[xshadow]

HI

I don't understand too much the silyl enol ether formation


Why if I have an Enolate + TMSC (CH₃SiCl) the enolate attacks the Si using his O -electrons

I usually have seen an enolate  - acting as a nucleophile- attacking an electrophilic atom (like C=O
) with the C carbon atom of enolate...the bond is created between the nucleophilic carbon of an enolate and the electrophilic atom , for example a C- carbonyl


Now here I have that the nucleohilic enolate bond with Si of TMSC through the O-enolates atom ...and NOT the C-enolates atom

Why??!

Thanksss so much

[rolnor]

The silylhalide is a hard electrophile and reacts with the hard nucleophile oxygen. The enolate carbon is a soft electrophile.
Here is a link with nice info about this topic:

https://youtu.be/04NYWxuD6d4

[xshadow]

Saw the video but I have some doubt about hard and soft

For example:

PH3 vs NH3 ....I think that PH3 is a softer base/nucleophile  than NH3 because the donor atom,P,is larger than N

N3- vs NH2-

Here I don't understand which one is softer ...
Some help? N is the donor atom and in both I have a negative charge
Thankss!

[rolnor]

I think the video is about giving you a generall idea about the concept, not quantifying exactly the nucleophiles being softer or harder.