AAMC 4 Organic Chemistry Questions

[MedGrl@2022]

Hi everyone,

I was/am having some issues understanding some practice AAMC organic chemistry problems. In AAMC 4, I specifically had issues with Passage III Item 109 and 106.
Item 109 Asks:

Based on the passage, Compound A most likely contains which of the following functional groups?

A) Ether
B) Ester
C) Ketone
D) Aldehyde

I guessed A because I think EK said something about Ethers being good solvents because they are polar. Obviously, that was not the right answer since the answer is B… Ester”. I am not sure how to even go about solving a problem like this though.
This is AAMC’s explanation: “The passage states the Compound A is soluble in dilute HCl, which implies the presence on an amine functional group in Compound A. The treatment of Compound A with hot NaOH produces two new compounds, ethanol and Compound C. Compound C retains the amine functional group because it remains soluble in dilute HCl, it also contains a new carboxylic acid functional group, because it is also soluble in dilute NaOH. Since the basic hydrolysis of Compound A produces an alcohol and a carboxylic acid Compound A contains an ester. An ester can be synthesized by an acid-catalyzed reaction between an alcohol and a carboxylic acid. When hydrolyzed in base and then acidified, an ester yields an alcohol and a carboxylic acid. Thus, answer choice B is the best answer.”

So here is what I understand… after reviewing my EK Organic Chemistry textbook in the Extraction section… amines are soluble in HCl because the strong acid protonates bases like amines making them positively charged and polar. However my EK book says bases LIKE amines… thus Compound A could contain another base right?

We know that compound A is at least an ester or an ether because when Compound A was reacted with NaOH an alcohol was formed and then it was removed from the NaOH compound. I suppose that if it was an ester then saponification could happen right? But how do I know definitely that it is not an ether? Also, how am I supposed to know that a new carboxylic acid was produced from being soluble in NaOH? I am assuming that NaOH deprotonates the carboxylic acid making a carboxylic anion. I am also confused when AAMC says that “An ester can be synthesized by an acid-catalyzed reaction between an alcohol and a carboxylic acid.” Even though NaOH is not the catalyst it is basic, so shouldn’t the catalyst be basic as well? Is the catalyst HCl? What should have been my line of thinking with this question? What particular area on Organic Chemistry should I focus on to get questions like this right in the future?


Similarly, I had issues with 106: “The solubility data indicate that Compound C most likely contains which of the following functional groups?”

a) Carboxylic acid and amide
b) Amine and amide
c) Amide and nitro
d) Amine and carboxylic acid

The answer was D. “The passage states that Compound C is soluble in both dilute acid and base. Carboxylic acids are soluble in dilute base (e.g., 5% NaOH), and amines are soluble in dilute acid (e.g. 5% HCl). Amides and nitro compounds are not soluble in dilute acid or base. Thus answer choice D is the best answer.”

What does “refluxing aqueous NaOH” mean? Is it another term for dilute NaOH? The passage doesn’t seem to indicate that NaOH was dilute. Carboxylic acids and amines are very similar to amino acids which can be soluble in both basic and acidic solutions, right? Why aren’t amides and nitro groups soluble in dilute acid or base? In addition, what should have been my line of thinking with this question? What particular area on Organic Chemistry should I focus on to get questions like this right in the future?

Thank you for all your help!

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[NontradCA]

Compound C was identified as the last molecule which was an p amino benzoic acid...you're supposed to figure that out

 

[MedGrl@2022]

Compound C was identified as the last molecule which was an p amino benzoic acid...you're supposed to figure that out

Just from knowing that it is soluble in both a dilute acid and base? I don't think the passages states that Compound C is that compound. I am trying to figure out how to actually get to the point of figuring it out.

 

[NontradCA]

Yes or by knowing that nitro and amides aren't and eliminating those, which would give you the answer.

 

[MedGrl@2022]

Yes or by knowing that nitro and amides aren't and eliminating those, which would give you the answer.

Why aren't nitro and amide groups soluble? Nitro groups have charges that are stabilized by resonance and I think amides are polar. :-/

 

[MedGrl@2022]

Hi everyone,

I was/am having some issues understanding some practice AAMC organic chemistry problems. In AAMC 4, I specifically had issues with Passage III Item 109 and 106.
Item 109 Asks:

Based on the passage, Compound A most likely contains which of the following functional groups?

A) Ether
B) Ester
C) Ketone
D) Aldehyde

I guessed A because I think EK said something about Ethers being good solvents because they are polar. Obviously, that was not the right answer since the answer is B… Ester”. I am not sure how to even go about solving a problem like this though.
This is AAMC’s explanation: “The passage states the Compound A is soluble in dilute HCl, which implies the presence on an amine functional group in Compound A. The treatment of Compound A with hot NaOH produces two new compounds, ethanol and Compound C. Compound C retains the amine functional group because it remains soluble in dilute HCl, it also contains a new carboxylic acid functional group, because it is also soluble in dilute NaOH. Since the basic hydrolysis of Compound A produces an alcohol and a carboxylic acid Compound A contains an ester. An ester can be synthesized by an acid-catalyzed reaction between an alcohol and a carboxylic acid. When hydrolyzed in base and then acidified, an ester yields an alcohol and a carboxylic acid. Thus, answer choice B is the best answer.”

So here is what I understand… after reviewing my EK Organic Chemistry textbook in the Extraction section… amines are soluble in HCl because the strong acid protonates bases like amines making them positively charged and polar. However my EK book says bases LIKE amines… thus Compound A could contain another base right?

We know that compound A is at least an ester or an ether because when Compound A was reacted with NaOH an alcohol was formed and then it was removed from the NaOH compound. I suppose that if it was an ester then saponification could happen right? But how do I know definitely that it is not an ether? Also, how am I supposed to know that a new carboxylic acid was produced from being soluble in NaOH? I am assuming that NaOH deprotonates the carboxylic acid making a carboxylic anion. I am also confused when AAMC says that “An ester can be synthesized by an acid-catalyzed reaction between an alcohol and a carboxylic acid.” Even though NaOH is not the catalyst it is basic, so shouldn’t the catalyst be basic as well? Is the catalyst HCl? What should have been my line of thinking with this question? What particular area on Organic Chemistry should I focus on to get questions like this right in the future?


Similarly, I had issues with 106: “The solubility data indicate that Compound C most likely contains which of the following functional groups?”

a) Carboxylic acid and amide
b) Amine and amide
c) Amide and nitro
d) Amine and carboxylic acid

The answer was D. “The passage states that Compound C is soluble in both dilute acid and base. Carboxylic acids are soluble in dilute base (e.g., 5% NaOH), and amines are soluble in dilute acid (e.g. 5% HCl). Amides and nitro compounds are not soluble in dilute acid or base. Thus answer choice D is the best answer.”

What does “refluxing aqueous NaOH” mean? Is it another term for dilute NaOH? The passage doesn’t seem to indicate that NaOH was dilute. Carboxylic acids and amines are very similar to amino acids which can be soluble in both basic and acidic solutions, right? Why aren’t amides and nitro groups soluble in dilute acid or base? In addition, what should have been my line of thinking with this question? What particular area on Organic Chemistry should I focus on to get questions like this right in the future?

Thank you for all your help!

anyone else have any great advice, hints, etc.? :-/

 

[MedGrl@2022]

Hi everyone,

I was/am having some issues understanding some practice AAMC organic chemistry problems. In AAMC 4, I specifically had issues with Passage III Item 109 and 106.
Item 109 Asks:

Based on the passage, Compound A most likely contains which of the following functional groups?

A) Ether
B) Ester
C) Ketone
D) Aldehyde

I guessed A because I think EK said something about Ethers being good solvents because they are polar. Obviously, that was not the right answer since the answer is B… Ester”. I am not sure how to even go about solving a problem like this though.
This is AAMC’s explanation: “The passage states the Compound A is soluble in dilute HCl, which implies the presence on an amine functional group in Compound A. The treatment of Compound A with hot NaOH produces two new compounds, ethanol and Compound C. Compound C retains the amine functional group because it remains soluble in dilute HCl, it also contains a new carboxylic acid functional group, because it is also soluble in dilute NaOH. Since the basic hydrolysis of Compound A produces an alcohol and a carboxylic acid Compound A contains an ester. An ester can be synthesized by an acid-catalyzed reaction between an alcohol and a carboxylic acid. When hydrolyzed in base and then acidified, an ester yields an alcohol and a carboxylic acid. Thus, answer choice B is the best answer.”

So here is what I understand… after reviewing my EK Organic Chemistry textbook in the Extraction section… amines are soluble in HCl because the strong acid protonates bases like amines making them positively charged and polar. However my EK book says bases LIKE amines… thus Compound A could contain another base right?

We know that compound A is at least an ester or an ether because when Compound A was reacted with NaOH an alcohol was formed and then it was removed from the NaOH compound. I suppose that if it was an ester then saponification could happen right? But how do I know definitely that it is not an ether? Also, how am I supposed to know that a new carboxylic acid was produced from being soluble in NaOH? I am assuming that NaOH deprotonates the carboxylic acid making a carboxylic anion. I am also confused when AAMC says that “An ester can be synthesized by an acid-catalyzed reaction between an alcohol and a carboxylic acid.” Even though NaOH is not the catalyst it is basic, so shouldn’t the catalyst be basic as well? Is the catalyst HCl? What should have been my line of thinking with this question? What particular area on Organic Chemistry should I focus on to get questions like this right in the future?


Similarly, I had issues with 106: “The solubility data indicate that Compound C most likely contains which of the following functional groups?”

a) Carboxylic acid and amide
b) Amine and amide
c) Amide and nitro
d) Amine and carboxylic acid

The answer was D. “The passage states that Compound C is soluble in both dilute acid and base. Carboxylic acids are soluble in dilute base (e.g., 5% NaOH), and amines are soluble in dilute acid (e.g. 5% HCl). Amides and nitro compounds are not soluble in dilute acid or base. Thus answer choice D is the best answer.”

What does “refluxing aqueous NaOH” mean? Is it another term for dilute NaOH? The passage doesn’t seem to indicate that NaOH was dilute. Carboxylic acids and amines are very similar to amino acids which can be soluble in both basic and acidic solutions, right? Why aren’t amides and nitro groups soluble in dilute acid or base? In addition, what should have been my line of thinking with this question? What particular area on Organic Chemistry should I focus on to get questions like this right in the future?

Thank you for all your help!

anyone else???

 

[sdm33]

106: "The solubility data indicate that Compound C most likely contains which of the following functional groups?"
Use POE
a) Carboxylic acid and amide
b) Amine and amide
c) Amide and nitro
d) Amine and carboxylic acid
D is correct
Unlike amines, amides show no measurable basicity. Two factors account for this. Most
importantly, the lone pair of electrons on nitrogen interacts with the carbonyl π-bond much like
the π-bonds in benzene interact with each other. Also, the electronegative oxygen pulls the lone
pair of electrons towards itself. The effect is to render these electrons unavailable for acid/base
reactions. Also the passage said that it is Optically Inactive

Based on the passage, Compound A most likely contains which of the following functional groups?

A) Ether
B) Ester
C) Ketone
D) Aldehyde

I just thought of Ester and NaOH and Saponification