Organic Chemistry Module 7

SN1, SN2, E1, E2

what makes a good Leaving group

halogens and a weak base (CB of a Strong acid)

SN2 reactions operate with a strong or weak nucleophile

strong

What type of carbons does SN2 reactions prefer (primary, secondary, tertiary)

primary and secondary

SN2 reactions operate with a strong or weak base or both?

both

What type of nuc and base is this? (options are strong and weak) I-

SN/WB

What type of nuc and base is this? (options are strong and weak) Br-

SN/WB

What type of nuc and base is this? (options are strong and weak) Cl-

SN/WB

What type of nuc and base is this? (options are strong and weak) CH3COO-

SN/WB

What type of nuc and base is this? (options are strong and weak) Ch3O-/NaOMe

SN/SB

What type of nuc and base is this? (options are strong and weak) CH3CH2O-/NaOET

SN/SB

If something is a primary carbon and the substrate is a SN/WB, what type of rxn is it?

SN2

If something is a secondary carbon and the substrate is a SN/WB, what type of rxn is it?

SN2

If something is a tertiary carbon and the substrate is a SN/WB, what type of rxn is it?

SN1

If something is a primary carbon and the substrate is a SN/SB, what type of rxn is it?

SN2

How many steps is E2?

one

How many steps is E1? What intermediate does it have?

two; carbocation

which type of reactions form alkenes by removing a LG and a neighboring proton (beta hydrogen)

E1 and E2 (elimination)

What reaction proceeds on a secondary and tertiary carbon with a Strong base and a Strong nuc

E2 (Zaitsev)

what reaction proceeds on a bulky SB and a weak nuc on a primary, secondary, and tertiary carbon

E2 (Hofmann)

What reaction proceeds with a weak nuc and a weak base on a primary carbocation

No reaction

What reactions proceeds with a weak nuc and a weak base on a secondary and tertiary carbocation (2)

Sn1 and E1

tbuok is what type of nuc/base

WN and SB

lda is what type of nuc/base

WN and SB

NaH is what type of nuc/base

Wn/SB

H2o and Ch3OH are what type of Nuc/Base

WN/WB

EtOH and CH3COOh are what type of base/nuc

WN/WB

Can E2 be rearranged?

no

Does E2 want to be anti-periplanar?

yes

Does E1 favor cis isomers

no; trans

which mechanism requires a Newman projection to see if the leaving group is anti-periplanar?

E2

Does e1 need a Newman projection

no

Is it E1 or E2 that can yield a Hofmann (both zaitsev and hofmann are possible)

E2

E1 reactions typically yield zaitsev or hofmann

zaitsev

Does E2 require a strong or weak base?

strong

does e1 require a strong or weak base

weak base

Sn1 vs E1: which reaction occurs under high heat

E1

E1 vs SN1; bulky and weak reagents (H2SO4, H3PO4) favor ___ while small weak reagents (H2O or ROH) favor ____

E1; SN1

What rxn is this? The LG leaves first and creates a stable carbocation intermediate. Carbocation rearrangement happens if possible. Then, a weak nuc: attacks the carbocation and if it’s originally neutral, it becomes positive before the excess solvent takes away the extra proton

SN1

Does SN1 or SN2 have rearrangements/shifts?

SN1

Does SN1 use a weak or strong nuc:

weak

Does SN1 prefer a tertiary carbon or a primary carbon

tertiary

____ is racemic while ____has a complete inversion

SN1; SN2

___ prefers polar protic (H2o, EtOH w/ h-bonds) while ___ prefers polar aprotic (DMSO, DMF, Acentone) solvents?

SN1; SN2

You can get both SN2 and E2 products when you have a secondary substrate with what type of base or nucleophile? (NaOH, NaOMe, NaOEt)

SB;SN

If you’re competing with Sn2 and E2 and you only want E2, switch to what type of base? If you only want SN2, switch to what type of base and nuc:?

bulky; WB/SN

Tertiary substrate with a Weak Base and nucleophile (H2o, MeOH, EtOH) at room temp gives you which TWO reactions?

SN1/E1

How do you favor E1 if you have a tertiary substrate with a WB and WN?

turn up the heat

solvolysis

solvent acts as the nuc: or base

For cyclo rings, use chair conformations. The Leaving group and beta Hydrogen must both be…if they’re equatorial, what do you need to do?

axial; flip the chair to get axial positions

In the chair conformations, if your LG is axial up, the neighboring H’s must be axial ___

down

In the chair conformations, if your LG is axial down, the neighboring H’s must be axial ___

up

If you see a big bulky group on a cyclohexane ring, will it be axial or equatorial? Can you flip it? If your LG is equatorial, can the E2 rxn happen?

equatorial; no; no