CHEM 2811 Final Question and
answers correctly solved 2025
What is the major dehydration products of 2-methylcyclohexanol? Why? -
correct answer 1-methylcyclohexene because it's the Zaitsev product
What is the catalyst used during the dehydration of 2-methylcyclohexanol?
Why? - correct answer H₃PO₄
we don't want it to attach to one of the rings like if we used a hydracid
What is lost as the dehydration 2-methylcyclohexanol proceeds? - correct
answer water because heat is needed
How are the products isolated during the dehydration of 2-
methylcyclohexanol? - correct answer steam distillation, which is used for
liquids that are immiscible
Is carbocation rearrangement possible during the dehydration of 2-
methylcyclohexanol?? How would that change the outcome? - correct answer
Yes, it can rearrange to form methylenecyclohexane, but it won't show up on
the GC-MS
How does steam distillation work? - correct answer Steam is used to provide
one of the immiscible phases
You can't use a liquid that miscible with water because it'll mix together with
one of the immiscible layers
Mixture of immiscible liquids will boil at a lower temperature than the boiling
points of the separate components
Once the distillate is cooled, the desired component separates from water
,What were the tests for unsaturation during the dehydration of 2-
methylcyclohexanol? - correct answer mix with bromine, mix with KnMnO₄
What's a positive test for the reaction with bromine? - correct answer color
changes from orange (or reddish/brown) to colorless
What's a positive test for the reaction with KMnO₄? - correct answer formation
of brown precipitate
What affects the rate at which compounds travel through the column in gas
chromatography? - correct answer Volatility
Strength of the interaction with the stationary phase
Boiling points (low BP comes out first)
What is the detector response in a gas chromatogram proportional to? -
correct answer the amount of compound passing through it
You can quantify amounts by comparing peak areas
Peak area = (peak height)x(peak width at ½ height)
The ratio between the products is equal to the ration between the two peak
areas
What is the Heck reaction? - correct answer palladium-catalyzed coupling (C-
C bond forming) reactions
Why is a base needed in the Heck reaction? - correct answer to remove
hydracid formed in reaction to stop addition of hydracid to alkene product and
to regenerate final catalyst
, What is the amount of catalyst needed in palladium catalyzed coupling rxns? -
correct answer 0.001%-5% mols of the limiting reagent
What is Palladium's oxidation state in the Heck reaction mechanism? - correct
answer 0
Are Heck reactions stereospecific? If so, how? - correct answer yes, highly
the sterically more accessible carbon is the one involved in the double bond
there is high trans selectivity
What are disadvantages to the Heck reaction? - correct answer Aryl chlorides
aren't usually good substrates b/c they tend to react very slowly
The halide cannot have beta hydrogens or it will undergo beta hydride
elimination
What are the catalyst, base, and phase transfer catalyst in the reaction of 4-
methoxycinnamic acid? - correct answer PdCl₂ is the catalyst
K₂CO₃ is the base
TBABr is the phase transfer catalyst
What is TBABr in the synthesis of 4-methoxycinnamic acid? - correct answer
tetrabutyl ammonium bromide
quaternary ammonium salt
Allows for reaction to continue bc allows contact between interacting species
and reagent
What is the configuration of the new C-C bond formed in the Heck reaction? -
correct answer same as the configuration of the old bond
answers correctly solved 2025
What is the major dehydration products of 2-methylcyclohexanol? Why? -
correct answer 1-methylcyclohexene because it's the Zaitsev product
What is the catalyst used during the dehydration of 2-methylcyclohexanol?
Why? - correct answer H₃PO₄
we don't want it to attach to one of the rings like if we used a hydracid
What is lost as the dehydration 2-methylcyclohexanol proceeds? - correct
answer water because heat is needed
How are the products isolated during the dehydration of 2-
methylcyclohexanol? - correct answer steam distillation, which is used for
liquids that are immiscible
Is carbocation rearrangement possible during the dehydration of 2-
methylcyclohexanol?? How would that change the outcome? - correct answer
Yes, it can rearrange to form methylenecyclohexane, but it won't show up on
the GC-MS
How does steam distillation work? - correct answer Steam is used to provide
one of the immiscible phases
You can't use a liquid that miscible with water because it'll mix together with
one of the immiscible layers
Mixture of immiscible liquids will boil at a lower temperature than the boiling
points of the separate components
Once the distillate is cooled, the desired component separates from water
,What were the tests for unsaturation during the dehydration of 2-
methylcyclohexanol? - correct answer mix with bromine, mix with KnMnO₄
What's a positive test for the reaction with bromine? - correct answer color
changes from orange (or reddish/brown) to colorless
What's a positive test for the reaction with KMnO₄? - correct answer formation
of brown precipitate
What affects the rate at which compounds travel through the column in gas
chromatography? - correct answer Volatility
Strength of the interaction with the stationary phase
Boiling points (low BP comes out first)
What is the detector response in a gas chromatogram proportional to? -
correct answer the amount of compound passing through it
You can quantify amounts by comparing peak areas
Peak area = (peak height)x(peak width at ½ height)
The ratio between the products is equal to the ration between the two peak
areas
What is the Heck reaction? - correct answer palladium-catalyzed coupling (C-
C bond forming) reactions
Why is a base needed in the Heck reaction? - correct answer to remove
hydracid formed in reaction to stop addition of hydracid to alkene product and
to regenerate final catalyst
, What is the amount of catalyst needed in palladium catalyzed coupling rxns? -
correct answer 0.001%-5% mols of the limiting reagent
What is Palladium's oxidation state in the Heck reaction mechanism? - correct
answer 0
Are Heck reactions stereospecific? If so, how? - correct answer yes, highly
the sterically more accessible carbon is the one involved in the double bond
there is high trans selectivity
What are disadvantages to the Heck reaction? - correct answer Aryl chlorides
aren't usually good substrates b/c they tend to react very slowly
The halide cannot have beta hydrogens or it will undergo beta hydride
elimination
What are the catalyst, base, and phase transfer catalyst in the reaction of 4-
methoxycinnamic acid? - correct answer PdCl₂ is the catalyst
K₂CO₃ is the base
TBABr is the phase transfer catalyst
What is TBABr in the synthesis of 4-methoxycinnamic acid? - correct answer
tetrabutyl ammonium bromide
quaternary ammonium salt
Allows for reaction to continue bc allows contact between interacting species
and reagent
What is the configuration of the new C-C bond formed in the Heck reaction? -
correct answer same as the configuration of the old bond
