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Propanoyl Chloride + Butylamine = ?

Damien_Dalgaard

Came across this question.

I thought it would produce CH3-CH2-C=O
\N-CH3-CH2

+ CH3CH2Cl.

Am I right?

Reply 1

She-Ra

Universities Forum Helper

Original post by Damien_Dalgaard

Came across this question.

I thought it would produce CH3-CH2-C=O
\N-CH3-CH2

+ CH3CH2Cl.

Am I right?

Moved this to the chemistry study help forum for you :smile:

Reply 2

Damien_Dalgaard

Original post by She-Ra

Moved this to the chemistry study help forum for you :smile:

noooooo

Thought you knew what to do cd

Thanks though :d

Reply 3

GDN

that reaction produces N-butylpropanamide

Reply 4

Chlorophile

Original post by Damien_Dalgaard

Came across this question.

I thought it would produce CH3-CH2-C=O
\N-CH3-CH2

+ CH3CH2Cl.

Am I right?

No, you'd have N-butylpropanamide, i.e. CH3CH3CONHCH2CH2CH2CH3

Reply 5

Damien_Dalgaard

Original post by Chlorophile

No, you'd have N-butylpropanamide, i.e. CH3CH3CONHCH2CH2CH2CH3

Can you please explain to me why that is?

Reply 6

Chlorophile

Original post by Damien_Dalgaard

Can you please explain to me why that is?

Have you studied this mechanism? The amine group acts as a nucleophile (because of its lone pair) and attacks the delta positive carbon in the propanoyl chloride. The nitrogen is then positively charged but gains the electron pair from one of the N-H bonds. The chlorine gains the electron pair from the C-Cl bond, and then reacts with the lost proton from the nitrogen to leave N-butylpropanamide and Hydrogen Chloride.

Reply 7

Lex100

Hi Damien,

Included a mechanism for you, I hope it helps you unravel what's going on.

Few pointers:

With a mechanism check your partial charges from electronegative atoms as your first observation. Assign your delta positive and delta negatives to see how your molecules will behave.

The amine group in this molecule(NH2) acts as a nucleophile with the lone pair on nitrogen.

The chlorine molecule, and other halogens act as excellent leaving groups and that is why it is able to leave as a negative ion part way through the mechanism.

As for the oxygen having the double bond pair of electrons pushed onto the atom, I explain it as the oxygen being a sink for a single negative charge where needed, but will not remain like that for long as it is high energy, so in this case it has reformed the double bond and 'kicked off' the chlorine atom. You need to be able to spot when this may happen as there are a few mechanisms which need this.

And as a personal preference, in mechanisms I advise people to 'bubble' their charges so they can't look like double bonds or the dreaded five bonded carbon and such.

Good luck with it.

(edited 9 years ago)