[zsinger]

All…..I am an advanced O-Chem student (Synthetic) and I have come across 2 books which SWEAR that 2 different facts are correct, so I want the general consensus.  One book says that a Gilman Reagent is as strong of a Nuc- and base as a Grignard.  I found this HIGHLY unlikely, as it took me almost 3 tries to get the Grignard PERFECTLY dry(They weren't kidding about this B/L AB runs happening quickly!!!!!).  While Grignard gets better yields (for me anyways), the organo-copper rnxs. are usually MUCH MUCH MUCH less finicky, leading me to the less nucleophilic, less basic hypothesis.  Any help appreciated.
      Stumped Chemist in Tampa

[discodermolide]

The ease or difficulty of these reactions is not due to differences in reactivity as you describe. It is to do with your skill in carrying out the experiment.
Operator variability is a tremendous factor in getting a reaction to work properly, especially in dealing with organometallic chemistry.

[zsinger]

TOTALLY TOTALLY agreed……I'm talking in absolute value of basicity/nucleophilicity of Grignard vs. Gilman

[zsinger]

They can't be exactly the same……..A gilman adds one alkyl group, while a Grignard adds two provided there is a good enough leaving group the first time.  The carbonyl re-formation is obviously the last step.

[discodermolide]

Obviously they are not the same chemical species. However I felt the emphasis in your post was directed more towards the preparative aspect of the chemistry.

[zsinger]

Gotcha….not trying to open a can of worms .  Just looking for an answer.  Your right about the individual chemist though!  I had CRAPPY practical lab teachers who were just PhD students who didn't give a crap!  Learning from Strike, Osmium, and the whole Total Synthesis taught me much of what I know about practical lab knowledge.  Im sure y'all are aware of the cult legend Strike .

[spirochete]

Keep in mind basicity and nucleophilicity are different: basicity usually refers to thermodynamics and nucleophilicity usually refers to kinetics. Obviously, as others have pointed out, a Gilman is certainly less (kinetically) nucleophilic than a grignard because it adds once to an acid chloride, whereas a grignard often adds twice. There is also the soft/hard aspect that causes gilmans to add to the four position as opposed to the two position on an alpha beta unsaturated ketone.

 I am not sure exactly what aspect of the gilman makes it less nucleophilic; perhaps it could even have to do with differences in the way the lewis acidic counter ion is able to activate the electrophile.

As for actual thermodynamic basicity, I am not 100% sure because I haven't thought about it much. In the end I don't think the difference in thermodynamic basicity would have that much practical effect on many chemical reactions.

[zsinger]

As for actual thermodynamic basicity, I am not 100% sure because I haven't thought about it much. In the end I don't think the difference in thermodynamic basicity would have that much practical effect on many chemical reactions.
[/quote]

B/L A/B Reaction?

[spirochete]

As for actual thermodynamic basicity, I am not 100% sure because I haven't thought about it much. In the end I don't think the difference in thermodynamic basicity would have that much practical effect on many chemical reactions.

B/L A/B Reaction?
[/quote]

Bronsted lowry? Is that what you're saying? I'm not sure...

[zsinger]

Yes.

[spirochete]

Then yes, I was mainly talking about Bronsted Lowry. Although similar ideas can be applied to thermodynamic lewis acidity and basicity.