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)