Question

Can anyone help me with this multiple choice question?

The answer is C

Answer 1

This is the question

Answer 2

Can you draw out all the structures A, B, C and D?

Answer 3

The question is in the PNG file

Answer 4

Yes, I know, I'm asking you to draw them.

Answer 5

just a min

Answer 6

ok

Answer 7

So basically (no pun intended!) this comes down to how sodium reacts with alcohol, carboxylic acid, and carbonyl groups. What it does is a simple redox reaction where it oxidizes the organic compound by stripping the hydrogens from the alcohol and carboxylic acid groups. The ketone and aldehyde groups don't have any hydrogen to give up, so they're fine.

So in the first step, the only possibilities of things with 3 hydrogen to lose are A and C, so even if this is all you know, you still have a 50/50 shot at making a guess. Ok, so if that makes sense, then we'll go on to the next step!

Answer 8

The part about H+ is replaced by Na is clear to me but it's the next part that I don't get :/

Answer 9

Because when I asked this somewhere else, he said something like this:
"C is the correct choice. Reaction with Na metal will remove H+ from the carboxylate and both hydroxyl groups to give an anion with a charge of -3. Aqueous alkali will only form the carboxylate salt."

Answer 10

So the part that I didn't is when said "Aqueous alkali will only form the carboxylate salt."

Answer 11

Alright awesome, so we're halfway there.

Next they're adding aqueous sodium hydroxide. This literally means they're adding NaOH and H2O. At this point, you have to have a knowledge of pKa values and the concept of chemical equilibrium.

Generally speaking we know carboxylic acids are fairly stable deprotonated as they have a resonant form while alcohol groups aren't. Here's a little more about it describing how the equilibrium lies to the left.

http://en.wikipedia.org/wiki/Alcohol#Deprotonation

Answer 12

All I'm saying is that H2O and the deprotonated alcohol group will react together to form the alcohol and NaOH since that is the lowest energy state.

Answer 13

When Alcohol and Carboxylic group react together,they form an ester and water, and then when NaOH is added to an ester, it breaks to alcohol and carboxylic acid but H in COOH group is replaced by Na, does it have anything to do with this?

Answer 14

No, but it is slightly similar in a sense. What you're describing is a dehydration reaction and then reversing it.

What I'm describing is that NaOH and H2O with a carboxylate group (deprotonated carboxylic acid) will not react but NaOH and H2O with a deprotonated alcohol group will react to make an alcohol group. So it will turn this:

Answer 15

When you say deprotonated, do you mean by this?
(it's part of our book, and so far there is no mentioning of deprotonated alcohol other than this)

Answer 16

Well in your original question you did 2 reactions. This part of your book is describing the first reaction which is different from the other reaction in that it is a reaction with water. Notice there is no H2O in that description.

Answer 17

Wait I think now I got it LOL
me and my friend filled eachothers doubts!

Answer 18

Oops also forgot to say; THANK YOUUU!!! :D

Answer 19

Glad I could help! =)