2.2 synthesis - general Flashcards
explain homolytic fission
involves the bond breaking evenly, meaning that one electron from the shared pair in the bond goes to each atom
what does homolytic fission create?
free radicals
where does homolytic fission most commonly occur?
non-polar bonds
explain heterolytic fission
involves the bond breaking unevenly, with one atom in the bond receiving both electrons and the other atom receiving none
what does heterolytic fission create?
positive and negative ions
where does heterolytic fission most commonly occur?
in polar bonds
what are characteristics of electrophiles?
- deficient in electrons
- positive or partial positive charge
- able to accept electrons
- attracted to region of negative charge/groups that can donate electrons
what are characteristics of nucleophiles?
- rich in electrons
- negative or partial negative charge
- able to donate to electrons
- attracted to region of positive charge/groups that can accept electrons
what are examples of electrophiles?
Na+, Mg(2+), NH4+, NO2+, general carbocation
what are examples of nucleophiles?
Cl-, CN-, H2O, C=C, OH-, NH3
why do primary and secondary haloalkanes undergo SN2, while tertiary undergoes SN1?
steric hindrance - in primary and secondary, there is space for a nucleophile to approach the carbon. in tertiary there is not.
carbonation stability - tertiary CARBOCATIONS are more stable so can survive exist enough to under SN1
what reacts with haloalkanes to form ethers?
alkoxide
in which molecules can two alkenes form from elimination?
in larger molecules where the halogen/hydroxyl group makes it asymmetrical
state Markovnikov’s rule
when an asymmetrical molecule is attached to an asymmetrical alkene, the hydrogen atom becomes attached to the carbon with the most hydrogens already attached
why does Markovnikov’s rule occur?
the secondary carbocation intermediate is more stable than the primary carbocation
