Experiment 9: Dehydrating Cyclohexanol
more substituted
The _________ alkene is favored due to the fact that in the transition state, a double bond is partially formed.
dehydration
elimination of water from alcohol is a ___________ reaction
SN1
if you have a good nucleophile you get more ________ product
more E1 product
if you have a stronger Bronsted base you get more ________ product
The dehydration of cyclohexanol
this is the reaction mechanism for:
◦ H3PO4
what acid was used in the dehydration of cyclohexanol?
Bromine (Br2)
what chemical was used to test for the presence of a double bond (alkene) within the structure of cyclohexene?
ammonium cerium (IV) nitrate ((NH4)2Ce(NO3)6)
what chemical was used to test for the presence of a hydroxyl group within the structure of cyclohexene?
Cyclohexane
what compound is this?
cyclohexanol
what compound is this?
Bromine (Br2) test - will test for the presence of a double bond
what qualitative test reaction is this? what is it testing for?
did ammonium cerium (IV) nitrate ((NH4)2Ce(NO3)6) test - will test for the presence of a hydroxyl group
what qualitative test reaction is this? what is it testing for?
a good nucleophile
you get more SN1 product if you have:
carbocation
As in the SN-1 reaction, the slow step is the ionization of the substrate to give a ___________.
substrate
As in the SN-1 reaction, the slow step is the ionization of the ___________ to give a carbocation.
the number of alkyl groups attached to the carbon bearing the -OH group.
Alcohols are classified by what?
slow step
As in the SN-1 reaction, the ___________ step is the ionization of the substrate to give a carbocation.
ionization
As in the SN-1 reaction, the slow step is the __________ of the substrate to give a carbocation.
intermediate carbocation
As in the SN-1 reaction, the slow step is the ionization of the substrate to give a carbocation. The _______________ can either add a nucleophile to finish off the SN-1 reaction, or lose a proton to produce an alkene in the E1 reaction
add a nucleophile
As in the SN-1 reaction, the slow step is the ionization of the substrate to give a carbocation. The intermediate carbocation can either _____________ to finish off the SN-1 reaction, or lose a proton to produce an alkene in the E1 reaction
lose a proton
As in the SN-1 reaction, the slow step is the ionization of the substrate to give a carbocation. The intermediate carbocation can either add a nucleophile to finish off the SN-1 reaction, or ____________ to produce an alkene in the E1 reaction
an alkene
As in the SN-1 reaction, the slow step is the ionization of the substrate to give a carbocation. The intermediate carbocation can either add a nucleophile to finish off the SN-1 reaction, or lose a proton to produce _____________ in the E1 reaction
the SN-1 reaction
As in the SN-1 reaction, the slow step is the ionization of the substrate to give a carbocation. The intermediate carbocation can then add a nucleophile to finish off ______________
E1
As in the SN-1 reaction, the slow step of the ______ reaction is the ionization of the substrate to give a carbocation.
SN-1
As in the _________ reaction, the slow step of the E1 reaction is the ionization of the substrate to give a carbocation.
H+ acceptor
Bronsted bases
◦Elimination of water from alcohols ◦Acid catalyzed ◦E1 mechanism
Dehydration reactions involve which 3 key points?
Bronsted bases
H+ acceptor
Occurs when one atoms leaves a compound with both electrons of the original bond, resulting in the formation of ions.
Heterolytic bond cleavage :
hydrogen
In many E1 reactions, more than one __________ can be removed from the carbocation intermediate.
first order process
Rate law is a _________ process
Favored by a highly basic nucleophile
The carbocation intermediate is favored by what kind of nucleophile for an E1 reaction?
Favored by a highly nucleophillic nucleophile
The carbocation intermediate is favored by what kind of nucleophile for an SN1 reaction?
Tertiary > Secondary >Primary
The ease of alcohol dehydration based on the type of alcohol in involved is ranked from......
stability
The ease of alcohol dehydration is ranked from Tertiary > Secondary>Primary because of the ________ of the carbocation formed
carbocation
The ease of alcohol dehydration is ranked from Tertiary > Secondary>Primary because of the stability of the _________ formed
Tertiary
The easiest alcohol dehydration will occur with a _________ alcohol
substituted
The favoring for the formation of them more ________, more stable alkene is known as Saytzeff's Rule.
stable
The favoring for the formation of them more substituted, more _________ alkene is known as Saytzeff's Rule.
alkene
The favoring for the formation of them more substituted, more stable ________ is known as Saytzeff's Rule.
Saytzeff's Rule
The favoring for the formation of them more substituted, more stable alkene is known as __________.
transition state
The more substituted alkene is favored due to the fact that in the _________, a double bond is partially formed.
double bond
The more substituted alkene is favored due to the fact that in the transition state, a ___________ is partially formed.
partially formed
The more substituted alkene is favored due to the fact that in the transition state, a double bond is __________.
increased stability
The more substituted alkene is favored due to the fact that in the transition state, a double bond is partially formed. The ___________ of more substituted double bonds will be felt, and more thermodynamically favored.
substituted double bonds
The more substituted alkene is favored due to the fact that in the transition state, a double bond is partially formed. The increased stability of more ___________ will be felt, and more thermodynamically favored.
thermodynamically
The more substituted alkene is favored due to the fact that in the transition state, a double bond is partially formed. The increased stability of more substituted double bonds will be felt, and more ____________ favored.
Primary
The most difficult alcohol dehydration will occur with a _________ alcohol
E1 reaction
The slow step is the ionization of the substrate to give a carbocation. The intermediate carbocation can then lose a proton to produce an alkene in the _________ reaction
◦Occurs when a small molecule (H-X) is expelled from the adjacent carbon atoms. ◦A pi-bond is formed, good for producing alkenes and alkynes. ◦Heterolytic bond cleavage : Occurs when one atoms leaves a compound with both electrons of the original bond, resulting in the formation of ions.
What are 3 characteristics discussed in lab in which define an elimination reaction?
Bromine (Br2) will test for the presence of a double bond (alkene)
What functional group did bromine (Br2) test for within the structure of cyclohexene?
the formation of them more substituted, more stable alkene will be favored (will be the major product)
What is Saytzeff's Rule?
As in the SN-1 reaction, the slow step is the ionization of the substrate to give a carbocation
What is the slow step of an E1 reaction? How does this relate to an SN-1 reaction?
In many E1 reactions, more than one hydrogen can be removed from the carbocation intermediate, leading to more than one possible product
Why can more than one product sometimes be formed during an E1 reaction?
a stronger Bronsted base
You get more E1 product if you have:
elimination
_________ of water from alcohol is a dehydration reaction
a color change from yellow to red
a positive ammonium cerium (IV) nitrate test for the presence of a hydroxyl group within the structure of cyclohexene is indicated by:
Br2 will react with an alkene to form a colorless compound. Will change from red-brown to colorless
a positive bromine test for the presence of a double bond (alkene) within the structure of cyclohexene is indicated by:
strong Bronsted bases will be more effective than weak Bronsted bases
in E1 reactions, __________ will be more effective at removing the proton than________________
removing the proton
in E1 reactions, strong Bronsted bases will be more effective at ____________ than weak Bronsted bases
Ethylene < 1-Butene < cis-2-butene < trans-2-Butene < 2-Methyl-2-butene < 2,3-Dimethyl-2-butene
rank the following alkenes from least to most stable 2-Methyl-2-butene 2,3-Dimethyl-2-butene Ethylene trans-2-Butene 1-Butene cis-2-butene
Rate (v) = k [R-----L]
rate law (equation)
