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3 factors that affect the rate of SN2:

1. Substrate structure

2. Nucleophile strength

3. Leaving group ability

2 factors that affect LGA:

1. Polarizability

2. Bond strength

4 factors that affect nucleophile strength

1. Charge

2. Polarizability

3. Steric hinderance

4. Solvation

3 factors that affect substrate structure

1. steric hinderance

2. hybridization

3. conjugation

how does the polarizability of an atom change between rows

larger atoms are stronger nucleophile

how does polarizability affect atoms differently when comparing two atoms in the same row?

electronegativity (more EN = less willing to form a bond = less reactive in Sn2)

protic solvent means

h-bond donor

polar aprotic means

no h-bond donor

Sn2 reactions wiith Methoxide (MeO^-) are faster in __________ solvents. Why?

faster in polar APROTIC solvents because the protic solvents stabilize the methoxide (more stable Nu = weaker/less reactive)

Nucleophile charge affects the _______.

starting material energy

Polarizability of larger atoms affects the _______

transition state energy

Steric hinderance affects the _____

transition state energy

Solvation affects the ______

starting material energy

3 things in an elimination reaction

1. substrate

2. base

3. product

3 requirements for a substrate in an E2 elimination rxn

1. excellent or fair leaving group

2. must have beta proton

3. carbons at A and B positions must be sp³ hybridized

bases for E2 elimination must be _____ and have pKa values above ____

bases for E2 elimination must be STRONG BASES and have pKa values above 12

the two arrow mechanisms in an E2

PT and LGL

in the TS state of the E2 elimination reaction, the B proton and LG must be ________.

anti-coplanar

why are more substituted alkenes generally more stable than less substituted alkenes?

hyperconjugation

entropy of E2 reactions says they are _____ because….

FAVORABLE because the reaction goes from 2 to 3 molecules (increasing randomness = the universe likes it more)

enthalpy says E2 is favorable because reactions go from _________

high to low energy (decreasing energy)

E2 reactions are (irreversible/reversible)?

IRREVERSIBLE

Product outcome of E2 reactions are dictated by _____ and not by _____

dictated by Ea and NOT by delta G

3 principles of the TS that affect the rate of E2 reactions

1. LGA

2. pi-bond stability

3. basicity

in E2 reactions, more substituted alkene does what to the T.S.?

lowers the T.S. energy

in E2 reactions, the base strength does what to the energy of the reaction?

increasing the starting material energy (closer to the T.S. thus lowering the activation energy)

in E2 reactions, a better LG does what to the energy of the reaction?

lowers the T.S. energy

in E2 reactions, larger atom = ____ leaving group

better LG (more polarizable so the T.S. energy is lower)

regioselectivity means what?

which direction is preferred by the reaction

Zaitsev vs. Hofmann—which is the least substituted?

Hofmann

Zaitsev vs. Hofmann—which is the most substituted?

Zaitsev

in E2 reactions, small bases form the _____ substituted alkene

in E2 reactions, small bases form the MOST substituted alkene

in E2 reactions, bulky bases form the _____ substituted alkene

in E2 reactions, bulky bases form the LEAST substituted alkene

regioselectivity applies when there are _____ beta protons available

at least TWO DIFFERENT beta protons

For E2 eliminations where only one β-hydrogen is available, the reaction is ______ because there is only one possible transition state that satisfies the anti-periplanar requirement.

only one β-hydrogen available - stereospecific

E2 eliminations are considered _______ when there are multiple β-hydrogens available, allowing the reaction to favor the more stable alkene product (typically the E-alkene due to lower steric hindrance).

multiple β-hydrogens = stereoselective

when predicting the major product of an E2 reaction, start with ______, then go to ________

1. start with regioselectivity

2. then go to stereospecificity/selectivity

in E2 reactions with cyclohexanes, anti-coplanar conformation only occurs with the LG and β-hydrogens in the ______ positions

axial positions