Alkylation by p-toluenesulfonic esters

Like dimethyl sulfate, aromatic sulfonic esters are powerful alkylating agents. Aqueous or anhydrous alkali can be used for alkylation of phenols 

Phenetole 703 Phenol (19 g, 0.2 mole) is dissolved in 3N-sodium hydroxide solution (0.2mole of NaOH), treated with ethyl / -toluenesulfonate (40 g), and heated and stirred under reflux on a boiling water-bath. Further 6N-sodium hydroxide solution (10 ml) was added and the whole heated for a further 30 min. After cooling, the upper, organic, layer was taken up in ether, washed with dilute sodium hydroxide solution, dried, and evaporated. The residue, distilled in a vacuum, gave the ethyl ether (19.2 g, 78.7%), //D20 1.5075. 

It is not always necessary to isolate the sulfonic ester the same ethers can be obtained by using //-toluenesulfonyl chloride,703, 704 an alcohol, and a phenol. However, after reaction of the sulfonyl chloride with the alcohol it is necessary to adjust the alkali concentration to that required for alkylation before the phenol is added. 

Nerolin 703/ -Toluenesulfonyl chloride (47.5 g, 0.25 mole) and ethanol (20 g,0.45 mole) are treated at 15° with 25% sodium hydroxide solution (40 ml) and stirred for 3 h at 15°. Then -naphthol (29 g, 0.2 mole), sodium hydroxide (8 g, 0.2 mole), and water (10 ml) are added, bringing the sodium hydroxide concentration to about 4n. This mixture is heated for 30 min on a boiling water-bath, treated with 6N-sodium hydroxide solution (10 ml), and again heated for 30 min. A mass of crystals separates on cooling this is filtered off, washed with dilute sodium hydroxide solution and with water, and dried. It constitutes ethyl -naphthyl ether (nerolin), m.p. 36°, in a yield of 96% calculated on jS-naphthol (i.e., 33.0 g). 

Aliphatic alcohols can also be converted into their ethers by /7-toluene-sulfonic esters. For this purpose, either the anhydrous alcohol is treated with the amount of sodium necessary for formation of the alkoxide or the corresponding amount of alkali hydroxide is dissolved in an excess of the alcohol, and the resulting mixture is brought into reaction with the /7-toluenesulfonic ester. Yields are about 70-80% by both methods. When the costly higher aliphatic alcohols are in question the sodium alkoxide is prepared in benzene, and that mixture is treated at the boiling point with the sulfonic ester. 

---