CHEM 219 Modules 2, 4, 5 And 6
Questions With Correct Answers ||
Graded A+
What are hydrocarbons? - ANSWER Molecules composed of only the elements
carbon and hydrogen
What are the two major classes of hydrocarbons? - ANSWER Aromatic (benzene)
and aliphatic (alkanes, alkenes, alkynes)
What is the main source of hydrocarbons? - ANSWER Fossil fuels like coal,
petroleum, and natural gas obtained by mining and drilling.
What are Alkanes? - ANSWER They are saturated hydrocarbons because their
skeleton is only composed of C-C single bonds.
How can alkanes exist? - ANSWER They can be linear, branched or exist in ring
formations called cycloalkanes.
Describe a higher/more complex alkane structure: - ANSWER They will have
more carbons and/or increased structural diversity.
alcohols - ANSWER Generic formula R-OH
Defined by presence of hydroxyl group, derivatives of water (one H atoms is
replaced by an alkyl group (carbon-based group))
Phenols - ANSWER hydroxyl group connected to benzene ring
Nomenclature alcohols - ANSWER replace suffix of parent chain with -ol
*Hydroxyl group will have lowest possible number
Unsaturated alcohol nomenclature - ANSWER 2 endings needed: one for the
C=C or C triple bond C and one for the alcohol functional group; -ol suffix
Put number on the lowest part of the double or triple bond
(ex: 2-propen-1-ol)
, polyols - ANSWER Molecules with more than one -OH group
*prefix describing number of -OH added to IUPAC name
(ex: ethane-1,2-diol)
diol, triol, etc
phenol - ANSWER refers to a specific molecule (hydroxybenzene) and to the
parent name of all hydroxy-substituted aromatic molecules (-OH attached to
benzene ring)
primary vs secondary vs tertiary alcohols - ANSWER how many carbon atoms
(alkyl groups) directly attached to the carbon bearing the -OH group
methyl alcohol - ANSWER only hydrogen connected to carbon bearing the -OH
group
Alcohol properties - ANSWER strong hydrogen bonding interactions with one
another because of presence of hydroxyl group (the O-H bond is highly polarized
by the electronegative oxygen)
-->causes alcohols to have higher boiling points than other molecules of similar
molecular weight
-freely hydrogen bond to other molecules possessing O-H, N-H, or S-H
-lower MW alcohols are soluble in water
alcohol acidity and basicity - ANSWER can act as weak acids (donating O-H
proton as H+) or as weak bases (accepting H+ using a long pair on the O atom)
depending on the environment surrounding them aka AMPHOTERIC substances
Acid dissociation of alcohols - ANSWER unfavorable (lies towards left) as
dissociation produces an alkoxide ion (conjugate base of an alcohol), which is a
very strong base
typically, acid-base rxn formation of weaker conjugate acids/bases
to promote formation of the alkoxide ion - ANSWER alcohol can be treated with
sodium or potassium metal (Na or K) or a base that is stronger than the RO- ion
produced
product of the protonation of an alcohol is known as an
,*using lone pair on oxygen atom of hydroxyl group, alcohols can accept a proton
when they are placed in an acidic environment - ANSWER alkyloxonium ion
dehydration of alcohols - ANSWER when heated with strong mineral acids like
sulfuric or phosphoric, refers to loss of water
alcohol loses H20 and forms an alkene
*specific type of elimination rxn as alcohol substrate losing the hydroxyl (OH)
from one carbon (the alpha-carbon) and a hydrogen atom from the adjacent beta
carbon
*opposite of hydration of alkenes
ethanol (ethyl alcohol) can be dehydrated to - ANSWER ethene
function of acid in dehydration of an alcohol - ANSWER protonate the OH group
of the alcohol
first step of dehydration of alcohol - ANSWER alcohol acts as base and
protonation of the hydroxyl group making it a better leaving group, leaves neutral
molecule of water
steric bulky (tertiary) alcohols dehydrate by __ mechanism - ANSWER E1 - the
OH group is protonated and then dissociates forming a carbocation
typically water (acting as a base) removes a beta-hydrogen to form the alkene
non-bulky (primary) alcohols dehydrate by __ - ANSWER E2 because these
substrates do not form stable carbocation intermediates; protonation of hydroxyl
group is eliminated in a single step by removal of beta-hydrogen
Ease of dehydration (easiest to hardest) - ANSWER tertiary (least harsh
conditions) > secondary > primary (harsh conditions)
when more than one beta-carbon on alcohol, dehydration can produce -
ANSWER more than one alkene product (major and minor)
Zaitsev's rule - ANSWER major product is the more highly substituted alkene
(which is the alkene whose C=C has more alkyl groups attached)
Conversion of alcohol to alkyl halide using hydrogen halides - ANSWER alcohol
+ hydrogen-halide -----> alkyl halide + water
R-OH + H-X ----> R-X + H-OH
, *substitution over elimination since halide ions are good nucleophiles but weak
bases
*acid protonates hydroxyl group of alcohol, making it a good leaving group
order of reactivity of alcohols with hydrogen halides - ANSWER same as
dehydration; tertiary easiest > secondary > primary hardest
Tertiary alcohols react via ____ to become an alkyl halide - ANSWER Sn1
mechanism
Primary alcohols react via an ______ mechanism to become an alkyl halide -
ANSWER Sn2
Conversion of alcohol to alkyl halide (chloride/bromide) using Phosphorus
Halides - ANSWER Use phosphorus trihalide reagent (PX3, typically X=Cl or Br)
*very efficient since one PX3 can convert three molecules of alcohol to
corresponding alkyl
Conversion of alcohol to alkyl halide (chloride) using thionyl chloride -
ANSWER reagent thionyl chloride (SOCl2) can be used to convert alcohols to
corresponding alkyl chlorides
*very efficient for primary and secondary alcohols
*adv is that main byproduct (SO2) is formed as a gas and leaves rxn mixture
Conversion of alcohols to carbonyl-containing molecules - ANSWER primary
and secondary alcohols are converted via oxidation
oxidation - ANSWER increasing oxygen content (number of atoms) or oxygen
character (bonds to oxygen)
Primary alcohols oxidized initially to ______ and can be further oxidized to
__________ - ANSWER aldehydes, carboxylic acids
Secondary alcohols are oxidized to ________ - ANSWER ketones
aldehyde - ANSWER R-(C=O)-H
carboxylic acid - ANSWER R-(C=O)-OH
Ketone - ANSWER R-(C=O)-R'
Questions With Correct Answers ||
Graded A+
What are hydrocarbons? - ANSWER Molecules composed of only the elements
carbon and hydrogen
What are the two major classes of hydrocarbons? - ANSWER Aromatic (benzene)
and aliphatic (alkanes, alkenes, alkynes)
What is the main source of hydrocarbons? - ANSWER Fossil fuels like coal,
petroleum, and natural gas obtained by mining and drilling.
What are Alkanes? - ANSWER They are saturated hydrocarbons because their
skeleton is only composed of C-C single bonds.
How can alkanes exist? - ANSWER They can be linear, branched or exist in ring
formations called cycloalkanes.
Describe a higher/more complex alkane structure: - ANSWER They will have
more carbons and/or increased structural diversity.
alcohols - ANSWER Generic formula R-OH
Defined by presence of hydroxyl group, derivatives of water (one H atoms is
replaced by an alkyl group (carbon-based group))
Phenols - ANSWER hydroxyl group connected to benzene ring
Nomenclature alcohols - ANSWER replace suffix of parent chain with -ol
*Hydroxyl group will have lowest possible number
Unsaturated alcohol nomenclature - ANSWER 2 endings needed: one for the
C=C or C triple bond C and one for the alcohol functional group; -ol suffix
Put number on the lowest part of the double or triple bond
(ex: 2-propen-1-ol)
, polyols - ANSWER Molecules with more than one -OH group
*prefix describing number of -OH added to IUPAC name
(ex: ethane-1,2-diol)
diol, triol, etc
phenol - ANSWER refers to a specific molecule (hydroxybenzene) and to the
parent name of all hydroxy-substituted aromatic molecules (-OH attached to
benzene ring)
primary vs secondary vs tertiary alcohols - ANSWER how many carbon atoms
(alkyl groups) directly attached to the carbon bearing the -OH group
methyl alcohol - ANSWER only hydrogen connected to carbon bearing the -OH
group
Alcohol properties - ANSWER strong hydrogen bonding interactions with one
another because of presence of hydroxyl group (the O-H bond is highly polarized
by the electronegative oxygen)
-->causes alcohols to have higher boiling points than other molecules of similar
molecular weight
-freely hydrogen bond to other molecules possessing O-H, N-H, or S-H
-lower MW alcohols are soluble in water
alcohol acidity and basicity - ANSWER can act as weak acids (donating O-H
proton as H+) or as weak bases (accepting H+ using a long pair on the O atom)
depending on the environment surrounding them aka AMPHOTERIC substances
Acid dissociation of alcohols - ANSWER unfavorable (lies towards left) as
dissociation produces an alkoxide ion (conjugate base of an alcohol), which is a
very strong base
typically, acid-base rxn formation of weaker conjugate acids/bases
to promote formation of the alkoxide ion - ANSWER alcohol can be treated with
sodium or potassium metal (Na or K) or a base that is stronger than the RO- ion
produced
product of the protonation of an alcohol is known as an
,*using lone pair on oxygen atom of hydroxyl group, alcohols can accept a proton
when they are placed in an acidic environment - ANSWER alkyloxonium ion
dehydration of alcohols - ANSWER when heated with strong mineral acids like
sulfuric or phosphoric, refers to loss of water
alcohol loses H20 and forms an alkene
*specific type of elimination rxn as alcohol substrate losing the hydroxyl (OH)
from one carbon (the alpha-carbon) and a hydrogen atom from the adjacent beta
carbon
*opposite of hydration of alkenes
ethanol (ethyl alcohol) can be dehydrated to - ANSWER ethene
function of acid in dehydration of an alcohol - ANSWER protonate the OH group
of the alcohol
first step of dehydration of alcohol - ANSWER alcohol acts as base and
protonation of the hydroxyl group making it a better leaving group, leaves neutral
molecule of water
steric bulky (tertiary) alcohols dehydrate by __ mechanism - ANSWER E1 - the
OH group is protonated and then dissociates forming a carbocation
typically water (acting as a base) removes a beta-hydrogen to form the alkene
non-bulky (primary) alcohols dehydrate by __ - ANSWER E2 because these
substrates do not form stable carbocation intermediates; protonation of hydroxyl
group is eliminated in a single step by removal of beta-hydrogen
Ease of dehydration (easiest to hardest) - ANSWER tertiary (least harsh
conditions) > secondary > primary (harsh conditions)
when more than one beta-carbon on alcohol, dehydration can produce -
ANSWER more than one alkene product (major and minor)
Zaitsev's rule - ANSWER major product is the more highly substituted alkene
(which is the alkene whose C=C has more alkyl groups attached)
Conversion of alcohol to alkyl halide using hydrogen halides - ANSWER alcohol
+ hydrogen-halide -----> alkyl halide + water
R-OH + H-X ----> R-X + H-OH
, *substitution over elimination since halide ions are good nucleophiles but weak
bases
*acid protonates hydroxyl group of alcohol, making it a good leaving group
order of reactivity of alcohols with hydrogen halides - ANSWER same as
dehydration; tertiary easiest > secondary > primary hardest
Tertiary alcohols react via ____ to become an alkyl halide - ANSWER Sn1
mechanism
Primary alcohols react via an ______ mechanism to become an alkyl halide -
ANSWER Sn2
Conversion of alcohol to alkyl halide (chloride/bromide) using Phosphorus
Halides - ANSWER Use phosphorus trihalide reagent (PX3, typically X=Cl or Br)
*very efficient since one PX3 can convert three molecules of alcohol to
corresponding alkyl
Conversion of alcohol to alkyl halide (chloride) using thionyl chloride -
ANSWER reagent thionyl chloride (SOCl2) can be used to convert alcohols to
corresponding alkyl chlorides
*very efficient for primary and secondary alcohols
*adv is that main byproduct (SO2) is formed as a gas and leaves rxn mixture
Conversion of alcohols to carbonyl-containing molecules - ANSWER primary
and secondary alcohols are converted via oxidation
oxidation - ANSWER increasing oxygen content (number of atoms) or oxygen
character (bonds to oxygen)
Primary alcohols oxidized initially to ______ and can be further oxidized to
__________ - ANSWER aldehydes, carboxylic acids
Secondary alcohols are oxidized to ________ - ANSWER ketones
aldehyde - ANSWER R-(C=O)-H
carboxylic acid - ANSWER R-(C=O)-OH
Ketone - ANSWER R-(C=O)-R'
