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Author: Subject: BuLi + C2H2 -> BuH + LiCCH
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[*] posted on 24-5-2015 at 13:28
BuLi + C2H2 -> BuH + LiCCH


Hello, i'm not very good with calculators.

I understand that pKa Butane ~ 50 whereas acetylene ~25.

In reaction BuLi + HCCH -> BuH + LiCCH

what do pKa numbers actually mean exactly?

How many time more strongly acidic are ethyne protons relative to butane (sp v sp3)?

Based on numbers it looks like two times the amount but it is log scale etc i forgot it.
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clearly_not_atara
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[*] posted on 24-5-2015 at 13:48


It's logarithmic: a difference of 25 means that acetylene is 10^25 = 10000000000000000000000000 times as acidic as butane. However since n-BuLi has some covalent character and the reaction occurs in a nonpolar solvent the effect isn't quite as dramatic.
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Nicodem
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25-5-2015 at 06:57

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