Mechanisms Guide

- What can it be made into?, What mechanism, What conditions (environment and substances), How to draw

Alkanes - What can it be made into?

Alkanes - What can it be made into?

Halogenoalkanes

Alkanes - What mechanism?

Free Radical substitution

Alkanes - What conditions?

• UV light

Draw mechanism for Cl2 and methyl butane under UV light? Name stages

• Initiation

  Cl2 - 2Cl*

• Propagation

  CH3CH2CH(CH3)CH3 + Cl* → CH3CH2CH(CH3)CH2* + HCl

  CH3CH2CH(CH3)CH2* + Cl2 → CH3CH2CH(CH3)CH2Cl + Cl*

• Termination

  Cl* + Cl* → Cl2

  CH3CH2CH(CH3)CH2* + CH3CH2CH(CH3)CH2* - CH3CH2CH(CH3)CH2CH2CH2CH(CH3)CH3

  Cl* + CH3CH2CH(CH3)CH2* → CH3CH2CH(CH3)CH2Cl

Halogenoalkanes - What can it be made into?

Alcohols, Amines, Nitriles, Alkenes

Halogenalkanes - What mechanisms?

Nucleophilic Substitution → Alcohols, Amines, Nitriles

Elimination → Alkenes

Halogenoalkanes - What conditions?

• Nucleophilic Substitution Alcohol - heated under reflux, sodium or potassium hydroxide solution, in a (mixture of ethanol) and water

• Nucleophilic Substitution Amines - Heated in sealed container, Ammonia solution in ethanol, ammonia in excess

• Nuclephilic Substitution Nitriles - heated under reflux, with a solution of sodium or potassium cyanide, in ethanol

• Elimination Alkenes - higher temperatures, concentrated solution of sodium or potassium hydroxide, pure ethanol as the solvent.

Halogenoalkanes - Draw mechanism for bromomethane in aqueous conditions under gentle reflux with NaOH.

Halogenoalkanes - Draw mechanism for potassium cyanide in ethanol with bromomethane, heated under reflux

Halogenoalkanes - Draw first mechanism for bromomethane with ammonia in ethanol in sealed container heated with ammonia in excess

Halogenoalkanes - Draw second mechanism for bromomethane with ammonia in ethanol in sealed container heated with ammonia in excess

Halogenoalkanes - Draw mechanism for bromomethane with ethanolic OH- ions at high temperatures

Alkenes - What can it be made into?

halogenoalkanes, alkyl hydrogensulphates, alcohols

Alkenes - What mechanism?

electrophilic addition, direct hydration

Alkenes - What conditions?

Cold - e.g.pure bromine liquid, sulphuric acid

Direct hydration - aqueous conditions, 300 degrees C, phosphoric acid catalyst, high pressure

Alkenes - Draw mechanism for ethene with H-Br

Alkenes -Draw mechanism for ethene with Br2 (l)

Alkenes -Draw mechanism for ethene with H2SO4 (l)

Alkyl hydrogen sulphates - What can it be made into?

Alcohols

Alcohols - What can it be made into?

Alkenes, Aldehydes, Ketones, Carboxylic acids

Alcohols - What mechanisms?

Elimination

Oxidation

Alcohols - what conditions

Elimination - excess hot conc sulphuric acid, aluminium oxide catalyst

Oxidation - potassium dichromate K2Cr2O7 2- ->Cr3+

, H2SO4 heat and distill or heat under reflux.

Alcohols - Draw ethanol with hot con sulphuric acid and aluminium oxide catalyst

Aldehydes and Ketones - What can they be made into?

hydroxynitriles, alcohols

Aldehydes and ketones - What mechanism

Nucleophilic addition

Aldehydes and Ketones - What conditions?

• NaBH4 aqueous → alcohol

• KCN + H2SO4 → hydroxynitrile

Aldehydes and Ketones - Draw mechanism for ethanal with aqueous NaBH4

Aldehydes and Ketones - Draw mechanism for propanone with KCN and H2SO4

Name product

2 Hydroxy- methyl propanenitrile

Carboxylic acids - What can it be made into?

• esters

• carboxylate salts

Carboxylix acids - What type of reactions?

• esterification - dehydration

Carboxylic acids - What conditions?

• esters —> strong acid catalyst e.g. H2 SO4

• carboxylate salts → Na2CO3 (reaction of acid so CO2 and water product)

Esters - What can they be made into?

• Carboxylic acid and alcohol

• carboxylate salt and alcohol

• another ester (transesterification)

Esters - What are the reaction types?

• hydrolysis

• transesterification

Esters - What are the reaction conditions?

• water + acid → carboxylic acid + ethanol

  (reversible reaction)

• aqueous NaOH → carboxylate salt + ethanol

  (not reversible)

• 3 methanol and triglyceride → methyl long chain carboxylate (biodiesel) + glycerol

Acyl chlorides - What can they be made into?

carboxylic acid, ester, amide, N-substituted amide

Acyl chlorides - What mechanisms?

nucleophilic addition -elimination

Acyl chlorides - What conditions?

• water—> carboxylic acid

• alcohol → ester

• ammonia → amide

• primary amine → N - substituted amide

Acyl chloride - Draw mechanism for ammonia with ethanoyl chloride

HCl product

Acid anhydrides - What can they be made into?

carboxylic acid, ester, amide, N-substituted amide

Acid anhydrides - What mechanism?

nucleophilic addition-elimination

Acid anhydrides - What conditions?

water - carboxylic acid

alcohol - ester

ammonia - amide

primary amine - N-substituted amide

Acid anhydride - Draw mechanism/reaction for ethanoic anhydride with salicylic acid