Edexcel A-level Chemistry Organic Chem Reactions Save

Alkane to Halogenoalkane

Halogen and UV light (free radical substitution)

Alkene to Alkane

Hydrogen gas, Nickel catalyst and 150°C (addition)

Use of catalytic hydrogenation

Manufacture of margarine from unsaturated vegetable oils

Alkene to Dihalogenoalkane

Add bromine LIQUID and shake (electrophilic addition)

Alkene to hydroxyhalogenoalkane

Add bromine WATER and shake (electrophilic addition: CH2(OH)CH2(Br)

Alkene to Alcohol

Steam (water), phosphoric (v) acid catalyst (reversible)

Alkenes to diol

Shake in acidified potassium manganate solution: purple solution decolourises (oxidation)

Alkene to Halogenoalkane

Hydrogen halide

Halogenoalkane to Alcohol

Reflux with aqueous KOH

Halogenoalkane with aqueous silver nitrate in ethanol

Forms alcohol + halide ion --> forms AgX precipitate (water acts as nucleophile)

Halogenoalkane to Nitriles

Reflux with KCN in ethanol

Halogenoalkane to Primary amine

Heat in sealed tube with excess conc ammonia

Halogenoalkane to Alkene

Reflux with KOH in ethanol (elimination)

Alcohol to Iodoalkane

Red phosphorus and iodine

Alcohol to Chloroalkane

PCl5

Alcohol to Bromoalkane

KBr, 50% conc H2SO4

Primary alcohol to Aldehyde

K2Cr2O7, H2SO4, heat and distil

Alcohol to Alkene

Concentrated phosphoric (v) acid + warm

Primary alcohol to carboxylic acid

Excess K2Cr2O7, H2SO4 and heat under reflux

Secondary alcohol to Ketone

Excess K2Cr2O7, H2SO4 and heat under reflux

Aldehyde to Primary alcohol

LiAlH4 in dry ether

Ketone to Secondary alcohol

LiAlH4 in dry ether

Carbonyl compound to hydroxy nitrile + conditions

HCN in KCN (CN from KCN acts as catalyst), pH6-8

Nitrile to Carboxylic acid

Reflux with dilute HCl//OH- then strong acid (hydrolysis)

Carboxylic acid to Primary alcohol

LiAlH4 in dry ether --> hydrolysis by dilute acid

Carboxylic acid to Acyl chloride

Phosphorous (v) chloride

Alcohol + Carboxylic acid to Ester

Heat with concentrated H2SO4 (reversible)

Testing ester by smell

Add dilute sodium hydrogencarbonate solution --> smell

Ester to Alcohol + Carboxylic acid

Reflux with dilute acid (HCl or H2SO4)

Ester to Alcohol + Carboxylate ion

Reflux with dilute alkali (NaOH)

Acyl chloride to Ester

Alcohol (quicker reaction than carboxylic acid + alcohol)

Acyl chloride to primary amide

NH3 (in excess NH3, white smoke of NH4Cl formed from NH3 + HCl)

Acyl chloride to N-subsitututed amide

Primary amine

Benzene to bromobenzene

Br2 + Fe --> FeBr3 catalyst formed in situ

Arene to Alkyl benzene

Reflux with chloroalkane and AlCl3 (Friedel-Crafts)

Arene to Phenylketone

Reflux with acyl chloride and AlCl3 (Friedel-Crafts)

Benzene to Nitrobenzene

Warm with concentrated HNO3 and H2SO4

Phenol to 2,4,6-Tribromophenol

Shake with bromine water

Observations of 2,4,6,-tribromophenol

white ppt, antiseptic properties

Amine + water

R-NH3+ + OH- (alkaline solution, reversible reaction)

Amine + dilute acid

R-NH3+Cl- salt

Amine + acyl chloride

Amide + HCl

Amine + Halogenoalkane

R-(NH2+Cl-)-R

C2H5NH2 amine + [Cu(H2O)6]2+

[Cu(C2H5NH2)4(H2O)2]2+ complex ion + 4H2O

Halogenoalkane to straight chain amine

Excess conc ammonia in ethanol, heat in sealed tube

Nitrile to Primary amine

LiAlH4 in dry ether followed by dilute acid

Nitrobenzene to Aromatic amine

Reflux with tin and concentrated HCl

Amine to N-Substituted amide

Add acyl chloride

Grignard reagent formation

Halogenoalkane + Mg --> R-MgX --> R- + MgX+

Grignard reaction with CO2

Add dilute acid --> carboxylic acid

Grignard reaction with carbonyl in dry ether

Add dilute acid --> primary alcohol

Thermal Cracking

- High temperatures (1000C)
- High pressure (up to 70atm)
- Produces ALKENES
- E.g. ethene --> polyethene

Catalytic Cracking

- Zeolite catalyst
- Slight pressure
- High temperature (450C)
- Produces AROMATICS

Reformation

Alkanes --> cycloalkanes/ aromatic hydrocarbons
- Straight chain alkanes are a lot more likely to 'knock'
- Pt Catalyst (ct)

Alkene → Alkane

- Hydrogen
- 150C
- Ni ct
- Hydrogenation
- Irreversible

Alkene → Halogenoalkane

- Electrophilic Addition
- Bromine water
- Orange --> colourless
- Irreversible

Alkene → Alcohol

- H20 (steam)
- 300C
- Phosphoric Acid
- Reversible rxn

Alkenes → Diol

- Acidified potassium manganate
- Purple to colourless

Halogenoalkane → Alcohol

- Water
- warm Aqueous KOH and REFLUX

Compare reactivities of halogenoalkanes

- aqueous AgNO3, ethanol and R-X

R-X and H2O --> R-OH and X-

Halogenoalkanes → Nitriles

- REFLUX
- KCN (ethanol)

Halogenoalkanes → amines

- NH3 (ethanol)
- primary amine -> secondary ->

Halogenoalkane → alkene

- KOH (ethanol)
- REFLUX

PRODUCTS: H20 and KBr

Alcohol → chloroalkanes

- PCl5 or HCl (tertiary)
ROH + PCl5 --> POCl3 + RCl + HCl

Alcohol → bromoalkane

- KBr and 50% conc sulfuric acid
- RTP

Alcohol → iodoalkane

- red phosphorus and iodine in situ

ROH +PI3 --> RI + H3PO3

Alcohol → alkene

- H3PO4
-Heat mixture

alcohol --> alkene and water

Refluxing

Organic reactions are allow and are flammable/ volatile/
Reflux = mixture is heated in a flask with a vertical Liebig condenser

Tollen's Reagent

Colourless solution of AgNO3 (ammonia)
+ve = silver mirror
Ag(NH3)2+ + electron --> Ag + NH3

Fehling's solution

Blue solution of complexed Cu2+ dissolved in NaOH
Aldehyde: blue --> red
Ketone blue --> blue

Aldehyde → primary alcohol
Ketone → secondary alcohol

LiAlH4 in dry ether

Carbonyl → hydroxynitrile

NUCLEOPHILIC ADDITION
- HCN → H+ + CN-
CN- attacks oxygen on C=O bond
HCN is a highly toxic gas, instead in the lab acidified KCN is used
- carbonyl is planar so the CN- can attack it from either side creating a racemic mixture

2,4 -DNPH

2,4 -DNPH is dissolved in methanol and conc H2SO4
+ve = bright orange ppt = carbonyl group (not COOH)
orange ppt can be recrystallised --> measure bp

Carbonyl and Iodine

- carbonyls with a methyl carbonyl group (so ethanal or ketone)
- produced CHI3 = yellow ppt and antiseptic smell

Primary alcohol → COOH

- XS acidified potassium dichromate
- orange --> green
REFLUX

Nitrile --> COOH

hydrolysis of nitriles
- Reflux with HCl and distill off COOH

COOH and NaOH

COOH and NaOH→ COO-Na+ and H20

COOH and Na

COOH and Na → COO- and H2

COOH → primary alcohol

LiAlH4 in dry ether

COOH → acyl chloride

COOH and PCl5 --> COCl + PCl3 + HCL

Making esters from alcohols and COOH

- Heat a COOH and an alcohol with AN ACID Ct
- Sulfuric acid
ESTERIFICATION
e.g. ethanoic acid and ethanol --> ethyl ethanoate and water
REVERSIBLE RXN
Collect the product by distillation - 80C
Ethyl ethanoate is pear smelling and is used as a pineapple flavouring and a solvent in chromatography

Acid hydrolysis of esters

ester + water --> alcohol + COOH
- reflux with dilute HCl
- reversible rxn

Base hydrolysis of esters

ester + OH- → COO- + ethanol

Acyl Chloride and water

- vigorous rxn in cold water
- COOH + HCl made

Acyl Chloride and alcohols

- vigorous rxn in alcohol
- Ester + HCl is made

Acyl Chloride and conc NH3

- vigorous rxn at RTP
- Amide + HCl rxn

Acyl Chloride and amines

- vigorous rxn at RTP
- N-subsitiuted amide made

Benzene --> bromobenzene

Br2 + FeBr3 --> FeBr4- + Br+

Friedel-Crafts Alkylation

- Adds alkyl group onto benzene
- Reflux
- Halogen Carrier
C6H6 + RX --> C6H5R + HX

Friedel Crafts Acylation

- Adds an alkyl group onto benzene using a halogen carrier
C6H6 + RCOCl --> C6H5COR + HCl
Reflux benzene with acyl chloride

Benzene --> Nitrobenzene

- conc sulfuric acid and nitric acid
HNO3 and H2SO4 --> H2NO3+ + HSO4-
H2NO3 --> NO2+ + and H2O
If you only want to add one NO2 group (mono nitration) then keep the temperature below 55C --> above this temperature there will be further substitutions

Why is phenol more reactive than benzene?

Phenol has an -OH group, where one of the lone pair of electrons in a p orbital overlaps with the delocalised pi bonds. The lone pair are PARTIALLY delocalised --> increases the electron density of the ring. This makes the tin more likely to be attacked by electrophiles.

Phenol and bromine water

If you shake phenol with orange bromine water it will decolourise.
-OH gourd encourages further substitution.
- final product of Br2 and benzene --> 2,4,6-tribromophenol.
- 2,4,6-tribromophenol is insoluble in water and precipitates out of the mixture --> smells of antiseptic.

Making aspirin

Salicylic acid and ethnanoic anhydride --> aspiring and ethanoic acid
ESTERIFICATION RXN.
1) Add ethanoic anhydride and phosphoric acid to salicylic acid.Add a few drops of phosphoric acid.
2) warm the mixture 50C and leave for about 15mins
3) Add cold water to the solution and place into an ice bath. Aspirin crystals should form.
4) Filter the crystals under reduced pressure.
5) Recrystallise the aspirin in a mixture of water and ethanol.