PORTAGE LEARNING CHEM 210 MODULE 4
EXAM COMPLETE STUDY GUIDE WITH
QUESTIONS AND ANSWERS
◉ Because two molecules, namely, the nucleophile AND the substrate,
are directly involved in the key step (the only step) of the mechanism.
Thus, increasing the concentration of either the nucleophile or substrate
will increase the rate of the reaction.
The number 2 (second order overall in terms of the reaction kinetics) in
the label of the mechanism indicates the reaction is bimolecular for this
reason.. Answer: Why is the number 2 is used to label the SN2
mechanism?
◉ Increasing the concentration of either the nucleophile or substrate will
increase the rate of the reaction.. Answer: What would happen if either
the concentration of nucleophile or substrate increase?
◉ SN2 reactions depend on a strong nucleophile. Strong nucleophiles
typically are negatively charged and, as a result, seek positive charge
more strongly than neutral molecules. An example is hydroxide ion
(HO-) versus water (H2O). While both are nucleophiles, hydroxide is a
,much stronger nucleophile than water. An SN2 reaction that occurs in
pure water would be slower than one that happens in aqueous sodium
hydroxide for this reason.. Answer: How does the strength of the
nucleophile impact the SN2 mechanism path?
◉ bulky. Answer: The SN1 mechanism typically occurs when the alkyl
halide is _____, meaning 3° and some 2° halides (when the alkyl groups
attached to the leaving group carbon are large).
◉ True. Answer: True or False: Since the rate of an SN1 reaction is not
at all affected by the nucleophile, none of the characteristics of the
nucleophile (size, strength, concentration, electronegativity, etc.) have an
impact on the rate of an SN1 reaction.
◉ Larger nucleophiles are more efficient at backside attacks than small
nucleophiles. Thus, bisulfide (HS-) as a nucleophile would react faster
than hydroxide (HO-) due to the larger sulfur atom (with all other things
being equal). Answer: How does the size of the nucleophile impact the
SN2 mechanism path?
◉ The nucleophile uses a lone pair of electrons to bond to the substrate,
so if the atom that holds the lone pair is very electronegative, it tends to
hold those electrons tightly and thus, is less nucleophilic. Within any
given row of the periodic table, electronegativity increases to the right;
therefore (as one example), ammonia (NH3) is a stronger nucleophile
than water (H2O) because N is less electronegative than O.. Answer:
, How does the electronegativity of the nucleophilic atom impact the SN2
mechanism path?
◉ Mechanisms. Answer: show the flow of electrons between molecules
and ions as the reagents are converted to products.
◉ Curved arrow notation. Answer: ________ is used to draw
mechanisms in organic chemistry, just like when showing electron
resonance.
◉ structure. Answer: The mechanism observed for a particular reaction
depends (in large part) on the _______ of the alkyl halide substrate in
the reaction.
◉ SN2. Answer: This reaction mechanism occurs in a single step
◉ "backside attack".. Answer: In an SN2 mechanism, The nucleophile
uses a lone pair of electrons to begin making a bond to the carbon.
Simultaneously, the bond between the carbon and leaving group begins
to break. This process is known as a _______
◉ By their nature, alkyl halides and nucleophiles tend to be polar
species (nucleophiles can be fully anionic as well) and, thus, require
polar solvents to dissolve them. Since the SN2 mechanism relies on the
nucleophile being uninhibited during backside attack, SN2 reactions are
EXAM COMPLETE STUDY GUIDE WITH
QUESTIONS AND ANSWERS
◉ Because two molecules, namely, the nucleophile AND the substrate,
are directly involved in the key step (the only step) of the mechanism.
Thus, increasing the concentration of either the nucleophile or substrate
will increase the rate of the reaction.
The number 2 (second order overall in terms of the reaction kinetics) in
the label of the mechanism indicates the reaction is bimolecular for this
reason.. Answer: Why is the number 2 is used to label the SN2
mechanism?
◉ Increasing the concentration of either the nucleophile or substrate will
increase the rate of the reaction.. Answer: What would happen if either
the concentration of nucleophile or substrate increase?
◉ SN2 reactions depend on a strong nucleophile. Strong nucleophiles
typically are negatively charged and, as a result, seek positive charge
more strongly than neutral molecules. An example is hydroxide ion
(HO-) versus water (H2O). While both are nucleophiles, hydroxide is a
,much stronger nucleophile than water. An SN2 reaction that occurs in
pure water would be slower than one that happens in aqueous sodium
hydroxide for this reason.. Answer: How does the strength of the
nucleophile impact the SN2 mechanism path?
◉ bulky. Answer: The SN1 mechanism typically occurs when the alkyl
halide is _____, meaning 3° and some 2° halides (when the alkyl groups
attached to the leaving group carbon are large).
◉ True. Answer: True or False: Since the rate of an SN1 reaction is not
at all affected by the nucleophile, none of the characteristics of the
nucleophile (size, strength, concentration, electronegativity, etc.) have an
impact on the rate of an SN1 reaction.
◉ Larger nucleophiles are more efficient at backside attacks than small
nucleophiles. Thus, bisulfide (HS-) as a nucleophile would react faster
than hydroxide (HO-) due to the larger sulfur atom (with all other things
being equal). Answer: How does the size of the nucleophile impact the
SN2 mechanism path?
◉ The nucleophile uses a lone pair of electrons to bond to the substrate,
so if the atom that holds the lone pair is very electronegative, it tends to
hold those electrons tightly and thus, is less nucleophilic. Within any
given row of the periodic table, electronegativity increases to the right;
therefore (as one example), ammonia (NH3) is a stronger nucleophile
than water (H2O) because N is less electronegative than O.. Answer:
, How does the electronegativity of the nucleophilic atom impact the SN2
mechanism path?
◉ Mechanisms. Answer: show the flow of electrons between molecules
and ions as the reagents are converted to products.
◉ Curved arrow notation. Answer: ________ is used to draw
mechanisms in organic chemistry, just like when showing electron
resonance.
◉ structure. Answer: The mechanism observed for a particular reaction
depends (in large part) on the _______ of the alkyl halide substrate in
the reaction.
◉ SN2. Answer: This reaction mechanism occurs in a single step
◉ "backside attack".. Answer: In an SN2 mechanism, The nucleophile
uses a lone pair of electrons to begin making a bond to the carbon.
Simultaneously, the bond between the carbon and leaving group begins
to break. This process is known as a _______
◉ By their nature, alkyl halides and nucleophiles tend to be polar
species (nucleophiles can be fully anionic as well) and, thus, require
polar solvents to dissolve them. Since the SN2 mechanism relies on the
nucleophile being uninhibited during backside attack, SN2 reactions are
