Chemistry > General Organic Chemistry > 9.0 Organic reactions
General Organic Chemistry
1.0 Introduction
2.0 Classification of organic compounds
3.0 Homologous series
4.0 Nomenclature of hydrocarbons
4.1 The alkanes $(C_nH_{2n+2})$
4.2 The alkenes $(C_nH_{2n})$
4.3 The alkynes $(C_nH_{2n-2})$
4.4 Combined alkenes and alkynes
4.5 Cyclic hydrocarbons
5.0 Nomenclature of compounds containing halogens and nitro groups
6.0 Nomenclature of compounds with functional groups named as suffixes
6.1 Ethers and thioethers
6.2 Alcohols & thiols
6.3 Acids, salts of acids and acid anhydrides
6.4 Esters
6.5 Acid halides
6.6 Amides
6.7 Nitriles
6.8 Aldehydes
6.9 Ketones
6.10 Amines and ammonium salts
7.0 Nomenclature of aromatic compounds
7.1 Halogen and nitro-substituted aromatics
7.2 Carboxylic acids and derivatives
7.3 Phenols and thiophenols
7.4 Aldehydes & Ketones
7.5 Sulfonic acids and sulfonic acid derivatives
7.6 Aromatic amines
7.7 Diazonium ions $\left( {ArN_2^ + } \right)$
8.0 Radicofunctional naming
9.0 Organic reactions
9.1 Substitution or displacement reactions
9.2 Addition reaction
9.3 Elimination reaction
9.4 Rearrangement reactions
10.0 Electrophiles
11.0 Nucleophiles
12.0 Breaking and forming of bonds
13.0 Reaction intermediates
13.1 Carbocations
13.2 Carbanions
13.3 Carbon radical
13.4 Carbenes
13.5 Nitrenes
13.6 Arenium ions
13.7 Benzynes
14.0 Electron displacement effects
15.0 Inductive effects
16.0 Hyperconjugation
17.0 Resonance
18.0 Mesomeric effect
19.0 Electromeric effect
20.0 Inductomeric effect
21.0 Steric inhibition of resonance
22.0 Ortho effect
9.3 Elimination reaction
4.2 The alkenes $(C_nH_{2n})$
4.3 The alkynes $(C_nH_{2n-2})$
4.4 Combined alkenes and alkynes
4.5 Cyclic hydrocarbons
6.2 Alcohols & thiols
6.3 Acids, salts of acids and acid anhydrides
6.4 Esters
6.5 Acid halides
6.6 Amides
6.7 Nitriles
6.8 Aldehydes
6.9 Ketones
6.10 Amines and ammonium salts
7.2 Carboxylic acids and derivatives
7.3 Phenols and thiophenols
7.4 Aldehydes & Ketones
7.5 Sulfonic acids and sulfonic acid derivatives
7.6 Aromatic amines
7.7 Diazonium ions $\left( {ArN_2^ + } \right)$
9.2 Addition reaction
9.3 Elimination reaction
9.4 Rearrangement reactions
13.2 Carbanions
13.3 Carbon radical
13.4 Carbenes
13.5 Nitrenes
13.6 Arenium ions
13.7 Benzynes
These reactions are essentially the reversal of addition reaction and involve loss of atoms or group of atoms from a molecule to form multiple linkages. Most commonly, loss of atoms or group of atoms occurs from adjacent carbon atoms to yield an olefin.
Example:
$$C{H_3}C{H_2}Cl\quad \underrightarrow {{\text{alc. KOH}}}\quad C{H_2} = C{H_2} + HCl$$
In elimination reactions, $\sigma$-bonds are converted to $\pi$ bond, i.e. the state of hybridization of carbon changes from $sp^3$ to $sp^2$ and $sp^2$ and $sp$. Unlike above two types, elimination reactions are not categorised depending on the nature of attacking reagent. These reactions are generally classified on the basis of molecularity of the reactions are called unimolecular ($E_1$) elimination and bimolecular ($E_2$) elimination reactions and $E_1CB$ (Elimination unimolecular conjugate base) reaction.
