review

Question 1

Electrophile

Answer 1

molecules that accept electrons to form a new bond

Question 2

What charges do electrophiles have?

Answer 2

positive or partially positive charge

Question 3

R1 and R2 directly bound to the carbonyl could affect what?

Answer 3

Electrophilicity

Question 4

What ways could R1 and R2 affect the carbon’s electrophilicity?

Answer 4

if R1 or R2 donates an electron density, then the carbons is less electrophilic

Question 5

What are the two ways that R1 and R2 could affect electrophilicity?

Answer 5

Resonance and Hyperconjugation

Question 6

Resonance

Answer 6

delocalization of electron within a certain molecule

Question 7

Hyperconjugation

Answer 7

a weak overlap between p orbital in the carbonyl carbon and sp3 in the ch3 group. Usually happens between c-c or c-h groups. (very week electron donation).

Question 8

Could aldehydes have resonance or hyperconjugation?

Answer 8

No (best electrophile)

Question 9

Could ketones have resonance or hyperconjugation

Answer 9

No resonance but can undergo hyperconjugation

Question 10

Could esters have resonance or hyperconjugation

Answer 10

Yes (least electrophile)

Question 11

Nucleophile

Answer 11

a molecule that donates electron density to an electrophile so as to form a new bond

Question 12

what charges are the nucleophiles

Answer 12

negative or partially negative

Question 13

How do nucleophiles react with electrophiles

Answer 13

they attack the carbonyl carbon making the π electrons to be pushed to oxygen

Question 14

What are the two types of additions

Answer 14

reversible and irreversible

Question 15

What happens during a reversible addition

Answer 15

Nucleophile attacks and a weak bond is formed that could usually go backward (reverse). Usually, the nucleophile used is weak

Question 16

What happens during irreversible addition

Answer 16

Nucleophile attacks and a strong bond that can’t go reverse (backward) is formed. Usually, a strong and reactive nucleophile is used.

Question 17

what are the two types of irreversible additions

Answer 17

organometallic reagents and hydride reagent

Question 18

What is an organometallic reagent

Answer 18

This is a carbonion with a metallic countercation

Question 19

What are the two types of Organometallic reagents

Answer 19

Organolithiums (Li) and Grignard reagents (MgBr)

Question 20

How do organometallic reagents react with carbonyls

Answer 20

Step 1 is the addition of the R organometallic reagent with ethereal solvent and step2 you add H+

Question 21

What shape do the carbonyl carbons changes from and to after the addition of organometallic reagents

Answer 21

From sp2 to sp3

Question 22

Why should we always make sure that in organometallic reaction the rxn is anhydrous?

Answer 22

since water is an acid and also a base, it could react with carbonyl to form an acid-base rxn. deprotonation rxn usually kills the nucleophiles. This why H+ is added at the second step of the rxn.

Question 23

What is a hydride reagents

Answer 23

additions of hydrides (H-) which a very strong and a reactive nucleophile to electrophiles

Question 24

what are the two types oh hydride reagents

Answer 24

Sodium borohydride (NaBh4) and lithium aluminum hydride(LAH)

Question 25

What electrophiles do both nabh4 and lah react with

Answer 25

aldehydes and ketones

Question 26

what are two differences between lah and nabh4

Answer 26

1. nabh4 uses a solvent as proton source(MEOH OR ETOH) while lah uses H+ as a proton source in which u add it at the second step. 2. Lah is more nucleophilic and basic than nabh4

Question 27

what are hydride reactions usually referred to?

Answer 27

reduction. This is because the number of bonds to oxygen has been reduced.

Question 28

What is the difference between hydride rxn and an organometallic rxn

Answer 28

in hydride rxns, we don't add any new carbon element in the rxn but in organometallic rxns, we add carbon elemets

Question 29

why is it that nabh4 can react with esters and carboxylic acids

Answer 29

This is because nabh4 is a weak nucleophile and since both esters and carboxylic acids are weak electrophiles, they need a strong nucleophile to react. That is why we use Lah to reduces them

Question 30

what do we call the reactions in which nucleophiles displace a leaving group in an alkyl electrophile?

Answer 30

SN1 and SN2

Question 31

what do sn1 and Sn1 stand for?

Answer 31

substitution nucleophilic (bimolecular or unimolecular)