Can you synthesize phenol from salicyladehyde? Well for starters I know that salicyladehyde can be obtained from phenol through Reimer–Tiemann reaction but I was wondering if the reverse was possible.
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5$\begingroup$ Oxidation and decarboxylation. But this is an expensive way to make phenol. $\endgroup$– LighthartMar 22, 2016 at 19:35
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2$\begingroup$ An even more expensive way: stoichiometric rhodium decarbonylation. Apparently, though, that is now possible catalytically. $\endgroup$– SendersReagentMar 22, 2016 at 20:49
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1 Answer
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It is possible to convert salicylaldehyde into phenol in a two-step process. Firstly, salicylaldehyde is oxidized to salicylic acid with a standard reagent like $\ce{KMnO4}$ (see the answers to this question).
In the second step, salicylic acid is thermally decarboxylated to phenol in a simple distillation apparatus. Solid salicylic acid is strongly heated in a round-bottom flask equipped with a short path distillation head with thermometer. Heating is maintained to keep a reasonable distillation rate of the desired product (phenol passes over at a temperature range from 145 to 165 °C). Most by-products of the reaction, like phenyl salicylate, have higher boiling points and remain in the residue. The crude product can finally be purified by vacuum distillation, for example, at a pressure of 30 Torr and a temperature range of 85 - 90 °C (reference).
answered Mar 26, 2016 at 15:09