Sn1, Sn2, E1, E2 Reactions

Front 1

SN2 - Best Substrate?

Back 1

Methyl or primary substrates work best

Front 2

SN2 - Best Nucleophile?

Back 2

Negatively charged. Neutral works too.

Front 3

SN2 - Best Solvent?

Back 3

Polar, aprotic.

Front 4

SN2 - Best Leaving Group?

Back 4

More stable anions.

Front 5

SN1 - Best Substrate?

Back 5

Tertiary, allylic, and benzylic halides. Anything that yields the most stable carbocations.

Front 6

SN1 - Best Leaving Group?

Back 6

H2O

Front 7

SN1 - Best Nucleophile?

Back 7

Neutral nucleophiles. Anything nonbasic. Basic nucleophiles compete for elimination reaction. Tend to be the solvents for the reaction.

Front 8

SN1 - Best Solvent?

Back 8

Polar protic solvents, like water, alcohols, and carboxylic acids. Also tend to be nucleophiles for the reactions.

Front 9

SN1 Stereochemistry?

Back 9

If a stereocenter is formed from the reaction, there will be a mixture of products because the nucleophile can attack from either side of the flat carbocation.

Hint 9

Has to do with stereocenter being formed.

Front 10

SN2 Stereochemistry?

Back 10

If a stereocenter is present, the SN2 reaction will invert the stereochemistry.

Hint 10

Has to do with the presence of a stereocenter.

Front 11

E2 Occurs?

Back 11

When alkyl halide treated with strong base (OH- or RO-)
Most common pathway for elimination

Front 12

E2 Rate Limiting Step

Back 12

Breaking of the C-H bond

Front 13

E2 vs SN2 Leaving Groups

Back 13

SN2 - electron pair from nucleophile pushes out LG
E2 - electron pair from neighboring C-H bond pushes out LG

Front 14

E2 and cyclohexane rings

Back 14

HX must be antiperiplanar for reaction to occur
Can produce anti-Zaitsev products
If either are equatorial, reaction cannot occur
Can ring flip to perform E2 (rate limiting step)

Front 15

E1 vs SN1

Back 15

Dissociation followed by loss of H+ from adjacent C rather than by substitution

Front 16

E1 and SN1 occur together

Back 16

Whenever HX treated with protic solvent with a non-basic nucleophile

Front 17

E1 best substrate

Back 17

Same as SN1 substrates

Front 18

E1 products

Back 18

Mix of substitution and elimination products usually

Front 19

E1 geometry requirement

Back 19

No geometry requirement

Front 20

E2 geometry requirement

Back 20

Must be periplanar

Front 21

Primary alkyl halides

Back 21

Good nucleophile - SN2
Strong, sterically hindered base - E2

Front 22

Secondary alkyl halides

Back 22

Weakly basic nucleophile in polar, aprotic solvent - SN2
Strong base - E2
Secondary allylic and benzylic alkyl halides with weakly basic nucleophile in protic solvent - SN1 and E1

Front 23

Tertiary alkyl halides

Back 23

Strong base - E2
Neutral conditions - SN1 and E1