Question

Explain why for condensation reactions occurring at the α-carbon you often use a weak base (like -OH) to create the enolate when for reactions such as halogenation you would use a strong base (like LDA). Under what conditions (give an example) could you use LDA for a condensation reaction?

Explain as in-depth as possible and I will give you a thumbs up!

Thanks :)

Answer 1

The use of a Oho (Less hindered base) and LDA (comparatively hindered base) depends on the Structure of the ketone /aldehyde from which we to are gonna abstract proton. Let us take a model kefone a l Now, of we have two choices of abstracting protons, 'as 'b'. The structure of LDA isa ol (sterically bielky due to the lor groups) Thus, use of base LOA is very cle crucial depending on the endate we warnt. OHe gives us a Thermodynamically stable enolate, while LDA gives us kinetically formed enolate. LDA LOLA Thermo Kinetical This is dynamical sterically inhibited by LDA. Thus, where there is no hindbence, we come LDA extensively while in a hindered bos ceid, we htеd оvе оnе. One more example will clear the fact: LOHO CJ à Shermodynamic.