Acid-base equilibria
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Please explain to me the effects of CH3- and CH2Cl- on the dissociation constants, as illustrated by ethanoic acid and monochloroethanoic acid compared with that of methanoic acid.
Ulex writes
There is evidence that the methyl group is electron-releasing, which means that the acid proton in ethanoic acid is less likely to be lost as a proton than is the case in methanoic acid.
On the other hand, chlorine atoms are electron-withdrawing which means that the acid proton in monochloroethanoic acid is more easily converted into a proton than is the case in methanoic acid. Reference to p122 of the Nuffield Book of Data shows that the order of acidic strength is
Monochloroethanoic > methanoic > ethanoic
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updated: 21 February 2006
