organic 4

Question 1

how do we form an enolate

Answer 1

we remove an alpha H and move e- to the carbonyl

Question 2

what can we do with an enolate

Answer 2

we can use it to form bonds to other carbonyls!!!

Question 3

is an enolate more reactive to a ketone or an aldehyde + why

Answer 3

an aldehyde!!

bc less inductive effect moving the e- towards the partially positive carbonyl

bc it only has 1 R group!!

Question 4

what do end equivalents do

Answer 4

they help control the regioselectivity and reactivity of enolates and enols!!

Question 5

what stops us from generating enols

Answer 5

if there’s no alpha protons to remove by the carbonyl

Question 6

benzaldehyde + LDA reaction product and conditions

Answer 6

• 78*C

enolate but with Li bonded to the O!!!! and no negative charge

Question 7

what is LDA

Answer 7

a strong and powerful base

kinda hindered so it helps us control the reaction

Question 8

when
ketone is reacted with LDA,,, can we stop at the enolate

Answer 8

yessss

the reaction is rlly slow due to the low temp of -78*C!!!

Question 9

what is LDA

Answer 9

lithium
di isopropylamide

N with 2 claw machine things and Li

Question 10

describe the reaction between LDA and a ketone

Answer 10

Li-N bond attacks Alpha H
double bond attacks LI

u get an enolate type thing but with Li on the oxygen,, u still get the double bond aswell

Question 11

LDA after reacting with a ketone isss

Answer 11

N claw claw H

bc u removed the Li but attacked the alpha H.

Question 12

what does LDA attack

Answer 12

the least hindered alpha H

bc it’s a powerful but bulky base!!!

Question 13

product of LDA a ketone and then the reaction with a carbonyl

Answer 13

Li- N attacks alpha H
double bond attacks Li
u get enolate but with Li on the neutral O.

u get H N claw claw as ur product

the Li enolate type thing then uses it’s lone pair and double bond to attack a carbonyl C.

the O will then be (+) bc it’s bonded twice to C and once to Li.

Question 14

what is the lithium enolate called

Answer 14

lithium enolate

Question 15

how does the powerpoint say lithium enols react

Answer 15

they say that the O -Li bond reforms the carbonyl

and that the double bond attacks the Carbonyl C

then the other Carbonyls double bond bonds with the Li.

this forms a little circle between the O’s and the Li.

this is then reacted with acid to get OH and a carbonyl on the original carbonyl.

Question 16

ketone + TMS + Et3N

Answer 16

O bonded to TMS (single bond)
double bond between where the H was removed and the carbonyl

Question 17

ketone + TMS + Et3N thermodynamic major product

Answer 17

most substituted double bond

Question 18

ketone + TMS + LDA major kinetic product

Answer 18

TMS bonded to O (single bond)

double bond between the least hindered H that was removed and the carbonyl

LDA THINK LOW TEMP

Question 19

kinetic product

Answer 19

least hindered H is removed

LDA IS USED SO LOW TEMP TOO

Question 20

thermodynamic product

Answer 20

most stable double bond is formed

Question 21

aldol reaction using the TMS enolate

Answer 21

lone pair on O reforms the carbonyl double bond

double bond attacks Carbonyl C

Question 22

if ur enol product has a carbonyl on one end and smt else on the other,, what can u do to make the random group into an OH

Answer 22

u add H3O + and do a work up

Question 23

how can we make benzaldehyde more reactive

Answer 23

add TiCl3

the carbonyl O is weakly basic so will attack TiCl3

TiCl3 is a strong lewis acid (accepts lone pair l)

Question 24

benzaldehyde and TiCl3

Answer 24

makes benzaldehyde more reactive

u still have a carbonyl but the O is positive as it’s bonded twice to the C and once to the TiCl3

other things can then react with it. (enolates!!)

Question 25

most important use of LDA

Answer 25

making lithium enolates gets least hindered H its a bulky base

Question 26

what is a silyl enol ether

Answer 26

enolate but with SiMe3 bonded to the O (which is neutral)

Question 27

ether functional group

Answer 27

R ‘ - O - R ‘2 where it’s a single bond

Question 28

enol functional group

Answer 28

protonated enolate OH near connected to a double bond

Question 29

how to make a silyl enol ether

Answer 29

carbonyl + Me3SiCl (bc they’re hard) the O attacks the Si the Cl kinda just goes away. hard + strong bond so favoured!!

Question 30

enol description

Answer 30

double bond OH

Question 31

enolate description

Answer 31

double bond O-

Question 32

lithium enolate description

Answer 32

double bond O - Li

Question 33

silyl enol ether description

Answer 33

double bond O - SiMe3

Question 34

making a silyl enol ether (3 ways)

Answer 34

enolate lone pair attacks Si kicks off Cl Et3N is then used to remove the enol H to neutralise the O ——————————————————— lone pair on O on a carbonyl attacks the Si of the Me3SiCl kicks off Cl Et3N uses its lone pair to take off an alpha H,, which is then resonated to give a neutral oxygen ——————————————————— lithium enolate bond attacks Si and removed Cl forms the silyl enol ether just like that

Question 35

do silyl enol ethers react with all carbonyls

Answer 35

nopeeee the other carbonyl needs to be ‘activated’ using TiCl4 or another lewis acid the lewis acid needs to be making the other carbonyls Oxygen positive

Question 36

NEt3 will do whattt

Answer 36

it’s a base so it will steal a alpha H it steals the one that will give the most stable double bond

Question 37

the way the teacher draws the silyl enol ether being made

Answer 37

the O- attacks the Si - Me3 it kicks off the Cl

Question 38

if u have like a diester,, so like 2 carbonyls on molecule but further apart,, the symmetric looking ones,, how is a hydrogen bond created

Answer 38

EtO- // base can attack the alpha H's this can form a double bond and make O-. this can then attack a H to form OH. hydrogen bond forms between the carbonyl O and the OH so it forms a little ring type thing with dotted lines where the hydrogen bond is.

Question 39

bonding 2 diff carbonyls together + removing an OH from the added one! do it with di carbonyl and benzaldehyde: with benzaldehyde being the other carbonyl!! so this would drop down

Answer 39

knoevenagel reaction Eto removes an alpha H forms a double bond and O- the O- and double bond attacks another carbonyl and forms O- O- forms OH Eto removes remaining alpha H ,, forms a double bond and an O- O- and double bond is used to form another double bond and OH is removed (LG) kinda a bad LG so we had to go the long way. NaOH and H3O+ can be added to make the esters caerboxylic acids,, then H bonding between carbonyl O of 1 carb acid and OH of another carb acid. forms a ring type thing then arrows from double to H thats H bonded. OH bond to C from carbonyl and then the other arrow to remove the carboxylic aciddd. can tauterise it to give the ketone version using arrows: double bond attacks H,, OH bond makes carbonyl.

Question 40

doetner modification meaning

Answer 40

malonic acid : carboxylic acids on both sides with an aldehyde as another reactant u add a new R group and remove the old one as its a CO2

Question 41

decarboxylation

Answer 41

u get rid of some of the carbonyl groups

Question 42

deotner modification fully

Answer 42

di carboxylic acid type thing A hs are removed and it attacks a carbonyl OH bonds are formed betwee nthe old carboxylic acid ends!! with the new thing sticking out but its OH and not O-. then the bond between the original OH is moved to the C of the C=O near it,, then the middle bond is broken and given to the C connected to the R group and a double bond is formed. the OH of the new thing is also removed 💗 this gives u the beginning of the new thing with a c=c and the old carbonyl group at the endddd. pyridine and piperidine is the base thing and H donor. remember that this gives an allene and then the OH e- go to the C-O to give C=O,, and the double bond of the allene takes the H

Question 43

making a carboxylic acid from an ester,,

Answer 43

remove the alpha Hs,, get the double bond to keep attacking Bromines this will remove e- densigty from thr C of the carbonyl an OH- can attack it and it moves to the carboyl O giving O-,, this is ussed to remove the bromines to give a carboxylic acid

Question 44

if u see a long carbonyl,, aka a long chain with 2 carbonyls as a reactant,, and the product is a chain with a different R group and a double bond,, what do we do and what should we think. yk this girl 💗

Answer 44

okay so its a carbonyl so we know we probs neeed to form some sort of enolate,, and bc its a different R group we know that that is probably from the thing we reacted to. and bc enolates react with carbonyls we know that itll be 'C=O - new.R' and bc its a double bond we know we have to remove a water. and to get rid of the old part of the chain,, we need to form a hydrogen bond and then kick CO2 off 💗 this would give us an allene which then needs to attack the H and move the OH e-to reform the C=O bond

Question 45

ketone to carboxylic acid

Answer 45

attack alpha H with base form an enolate and use this to react with Br-Br. keep doing this until all H's are Br. attack the C in C=O with OH,, then use the O- to kick off the CHBr3 to give a carboxylic acid.