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Chapter 14: Ethers, Epoxides, and Thioethers
Chapter 14: Ethers, Epoxides, and Thioethers
146
Organic Chemistry
Undergraduate 2
06/03/2019

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Term
ether
Definition
compound of formula R-O-R', where R and R' can be an alkyl or aryl group
Term
difference between alcohols and ethers
Definition
in alcohols, one H is replaced by an alkyl group

in ethers, both H's are replaced by an alkyl group
Term
reactivity or ethers
Definition
relatively unreactive, except for epoxides
Term
bp of ethers compared to alcohols of identical molecular weights
Definition
ethers tend to have boiling points about 100°C lower than those of alcohols of identical weight
Term
the intermolecular forces ethers do have
Definition
-London forces
-dipole-dipole interactions
Term
molecules ethers can H-bond with
Definition
molecules that have a O-H or N-H group; these molecules can donate a H-bond to the ether and the ether can accept it
Term
the ions ether tends to solvate better
Definition
cations
Term
the ions ether tends to not solvate as well
Definition
abnions
Term
why alcohols can't be used as solvents for bases stronger than the alkoxide ion
Definition
because the hydroxy group quickly protonates the base
Term
nonhydroxylic
Definition
having no hydroxy group
Term
how ether interacts with Grignard reagent
Definition
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Term
formation of BH3 · THF
Definition
[image]
Term
crown ether
Definition
large cyclic polyether that specifically solvates a certain metal cation by complexing it in the center of the ring

[image]
Term
an important use of crown ethers
Definition
helps polar inorganic salts dissolve in nonpolar inorganic solvents; complexes with the cation and leaves the anion bare and highly reactive
Term
heterocyclic compound
Definition
contains a ring in which at least one member is something other than C
Term
reagent that is often used to convert alkenes to epoxides
Definition
peroxybenzoic acid
[image]
Term
[image]
Definition
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Term
epoxides aka...
Definition
oxiranes
Term
oxetane
Definition
4-membered cyclic ether
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Term
[image]
Definition
oxetane
Term
furan
Definition
[image]
Term
[image]
Definition
furan
Term
furans aka...
Definition
oxolanes
Term
tetrahydrofuran (THF) (oxolane)
Definition
[image]
Term
[image]
Definition
tetrahydrofuran (THF) (oxolane)
Term
something THF can be used for
Definition
solvating polar reagents
Term
pyran
Definition
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Term
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Definition
pyran
Term
pyrans aka...
Definition
oxanes
Term
tetrahydropyran (THP) (oxane)
Definition
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Term
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Definition
tetrahydropyran (THP) (oxane)
Term
dioxanes
Definition
6-membered heterocyclic ethers with 2 O's in the ring
Term
how IR spectroscopy can be used to determine whether or not the compound is an ether
Definition
ethers and many other compounds give a C-O stretch around 1000 to 1200 cm-1 in the fingerprint region, but if a molecule containing an oxygen has no O-H or C=O group, then it's possibly an ether
Term
the most common fragmentation of ethers
Definition
cleavage next to one of the C atoms bonded to O
Term
α Cleavage of an ether
Definition
[image]
Term
[image]
Definition
α Cleavage of an ether
Term
why α Cleavage is favorable for an ether
Definition
because the resulting oxonium ion is resonance-stabilized
Term
another common cleavage of ether
Definition
loss of either of the 2 alkyl groups, yielding an oxonium ion or an alkyl cation
Term
cleavage of ether by loss of alkyl group
Definition
[image]
Term
[image]
Definition
cleavage of ether by loss of alkyl group
Term
the most reliable an versatile method of ether synthesis
Definition
Williamson ether synthesis
Term
mechanism for Williamson ether synthesis
Definition
[image]
Term
why use of a secondary alkyl halide is less effective than primary in Williamson ether synthesis
Definition
because elimination competes, often resulting in poor yields
Term
alkoxymercuration-demurcuration
Definition
adds an -OR group on one end of the double bond; puts that -OH group in the Markovnikov position
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Term
the cheapest method of synthesizing symmetrical ethers
Definition
bimolecular condensation of alcohols
Term
bimolecular condensation of alcohols
Definition
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Term
the type of alcohol that must be used in bimolecular condensation of alcohols
Definition
primary
Term
cleavage of ethers using HBr and HI
Definition
[image]
Term
mechanism for cleavage of ethers using HBr and HI
Definition
[image]
Term
conditions under which ethers can react
Definition
acidic
Term
the mechanism that usually takes place in cleavage of ethers using HBr and HI
Definition
SN2
Term
iodide and bromide ions are ______ nucleophiles
Definition
good
Term
iodide and bormide ions are ______ bases
Definition
weak
Term
type of alcohol where the HBr and HI won't convert it to an alkyl halide
Definition
phenols
Term
the type of substitution that occurs when a protonated alcohol reacts with bromide or iodide ion
Definition
SN1 or SN2
Term
hydrohalic acids in order of their reactivity towards the cleavage of ethers
Definition
HI > HBr >> HCl
Term
why phenols do not react to produce halides
Definition
because the sp2 hybridized C atom of the phenol can't do the SN2 or SN1 rxn needed to make the halide
Term
mechanism of phenyl ethers reacting with HBr and HI
Definition
[image]
Term
autoxidation
Definition
oxidation of ethers when stored in presence of atmospheric O; this forms hydroperoxides and dialkyl peroxides
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Term
thioethers
Definition
ethers with a S in place of the O
Term
thioethers aka...
Definition
sulfides
Term
[image]
Definition
thioether
Term
thioether
Definition
[image]
Term
silyl ethers
Definition
ethers with a substituted Si atom replacing one of the alkyl groups of an ether
Term
[image]
Definition
silyl ether
Term
silyl ether
Definition
[image]
Term
difference between ethers and thioethers aka sulfides
Definition
thioethers can undergo oxidation and alkylation of the S atom
Term
difference between silyl ethers and ethers
Definition
silyl ethers are more easily formed and more easily hydrolyzed
Term
important use of silyl ethers
Definition
used to protect alcohols
Term
mechanism of synthesizing thioethers using Williamson ether synthesis
Definition
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Term
generation of thiolate ions
Definition
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Term
reactivity of sulfides vs. reactivity of ethers
Definition
sulfides are much more reactive than ethers
Term
oxidation of sulfide aka thioester
Definition
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Term
sulfoxide
Definition
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Term
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Definition
sulfoxide
Term
sulfone
Definition
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Term
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Definition
sulfone
Term
reduction of ozonide
Definition
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Term
ozonide
Definition
[image]
Term
[image]
Definition
ozonide
Term
formation of a sulfonium salt
Definition
[image]
Term
sulfonium salt
Definition
[image]
Term
[image]
Definition
sulfonium salt
Term
why sulfonium salts are strong alkylating agents
Definition
because sulfonium salts polarize the C atom, making it electrophilic
Term
nucleophilic attack on a sulfonium salt
Definition
[image]
Term
characteristics of a good protecting group
Definition
-easy to add to the group it protects
-resistant to the reagents used to modify other parts of the molecule
-easy to remove to restore the original functional group
Term
a type of ether that's a good protecting group
Definition
silicon-based ethers (silyl ethers)
Term
why the fluoride ion removes silyl ethers under gentle conditions
Definition
because the Si-F bond is exceptionally strong
Term
a type of silyl ether that makes a good protecting group
Definition
triisopropylsilyl (TIPS)
Term
triisopropylsilyl (TIPS)
Definition
[image]
Term
[image]
Definition
triisopropylsilyl (TIPS)
Term
synthesis of triisopropylsilyl (TIPS)
Definition
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Term
triisopropyl ether (TIPS) being used as a protecting group
Definition
[image]
Term
reagent often used in synthesis of triisopropylsilyl ether (TIPS)
Definition
tertiary amine, such as Et3N
Term
example of triisopropyl ether being used as a protecting group
Definition
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Term
peroxyacid
Definition
[image]
Term
[image]
Definition
peroxyacid
Term
synthesis of epoxide using epoxyacid
Definition
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Term
conditions under which the epoxide opens to a glycol
Definition
aqueous acid
Term
desirable conditions under which to make an epoxide
Definition
in the absence of strong acids
Term
peroxyacid that is often used in peroxyacid epoxidation
Definition
meta-chloroperoxybenzoic acid (mCPBA)
Term
meta-chlorperoxybenzoic acid (mCPBA)
Definition
[image]
Term
[image]
Definition
meta-chlorperoxybenzoic acid (mCPBA)
Term
mechanism for epoxide synthesis using peroxyacid
Definition
[image]
Term
magnesium monoperoxyphthalate (MMPP)
Definition
[image]
Term
synthesis of an epoxide using MMPP
Definition
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Term
mechanism for base-promoted cyclization of halohydrins
Definition
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Term
mechanism for forming a chlorohydrin
Definition
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Term
mechanism for displacing a chlorohydrin to form an epoxide
Definition
[image]
Term
base that is often used in converting halohydrins into cyclic ethers (5, 6, 7, and occasionally 4-membered rings)
Definition
2,6-lutidine
[image]
Term
2,6-lutidine
Definition
[image]
Term
[image]
Definition
2,6-lutidine
Term
mechanism for converting chlorohydrin into cyclic ether using 2,6-lutidine
Definition
[image]
Term
base-promoted cyclization of halohydrins
Definition
[image]
Term
what epoxides do in acidic conditions
Definition
they open to form glycols
Term
mechanism of acid-catalyzed opening of epoxides in water
Definition
[image]
Term
direct hydroxylation of alkenes
Definition
[image]
Term
what acid-catalyzed opening of an epoxide in alcohol produces
Definition
an alkoxy alcohol with anti stereochemistry, because the alcohol becomes an alkoxide ion
Term
mechanism for acid-catalyzed opening of epoxides in alcohol
Definition
[image]
Term
opening epoxides using hydrohalic acids
Definition
[image]
Term
why most ethers do not undergo nucleophilic substitution
Definition
because alkoxide ion is a poor leaving group
Term
base-catalyzed opening of epoxides
Definition
[image]
Term
rxn coordinate diagram comparing epoxides to acyclic ethers
Definition
[image]
Term
mechanism for base-catalyzed opening of epoxides
Definition
[image]
Term
what base-catalyzed opening of epoxides produces
Definition
trans-glycols
Term
a type of amine that can open an epoxide
Definition
aqueous ammonia (NH3)
Term
mechanism for opening epoxide using aqueous ammonia (NH3)
Definition
[image]
Term
ethanolamine further reacting with epoxides
Definition
[image]
Term
opening of epoxide under acid-catalyzed conditions
Definition
[image]
Term
opening of epoxide under base-catalyzed conditions
Definition
[image]
Term
mechanism for base-catalyzed opening of an epoxide
Definition
SN2 [image]
Term
mechanism for acid-catalyzed opening of an epoxide
Definition
[image]
Term
the carbon that gets attacked in acid-catalyzed opening of epoxides
Definition
the more substituted one, since it has more + charge
Term
the carbon that gets attacked in base-catalyzed opening of epoxides
Definition
the less substituted one, since it's less hindered
Term
comparison of acid-catalyzed and base-catalyzed opening of epoxide
Definition
[image]
Term
opening of epoxide with Grignard or organolithium reagent
Definition
[image]
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Term
mechanism for opening of epoxide with Grignard reagent
Definition
[image]
[image]
Term
which type of reagent is more selective? Grignard or organolithium?
Definition
organolithium reagents are more selective (Grignards can attack more substituted C's)
Term
how epoxy resins form good quality glues as they harden
Definition
by polymerizing with each other
[image]
[image]
[image]
Term
how cross-links are formed between chains of epoxy polymers in glue
Definition
[image]
Term
Acid-catalyzed epoxide opening in water
Definition
[image]
Term
Acid-catalyzed epoxide opening in alcohol
Definition
[image]
Term
using hydrohalic acids to open epoxides
Definition
[image]
Term
base-catalyzed epoxide opening with alkoxodes or hydrides
Definition
[image]
Term
base-catalyzed epoxide opening with organometallics
Definition
[image]
Term
the reagent that must be used to remove the silyl ether (R-O-SiR3) group
Definition
Bu4N+F-
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