homolytic and heterolytic fission

reaction mechanisms

series of steps that take place in the course of the overall reaction

homolytic fission

both atoms at each end of the bond leave with one electron from the pair forming the covalent bond

free radicals

formed post homolytic fission…have an unpaired electron represented by a dot

initiation step

energy is input which results in the breaking of a covalent bond to form 2 free radicals

propagation step

formed free radicals can then attack reactant molecules to form more free radicals

termination step

two free radicals react with each other to form a molecule with no free radicals

heterolytic fission

the more electronegative atom takes both the electrons in the covalent bond

C-X bonds

small curly arrow shows electron movement…X is more electronegative than carbon

carbocation

alkyl group with a single positive charge on one of its carbon atoms…formed during reaction mechanisms

primary carbocation

least stable with one alkyl group

secondary carbocation

partially stable with two alkyl groups

tertiary carbocation

most stable with 3 alkyl groups

inductive effect

uneven sharing of electrons from a covalent bond…electron donors like alkyl groups are positive inductive and electron takers like oxygen are negative inductive

alkyl groups

push electrons away from themselves and reduce charge density of positive charge on carbocation

stability

the more alkyl groups there are, the more stable the carbocation is

electrophile

species that can act as an electron pair acceptor like carbocations…forms a new covalent bond

nucleophiles

species that can act as a donor of an electron pair…forms a new covalent bond with the electron deficient atom under-attack