Sodium benzenolate

In most cases, O-alkylation predominates. However, with 2-propenyl halides either reaction can be made essentially the exclusive reaction by proper choice of solvent. With sodium benzenolate the more polar solvents, such as... 

It should be noted that formation of 2-(2-propenyl)benzenol in nonpolar solvents is not the result of O-propenylation followed by rearrangement, even though the C-propenylation product is thermodynamically more stable. Rearrangement in fact does occur, but at much higher temperatures (above 200°) than required to propenylate sodium benzenolate ... 

The Kolbe-Schmitt reaction produces O- and C-carboxylation through the reaction of carbon dioxide with sodium benzenolate at 125° ... 

Sodium benzenolate absorbs carbon dioxide at room temperature to form sodium phenyl carbonate (O-carboxylation) and, when this is heated to 125° under a pressure of several atmospheres of carbon dioxide, it rearranges to sodium 2-hydroxybenzoate (sodium salicylate). However, there is no evidence that this reaction is other than a dissociation-recombination process, in which the important step involves electrophilic attack by carbon dioxide on the aromatic ring of the benzenolate ion (C-carboxylation) ... 

With the sodium benzenolate at temperatures of 125° to 150°, ortho substitution occurs at higher temperatures (250° to 300°), particularly with the potassium salt, the para isomer is favored. 

In the somewhat related Reimer-Tiemann reaction, sodium benzenolate with trichloromethane in alkaline solution forms the sodium salt of 2-hydroxy-benzenecarbaldehyde (salicylaldehyde). The electrophile in this case probably is dichlorocarbene (Section 14-7B) ... 

The reactivities of aryl halides, such as the halobenzenes, are exceedingly low toward nucleophilic reagents that normally effect displacements with alkyl halides and activated aryl halides. Substitutions do occur under forcing conditions of either high temperatures or very strong bases. For example, chlorobenzene reacts with sodium hydroxide solution at temperatures around 340° and this reaction was once an important commercial process for the production of benzenol (phenol) ... 

Exercise 14-20 In the hydrolysis of chlorobenzene-1-14C with AM aqueous sodium hydroxide at 340°, the products are 58% benzenol-1-14C and 42% benzenol-2-14C. Calculate the percentage of reaction proceeding (a) by an elimination-addition mechanism, and (b) by direct nucleophilic displacement. Would you expect the amount of direct displacement to increase, or decrease, if the reaction were carried out (a) at 240° and (b) with lower concentrations of sodium hydroxide Give your reasoning. 

Exercise 22-5 Predict the effect on the ultraviolet spectrum of a water solution of benzenamine when hydrochloric acid is added. Explain why a solution of sodium benzenoxide absorbs at longer wavelengths than a solution of benzenol (see Table 22-3). 

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