H2 Organic Chemistry Summary 2026

1 1. Types of Organic reaction you need to know Types of reaction Sub Reaction Comments Substitution (carbon centre is saturated/ resonance stabilised) Free Radical Substitution Homolytic fission of alkane leading to unpaired eln. H2 Topic: Alkane Electrophilic Substitution Electrophilic: reacting carbon-centre is eln rich; thus it attacks electrophile. H2 Topic: Arene Nucleophilic Substitution Nucleophilic: reacting carbon centre is eln poor; thus attacked by nucleophile. H2 Topic: Halogenoalkane Addition (carbon centre is unsaturated) Electrophilic Addition Electrophilic: C=C double bond is eln rich, thus it attacks electrophile. H2 Topic: Alkene Nucleophilic Addition Nucleophilic: reacting carbon centre is eln poor, thus attacked by nucleophile. H2 Topic: Carbonyl compound Oxidation Either increase in O atom/ decrease in H atom/ increase in OS Reduction Either decrease in O atom/increase in H atom/ decrease in OS Acid base reaction Bronsted Lowry Bronsted Acid donates H+. Bronsted Base accepts H+ Lewis Lewis acid accepts eln pair; Lewis base donates eln pair Hydrolysis Reaction whereby a molecule is cleaved into two molecules by H2O. Eg: Esters hydrolysis, Amide hydrolysis, Acid chlorides hydrolysis, Nitrile hydrolysis. Condensation Reaction between two functional groups to eliminate a small molecule such as water or ammonia. (one of these molecules involve a −C=O group) Eg. Carboxylic acid + alcohol, acid chloride + ammonia, etc) Elimination Reaction to remove a small molecule from an organic molecule (eg. Removal of HX from halogenoalkane; H2O from alcohol) Precipitation Chemical reaction that cause formation of solid from two aq. Soln. ** for reactions in italic, you need to know the mechanism.

2 2. Common reagents for synthesis Reagents & Condition Type of reaction Functional group Observations Products √ ? Section A: Oxidation KMnO4 with H2SO4 (aq), heat Or KMnO4 with NaOH, heat, followed by acidification KMnO4 with H2SO4 (aq), heat Oxidation (Oxidative cleavage) C H H Terminal alkene Decolourisation of purple soln; Effervescence observed. CO2 + H2O C R H Decolourisation of purple soln RCO2H formed. CH3CH=CH2 + 5[O] → CH3CO2H + H2O + CO2 Note: So if elucidation abt vigorous oxidation of alkene shows an increase of 2 O, the alkene contains this feature. C R R' Ketone formed. (CH3)2C=CH2 + 4[O] → (CH3)2CO + H2O + CO2 Note: So if elucidation abt vigorous oxidation of alkene shows an increase of 1 O, the alkene contains this feature. Oxidation (Side chain oxidation- occurs when C directly bonded to benzene ring has a H or O directly attached) CH3 Benzoic acid formed. C6H5CH3 + 3[O] → C6H5CO2H +H2O C H R R Decolourisation of purple soln; Effervescence observed. Benzoic acid formed. The rest of the chain get oxidised to CO2 & H2O unless question says otherwise