OChem units 6 and 7 (important info)

radio waves in NMR change what of H1

the nuclear spins

On the H-spectrum 1-1.5

C sp3 carbonized (not attached to any electronegative atoms)

1.5 - 2.5

sp2-C (double bonded to a Z ike C, O, N) next to a sp3 Carbon

2.5 - 4.5

sp3-carbon attached to a halogen (F, Br, I) or N, O

4.5 - 6.5

sp2 carbon alkene

6.5 - 8

aromatic compound

9 - 12

Carboxyllic acid (stump) or Aldehyde (sharp)

Degrees of Unsaturation

(2C + 2 + N - X - H)/2

(leaving groups and why?) Cl-, I-, Br-

Good leaving groups because they’re weak bases that are stable with the negativity

H2O (good or bad leaving group?)

good

F- (Good or bad leaving group?)

bad (because its a relatively good base)

OH- (good or bad leaving group?)

excellent base, can’t stay stable as a negative ion

NH2- (good or bad leaving group?)

bad

H- (good or bad leaving groups?)

good base so weak leaving group

What’s the most important for SN2 reactions

whether the anti-bond can align with the nucleophile; if there’s bulky groups on the alpha carbon, its difficult to align with the antibond

Which hybridization doesn’t do SN2

tertiary (three groups that are not leaving groups or hydrogens; aka. R-groups)

Which solvent is the best SN2

polar Aprotic

What’s the most important for SN1 reactions?

stability of the carbocation; the carbocation has to be geometrically flat to accommodate a front and a back attack (this means it also needs an unhybridized p-ortibal for the positive to go into)

which one can’t do SN1 reactions

primary carbon, because that would make a very unstable carbocation. BUT if that primary carbon can share its positivity with the molecule through resonance then that be more stable than a tertiary carbon

Which solvent is the best for SN1 reactions?

polar protic

Weak nucleophile (neutral) SN2 or SN1?

SN1

Strong nucleophile (negative charge) SN2 or SN1?

SN2

What kind of reagent do we need for E2?

Strong BASES (pKa of conjugate acids being greater than 11)

Reaction rate (SN2/E2?)
3 > 2 > 1

E2 (SN2 does NOT like tertiary)

Zaitsev Rule

Most stable Alkene (most substituted alkene more groups on the alkene)

Hofman product

least sterically hindered (least substituted alkene)

pka Acid: HI Base: I-

-10

pka Acid: HBr Base: Br-

-9

pka Acid: HCl Base: Cl-

-7

pka Acid: H₃O+ Base: H₂O

-2

pka Acid: HF Base: F-

3

pka Acid: Carboxyllic Acid Base: deprotonated

5

pka Acid: HN₃ Base: N₃^-

5

pka Acid: H₂S Base: HS^-

7

pka Acid: HCN Base: CN^-

9

pka Acid: aromatic ring + alcohol Base: aromatic ring + O-

10

pka Acid: H₂O Base: OH^-

16

pka Acid: MeOH Base: MeO-

16

Hydrogen attached to an Alkyne pka

25

H2 pKa

35

Acid: NH3 Base: NH2- pka

38

Alkene pka

44

Acid CH4 Base CH3- pka

50

Which Mechanism? Leaving grouping attached to a Methyl

SN2 only

Which Mechanism? Primary carbon leaving carbon

Strong Nucleophile/Base: SN2

Bulky Nucleo: E2

Which Mechanism? Secondary carbon leaving carbon

Strong base: E2

Strong nucleophile: SN2

Weak nu/base: SN1/E1

Which Mechanism? Tertiary carbon attached to a leaving group

SN2 IMPOSSIBLE

Strong base E2

Weak nu/base SN1/E1