organic 8 Flashcards
alkene + Br2
bromonium ion formed (+)
water attacks one of the carbons
BR will be wedged
OH2 will be dashed
h2o is deprotonated to give OH.
OH is deprotonated to give O..
: attack C which kicks off Br.
gives an epoxide,, both things are dashed.
if the 2 r groups are pointing in different ways the epoxide is called
trans
z alkene + mcpba
epoxide + mcba
bond attacks the OH O
O_O bond to OC,,, bond = attacks the H
cis epoxide is formed
how can we speed up epoxidation when we start with an alkene
make sure its a substituted alkene as it will be more nucleophilic due to inductive effects at the double bond.
itll be more attracted to the O on mcpba and react faster
descrive dmdo
chair with 2 O,s and 2 Me’s
describe Z alkene and DMDO
bond attacks the O,
that O’s lone pair attacks the double bond - epoxide is formed
O-O bond goes onto O and forms O-,, O- goes to the C and the C-O bond breaks which disconnects it from the epoxide
this gives a cis epoxide bc the Rr groups are tilted to the same side
cyclohexene to trans 1,2 diol (2 alcohols) (trans dihydroxylation)
cyclohexene + mcpba
gives a epoxide
epoxide attacks a H
O is now +
H2o attacks a C,, e- go to O to form O-
O- is protonated and wedged
OH2 is deprotonated to give OH and is dashed.
cyclohexene and Os 4(=O) syn dihydroxylation
Os=O attacks C on C=C
double bond attacks an o,, o=os e- go to Os.
gives a osmate ester
cyclohexene is now cyclohexane and 2C’s are bonded to 2 O’s on the Os =o =o =o =o which are now -o -o =o =o bc O needs 2 bonds only.
both are wedged.
H20 attacks the Os and kicks off an O to the cyclohexane,, its then protonated and the same thing happens on the other side to give cis 1,2, diol.
and Os - OH -OH =o =o
what can we do with the cis diol cyclohexane
we can cleave it - aka break one of the bonds
how can we cleave a bond on cyclohexane 1,2 diol
we use I =o =o =o -o-
:OH attacks the I and moves onto the O to give O-
HO+ is neutralised by removing the H on OH using the O-.
the other OH then also attacks the I and makes O-,, this then also deprotonates the OH to make it neutral.
the bond between the O is broken and given to one of the Os to form a double bond, O-I e- then go to the I,, I-O e- then go to the other O
this gives a broken cyclohexane with couble bonds to O.
ozonolysis
alkene to aldehydessss
using alkene + o-o=o
middle o is (+)
last o is o-
double bond attacks the o with the double bond,, double bond moves to the centre and neutralises the middle positive o, o- attacks the double bond
this gives a primary ozonide (ring type thing)
bonds then break between the Rs and the O’s to give a secondry ozonide.
SMe2 attacks the O using its lone pair and then O- uses its charge to kick off the S(+),, this gives 2 aldehydes with different R groups.
cyclohexene + O3 + NaBH4 givesss
cleaved cyclohexane 1,2diol
cyclohexane + O3 + H2O2 gives
cleaved cyclohexane with Carboxylic acids on the endsss
