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Amine + NaOH - why is there no reaction?

In my textbook, it lists that there are no reaction between isopropyl amine and NaOH. I don't understand why? I thought -OH would be strong enough to pull an proton from the amine?

Reply 1

Jacd1991

Original post by emeryx09

In my textbook, it lists that there are no reaction between isopropyl amine and NaOH. I don't understand why? I thought -OH would be strong enough to pull an proton from the amine?

Your book is correct. Amines such as isopropyl amine are very weak acids, with PKas around 35, so you'd need a much stronger base than -OH to deprotonate them.

Reply 2

emeryx09

Original post by Jacd1991

Your book is correct. Amines such as isopropyl amine are very weak acids, with PKas around 35, so you'd need a much stronger base than -OH to deprotonate them.

Oh, okay. So, it's because -OH's conjugate base is water, which has a pKa of around 16, which is more acidic than amine?

Reply 3

charco

Study Forum Helper

Original post by emeryx09

Oh, okay. So, it's because -OH's conjugate base is water, which has a pKa of around 16, which is more acidic than amine?

The conjugate base of the hydroxide ion is the oxide ion ...

Reply 4

Jacd1991

Original post by emeryx09

Oh, okay. So, it's because -OH's conjugate base is water, which has a pKa of around 16, which is more acidic than amine?

That's right. You need to compare the pka of the two conjugate acids involved, in this case water and isopropylamine. Since water has a lower pka, you can deduce that the system has an energetic preference for a state involving hydroxide and the neutral amine, rather than water and the deprotonated amine.

Reply 5

emeryx09

Original post by charco

The conjugate base of the hydroxide ion is the oxide ion ...

Oops. I meant conjugate acid.

Original post by Jacd1991

I understand. Thank you!

Reply 6

Anon#9

Do aliphatic amines react with bases such as NaOH?

Original post by charco

The conjugate base of the hydroxide ion is the oxide ion ...

Reply 7

charco

Study Forum Helper

Original post by Saman_B9

Do aliphatic amines react with bases such as NaOH?

no, aliphatic amines ARE bases

Reply 8

username4355882

I read amine as anime :rofl:

I really can't science lmao

Reply 9

charco

Study Forum Helper

Original post by batter mix

I read amine as anime :rofl:

I really can't science lmao

or construct sentences in English ...

Reply 10

Anon#9

Sorry, forgot that
Thanks for helping

Original post by charco

no, aliphatic amines ARE bases

Reply 11

Mutd161

Both are negatively charged and have a lone pair so repel

Reply 12

username4355882

Original post by charco

or construct sentences in English ...

Whatever do you mean by that? :angry:

Using "science" as a verb only goes to reflect upon my very creative mind, I'll have you know, Mr. Science Person.

Reply 13

charco

Study Forum Helper

Original post by batter mix

Whatever do you mean by that? :angry:

Using "science" as a verb only goes to reflect upon my very creative mind, I'll have you know, Mr. Science Person.

reflect (up)on (something)
1. Literally, to be displayed as a duplicate light or image on something. Technically, moonlight is just sunlight that bounces off the moon and is reflected on the Earth. Though his back was to me, I could see his worried face reflected on the small pool of water.
2. To consider or think back on something with close or careful attention. Stuck in bed with a broken leg, all I could do was reflect on the accident that put me there. After coming to terms with not getting the promotion, Janet reflected upon her boss's criticism and vowed to improve her work.

shameless copy/paste from https://idioms.thefreedictionary.com/reflect+upon+something