Organic Chem Lab Exam 2-- Electrophilic Aroma c
Subs tu on (EAS)| Ques ons and answer|Updated
RATED A+
general overview of EAS experiment
to a empt an EAS reac on using 4,6,8-trimethylazulene with trifluoroace c anhydride followed
by a water workup and purifica on using column chromatography; then conduct NMR analysis
on star ng material and product to determine iden ty of each
what were the two star ng materials?
4,6,8-trimethylazulene
trifluoroace c anhydride
what was the solvent?
hexanes
azulenes are a class of...
aroma c hydrocarbons
two reasons azulenes are an interes ng class of hydrocarbons
1) intensely colored (blue or purple usually)
2) reac vity dominated by molecule's ability to retain aroma c subunits when undergoing both
electrophilic and nucleophilic a ack
when were azulenes first no ced?
during the isola on of certain essen al oils from plants; some sesquiterpenes (15 C compounds
derived from isoprene units) would undergo isomeriza on to subs tuted azulenes during
dis lla on/other manipula ons resul ng in dis nc ve colora on
what natural product do azulenes occur in?
crude oil (coloring a por on of the dis llate blue)
when were synthe c procedures for azulene prep first developed?
1950's
, the reac vity of azulenes illustrates several features of...
non-benzoid aroma city
what type of electrons does the azulene contain?
what type of system does this qualify the azulene as?
10 pi electrons
a 4N+2 aroma c system (n=2)
azulene is not as aroma c as...
what is the result of this?
the corresponding benzenoid system napthalene
azulene is much more reac ve toward electrophiles in an EAS type reac on
when a acking electrophiles, how does the a ack always occur?
what is the result of this?
u lizing the 1 or 3 posi ons
results in the forma on of an aroma c cycloheptatrienyl ca on as the sigma complex
intermediate
what does nucleophilic a ack using the 1 or 3 posi on result in?
a larger number of resonance forms than if the 2-posi on was the nucleophilic posi on
how does the intermediate return to to a fully aroma c system following nucleophilic a ack
using the 1 or 3 posi on?
by a deprotona on step
which type of rxn typically requires a strong Lewis Acid like AlCl3 or BF3?
what does this type of rxn usually follow?
acyla on of benzenoid aroma cs with anhydrides
follows the Friedel-Cra=s acyla on mechanis c pathway
Subs tu on (EAS)| Ques ons and answer|Updated
RATED A+
general overview of EAS experiment
to a empt an EAS reac on using 4,6,8-trimethylazulene with trifluoroace c anhydride followed
by a water workup and purifica on using column chromatography; then conduct NMR analysis
on star ng material and product to determine iden ty of each
what were the two star ng materials?
4,6,8-trimethylazulene
trifluoroace c anhydride
what was the solvent?
hexanes
azulenes are a class of...
aroma c hydrocarbons
two reasons azulenes are an interes ng class of hydrocarbons
1) intensely colored (blue or purple usually)
2) reac vity dominated by molecule's ability to retain aroma c subunits when undergoing both
electrophilic and nucleophilic a ack
when were azulenes first no ced?
during the isola on of certain essen al oils from plants; some sesquiterpenes (15 C compounds
derived from isoprene units) would undergo isomeriza on to subs tuted azulenes during
dis lla on/other manipula ons resul ng in dis nc ve colora on
what natural product do azulenes occur in?
crude oil (coloring a por on of the dis llate blue)
when were synthe c procedures for azulene prep first developed?
1950's
, the reac vity of azulenes illustrates several features of...
non-benzoid aroma city
what type of electrons does the azulene contain?
what type of system does this qualify the azulene as?
10 pi electrons
a 4N+2 aroma c system (n=2)
azulene is not as aroma c as...
what is the result of this?
the corresponding benzenoid system napthalene
azulene is much more reac ve toward electrophiles in an EAS type reac on
when a acking electrophiles, how does the a ack always occur?
what is the result of this?
u lizing the 1 or 3 posi ons
results in the forma on of an aroma c cycloheptatrienyl ca on as the sigma complex
intermediate
what does nucleophilic a ack using the 1 or 3 posi on result in?
a larger number of resonance forms than if the 2-posi on was the nucleophilic posi on
how does the intermediate return to to a fully aroma c system following nucleophilic a ack
using the 1 or 3 posi on?
by a deprotona on step
which type of rxn typically requires a strong Lewis Acid like AlCl3 or BF3?
what does this type of rxn usually follow?
acyla on of benzenoid aroma cs with anhydrides
follows the Friedel-Cra=s acyla on mechanis c pathway
