FREE RADICAL REACTIONS

Refer to organic reaction mechanisms

COMMON RADICAL INIATORS:

UV light, Br₂, Cl₂, I₂, SmI₂, O₂(triplet) , etc.

Common radical reactions.
Examples

Long term degradation of methylene chloride to HCl and other gases when exposed to sunlight.

2CH₃Cl + UV light + 4Cl₂ ^________> 2CHCl₃ + 4HCl
2CH₃Cl + UV light + Cl₂ ^________> 2HCl + 2CH₂Cl₂

Mechanism

initiation reactions

Cl₂    + UV Light ^_____> Cl *   + Cl *

illustration by half arrow mechanism

Propagation  reactions [illustration only ]

CH₃Cl + Cl * ^________> *CH₃ + Cl₂

CH₃Cl + Cl *^________> HCl + *CH₂Cl

*CH₂Cl + HCl ^________> CH₃Cl + Cl

*CH₃ + Cl₂ ^________> CH₃Cl + Cl

*CH₃ + HCl ^________> CH₄ + Cl

CH₄ + *CH₂Cl^________> *CH₃ + CH₃Cl

CH₃Cl + *CH₂Cl^________> CH₂Cl₂ + *CH₃

*CH₂Cl + Cl₂ ^________> CH₂Cl₂ + Cl*

CH₂Cl₂ + Cl *^________> *CHCl₂ +HCl

Cl₂ + *CHCl₂ ^________> CHCl₃ + Cl *

CHCl₃ + Cl * ^________> *CCl₃ + HCl

Cl₂+ * CCl₃ ^________>  CCl₄ + Cl*

*CH₃ + CCl₄ ^________> *CCl₃ + CH₃Cl

COMBINATION

Cl* + * CCl₃ ^________> CCl₄

Cl * + *CHCl₂ ^________> CHCl₃

Cl * + *CH₂Cl ^________> CH₂Cl₂

*CH₃ + Cl * ^________> CH₃Cl

*CH₃ + *CH₃ ^________> CH₃CH₃