Question

Shown below is the reaction mechanism of the acetylation of salicylic acid with acetic anhydride in the presence of phosphoric acid to produce aspirin. H-A 1 lol l H COOH COOH COOH COOH COOH H COOH 2 OH OH 3 0 OH 4 ?? 5 0 HOO HO Which statement below best describes step 6 of the reaction mechanism? ? An oxygen on one of the carbonyl groups takes a proton from phosphoric acid activating the carbonyl group toward nucleophilic substitution giving rise to resonance forms. ? The nucleophilic alcohol oxygen attacks the now electrophilic carbon on the carbonyl, breaking the double bond and forming a tetrahedral intermediate. ? Deprotonation of the positively charged oxygen atom to the conjugate base of phosphoric acid. ? To become a better leaving group the oxygen atom takes a proton from phosphoric acid. ? The double bond re-forms with the neutral oxygen in the OH group. Because carbon does not want to have five bonds, electron transfer to the positively charged oxygen results in the group leaving as acetic acid. ? Now that the double bond has re-formed the positively charged oxygen is deprotonated by the conjugate base of phosphoric acid.

          Shown below is the reaction mechanism of the acetylation of salicylic acid with acetic anhydride in the presence of phosphoric acid to produce aspirin.
H-A 1
lol l
H
COOH
COOH
COOH
COOH
COOH
H
COOH
2
OH
OH 3
0
OH
4
?? 5
0
HOO
HO
Which statement below best describes step 6 of the reaction mechanism?
? An oxygen on one of the carbonyl groups takes a proton from phosphoric acid activating the carbonyl group toward nucleophilic substitution giving rise to
resonance forms.
? The nucleophilic alcohol oxygen attacks the now electrophilic carbon on the carbonyl, breaking the double bond and forming a tetrahedral intermediate.
? Deprotonation of the positively charged oxygen atom to the conjugate base of phosphoric acid.
? To become a better leaving group the oxygen atom takes a proton from phosphoric acid.
? The double bond re-forms with the neutral oxygen in the OH group. Because carbon does not want to have five bonds, electron transfer to the positively
charged oxygen results in the group leaving as acetic acid.
? Now that the double bond has re-formed the positively charged oxygen is deprotonated by the conjugate base of phosphoric acid.

Shown below is the reaction mechanism of the acetylation of salicylic acid with acetic anhydride in the presence of phosphoric acid to produce aspirin.
H-A 1
lol l
H
COOH
COOH
COOH
COOH
COOH
H
COOH
2
OH
OH 3
0
OH
4
?? 5
0
HOO
HO
Which statement below best describes step 6 of the reaction mechanism?
? An oxygen on one of the carbonyl groups takes a proton from phosphoric acid activating the carbonyl group toward nucleophilic substitution giving rise to
resonance forms.
? The nucleophilic alcohol oxygen attacks the now electrophilic carbon on the carbonyl, breaking the double bond and forming a tetrahedral intermediate.
? Deprotonation of the positively charged oxygen atom to the conjugate base of phosphoric acid.
? To become a better leaving group the oxygen atom takes a proton from phosphoric acid.
? The double bond re-forms with the neutral oxygen in the OH group. Because carbon does not want to have five bonds, electron transfer to the positively
charged oxygen results in the group leaving as acetic acid.
? Now that the double bond has re-formed the positively charged oxygen is deprotonated by the conjugate base of phosphoric acid.

Added by Amy M.

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