Organic Structures and Mechanisms 2

Question 1

“Me” abbreviation meaning

Answer 1

-CH3 Methyl

Question 2

“Et” abbreviation meaning

Answer 2

-CH2CH3 Ethyl

Question 3

“Pr” abbreviation meaning

Answer 3

-CH2CH2CH3 Propyl

Question 4

“iPr” abbreviation meaning

Answer 4

-CH(CH3)2 Iso-propyl

Question 5

“Bu” abbreviation meaning

Answer 5

-CH2CH2CH2CH3 Butyl

Question 6

“tBu” abbreviation meaning

Answer 6

-C(CH3)3 tert-butyl

Question 7

“Ph” abbreviation meaning

Answer 7

Phenyl

Question 8

“R” abbreviation meaning

Answer 8

Any alkyl group

Question 9

“Ar” abbreviation meaning

Answer 9

Any aromatic of substituted aromatic

Question 10

Define heteroatom

Answer 10

Anything not carbon

Question 11

What is a functional group level?

Answer 11

The no. bonds to heteroatoms from a given C atom

Question 12

What is an oxidation reaction?

Answer 12

gain of O2 OR loss of H2 OR loss of e-

Question 13

What is a reduction reaction?

Answer 13

gain of H2 OR loss of O2 OR gain of e-

Question 14

Define inductive effects

Answer 14

The way in which the electronegative atoms polarize e- density in the single bond framework of a molecule

Question 15

What does a -I effect mean?

Answer 15

e- withdrawing

Question 16

What does a +I effect mean

Answer 16

e- donating

Question 17

is -X -I or +I?

Answer 17

-I

Question 18

is -CX3 -I or +I?

Answer 18

-I

Question 19

is C=O -I or +I?

Answer 19

-I

Question 20

is C-Li -I or +I?

Answer 20

+I

Question 21

is C-Mg -I or +I?

Answer 21

+I

Question 22

is C-CH3 -I or +I?

Answer 22

+I

Question 23

is C-R -I or +I?

Answer 23

+I

Question 24

What is heterolytic bond cleavage?

Answer 24

Forms a cation and an anion

Question 25

What is homolytic bond cleavage?

Answer 25

Forms a radical

Question 26

How does the size of an energy barrier for a reaction affect the rate of reaction?

Answer 26

Smaller energy barrier = faster reaction

Question 27

What determines the size of the energy barrier to a reaction?

Answer 27

Depends on energy of the intermediate - stable intermediates reduce the energy barrier

Question 28

Define mesomeric effects (resonance)

Answer 28

The movement of e- density within the double bond/lone pair system of a molecule by resonance conjunction

Question 29

Which takes dominates? inductive or mesomeric effects?

Answer 29

Mesomeric

Question 30

What are hyperconjuction effects?

Answer 30

When there is a carbocation, an adjacent C-H or C-C bond can partially overlap with the carbocations empty orbital, donating a small amount of e- density to the empty orbital (a lot weaker than normal resonance)

Question 31

Basic rules for organic mechanisms

Answer 31

1) Electron flow must start from an electron rich site 2) Flow must move towards and electron poor site 3) Ensure that nothing has too many bonds 4) Balance charges 5) Repeat if possible/needed

Question 32

Define nucleophile (Nu-)

Answer 32

Electron rich species that will react with C+ or C delta +

Question 33

Define base (B:)

Answer 33

Electron rich species that will react with H+ or H delta +

Question 34

Define electrophile (E+)`

Answer 34

Electron poor species (usually C+ or C delta +) that reacts with a nucleophile

Question 35

Define acid (H+)

Answer 35

Electron poor H+ pr H delta + that will react with a base

Question 36

Define chemoselectivity

Answer 36

When several diff. sites could react, one does so with preferance

Question 37

How do you choose which site to prioritize in mechanisms for the e- rich site?

Answer 37

- Less electronegative is BETTER (more willing to donate electrons) I- > Br- > Cl- > F- R-NH2 > R-OH >> R-F - More resonance is WORSE - Steric hinderance is bad for nucleophiles (ie. a tertiary alcohol is worse than primary)

Question 38

How do you prioristise sites for choosing the electron poor site?

Answer 38

- High -I effect is good - High +M is bad - Resonance dominates inductive effect

Question 39

What is regioselectivity?

Answer 39

When multiple parts of a functional group could react but one is prefered

Question 40

Examples of an e- rich site

Answer 40

1) Negative charge 2) Lone pair 3) Double bond 4) Single bond

Question 41

Examples of e- poor site

Answer 41

1) carbocation/H+ 2) Atom adjacent to positive charge on heteroatom 3) Onward towards a positive charge 4) Partially positive charge 5) Partially positive charge at an alternating distance

Question 42

How do you prioritize an intermediate product?

Answer 42

You want a more stable intermediate (ie. the carbocation is bonded to more carbons)

Question 43

Criteria for most acidic site

Answer 43

- Generates the most stable conjugate base - Negative charges should be on the most electronegative atoms

Question 44

Criteria for most basic site

Answer 44

- Greatest electron density - Most able to donate e- (lone pairs/negative charges should be localized, less electronegative atoms can more easily donate e- denisty)