Why do phenols not react with carbonates? I read that stability and position of equilibrium have a part to play, but I can't seem to elucidate a rigorous explanation.
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asked May 4, 2017 at 6:54
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1$\begingroup$ Related: chemistry.stackexchange.com/questions/67382/… $\endgroup$– Nilay GhoshMay 4, 2017 at 8:07
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1 Answer
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Carbonic Acid ($\ce{H2CO3}$) and its conjugate $\ce{HCO3-}$ have a pKa of 6–7. So bicarbonate can deprotonate functional groups with a pKa < 8, but not those with a pKa > 8. The $\ce{HCO3-}$ ion is not strong enough to pull the hydrogen out of Phenol. Phenols have a range of pKa which lies between 8 to 14, on average 10. So Phenols don't react with $\ce{NaHCO3}$ despite being an acid.
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1$\begingroup$ $\ce{HCO3-}$ has a pKa of 10.3, according to Wikipedia. $\endgroup$ May 4, 2017 at 10:41
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$\begingroup$ Organic carbonates such as dimethyl carbonate, or inorganic such as sodium carbonate? Heat phenol with the latter and pKa will not matter so much as the equilibrium will be driven to the right through CO2 release $\endgroup$ May 6, 2017 at 0:48