Question

strong nucleophile weak base strong bulky base strong nucleophile strong base Promote SN2/E2 weak nucleophile weak base Promote SN1/E1 Promote SN2 Promote E2 CH Br HS NCT HO CHO CHÚCHO NaNO NaOH NOME Noe HOORS Conjugate acids have pka 16-18 Conjugate acids Recall, you make hydroxide have pka 11 or alkoxide ons from the corresponding alcohol or water and Nat CH,OH (MOH) HO CH,CH,OH (EXOH) | HC-Ć-o to CH tert-BUOK NOCH KOHBU NEOBU The structures above are all ways of referring to the tert-buto de lon ROH + NaHRONa+H Type of alkyl halide (or any RLG) Mechanism(s) possible (circle) Conditions Mechanism favored Methyl substrates CH,Br S1 E1 S 2 E2 ANY Primary (1) substrates CH,CHBE strong nucleophile weak base strong nucleophile strong base strong bulky base S1 E1 Sy2 E2 OTS Secondary (2) substrates Tomo o Sw1 E1 S2 E2 strong nucleophile weak base strong base/strong nucleophile strong bulky base weak base/weak nucleophile strong nucleophile strong base Tertiary (3) substrates Sw1 E1 S2 E2 strong bulky base weak base/weak nucleophile "No SN2o storically Vinyl and aryl substrates handed on SNIE1 c-x bond strength high Spec Xhinder 2 Sw1 E1 S2 E2 NONE talytic or 10 benzyfic substrates S1 E1 S2 E2 strong nucleophile weak base/weak nucleophile abocation resonance stad - SSN possible even though primary

Answer 1

For methyl substrate, SN₂ mechanism will be favoured.

For primary substate, with strong nucleophile or weak base, SN₂ mechanism will be favoured. With strong nucleophile and strong base, SN₂ and E₂ are favoured. With strong bulky base, only E₂ is favoured.

For secondary substrate, 1st conditions favour SN₂ mechanism, 2nd conditions favour SN₂ or E₂ mechanism, 3rd conditions favour only E₂ mechanism, 4th conditions favour SN₁ and E₁ mechanism.

For tertiary substrates, they favour SN₁ mechanism whatever the nucleophile may be and with strong bulky base they follow E₁ mechanism.

For vinyl and aryl substrates, they do not follow any of the mechanisms, so the answer will be none.

For primary allylic or benzylic substrates, strong nucleophile favours SN₂ mechanism while weak nucleophile favours SN ₁ mechanism.

As SN₂ mechanism involves a five- membered transition state, so, steric hindrance plays an important role. That is why tertiary substrates do not favour SN₂ mechanism. SN₁ mechanism involves a carbocation intermediate, so, whichever substrate can stabilize a carbocation favours SN₁ mechanism.