Why is dry ether necessarily used for #C-C# bond formation reactions?
You might have to clarify here........
Are you asking about a Grignard reaction, which is the premier
And the so-called Grignard reagent reacts reliably with dry ice, ketones, and aldehydes to give (upon work-up) alcohols and carboxylic acids.
The dry ether (diethyl ether or THF) is believed to solvate the Grignard reagent, and bring the organometallic species up into solution. Because Grignards and lithium reagents are highly water sensitive, the chemist takes great care and precautions to use dry solvents, and dry glassware, so as not to degrade the Grignard reagent.
And thus we can label an alkyl residue with a deuterium nucleus.....for use in a special reaction.