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?

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 bromoethane 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 but 2 ene 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 and resulting products?

How are these products used?

• water + ester + acid→ carboxylic acid + alcohol

  (reversible reaction)

• aqueous NaOH + ester→ carboxylate salt + ethanol

  (not reversible) (saponification)

• hydrophobic + hydrophilic properties of sodium or potassium carboxylate used in soap

• 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

What can benzene turn into and what are their respective reaction names (not mechanism)

nitrobenzene - nitration, phenylketones - Friedel-Crafts acylation

benzene - What mechanism?

electrophilic substitution

benzene - What reaction conditions?

• for acylation → AlCl3

• for nitration → H2SO4

Benzene with sulphuric acid and nitric acid - show the equation to form nitronium ions and mechanism

HNO3 + H2SO4 → (NO2+) +( HSO4- )+ H2O

Benzene with ethanoyl chloride and AlCl3

What can nitrobenzene form?

Aromatic amines - phenylamine

What is reaction type?

reduction

What reaction conditions? What is the use of the product?

Sn (tin) and con HCl followed by NaOH (aq)

or

H2 + Ni

• used in dye manufacture

What can amines form?

ammonium salts, Amide and N substituted amides

What is the mechanism?

nucleophilic substitution - ammonium salts

nucleophilic addition elimination - amides and N Substituted amide

What are the reaction conditions?

• halogenoalkane in excess

  ( heat under pressure

• alcoholic conditions )

• room temperature

• ethanoyl chloride and ammonia or primary amine or ethanoic anhydride and ammonia or primary amine

What can nitriles form?

amines

What reaction?

Reduction or hydrogenation

What conditions?

H2 and Ni catalyst or LiAlH4