Tells for substitutions and elminations

SN1

• only substrates that can form stable carbocation intermediates

• polar protic solvents - H2O, AcOH

• 2 step mechanism

• loss of stereochemistry

• weak nucleophile

SN2

• strong nucleophile

• polar aprotic solvent - DMF, MeCN, Acetone

• methyl undergoes fast Sn2 as least hindered

• simultaneous attack so 1 step mechanism

• trigonal bipyramidal transition state

• inversion

E1 elimination

• weak base

• more favourable at higher temperatures

• 2 step mechanism

• rate is unaffected by weak bases

• can produce both E and Z but E is favoured

E2 elimination

• simultaneous attack of base, formation of alkene, and loss of leaving group

• favoured by more basic reagents - strong bases

• has to be antiperiplanar

• sterically demanding bases are favoured

E1cB

• strong base, poor leaving group

• forms enolate intermediate that is stable

• occurs for substrates bearing and EWG adjacent to H being removed

addition of HX

• it follows markovnikov addition

  • hydrogen attaches to the carbon that has the most hydrogens already

addition of X2

• forms the triangle ion thing

• follows syn addition

• more substituted alkenes are more reactive

hydroboration/oxidation and hydrolysis

• reagents in order:

  • BH3

  • H2O2 and NaOH

• syn addition

• produces alcohols from alkenes

epoxidation

• mCPBA

• syn addition

epoxide ring opening

• under absic conditions = Sn2

• under acidic conditions = yields a mixture of regioisomers

• ring opening forms 1,2-Diols

dihydroxylation

• forms 1,2-diols from alkenes

• syn addition

• done with OsO4 or KMnO4

ozonylsis

• O3 then Zn/H2O or DMS

• cleaves alkene to carbonyls

alkyne + base

• reagent NaNH2

• forms acetylide anion

alkyne hydration

• reagents - HgSO4 / H2SO4 makes ketone

• reagents - BH3 makes aldehyde