Organic Synthesis

Alkane to Halogenoalkane

Reaction Type: Free Radical Substitution

Reagents & Conditions: Halogen in the presence of UV light.

Explanation: The UV light breaks the halogen bond (initiation) to create radicals, which then substitute hydrogen atoms on the alkane chain.

Alkene to Alkane

Reaction Type: Electrophilic Addition (Hydrogenation)

Reagents & Conditions: Hydrogen gas (H2) with a Nickel catalyst at 150°C.

Explanation: Used to turn unsaturated fats into saturated fats (margarine production).

Alkane to Alkene

Reaction Type: Cracking (Thermal or Catalytic)

Reagents & Conditions: High temperature (Thermal) or High temperature with a zeolite catalyst (Catalytic).

Explanation: Breaking long-chain alkanes into shorter, more useful alkanes and alkenes.

Alkene to Halogenoalkane

Reaction Type: Electrophilic Addition

Reagents & Conditions: Hydrogen halide (HCl, HBr) at room temperature.

Explanation: The double bond opens up to accept the hydrogen and the halogen.

Halogenoalkane to Alkene

Reaction Type: Elimination

Reagents & Conditions: Ethanolic KOH or NaOH, heated under reflux.

Note: It is crucial that the solvent is ethanol, not water.

Halogenoalkane to Amine

Reaction Type: Nucleophilic Substitution

Reagents & Conditions: Excess ethanolic ammonia (NH3), heated in a sealed tube/under pressure.

Explanation: Excess ammonia is used to prevent further substitution into secondary/tertiary amines.

Halogenoalkane to Nitrile

Reaction Type: Nucleophilic Substitution

Reagents & Conditions: Potassium cyanide (KCN) or Sodium cyanide (NaCN) in ethanol, heated under reflux.

Significance: This reaction increases the length of the carbon chain by one carbon atom.

Amine to Ammonium Salt

Reaction Type: Neutralization (Acid-Base)

Reagents & Conditions: Dilute acid (e.g. HCl).

Explanation: The lone pair on the nitrogen accepts a proton (H+) to form a positive ion.

Halogenoalkane to Alcohol

Reaction Type: Nucleophilic Substitution (Hydrolysis)

Reagents & Conditions: Aqueous NaOH or KOH, heated under reflux.

Note: Here water (aqueous) is the solvent, contrasting with reaction 5 (ethanolic).

Alcohol to Halogenoalkane

Reaction Type: Nucleophilic Substitution

Reagents & Conditions:

• For Chloroalkanes: PCl5 (room temp) or conc HCl.

• For Bromoalkanes: KBr + 50% conc H2SO4.

• For Iodoalkanes: PI3 (made in situ from red phosphorus + iodine).

Alcohol to Alkene

Reaction Type: Elimination (Dehydration)

Reagents & Conditions: Concentrated H2SO4 or H3PO4, heated to approx 170°C.

Explanation: Removes a water molecule from the alcohol.

Alkene to Alcohol

Reaction Type: Electrophilic Addition (Hydration)

Reagents & Conditions: Steam (H2O) with H3PO4 catalyst, 300°C, 60 atm (Industrial process).

Alkene to Diol

Reaction Type: Oxidation

Reagents & Conditions: Acidified Potassium Manganate(VII) (KMnO4), cold and dilute.

Observation: The purple solution turns colourless (manganese gets reduced).

Aldehyde to Carboxylic Acid

Reaction Type: Oxidation

Reagents & Conditions: Acidified Potassium Dichromate (K2Cr2O7), heated under reflux. (Aldehyde)

Alcohol (Primary) to Carboxylic Acids

Reaction Type: Oxidation

Reagents & Conditions: Excess Acidified Potassium Dichromate (K2Cr2O7), heated under reflux.

Ketone to Alcohol (Secondary)

Reaction Type: Reduction (to Secondary)

Reagents & Conditions: Warm with aqueous NaBH4 (Sodium Borohydride).

Alcohol (Secondary) to Ketone

Reaction Type: Oxidation

Reagents & Conditions: Acidified Potassium Dichromate (K2Cr2O7), heated under reflux.

Aldehyde to Alcohol (Primary)

Reaction Type: Reduction (to Primary)

Reagents & Conditions: Warm with aqueous NaBH4.

Alcohol (Primary) to Aldehyde

Reaction Type: Partial Oxidation

Reagents & Conditions: Acidified Potassium Dichromate (K2Cr2O7), gently heated and distilled immediately.

Explanation: Distillation removes the aldehyde before it can oxidize further into a carboxylic acid.

Aldehyde/Ketone to Hydroxynitrile

Reaction Type: Nucleophilic Addition

Reagents & Conditions: NaCN (Sodium Cyanide) and dilute H2SO4.

Explanation: This reaction extends the carbon chain.

Hydroxynitrile (or Nitrile) to Carboxylic Acid

Reaction Type: Hydrolysis

Reagents & Conditions: Dilute acid (HCl or H2SO4), heated under reflux.

Explanation: The -CN group is converted into a -COOH group.

Carboxylic Acid to Alcohol

Reaction Type: Reduction

Reagents & Conditions: LiAlH4 (Lithium Aluminium Hydride) in dry ether.

Note: This is a strong reducing agent capable of reducing the acid directly to a primary alcohol.

Alcohol to Ester

Reaction Type: Esterification (Condensation)

Reagents & Conditions: Carboxylic acid + concentrated H2SO4 catalyst, heated.

Ester to Alcohol

Reaction Type: Hydrolysis (Acidic or Alkaline)

Reagents & Conditions: Dilute acid or alkali, heated.

Ester to Carboxylic Acid

Reaction Type: Acid Hydrolysis

Reagents & Conditions: Dilute acid (HCl), heated under reflux.

Product: Produces the carboxylic acid and an alcohol. This reaction is reversible.

Carboxylic Acid to Ester

Reaction Type: Esterification

Reagents & Conditions: Alcohol + concentrated H2SO4 catalyst, heated.

Ester to Carboxylate

Reaction Type: Alkaline Hydrolysis (Saponification)

Reagents & Conditions: Aqueous NaOH or KOH, heated under reflux.

Product: Produces the carboxylate salt (e.g., Sodium Ethanoate) and an alcohol. This reaction is irreversible and has a high yield.