Organic Synthesis Flashcards
Alkanes –> Halogenoalkanes
Mechanism: Free Radical Substitution
Reagent: Chlorine/Bromine
Conditions: UV Light
Alkene –> Alkane
Addition/ Reduction
Reagent: Hydrogen
Conditions: Ni catalyst
N.B. CANNOT use LiAlH4 as it is a source of hydride ions, which will be repelled by electron rich double bond.
Alkene –> Dihalogenoalkane
Mechanism: Electrophilic Addition
Reagent: Bromine/ Chlorine (dissolved in organic solvent)
Conditions:Room temperature
Alkene –> Halogenoalkane
Mechanism Electrophilic Addition
Reagent: HCl/HBr
Conditions: Room temperature
Alkene –> Bromoalcohol
Addition
Reagent: Bromine water
Observation: brown to colourless
Test for carbon double bond
Alkene –> Bromoalcohol
Addition
Reagent: Bromine water
Observation: brown to colourless
Test for carbon double bond
Alkene –> Diol
Oxidation
Reagent: KMnO4 in acidified solution
Conditions: Room temperature
Observation: purple colour of MnO4- ions decolourises
Alkene –> Alcohol
Hydration
Reagent: water
Conditions: High T (300-600), High pressure (70 atm) and conc H3PO4 acid catalyst
Alkene –> Polymer
Addition Polymerisation
Halogenoalkane –> Alcohol (2)
Hydrolysis
Reagent; Water
Add silver nitrate which will react with halid leaving group to to produce silver halide ppt –> identification test
Halogenoalkane –> Alcohol (1)
Mechanism: Nucleophilic Substitution
Reagent: KOH/NaOH
Conditions: AQUEOUS solution, heat under reflux
Primary undergo SN2 mechanism and tertiary undergo SN1 mechanism
Halogenoalkane –> amine
Mechanism: Nucleophilic substitution
Reagent: Ammonia, dissolved in ethanol
Conditions: Heat under pressure in sealed tube
N.B. If ammonia added in aqueous solution, alcohol forms
Halogenoalkane –> Alkene
Mechanism: Elimination
Reagents: KOH/NaOH
Conditions: In ETHANOL; heat
Alcohol –> Chloroalkane
PCl5
observations: misty fumes
Alcohol –> Bromoalkane
KBr and 50% conc H2SO4
will produce HBr in situ to prevent its escape
Alcohol –> Iodoalkane
Red phosphorus and iodine (PI3 produced in situ)
Can’t use KI and H2SO4 as sulphuric acid will oxidise hydrogen halides to other products.
Alcohol –> Aldehyde
Oxidation
Reagent: K2Cr2O7 (acidified by dilute sulphuric acid)
Conditions: Use limited amount of dichromate, warm gently and distil out aldehyde as it forms.
Alcohol –> Carboxylic Acid
Oxidation
Reagent: K2CrO7 (acidifed with dilute sulphuric acid)
Conditions: use an EXCESS of dichromate and heat under reflux (distil off product after reaction)
Secondary alcohol –> Ketone
Oxidation
Reagent: K2CrO7 (acidified with dilute sulphuric acid)
Conditions: Heat under reflux
Alcohol –> Alkene
Acid catalysed elimination
Reagents: Concentrated phosphoric acid
Conditions: warm under reflux
Role of reagent: deyhdrating agent/catalyst
Aldehyde –> Carboxylic acid
Oxidation
Reagent: K2CrO7 (acidified with dilute sulphuric acid)
Conditions: Heat under reflux
Aldehydes –> Primary alcohols
Reduction
Reagent: LiAlH4 in dry ether
Conditions: Room temperature and pressure
Ketones–> Secondary alcohols
Reduction
Reagent: LiAlH4 in dry ether
Conditions: Room temperature and pressure
Carbonyl –> Hydroxynitrile
Mechanism: Nucleophilic addition
Reagent: HCN (in presence of KCN- catalyst)
Conditions: Room re and pressure
Iodoform reaction (test for methyl group adjacent to carbonyl group)
Reagents: NaOH and I2
Conditions: warm gently
Observations: yellow crystalline precipitate with antiseptic smell
Nitrile –> Carboxylic acid
Hydrolysis
Reagent: dilute HCl/ H2SO4
Conditions: Heat under reflux
Carboxylic acid –> Alcohol
Reduction
Reagents: LiAlH4 in dry ether
Condition: Room temperature and pressure
Carboxylic acid –> Carboxylate salt
Three methods:
- Add metal (Na)
- Add alkali (NaOH)
- Add carbonate (Na2CO3)
Carboxylic acid –> Acyl chloride
Reagent: PCl5
Conditions: Room temperature
Observations: Misty fumes (HCl)
Carboxylic acid –> Ester
Add alcohol
Conditions: strong acid catalyst (H2SO4), heat under reflux
Reaction is reversible. Low yield.
Ester –> Carboxylic acid + alcohol
Two ways for this hydrolysis:
- with acid
Reagent: dilute HCl
Conditions: Heat under refluc
This is a reversible reaction. - with NaOH
Reagent: dilute NaOH
Conditions: Heat under reflux
Reaction goes to completion! :)
Acyl chloride –> Carboxylic acid
Reagent: water
Condition: room temperature
Observations: Steamy white fumes of HCl
Acyl chloride –> ester
Reagent: alcohol
Conditions: room temperature
Observation: Steamy white fumes of HCl
Reaction not reversible so preferred method to make ester :)
Acyl chloride –> Primary Amide
Reagent: Ammonia
Conditions: Room temperature
Observation: White smoke of NH4Cl given off
Acyl chloride –> Secondary amide
Reagent: Primary amine
Conditions: room temperature
Polyester formation
- Dicarboxylic acid + diol –> polyester + water
2. Diacyl chloride + diol –> polyester + HCl
Benzene –> Bromobenzene
Mechanism: Electrophilic Substitution
Reagents: Bromine
Conditions: Aluminium (III) Bromide catalyst
Benzene –> Nitrobenzene
Mechanism: Electrophilic substitution
Reagents: Conc nitric acid in the presence of conc sulphuric acid (catalyst)
Electrophile is NO2+
Equation to form electrophile:
HNO3 + 2H2SO4 –> NO2+ + 2HSO4- + H3O+
Benzene –> Cyclohexane
Hydrogenation
Reagents: Hydrogen
Conditions: Ni catalyst at 200 T and 30 atm
Reactions: Addition and reduction
Benzene–> Alkylbenzene
Mechanism: Electrophilic Substitution
Reagents: Chloroalkane in the presence of anhydrous aluminium chloride catalyst
Conditions: Heat under reflux
Benzene –> Phenyl ketone
Mechanism: Electrophilic substitution
Reagents: Acyl chloride in presence of anyhydrous aluminium chloride catalyst
Conditions: Heat under reflux
Phenol –> 2,4,6-tribromophenol
Reagents: Bromine water
Conditions: Room temperature
Amine –> Ammonium salt
Acid : HCl/H2SO4
addition of NaOH to an ammonium salt will convert it back to amine
Primary amine –> secondary amine
Reagent: Halogenoalkane
Halogenoalkane –> nitrile
Reagents: KCN in ETHANOL
Conditions: heat under reflux
Nitrile –> Amine
Reagents : LiAlH4 in dry ether
Nitrobenzene –> aromatic amines
Reduction
Reagents: Sn and HCl
Conditions: heating
