How can something be a good Base, but a weak nucleophile??

[pineappletree]

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I thought those terms were almost synonymous

Also, How can a hydrogen Be more acidic, yet have a Stronger Bond than another acidic hydrogen??

 

[muhali3]

the classic example of a strong base/weak nucleophile is tert-butoxide. It is a strong base due to a negatively charged oxygen atom but is non-nucleophilic due to steric hindrance.

 

[PiBond]

I thought those terms were almost synonymous

Also, How can a hydrogen Be more acidic, yet have a Stronger Bond than another acidic hydrogen??

basicity and nucleophilicity correlate to some extent, but remember that the former is a thermodynamic term and the latter is a kinetic term. thus, there will be exceptions

you'll see wicked strong bases like LDA and KOtBu that can't act as nucleophiles because they are too sterically hindered

To your acidity question: are you referring to an sp-hybridized carbon? or is there an example you have?

 

[orgohacks]

I thought those terms were almost synonymous

Also, How can a hydrogen Be more acidic, yet have a Stronger Bond than another acidic hydrogen??

Bond strength reflects homolytic cleavage (to two radicals) whereas acidity reflects heterolytic cleavage (to ions). Methanol is a stronger acid than hexane because the conjugate base is more stable, yet has a stronger bond because the O radical is more unstable than the alkyl radical.

Hope this makes sense - James