Shared Flashcard Set

Details

Chapter 11: Reactions of Alcohols
Chapter 11: Reactions of Alcohols
205
Organic Chemistry
Undergraduate 2
06/03/2019

Additional Organic Chemistry Flashcards

 


 

Cards

Term
why alcohols are important
Definition
because thehydroxy group is easily converted to almosdt any other functional group
Term
name that reaction
[image]
Definition
[image]
Term
name that reaction
[image]
Definition
tosylation
Term
name that reaction
[image]
Definition
esterfication
Term
name that reaction
[image]
Definition
reduction
Term
name that reaction
[image]
Definition
substitution
Term
name that reaction
[image]
Definition
oxidation
Term
name that reaction
[image]
Definition
dehydration
Term
[image]
Definition
[image]
Term
[image]
Definition
[image]
Term
[image]
Definition
[image]
Term
[image]
Definition
[image]
Term
[image]
Definition
[image]
Term
[image]
Definition
[image]
Term
[image]
Definition
[image]
Term
OCHEM definition of oxidation
Definition
adding an oxidizing agent -O, O2 -X2 (halogens) -etc. OR losing H2
Term
OCHEM definition of reduction
Definition
adding reducing agent -H2 -H- -NaBH4 -etc. OR loss of -O, O2 -X2 (halogens)
Term
when an organic rxn is neither oxidation nor reduction
Definition
adding or losing -H+ --OH, H2O -HX, etc.
Term
how to tell whether or not an organic redox rxn has occurred
Definition
by counting the number of C-O bonds on that C
Term
what an organic redox rxn usually does
Definition
converts C-H bonds to C-O bonds
Term
chart of organic oxidation and reduction
Definition
[image]
Term
[O]
Definition
unspecified oxidizing agent
Term
oxidixing alcohols often results in...
Definition
-ketones
-aldehydes
-carboxylic acids
Term
some oxidizing agents that are used to oxidize alcohols
Definition
-chromium oxides
-permangenate
-nitric acid
-sodium hypochlorite (NaOCl)
Term
what all the oxidizing agents used have in common
Definition
-they have an element in a high oxidation state bonded to oxygen
-they follow similar mechanisms
Term
high (oxidized) oxidation state
Definition
more C-O bonds
Term
low (reduced) oxidation state
Definition
fewer C-O bonds
Term
when the chromic acid reagent (H2CrO4) is used to oxidize secondary alcohols
Definition
when less hazardous reagents, such as NaOCl (household bleach) fail to deliver a good yield
Term
how a chromate ester is formed
Definition
[image]
Term
how the chromate ester is eliminated and the carbinol atom is oxidized
Definition
[image]
Term
[image]
Definition
[image]
Term
NaOCl (sodium hypochlorite) can serve as a more selective oxidizing agent, especially when used with...
Definition
TEMPO
Term
[image]
Definition
TEMPO

this is a stable free radical that can catalyze many oxidation rxns
Term
TEMPO
Definition
[image]

this is a stable free radical that can catalyze many oxidation rxns
Term
[image]
Definition
[image]

or

[image]
Term
NaOCl with the right amount of TEMPO oxidizes primary alcohols to aldehydes, but what happens it there's excess TEMPO?
Definition
it oxidizes primary alcohols to carboxylic acids
Term
[image]
Definition
[image]
Term
PCC
Definition
pyridinium chlorochromate
Term
[image]
Definition
PCC (pyridinium chlorochromate)
Term
PCC (pyridinium chlorochromate)
Definition
[image]
Term
[image]
Definition
[image]
Term
why tertiary alcohols are more resistant to oxidation
Definition
because they have no H atoms on the carbnol C
Term
how tertiary alcohols are oxidized
Definition
by breaking of C-C bonds under severe conditions
Term
the type of alcohols that can't be oxidized by chromic acid nor PCC
Definition
tertiary alcohols
Term
Swern oxidation
Definition
uses dimethyl sulfoxide (DMSO) to oxidize alcohols to form ketones and aldehydes
Term
[image]
Definition
dimethyl sulfoxide (DMSO)
Term
dimethyl sulfoxide (DMSO)
Definition
[image]
Term
Swern oxidation
Definition
[image]
Term
[image]
Definition
[image]
Term
[image]
Definition
[image]
Term
[image]
Definition
Dess-Martin periodinane (DMP) reagent
Term
oxidation using the DMP reagent
Definition
[image]
Term
[image]
Definition
NaOCl (excess)-TEMPO
Term
[image]
Definition
-NaOCl-TEMPO
-Swern
-DMP
Term
[image]
Definition
-NaOCl-HOAc
-Swern
-DMP
Term
[image]
Definition
chromic acid
Term
[image]
Definition
PCC
Term
[image]
Definition
chromic acod or PCC
Term
why methanol is more toxic than ethanol
Definition
because it gets converted to formaldehyde, then to formic acid, both more toxic than methanol itself
Term
why alcohols are such vers\atile chemical intermediates
Definition
because they can function as both nucleophiles and electrophiles
Term
alcohol reacting as a weak nucleophile
Definition
[image]
Term
how alcohol is converted to a strong nucleophile
Definition
by forming its alkoxide ion
[image]
Term
the bond that's broken when an alcohol reacts as a nucleophile
Definition
O-H
Term
the bond that's broken when alcohol reacts as an electrophile
Definition
C-O
Term
why alcohol is a weak electrophile
Definition
because the hydroxy (-OH) group is a poor leaving group
Term
how to convert an alcohol to an electrophile that's compatible with basic nucleophiles
Definition
by converting it to an alkyl halide or making its tosylate ester
Term
tosylate ester (ROTs)
Definition
the product of condensation of an alcohol with p-toluenesulfonic acid (TsOH)
Term
converting an alcohol to an alkyl tosylate
Definition
[image]
Term
[image]
Definition
p-toluenesulfonic acid
Term
substitution with a tosylate ester
Definition
[image]
Term
elimination with a tosylate ester
Definition
[image]
Term
[image]
Definition
[image]
Term
how a tosylate ester (ROTs) is formed
Definition
[image]
Term
[image]
Definition
[image]
Term
[image]
Definition
[image]
Term
[image]
Definition
[image]
Term
[image]
Definition
[image]
Term
[image]
Definition
[image]
Term
[image]
Definition
[image]
Term
why the reduction of alcohols to alkanes is not common
Definition
because it removes a functional group
Term
reduction of an alcohol
Definition
[image]
Term
the process described here
[image]
Definition
reduction of an alcohol
Term
how an alcohol is reduced
Definition
[image]
Term
another way to reduce an alcohol
Definition
[image]
Term
how tertiary alcohols become alkyl halides
Definition
the hydroxy (-OH) group gets protonated, then it gets replaced by the halide (X-) the mechanis is SN1 or SN2
Term
why the SN2 mechanism is more favorable for converting primary alcohols to alkyl bromides
Definition
because the a primary carbocation is unstable
Term
the mechanism used in converting a primary alcohol to an alkyl bromide
Definition
SN2
Term
the mechanism used in converting a secondary alcohol to an alkyl bromide
Definition
SN1
Term
the mechanism used in converting a tertiary alcohol to an alkyl bromide
Definition
SN1
Term
a catalyst that's sometimes needed for reactions of primary and secondary alcohols with HCl
Definition
ZnCl2 (Lucas reagent)
Term
the role of ZnCl2 in reactions of primary alcohols with HCl
Definition
coordinates with the oxygen of that alcohol, but it coordinates more strongly than a proton does.
Term
the mechanism used for rxns of secondary alcohols with HCl
Definition
SN1
Term
the mechanism used for rxns of tertiary alcohols with HCl
Definition
SN1
Term
mechanism for the rxn of a secondary or tertiary alcohol with ZnCl2
Definition
SN1 (fast) [image]
Term
mechanism for the rxn of a primary alcohol with ZnCl2
Definition
SN2 (slow) [image]
Term
how the Lucas reagent (ZnCl2) helps distinguish among primary, secondary, and tertiary alcohols
Definition
by reacting with each at predictable rates
Term
how the Lucas test is done
Definition
by putting Lucas reagent (ZnCl2) into an unknown water-soluble alcohol and watching how quickly the second (water insoluble) phase forms
Term
the alcohols that react fastest with the Lucas reagent (ZnCl2)
Definition
tertiary (<1 min)
Term
the alcohols that react slowest with the Lucas reagent (ZnCl2)
Definition
primary (>6 min)
Term
Are ketones water soluble?
Definition
yes
Term
[image]
Definition
allyl alcohol
Term
allyl alcohol
Definition
[image]
Term
4 limitations of the uses of hydrohalic acids with alcohols
Definition
1: poor yields of alkyl chlorides from primary and secondary alcohols
2: eliminations
3: rearrangements
4: limited ability to make alkyl iodides
Term
some commercially available phosphorus halides that can be used to convert alcohols to alkyl halides
Definition
-PBr3 -PCl3 -PCl5
Term
some useful reactions of phosphorus halides with alcohols
Definition
[image]
Term
the type of alcohol phosphorus halides react poorly with
Definition
tertiary
Term
are phosphorus halides nucleophiles or electrophiles?
Definition
strong electrophiles
Term
mechanism for the reaction of an alcohol with PBr3
Definition
[image]
Term
mechanism for the rxn of an alcohol with thionyl chloride
Definition
[image]
Term
[image]
Definition
[image]
Term
the solvent used when using thionyl chloride ([image])
Definition
dioxane ([image])
Term
the type of chloride used when converting primary alcohols to alkyl halides
Definition
SOCl2
Term
the type of bromide used when converting primary alcohols to alkyl halides
Definition
PBr3 or HBr (HBr works only in selected cases)
Term
the type of iodide used when converting primary alcohols to alkyl halides
Definition
P/I2 that is, 2P + 3I2 <--> 2PI3
Term
the type of chloride used when converting secondary alcohols to alkyl halides
Definition
SOCl2 (SN1 mechanism) PCl3 or PCl5 (SN2 mechanism)
Term
the type of bromide used when converting secondary alcohols to alkyl halides
Definition
PBr3
Term
the type of iodide used when converting secondary alcohols to alkyl halides
Definition
P/I2 that is, 2P + 3I2 <--> 2PI3 this works only in selected cases
Term
the type of chloride used when converting tertiary alcohols to alkyl halides
Definition
HCl
Term
the type of bromide used when converting tertiary alcohols to alkyl halides
Definition
HBr
Term
the type of iodide used when converting tertiary alcohols to alkyl halides
Definition
HI

this works only in selected cases
Term
the mechanism by which the Lucas reagent (ZnCl2) reacts with primary alcohols
Definition
SN2
Term
the mechanism by which the Lucas reagent (ZnCl2) reacts with secondary alcohols
Definition
SN1
Term
the mechanism by which the Lucas reagent (ZnCl2) reacts with tertiary alcohols
Definition
SN1
Term
the mechanism by which HBr reacts with primary alcohols
Definition
SN2
Term
the mechanism by which HBr reacts with secondary alcohols
Definition
SN1
Term
the mechanism by which HBr reacts with tertiary alcohols
Definition
SN1
Term
the mechanism by which phosphorus trihalides react with primary alcohols
Definition
form a leaving group, then SN2
Term
the mechanism by which phosphorus trihalides react with secondary alcohols
Definition
form a leaving group, then SN2
Term
the mechanism by which phosphorus trihalides react with tertiary alcohols
Definition
they react very poorly with tertiary alcohols, but form a leaving group, then SN2
Term
mechanism by which thionyl chloride (SOCl2) reacts with alcohol
Definition
resembles Sn1, but retains stereochemistry because the halide is delivered by the leaving group
Term
why reactions with thionyl chloride (SOCl2) retain stereochemistry
Definition
because the halide is delivered by the leaving group
Term
the mechanism by which alcohol dehydration takes place
Definition
usually the E1 mechanism
Term
rxn energy diagram for dehydration of an alcohol
Definition
[image]
Term
the rate-limiting step for dehydration of an alcohol
Definition
the formation of a carbocation
Term
why the formation of a carbocation is the rate-limiting step of dehydration of an alcohol
Definition
because tertiary carbocations form more easily, and therefore quicker, than secondary, and secondary more than tertiary
Term
why tertiary alcohols are more easily dehydrated than secondary and secondary more easily than primary
Definition
because of the ease of forming the carbocation (tertiary easier than secondary easier than primary)
Term
why dehydration is not a good method for converting primary alcohols into alkenes
Definition
because the rxn conditions must be severe and the frequent occurrence of rearrangement
Term
dehydration of a primary alcohol
Definition
[image]
Term
E1 mechanism
Definition
[image]
Term
E2 mechanism
Definition
[image]
Term
bimolecular condensation / bimolecular dehydration
Definition
when a protonated primary alcohol is attacked by another molecule of that alcohol and undergoes an SN2 displacement
Term
condensation
Definition
rxn that joins 2 or more molecules, often at the expense of a small molecule like water
Term
the mechanism that occurs when an alcohol is dehydrated to give an alkene
Definition
elimination; this is unimolecular
[image]
Term
the mechanism that occurs when bimolecular condensation of alcohol occurs
Definition
substitution
[image]
Term
which has a more positive change in entropy (ΔS)? elimination or substitution?
Definition
elimination
Term
Gibbs free energy equation
Definition
ΔG = ΔH - TΔS
Term
ΔG
Definition
change in Gibbs free energy or "available energy" Δ = TΔStotal
Term
ΔH
Definition
change in enthalpy ΔH = TΔSsurr
Term
T
Definition
temperature (Kelvins)
Term
ΔS
Definition
entropy change ΔS = TΔSsystem
Term
the temperature at which dehydration of alcohols is favored over substitution
Definition
around 140°C
Term
the temperature at which substitution of alcohols is favored over dehydration
Definition
around 180°C
Term
electrons move from ______ to ______
Definition
nucleophile (electron donor) and electrophile (electron acceptor), respectively
Term
some reactions diols undergo that depend on 2 adjacent -OH groups
Definition
-pinacol rearrangement
-cleavage by periodic acid
Term
pinacol rearrangement
Definition
[image]
Term
mechanism for pinacol rearrangement
Definition
[image]
Term
when periodic acid cleaves a bond between 2 C atoms
Definition
only when there's a free _OH group on each C
Term
periodic acid cleavage of glycols
Definition
[image]
Term
how to produce an alkoxide salt
Definition
by deprotonating an alcohol using an active metal, like Na or K
[image]
Term
reactivity of Na and K with alcohols, most reactive to least reactive
Definition
methyl > primary > secondary > tertiary
Term
reagent that's often used when an alcohol reacts slowly with both Na and K
Definition
sodium hydride (NaH), usually in THF
Term
Williamson ether synthesis
Definition
an SN2 displacement in which an alcohol attacks a primary alkyl halide or tosylate to form an ether
Term
what usually happens when you try to do Williamson ether synthesis with a secondary or tertiary alkyl halide or tosylate?
Definition
elimination
Term
most important method for making ethers
Definition
Williamson ether synthesis
Term
mechanism for Williamson ether synthesis
Definition
[image]
Term
dimethyl sulfate
Definition
[image]
Term
[image]
Definition
dimethyl sulfate
Term
the mechanism by which alcohol dehydration takes place
Definition
usually the E1 mechanism
Term
rxn energy diagram for dehydration of an alcohol
Definition
[image]
Term
the rate-limiting step for dehydration of an alcohol
Definition
the formation of a carbocation
Term
why the formation of a carbocation is the rate-limiting step of dehydration of an alcohol
Definition
because tertiary carbocations form more easily, and therefore quicker, than secondary, and secondary more than tertiary
Term
why tertiary alcohols are more easily dehydrated than secondary and secondary more easily than primary
Definition
because of the ease of forming the carbocation (tertiary easier than secondary easier than primary)
Term
why dehydration is not a good method for converting primary alcohols into alkenes
Definition
because the rxn conditions must be severe and the frequent occurrence of rearrangement
Term
dehydration of a primary alcohol
Definition
[image]
Term
E1 mechanism
Definition
[image]
Term
E2 mechanism
Definition
[image]
Term
bimolecular condensation / bimolecular dehydration
Definition
when a protonated primary alcohol is attacked by another molecule of that alcohol and undergoes an SN2 displacement
Term
condensation
Definition
rxn that joins 2 or more molecules, often at the expense of a small molecule like water
Term
the mechanism that occurs when an alcohol is dehydrated to give an alkene
Definition
elimination; this is unimolecular
[image]
Term
the mechanism that occurs when bimolecular condensation of alcohol occurs
Definition
substitution
[image]
Term
which has a more positive change in entropy (ΔS)? elimination or substitution?
Definition
elimination
Term
Gibbs free energy equation
Definition
ΔG = ΔH - TΔS
Term
ΔG
Definition
change in Gibbs free energy or "available energy" Δ = TΔStotal
Term
ΔH
Definition
change in enthalpy ΔH = TΔSsurr
Term
T
Definition
temperature (Kelvins)
Term
ΔS
Definition
entropy change ΔS = TΔSsystem
Term
the temperature at which dehydration of alcohols is favored over substitution
Definition
around 140°C
Term
the temperature at which substitution of alcohols is favored over dehydration
Definition
around 180°C
Term
electrons move from ______ to ______
Definition
nucleophile (electron donor) and electrophile (electron acceptor), respectively
Term
some reactions diols undergo that depend on 2 adjacent -OH groups
Definition
-pinacol rearrangement
-cleavage by periodic acid
Term
pinacol rearrangement
Definition
[image]
Term
mechanism for pinacol rearrangement
Definition
[image]
Term
when periodic acid cleaves a bond between 2 C atoms
Definition
only when there's a free _OH group on each C
Term
periodic acid cleavage of glycols
Definition
[image]
Term
how to produce an alkoxide salt
Definition
by deprotonating an alcohol using an active metal, like Na or K
[image]
Term
reactivity of Na and K with alcohols, most reactive to least reactive
Definition
methyl > primary > secondary > tertiary
Term
reagent that's often used when an alcohol reacts slowly with both Na and K
Definition
sodium hydride (NaH), usually in THF
Term
Williamson ether synthesis
Definition
an SN2 displacement in which an alcohol attacks a primary alkyl halide or tosylate to form an ether
Term
what usually happens when you try to do Williamson ether synthesis with a secondary or tertiary alkyl halide or tosylate?
Definition
elimination
Term
most important method for making ethers
Definition
Williamson ether synthesis
Term
mechanism for Williamson ether synthesis
Definition
[image]
Term
dimethyl sulfate
Definition
[image]
Term
[image]
Definition
dimethyl sulfate
Term
[image]
Definition
oxalyl chloride
Term
oxalyl chloride
Definition
[image]
Supporting users have an ad free experience!