Here's what I read about which base to use in Claisen Condensation reaction (two esters or ester + carbonyl compound forming a beta keto-ester or beta-diketone):
The base used must not interfere with the reaction by undergoing nucleophilic substitution or addition with a carbonyl carbon. For this reason, the conjugate sodium alkoxide base of the alcohol formed (e.g. sodium ethoxide if ethanol is formed) is often used, since the alkoxide is regenerated. In mixed Claisen condensations, a non-nucleophilic base such as lithium diisopropylamide, or LDA, may be used, since only one compound is enolizable. LDA is not commonly used in the classic Claisen or Dieckmann condensations due to enolization of the electrophilic ester.
Here's what I didn't understand, particularly -
Why is the conjugate sodium alkoxide base of alcohol generated, used? The paragraph talks about regeneration of alkoxide ion; but I didn't really understand that part. (Seems like something related to chemical equilibrium?)
They said that Lithium Diisopropylamide is NOT generally used due to enolisation of electrophilic ester. What do they mean by it? Why can't we use LDA? Which bases can we use instead?
Could someone please answer the above two questions, with proper explanation? Thanks a lot!