ORGANIC CHEMISTRY Chapter 13 Reaction of propene with bromine varies depending on reaction conditions g At low temperature the halogen adds across the double bond g at high temperature or at very low concentration of halogen an allylIC substitution occurs low temperature CH,=CH—CH2+X CH,-CH—CH CCI (addition reaction) high temperature CH2=CH—CH3+X2 or low concentration of X CH2=CH—CH2X+HX Propene (substitution reaction Department of Chemistry, Xiamen University
ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 13 Reaction of propene with bromine varies depending on reaction conditions At low temperature the halogen adds across the double bond At high temperature or at very low concentration of halogen an allylic substitution occurs
ORGANIC CHEMISTRY Chapter 13 CH2=CH-CH3 X2 or A CH2-CH-CH2x +HX Allylic substitution Allylic hydrogen atoms H足 CH2=CH-CH2 Allylic radical Department of Chemistry, Xiamen University
ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 13 CH2 CH CH3 + X2 hv or CH2 CH CH2X + HX Allylic substitution C C C H H H H H CH2 CH CH2 Allylic radical Allylic hydrogen atoms
ORGANIC CHEMISTRY Chapter 13 13.2A Allylic Chlorination(High Temperature Allylic chlorination can be performed at high temperature in the gas phase 400°C CH2=CH-CH3 Cl2 CH=CH-CHoCI Hcl Relative stability of free radicals Allylic or allyl>3°>2°>1°> vinylic or vinyl Department of Chemistry, Xiamen University
ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 13 13.2A Allylic Chlorination (High Temperature) ¾ Allylic chlorination can be performed at high temperature in the gas phase CH2 CH CH3 + Cl2 400°C CH2 CH CH2Cl + HCl Allylic or allyl > 3° > 2° >1°> vinylic or vinyl Relative stability of free radicals: