#amide

[whats-in-a-sentence]

They assumed that, in conformations of greatest stability, all atoms in a peptide bond lie in the same plane and there is hydrogen bonding between the N-H of one peptide bond and the C=O of another, as shown in figure 24.9.

"Chemistry" 2e - Blackman, A., Bottle, S., Schmid, S., Mocerino, M., Wille, U.

[labphoto]

This fluorinated compound was obtained by the ammonolysis of an ester. Even through the compound was pure for most purposes, it was necessary to purify it before the next step by a recrystallization from chloroform.

It's adorable to watch the needles growing from the clear solution in a perfect purity. The crystallization took more than half an hour so the video is significantly faster. Watch the video: https://www.youtube.com/watch?v=fMtlLPFTOTI

[labphoto]

Performing a quite old reaction: a Hoffmann Degradation/Rearrangement.

It was discovered by August Wilhelm von Hofmann Hofmann in 1881. It is a transformation that converts a primary amide to a primary amine with one fewer carbon atom:

The reaction uses elemental bromine and works in a highly basic medium, in my case for every mol of amide 10 equivalent of NaOH was needed. As the reaction proceeds, my product separated as an orange powder (as seen on the gifs), as the end it was a highly basic (pH 15-16) orange slurry.  However it worked great and it was a quite spectacular reaction. 

Someone on Wikipedia draw the reaction mechanism, so let’s see it: 

Base abstracts an acidic N-H proton, yielding an anion.

The anion reacts with bromine in an α-substitution reaction to give an N-bromoamide.

Base abstraction of the remaining amide proton gives a bromoamide anion.

The bromoamide anion rearranges as the R group attached to the carbonyl carbon migrates to nitrogen at the same time the bromide ion leaves, giving an isocyanate.

The isocyanate adds water in a nucleophilic addition step to yield a carbamic acid (aka urethane).

The carbamic acid spontaneously loses CO2, yielding the amine product.

[tenth-sentence]

Amides are named by dropping the suffix -oic acid from the IUPAC name of the parent acid, or -ic acid from its common name, and adding -amide.

"Chemistry" 2e - Blackman, A., Bottle, S., Schmid, S., Mocerino, M., Wille, U.

[wynco]

I dreamt of nothing but functional groups last night

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