Draw the products of each proton transfer reaction. Label the acid and base in the starting mate

Draw the products of each proton transfer reaction. Label...

Key Concepts

Brønsted–Lowry Acid-Base Theory

This theory defines acids as species that can donate a proton and bases as species that can accept a proton. It is fundamental for understanding proton transfer reactions, where the transfer of a proton from an acid to a base results in the formation of a conjugate base and a conjugate acid, respectively.

Proton Transfer Reaction

A proton transfer reaction involves the movement of a proton (H?) from one species to another. Such reactions are the hallmark of acid-base chemistry under the Brønsted–Lowry framework, and they result in the interconversion of reactants to products where acid and base roles are switched.

Conjugate Acid-Base Pair

In any acid-base reaction, the species that remain after the proton donation (the acid) and proton acceptance (the base) are known as a conjugate base and a conjugate acid, respectively. These pairs are central to understanding the reversibility of acid-base reactions, as each acid is paired with a base that can reacquire a proton and vice versa.

Transcript

00:01 We need to draw the products of these acid -based reactions, as well as label the acid -based, conjugate acid, and conjugate base.

00:08 To start, i would draw in all of the lone pairs of electrons or pie bonds that can be used as bases.

00:16 So i'm just going to do that here in red.

00:20 So the oxygen of the alcohol has two lone pairs of electrons.

00:25 The nitrogen also has two lone pairs of electrons, but also has a negative charge.

00:32 Which is more stable with a negative charge? nitrogen or oxygen? well, oxygen.

00:38 Therefore, nitrogen is a better base than oxygen.

00:44 So we can use a lone pair of electrons on nitrogen, take the hydrogen that's on oxygen.

00:50 This is the most acidic hydrogen in this compound, and break that hydrogen -oxygen bond, which leaves us with methanol, methoxide and neutral nh3, ammonia.

01:15 All right.

01:16 So that means methanol was acting as our acid and amid acting as our base, b for base.

01:26 So if we look at our products, well, how do we go from our products back to our reactants? well, oxygen can act as a base, take a hydrogen from ammonia, and give nice back its lone pair of electrons, meaning that this oxygen is now acting as a base, and ammonia would act as an acid.

01:48 So in this case, this is the conjugate base to methanol.

01:54 This is the conjugate acid to the amid species.

01:59 Again, we come down here.

02:01 We could look at it at the opposite direction, which is the most acidic hydrogen in any of these species.

02:06 Well, here we have a hydrogen attached to carbon.

02:10 Here a hydrogen attached to carbon.

02:13 Both of those have pkk around 50.

02:15 They're pretty strong bonds to hydrogen.

02:18 Here we have an oxygen -hydrogen bond that when deprotonated, you would have a resonance structure stabilizing the negative charge that would form.

02:26 Therefore, this is a pretty acidic hydrogen.

02:29 The bond between hydrogen and oxygen is quite weak.

02:32 P -k is about four, so this is fairly acidic.

02:35 And then again, here we have another carbon hydrogen bond.

02:39 So here's our most acidic hydrogen, meaning this is going to act as our acid.

02:44 Do we have a good base? well, because there's a negative charge denoted here, that means there must be three sets of lone pairs on that oxygen.

02:56 That can definitely act as a base.

02:59 Oxygen could, a lone pair on oxygen could attack hydrogen, break the oxygen hydrogen hydrogen bond to form the conjugate base of the carboxylic acid.

03:12 So therefore, this is acting as our base.

03:16 What do you get? we get the carboxylate, which is our conjugate base, and we get methanol, which can now act as the acid...

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