Chemistry > General Organic Chemistry > 13.0 Reaction intermediates
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
13.3 Carbon radical
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
Carbon radical are those in which the carbon carries an unpaired electron. They are usually formed by the homolytic cleavage of bonds at high temperature in the gas phase, in non-polar solvents, by ultraviolet light or by the addition of the other radicals.
When the bond energy is low, the carbon radicals may be formed spontaneously or at low temperature.
Carbon radicals are neutral but are extremely reactive due to an unpaired electron. Hence a fast chain reaction occurs on homolytic cleavage.
Reactions of carbon radical
1. Propagation of chain reaction: Abstract an atom from a molecule to produce another free radical for the propagation of the reaction.
2. Polymerization
3. Termination of reaction: The radicals react with each other to stop the reaction.
Geometric shape: The carbon carrying the odd electron is supposed to be $sp^3$ or $sp^2$ hybridized.
Stability of the carbon radical: The stability of the carbon radical increases with the increase in the number of alkyl group attached to the carbon carrying the odd electron by hyperconjugation.
Hence the stability order of carbon radicals is $3^\circ > 2^\circ > 1^\circ > \mathop {\text{C}}\limits^{\text{ + }} {{\text{H}}_{\text{3}}}$.
Carbon radicals in suitable unsaturated systems are more stable than alkyl radicals due to delocalization of the unpaired electron.
