a positive charge on the N as neutral nucleophile donates a lone pair and form a new bond.

2nd NH₂ acts as a base and accepts an H⁺

NUCLEOPHILIC SUBSTITUTION

Reagent and Conditions Required:

Reagent = KCN

Conditions = Ethanol/water mixture

Explanation:

Aqueous (water) splits the KCN to K⁺ and CN^-

Ethanol acts as a solvent: mixes polar CN^- with relatively non-polar haloalkane

NUCLEOPHILIC SUBSTITUTION

Reagent and Conditions Required:

Reagent = KOH

Conditions = Water and lower temperature than elimination

(NO ETHANOL)

Explanation:

OH^- acts as a nucleophile ­– donates pair of electrons and forms bond with slightly positive carbon.

Memory trick = Substitutes get cold – but careful the mixture is still warmed (just not as hot as elimination)

ELECTROPHILIC ADDITION

Reagent and Conditions Required:

Reagent = H₂

Conditions = Ni Catalyst and heat

Explanation:

Dipole induced in H₂ by high electron density of C=C

ELECTROPHILIC ADDITION

Reagent and Conditions Required:

HX (e.g. HBr) OR X₂ (e.g. Br₂)

Explanation:

Slightly positive H attracted to high electron density of C=C

Dipole induced in non polar Br₂ by high electron density of C=C

ELECTROPHILIC ADDITION OF H₂SO₄ FOLLOWED BY HYDROLYSIS BY H₂O

Reagent and Conditions Required:

Reagent = H₂O (steam)

Conditions = Conc. sulfuric acid catalyst and high temperature

Explanation:

Sulfuric acid reacts with alkene in first step and forms a ….. hydrogen sulfate.

This then is replaced by OH of water

Reagent and Conditions Required:

Conditions = Conc. sulfuric acid catalyst and heat

Reagent and Conditions Required:

Heat

Distillation

Acidified K₂Cr₂O₇ (potassium dichromate)

Explanation:

Product can be removed by distillation upon formation due to lower boiling point than reactants. –OH -> C=O and therefore product loses ability to hydrogen bond

Reagent and Conditions Required:

Heat

Reflux

Acidified K₂Cr₂O₇ (potassium dichromate)

Conditions:

Initial products (intermediates) aldehyde must remain in the reaction mixture to be oxidised again to carboxylic acid

FERMENTATION

Reagents and Conditions Required:

Yeast

*Between 25 and 42^oC

Anaerobic

Neutral pH

Explanation:

Higher temperatures would kill the yeast fungi. Lower temperatures and the reaction would be too slow

= most important conditions