Organic acids
Virtually all organic compounds contain hydrogen, but they are not all acids.
Acid-base reactions are product-favoured if the reactant acid is stronger than the product acid.
The reaction of both carboxylic acids and phenols with hydroxide ion are product-favoured.
alcohol
carboxylic acid
phenol
Hydrogencarbonate ion (HCO3–) is a weaker base than OH–.
Carboxylic acids are sufficiently strong acids to react with HCO3– to release CO2 gas, but phenols are not.
carboxylic acid
Compounds that are better proton (H+) donors than water are referred to as acids.
H bonded to either carbon or trivalent nitrogen are not acidic.
H bonded to O is acidic if the O is also bonded to a group that can delocalize negative charge (C=O or C6H5 as seen below) and lower the energy of the anion arising from donating a proton.
H bonded to either carbon or trivalent nitrogen are not acidic.
H bonded to O is acidic if the O is also bonded to a group that can delocalize negative charge (C=O or C6H5 as seen below) and lower the energy of the anion arising from donating a proton.
increasing acidity of hydrogen bonded to O (O-H)  | ||||
| CH3CH2OH ethanol not acidic in water | HOH water |  phenol v weak acid |  carbonic acid weak acid |  ethanoic acid weak acid |
Acid-base reactions are product-favoured if the reactant acid is stronger than the product acid.
The reaction of both carboxylic acids and phenols with hydroxide ion are product-favoured.
Water-insoluble phenols and carboxylic acids may dissolve in aqueous hydroxide due to formation of the more polar carboxylate (or phenoxide) ion.
alcohol
| CH3CH2OH weaker acid | + | OH– |  no reaction |
| CH3CH2O– | + | H2O stronger acid |
carboxylic acid
| CH3CO2H stronger acid | + | OH– | |
| CH3CO2– | + | H2O weaker acid |
phenol
| C6H5OH stronger acid | + | OH– | |
| C6H5O– | + | H2O weaker acid |
Hydrogencarbonate ion (HCO3–) is a weaker base than OH–.
Carboxylic acids are sufficiently strong acids to react with HCO3– to release CO2 gas, but phenols are not.
carboxylic acid
| CH3CO2H stronger acid | + | HCO3– | |
| CH3CO2– | + | H2CO3 weaker acid | | H2O + CO2(g) |
| C6H5OH weaker acid | + | HCO3– | no reaction |
| C6H5O– | + | H2CO3 stronger acid |