is the answer to this question wrong

[Oh_Gee]

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please click this link for my post as i can't post AAMC questions in this forum which doesn't help because unless people are actively looking through AAMC BS SA thread, they won't see new posts. WHY MODS WHY?????

AAMC BS Self-Assessment Official Q&A

 

[Chrisz]

I dont know which question you was talking about. There are so many questions there. I believe you talking about the question hydrolysis of ester(coumpound C). The question is right. When you react ester group with OH-, How many products are produced. One alcohol and a carboxylate salt. If counpound C was alcohol, it will not show the carbonyl group but a broad peak at 3200-3600.

 

[Oh_Gee]

I dont know which question you was talking about. There are so many questions there. I believe you talking about the question hydrolysis of ester(coumpound C). The question is right. When you react ester group with OH-, How many products are produced. One alcohol and a carboxylate salt. If counpound C was alcohol, it will not show the carbonyl group but a broad peak at 3200-3600.

love your dog btw. always wanted one of those. are they expensive to raise relative to other dogs?

so you're saying compound c is the alcohol in what i think is the rxn that happened?
ester + NaOH >>> alcohol(compound C) + salt of carboxylic acid

if so then this would make sense to me

 

[justadream]

@Oh_Gee

Yes, I think it is the alcohol.

 

[Chrisz]

@Oh_Gee, yes, you are correct, this is the logic behind. If the IR was done on salt of caroxylate, you would be observing an IR at around 1600 for the carbonyl, and the OH group would not be observed since carboxylate does not have the OH group since it is deprotonated. For your info, my dog is a japanese breed, shiba inu. It is not that expensive, you usually can get one for around 1200. He's extremely intelligent and capable of logical reasoning. Once I bought pack of beef jerky and placed it on the shelf atop of a desk. However, he pushed a chair to the desk, then jumped onto the chair and then onto the desk, and my beef jerky was gone after I came back home. Another time, he was behaving so bad and chewing my mattress, so I scolded at him... At first, he stayed away from me. An hour later, he ripped my pillow open and pooped in the middle, these behavior are all due to the fact that he is extremely spoiled by me and my brother. However, this dog is extremely loyal, and can save you from danger. Just about a month ago, there was a fire in one of the apertment in my building. I did not notice that because I turned on the AC with my bedroom door closed, so I did not smell the smoke. He smelt it, and kept barking at me. I then opened my bedroom door, there was a lot of smoke flowing from outside. I grabbed him immediately and ran downstairs.

 

[BerkReviewTeach]

That is a great dog story. Way to go canine with great olfactory recognition!

In our house, we just nailed a bunch of jiffy pop instant popcorn containers to the walls for our fire alarm. If they start popping, then the walls are probably on fire.

 

[justadream]

@BerkReviewTeach

"an IR at around 1600 for the carbonyl"

Is that characteristic of carbonyl groups on COO-? If so, why is it below the typical 1700 carbonyl stretch?

 

[Chrisz]

That is a great dog story. Way to go canine with great olfactory recognition!

In our house, we just nailed a bunch of jiffy pop instant popcorn containers to the walls for our fire alarm. If they start popping, then the walls are probably on fire.

Lol, you must be kidding right, Does that actually work? Anyway, it reminds me of my fire alarm. It is still in my drawer. It was too sensitive. Everytime, I cooked, it just started go off. So, I removed it. Think gonna go ask the building manager to get me some other model

 

[Chrisz]

@justadream, the reason that carbonyl in carboxylate is that they have two resonance, and the CO bond is an average of C=O and C-O, so the frequency should be an average of these two frequencies. So the carbonyl frequency should be less than 1700. Actually, I remembered it wrong, it was not 1600, it is even less than 1600, somewhere between 1400-1500.

 

[Oh_Gee]

@justadream, the reason that carbonyl in carboxylate is that they have two resonance, and the CO bond is an average of C=O and C-O, so the frequency should be an average of these two frequencies. So the carbonyl frequency should be less than 1700. Actually, I remembered it wrong, it was not 1600, it is even less than 1600, somewhere between 1400-1500.

according to the almighty wikipedia, COO- Salt+ IR for carbonyl is 1550–1610 cm−1 whereas for COOH, its 1710.
http://en.wikipedia.org/wiki/Infrared_spectroscopy_correlation_table

but here is a more reputable website i guess

http://www.chem.ucla.edu/~webspectra/irtable.html