8_nano_radicals_post

8_nano_radicals_post - Free Radical Reactions Free Radical...

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Sec. 11 - free radicals 1 Free Radical Reactions Free Radical any atoms or groups of atoms that has one or more unpaired electrons. They usually has do not have a positive or negative charge, but are highly reactive and short lived reaction intermediates Production of Radicals Homolysis of relatively weak bonds such as O-O or X-X bonds can occur with addition of energy in the form of heat or light homolytic bond cleavage of σ bond
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Sec. 11 - free radicals 2 Free Radical Reactions Initiation Cl Cl + 246 kJ mol -1 2 Cl Propagation: The initial formation of a few radicals results in the propagation of new radicals in a self perpetuating reaction called a chain reaction. Cl + H CH 3 CH 3 Cl + Cl HCl + CH 3 CH 3 + Cl Cl Cl CH 2 Cl + H HCl + CH 2 Cl CH 2 Cl Cl Cl + ClCH 2 Cl + Cl Termination: The formation of stable molecules CH 3 Cl + ClCH 3 CH 3 + CH 3 CH 3 CH 3 etc. etc.
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Sec. 11 - free radicals 3 Can be made through a Free radical mechanism or cationic and ionic mechanism
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Sec. 11 - free radicals 4 Some vinyl polymers H 2 CC F 2 vinylidine fluoride used in piezoelectric material audio speakers and microphones styrene used in plastics, stryofoam and isolation N 4-vinylpyridine ion exchange resins O O methyl methacrylate plastics, plexiglas O O t -BOC styrene photoresists for microelectronics O HO acrylic acid thickeners adhesives sporting goods O O CH 2 2 OH hydroxy ethyl methacrylate (HEMA) soft contact lenses O O( C H 2 ) 6 OC N cyano-biphenyl mesogenic monomer side chain liquid crystal polymer H 2 C CHCl 2 Cl n vinyl chloride monomer PVC polymer
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Sec. 11 - free radicals 5
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This note was uploaded on 07/18/2011 for the course NE 122 taught by Professor Nano during the Winter '09 term at Waterloo.

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8_nano_radicals_post - Free Radical Reactions Free Radical...

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