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organic sem 2 > lecture 3 > Flashcards

lecture 3 Flashcards

1
Q

how is DMDO made

A

acetone + KHSO5

gives DMDO

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2
Q

name dmdo

A

di methyl dioxirane

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3
Q

what is KHSO5

A

potassium
peroxy mono sulfate

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4
Q

what is KHSO5 used for

A

used to react with acetone to give dmdo

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5
Q

highlight the 2 step process to making epoxiranes

A

alkene + Br2 and H2O (bromonium ion then open it using H2O)

bromonium ion + NaOH (removes most acidic H)
arrow kicks off Br using O- on the alcoholate
epoxilate is made with NaBr

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6
Q

in the reaction of making epoxirane, what is used to ring open the bromonium ion

A

H2O

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7
Q

in the epoxirane, what is used to remove the most acidic H

A

NaOH

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8
Q

describe an alcoholate

A

O-
with a halogen on adjacent C

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9
Q

how is an epoxide made from the alcoholate

A

the - charge is used to kick off the bromine (good LG)

and forms an epoxide

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10
Q

what is a toluene

A

benzene with CH3 attached

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11
Q

how is an epoxide made from a toluene

A

liver oxidase and O2
McBPA cannot react with aromatics

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12
Q

cyclohexane epoxide with HNMe2

A

N: attacks the other side of the epoxide

the NHMe ring opens the epoxide
the product is trans (one dashed one wedged) the O from the epoxide grabs a H. NHMe loses a H to make the N neutral

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13
Q

asymmetric epoxide with NaOMe and MeOH (stereospecific ring opening reaction 1 ) BASE CATALYSED EPOXIDE RING OPENING

A

the O- in NaOMe attacks the less hindered C and ring opens the epoxide
the O- epoxide grabs the H in HOMe
this gives an OH and an COMe alkene

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14
Q

asymmetric epoxide with H+ and MeOH ( 2nd stereospecific ring opening reaction ) ACID CATALYSED EPOXIDE RING OPENING

A

the epoxide is placed in an acidic environment (lots of H+) + is protonated

the O: attacks a H+ and forms an alcohol epoxide (still a ring)
then the MeOH ring opens it at the most stable section. gives an OH and OMe alkene

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15
Q

what do the reaction conditions of epoxides determine

A

determine what carbon will be attacked to ring open

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16
Q

normal asymmetric epoxide and
NaO-Me,, which epoxide C will be attacked

A

the most accessible one

the O- attacks the least hindered epoxide C

17
Q

normal asymmetric carbon and H+ aka an acidic environment

A

the lone pairs on the O attack the protons leading to an epoxide but the O is bonded to a H (alcohol)
the MeOH then ring opens it at the most stable CC+

18
Q

describe what a epichlorohydrin looks like

A

epoxide with a methyl tail and a Cl at the end

19
Q

name a bad way of making epichlorohydrin

A

alkyl chloride
and
McPBA

20
Q

why is making epichlorohydrin using alkyl chloride and mcPBA bad

A

it makes more mCBA than epichlorohydrin

more side product than desired product

21
Q

how else can epichlorohydrin be made

A

alkyl chloride
HOCl (hypochlorus acid)
NaOH

22
Q

steps of making epichlorohydrin using NaOH, HOCl and and alkyl chloride

A

alkyl chloride + Cl+
makes a chloronium ion
OH- attacks this and ring opens it
NaOH removes the most acidic proton
a epichlorohydrin is made

23
Q

steps of making epichlorohydrin using glycerine
E with OH at each end

A

glycerine + HCl
H+ protonates the groups
Cl- attacks the carbons and removes the H2O leaving groups

its treated with NaOH to make a epichlorohydrin

24
Q

3 ways to make an epoxide

A

alkene + mcpba
alkene + dmdo
alkene + Br2 + H2O + NaOH

25
Q

alkene + mcpba

A

epoxide
mcba

26
Q

alkene + dmdo

A

epoxide
acetone

27
Q

alkene + Br2 + H2O + NaOH

A

epoxide + NaBr

alkene
bromohydrin (OH and Br)
alcoholate (O- and Br)
then Br is kicked off bc its a good leaving group

28
Q

base catalysed ring opening reaction

A

epoxide + Na OMe + MeOH

O on epoxide = weak LG,, it must first be attacked by the nucleophile in order for the MeOH to attack.

the OMe will attack the least hindered carbon of the epoxide

29
Q

acid catalysed ring opening reaction

A

there is H+ present which allows O of epoxide to be protonated forming a good LG (OH),, this then doesnt need a nuc and so MeOH can attack the most stable c on epoxide

30
Q

acid catalysed ring opening

A

most stable cc+

31
Q

base catalysed ring opening reaction

A

least hindered carbon

organic sem 2 (14 decks)

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