organic 1 Flashcards
the carbonyl O is aaaaa
and what does this mean
weak base
means it can use its lone pair to attack a H+. it donates its lone pair
lewis acid
accepts
accepts electrons
lewis base
donates
donates electrons - its lone pair
alpha protons
the H’s on the carbon adjacent to the carbonyl
when can we add things directly to the carbonyl
when we resonate the double bond on C=O onto the O to give +C—O-
arrow from double bond to the O. makes C positive
how do we form a cyanohydrin and what does it look like
cyanohydrin = R R C OH CN
ester + CN- —> CN attacks the C,, arrow to O,, then O- acts as a base and attacks a H,, to give OH.
H3O+ can be used as a H donator. - forms water and cyanohydrin
at what angle should a nuc attack the C of a carbonyl (C=O)
at 107*
the burgi dunitz trajectory
into the LUMO
think butterfly,, 2 out the O and 2 larger ones out the C,, we draw arrow from NUC to 1/2 of the ones by the C.
from the nucs homo,, to the carbonyls lumoooo.
how do we normally draw the order of a nucleaophile attacking a carbonyl
the nuc attacks the C
move the e- from the double bond to the O and give the O- a negative charge.
why is the nuc attracted to the C of the carbonyl
bc O is more electronegative so there is a partial negative on the O and partial positive on the C.
how do we form a hydrate // gemdiol
take a ester
use H2O as the nuc and attack the C of ther carbonyl,,
move e- to the O-.
use the lone pair on O to attack a H+ to give R R C OH OH
if theres an electron withdrawing group on the C of the carbonyl,, what do we do
we use the O as a base and use its lone pairs to attack a H+.
before we attack the C.
describe an acetal
R R C OR OR
diff between gemdiol // hydrate and acetal
gemdiol // hydrate = R R C OH OH
acetal: R R C OR OR
how do we make an acetal
R R C O ( ketone)
O attacks a H
O becomes +
HOR attacks the C and e- go to O,, to neutralise it.
H e- go to the OR so H can be removed. R R OH OR
OH attacks a H to become H2O,, lone pair on O on OR is used to make a double bond and kick of water.
C=O+ - R is what we get
then another HOR is used to attck the C of the carbonyl.
and then its deprotonated to give R R C OR OR an acetal
how can we speed up the acetal synthesis when we use a ketone and alcohols,, HOR’s
add more acid: adds more H+ to it!!
remove water to prevent the back reaction from forming,, bc water is lost and the arrows are reversible.
how can we remove water from things to prevent their back reactions from occurring and to speed up reactions
we use seives
drying agents like magnesium sulfate
whats an imine
R R = N R
how do we form an imine
ester is attacked by amine - lone pair on N.
e- in = are moved to the O to give O-.
O- steals the H from the amine
this neutralises N and O
then the OH attacks a H+ to form water.
the lone pair on the N is used to remove water
the H is removed from the N+,, an imine is formed,, R R = N - R
the C on a carbonyl is aaaa
electrophile
lumo on carbonyl, where homo e- go
pi star orbital
pi antibonding orbital
what does an EWG on the C dooo
makes C more positive,,, more electrophilic.
more reactive to electrophiles.
makes electrophilic addition more favourable.
bc it takes away e- density from the C =,, giving it a more partial positive character.
name a source for H+ in acetal synthesis
H2SO4
TsOH
are aldehydes or ketones more reactive to electrophilic addition
aldehydessssss
bc H doesnrt donate electron density via inductive effect
ketones have R groups which donate e- density to the C making it less partially positive,, more partially negative and less likely that a nucleophile will attack.
whats more electrophilic,, ketones or aldehydes
aldehydes
alkyl groups areee
electron donatingggg
inductive effect
imine to amine is calledddd
reductive amination
gain of hydrogen so reduction
from double to single bond
explain reductive amination
imine R R C = N R
+Na -BH3 (CN) is used :e- from B-H bond attacks the C,, e- from = go to the N
N becomes N -
N- attacks a H+
R R C N R H amine is formed
why is Na(CN)BH3 used in reductive amination
bc it gives -BH3
and its a milder hydride donor than NaBH4 due to CN being an EWG.
this means it only reduces the imine and not the starting ketones + aldehydes (carbonyls)
why is using Me-I as a hydride donor badddd
bc u cant stop it after the first alkylation (adding an alkyl group to a molecule)
it keeps on adding Me until its quaternaryyyy.
arrow from amine N to Me and then to I,, kicks off I and Me stays. then repeats till all H’s are Me/R groups.
Na BH4 is used to what
joins carbonyl aldehydes and amines,, gets rid of carbonyl group and in its place will be a NH and then the rest of the amine
C - N explain partial charges
C is partially positive
N is partially negative
bc of electronegativity difference
what does N act like
like a nucleophile bc it has a lone pair
sources of e-
lone pair
- charge
bonds
whn electrons are moved,, where does the arrow normally end
somewhere good
somewhere that can hold a
(-) well
