CHEM 232 Unit 3 Exam with Complete
Solutions
Alkoxide - ANSWER-Deprotonated alcohol.
increases - ANSWER-Increased beta-branching of an alcohol __________ the pKa.
decreases - ANSWER-Increased alpha-branching of an alcohol __________ the pKa.
Oxonium - ANSWER-R3O+
Activation - ANSWER-Protonating alcohols to generate oxonium ions to act as great
leaving groups, since neutral oxygens are the worst leaving groups and water is the
best.
Amphoteric - ANSWER-A species that can act as either an acid or a base (ex.
alcohols).
Sn2 - ANSWER-Methyl and primary alkyl halides can be synthesized into alcohol using
the ______ rxn mechanism.
lone pair in sp3 orbital - ANSWER-Where is the HOMO on a negatively charged oxygen
atom?
electrophile - ANSWER-The LUMO is on the _____________.
carbonyl pi bond - ANSWER-Where is the LUMO on an ester?
Sn1/E1 - ANSWER-H2O leaving group at 2º C will always be (Sn1/E1 or Sn2).
Dehydration - ANSWER-A ____________ reaction allows us to target E1 over Sn1;
utilizes a non-nucleophilic acid to protonate the OH and requires an input of heat bc
endothermic. H2O is a fantastic leaving group so it will leave and form a stable alkene.
Follows Zaitzev's rule.
3º > 2º - ANSWER-For dehydration rxns, list most reactive starting material > least
reactive.
, 1º - ANSWER-__º alcohols are too unstable to form carbocations; reverts back to E2
instead of dehydration E1. If no strong base is present, the reaction can be
compensated with a very high temperature.
Neopentyl alcohol - ANSWER-Similar to a tert-butyl alcohol, but cannot perform Sn1/E1,
Sn2, or E2. Must rearrange by way of a concerted alkyl shift. beta-C has too many
groups attached to it (4º) even though the alpha-C is only 1º. Still too hindered though.
nucleophilic - ANSWER-Acids that are HX in which X = Cl, Br, or I are said to be
____________.
Sn1 - ANSWER-Activation of a 2º alcohol requires what kind of reaction?
dehydration reaction - ANSWER-An E1 reaction in which an alcohol is turned into an
alkene through the creation of a water molecule. The OH group in the base
deprotonates the hydroxide group in the alcohol, making it a better leaving group.
electrophile - ANSWER-PBr3 is a great electrophile, which drives the activation of
alcohols through the use of phosphorus tribromide or phosphorus trichloride.
Sn2 - ANSWER-Activation of alcohols using PBr3 or PCl3 occurs through an ______
reaction.
Pyridine - ANSWER-What kind of solvent is used in the activation of alcohols using
thionyl chloride (SOCl2)?
Pyridine - ANSWER-A weak base that is used in the activation of alcohols using thionyl
chloride; acts as a base during the acid/base neutralization step that occurs after SnAc.
lower - ANSWER-Ethers have ________ melting and boiling points than corresponding
alcohols. This is due to the absence of intramolecular hydrogen bonding.
inert - ANSWER-Ethers lack protons, making them _______ towards strong bases.
cations - ANSWER-In contrast to polar protics that solvate anything that is charged,
ethers only solvate _________.
Ionophore - ANSWER-A class of membrane transport proteins. Small, hydrophobic
molecules that increase membrane permeability to certain ions. An example of an ether
in a living system.
Monensin A - ANSWER-An ionophore that transports sodium ions across a
phospholipid bilayer. Wraps around cations.
Solutions
Alkoxide - ANSWER-Deprotonated alcohol.
increases - ANSWER-Increased beta-branching of an alcohol __________ the pKa.
decreases - ANSWER-Increased alpha-branching of an alcohol __________ the pKa.
Oxonium - ANSWER-R3O+
Activation - ANSWER-Protonating alcohols to generate oxonium ions to act as great
leaving groups, since neutral oxygens are the worst leaving groups and water is the
best.
Amphoteric - ANSWER-A species that can act as either an acid or a base (ex.
alcohols).
Sn2 - ANSWER-Methyl and primary alkyl halides can be synthesized into alcohol using
the ______ rxn mechanism.
lone pair in sp3 orbital - ANSWER-Where is the HOMO on a negatively charged oxygen
atom?
electrophile - ANSWER-The LUMO is on the _____________.
carbonyl pi bond - ANSWER-Where is the LUMO on an ester?
Sn1/E1 - ANSWER-H2O leaving group at 2º C will always be (Sn1/E1 or Sn2).
Dehydration - ANSWER-A ____________ reaction allows us to target E1 over Sn1;
utilizes a non-nucleophilic acid to protonate the OH and requires an input of heat bc
endothermic. H2O is a fantastic leaving group so it will leave and form a stable alkene.
Follows Zaitzev's rule.
3º > 2º - ANSWER-For dehydration rxns, list most reactive starting material > least
reactive.
, 1º - ANSWER-__º alcohols are too unstable to form carbocations; reverts back to E2
instead of dehydration E1. If no strong base is present, the reaction can be
compensated with a very high temperature.
Neopentyl alcohol - ANSWER-Similar to a tert-butyl alcohol, but cannot perform Sn1/E1,
Sn2, or E2. Must rearrange by way of a concerted alkyl shift. beta-C has too many
groups attached to it (4º) even though the alpha-C is only 1º. Still too hindered though.
nucleophilic - ANSWER-Acids that are HX in which X = Cl, Br, or I are said to be
____________.
Sn1 - ANSWER-Activation of a 2º alcohol requires what kind of reaction?
dehydration reaction - ANSWER-An E1 reaction in which an alcohol is turned into an
alkene through the creation of a water molecule. The OH group in the base
deprotonates the hydroxide group in the alcohol, making it a better leaving group.
electrophile - ANSWER-PBr3 is a great electrophile, which drives the activation of
alcohols through the use of phosphorus tribromide or phosphorus trichloride.
Sn2 - ANSWER-Activation of alcohols using PBr3 or PCl3 occurs through an ______
reaction.
Pyridine - ANSWER-What kind of solvent is used in the activation of alcohols using
thionyl chloride (SOCl2)?
Pyridine - ANSWER-A weak base that is used in the activation of alcohols using thionyl
chloride; acts as a base during the acid/base neutralization step that occurs after SnAc.
lower - ANSWER-Ethers have ________ melting and boiling points than corresponding
alcohols. This is due to the absence of intramolecular hydrogen bonding.
inert - ANSWER-Ethers lack protons, making them _______ towards strong bases.
cations - ANSWER-In contrast to polar protics that solvate anything that is charged,
ethers only solvate _________.
Ionophore - ANSWER-A class of membrane transport proteins. Small, hydrophobic
molecules that increase membrane permeability to certain ions. An example of an ether
in a living system.
Monensin A - ANSWER-An ionophore that transports sodium ions across a
phospholipid bilayer. Wraps around cations.
