Ch14: Epoxides & Ethers Flashcards
Ether compound structure
R-O-R’
Ethers other than ______ are relatively _______ therefor commonly used as ______
epoxides, unreactive, solvents
ethers have ______ boiling points than alcohols of similar molecular weights because no ________
lower, hydrogen bonding
ethers solvate ______
alcohols solvate _______
cations, not anions
cations and anions
ethers are usually _____ towards strong bases, therefore used as solvent for strong bases such as _______
unreactive, Grignard reagent
Ethers commonly complex with _______ to stabilize the compound, ex: _______
grignard reagents, or electrophiles; ex: BH3.THF
_____ ethers are large cyclic polyethers that specifically solvate _____
crown, metal cations
cyclohexene —peroxybenzoic acid—> ????
cyclohexene oxide
ethylene + peroxybenzoic acid —>
ethylene oxide/ozirane/1,2-epoxyethane + benzoic acid
oxetane
more reactive than larger cyclic ethers and open-chain ethers, but not as much as oxiranes
four-membered ring
furans (oxylanes), ex:______ hydrated, _____ unsaturated
five-membered ring
ex: tetrahydrofuran (THF), 3-methoxyfuran
pyrans (oxanes), ex: ______ hydrated, ______ unsaturated
six-membered ring
ex: tetrahydropyran (THP), 4-methylpyran
dioxanes, ex: ______ most commmon, ______ toxic group
six-membered rings
ex: 1,4-dioxane, dibenzo-1,4-dioxane/dioxin
IR identified by _____ at 1000-1200cm-1, no____ or _____
strong C-O stretch, no C=O or O-H
three fragmentations processes in mass spec
alpha cleavage: loss of either of the alkyl groups next to O produces oxonium ion
loss of an alkyl group: fragment next to O produces oxonium ion or alkyl cation
alpha cleavage + loss of group
Williamson ether synthesis
SN2 attack of alkoxide ion on unhindered primary alkyl halide or tosylate
cyclohexanol —[1]Na–>—[2]CH3CH2OTs–> ?????
ethoxycyclohexane
3,3-dimethylpentan-2-ol —[1]Na–>—[2]CH3I–> ?????
2-methoxy-3,3-dimethylpentane
a phenol can be used as the ______ fragment but not the ______ fragment for Williamson ether synthesis
alkoxide, halide ( can get attacked and joined to, but cannot be the added compound)
-H2C=C=H2- —??? in ??? —> -HC(-AcOHg)-CH(-O-R)- —-???–> -C(H)H-C(H)OR-
Hg(OAc)2 in ROH, NaBH4
CH3(CH2)3-CH=CH2 —[1]Hg(OAc)2, CH3OH–>—[2] NaBH4—> ?????
Mark or anti-Mark?
CH3(CH2)3-CH(-OCH3)-CH3
Markovnikov
Biomolecular condensation ______ in ______ gives you _____ + ________
2 primary alcohols in acid gives you symmetrical ether + water
ethers are cleaved by ___ or ___ to give you ___ or ____
HBr or HI to give you alkyl bromides or alkyl iodides
R-O-R’ + H-X ?????
protonated ether
R-O(H)-R (positive cation)
R-O(H)-R’ + X- —> ????
X-R + H-O-R’
H-O-R’ + ???? –> X-R’ + H2O
HX
cyclopentyl ethyl ether —> Br-CH2-CH3 and 1-bromocyclopentane MECHANISM (6 steps)
[1] H-Br protonate O of ether
[2] Br- attacks less hindered C, cleaves O-C bond producing Br-CH2-CH3 and cyclopentan-1-ol
[3] H-Br protonate O
[4] water leaves forming cation
[5] Br- binds to cation +, forming 1-bromocyclopentane
phenyl ethers react with ____ and ____ to give alkyl halides and _____
H-I and H-Br, phenols, phenols do not react further
ethyl phenyl ether —> phenol and ethyl bromide MECHANISM (2 steps)
[1] H-Br protonates ether
[2] Br- attacks less hindered C producing phenol and Br-CH2CH3
ether — excess O2 —> ???? and ????
R-O-CH2-R’
hydroperoxides
R-O-CH(OOH)-R’
dialkly peroxide
R-O-O-CH2-R’
thioethers another name
sulfides, S replaces O
silyl ether structure, useful for as _____ because they are more easily ______ and _____
R-O-(R’)Si(R’)-R, Si replaces a CH2
protecting group for alcohols, formed and hydrolyzed
thiolate ion formation, useful in producing _____ products with inversion or retension
thiol + Na+-OH
SN2, inversion
peroxide + acid, good _____ for sulfides (mild ____ agent)
oxidizing agents, reducing
Sulfide —???? in ????–> sulfoxide
stability?
H202 and CH3-COOH
peroxide and acetic acid
R-S(=O)-R’ R-S(-O)-R positive cation
sulfoxide —H2O2 and CH3COOH–>?
stability?
sulfone stabilized by resonance
R-(O=)S(=O)-R’ R-(O-)S(-O)-R 2+positive cation
ozonolysis of alkene
1-methyl cyclohex-1-ene —???—>??—> dimethyl sulfide and CH3(O=)C-(CH2)4-C(=O)H what happened to the first product?
O3 to give oxonide, dimethyl sulfoxide, sulfide breaks the ring, and is oxidized to dimethyl sulfoxide
sulfide + ??? —SN2—> sulfonium salt
alkyl halide
sulfonium salt + nucleophile —>?
Nuc: + CH3-S(R)-R —>?
alkyl (nuc) + sulfide
Nuc-CH3 + R-S-R
R-OH + [1] _____ in _____ —–> R-O-TIPS + [2] ____ in _____—–> R-OH + (i-Pr)3SiF
[1] does what?
[2] does what?
(i-Pr)3SiCl aka TIPSCl in Et3N:
Bu4N+-F in water
[1] TIPS replaces H, protecting the alcohol while a different part of the compound is changed
[2] Bu4N+-F removes TIPS and H2O reforms the alcohol
alkene + peroxyacid —>???
>C=C< + R-(O=)C-O-O-H
epoxide + acid
>COC< + R-(O=)C-O-H
MCPBA
meta-chloroperoxybenzoic acid
chlorine-benzene ring-C(=O)-O-O-H
cyclohexene -> epoxycyclohexane
MCPBA in CH2Cl2
MMPP
magnesium monoperoxyphthalate, water-soluble peroxyacid
halohydrin + base ???? —> epoxide
> C(-X)-C(< )-OH opposite sides + -OH
[1] dehydrogenation
[2] O attacks opposite C, halide leaves forming an epoxide
___ + ___ in _____ –> chlorohydrin
intermediate?
ex: trans-chorohydrin (Cl and OH opposite sides)
alkene + dichloride in water
produces a chloronium ion (Cl epoxide)
ex: cyclopentene + chlorine water
[1] chlorohydrin + ???–> [2] —> expoxide
[1] base
[2] alkoide, O attacks the opposite C, halide leaves
acid + epoxide in water –> ????
stereochemistry?
opens ring, trans-diol
anti
alkene + peroxyacid in H+ , H20 —>?
cis-diol
acid + epoxide in alcohol –> ????
stereochemistry?
alkoxy group bonds to the _____ carbon
opens ring attaches alcohol (O-R) and form hydroxy group (add H)
anti
OR binds to more highly substituted, OH binds to less substituted
ethers do not form alcohols easily instead ____ are used
epoxides
strong base + epoxide —> ????
trans-diol
these solvents can open epoxides
acids, strong bases, alkoxide ions (ex: CH3-O-+Na in CH3OH), amines, grignard, organolithium reagents
HOCH2CH2N:H2 + oxirane —> [1] + oxirane —> [2]
[1] (HOCH2CH2)2N:H
[2] (HOCH2CH2)3N:
basic conditions orientation of epoxide opening
attacks how?
give?
attack less hindered carbon
SN2 displacement, give alcohols, OR binds to less substituted, OH binds to more substituted
acidic conditions orientation of epoxide opening
attacks how?
give?
attacks the protonated carbon of the epoxide , give alcohols,
[1] Grignard reagent + epoxide in _____ —->[2]H20 —> ????
[1] ether
[2] ring-opened alcohol
Organolithium and grignard reagents attack the ______ carbon of an epoxide,
which is more specific?
less hindered, R bonds less substituted, OH bonds more substituted
organolithium is more specific
methyl oxirane + H+ in CH3-OH —>??
2methoxypropan-1-ol
CH3-CH(-OCH3)-CH2-OH
methyl oxirane + CH3-O-+Na in CH3OH—>??
1methoxypropan-2-ol
CH3-CH(-OH)-CH2-OCH3
methyl oxirane + [1] R-MgBr –>[2]-????–>???
[2] H30+
CH3-CH(OH)-CH2-R
R bonds to the less substituted carbon
