24.7 Naturally Occurring Phenols TABLE 24.3 Industrial Syntheses of Phenol Reaction and comments Chemical equation Reaction of benzenesulfonic acid w SO,H OH hydroxide This is the oldest method 300-350 ration of phenol. Benzene is sulfone benzenesulfonic acid heated with hydroxide Acidification of the reaction mixture Benzenesulfonic acid Phenol 1. NaOH Hydrolysis of chlorobenzene Heating chloroben- OH zene with aqueous sodium hydroxide at high pres- sure gives phenol after acidification Chlorobenzene Phenol From cumene Almost all the phenol produced in OOH the United States is prepared by this method. Oxi- dation of cumene takes place at the benzylic posi- CH(CH3)2 C(CH3) tion to give a hydroperoxide On treatment with dilute sulfuric acid, this hydroperoxide is converted Isopropylbenzene 1-Methyl-1-phenylethyl to phenol and acetone hydroperoxide OH +(CH3)2C=O hyd CH(CH3)h (isolated from defensive secretion OH HC HO CH(CH3h2 CH H2)CH (active component of marijuana) CH(CH3h2 the United States RE 24.2 Some occurr Back Forward Main MenuToc Study Guide ToC Student o MHHE Website24.7 Naturally Occurring Phenols 947 TABLE 24.3 Industrial Syntheses of Phenol Reaction and comments Reaction of benzenesulfonic acid with sodium hydroxide This is the oldest method for the prepa￾ration of phenol. Benzene is sulfonated and the benzenesulfonic acid heated with molten sodium hydroxide. Acidification of the reaction mixture gives phenol. Hydrolysis of chlorobenzene Heating chloroben￾zene with aqueous sodium hydroxide at high pres￾sure gives phenol after acidification. From cumene Almost all the phenol produced in the United States is prepared by this method. Oxi￾dation of cumene takes place at the benzylic posi￾tion to give a hydroperoxide. On treatment with dilute sulfuric acid, this hydroperoxide is converted to phenol and acetone. Chemical equation 1. NaOH 300–350°C 2. H SO3H Benzenesulfonic acid OH Phenol 1. NaOH, H2O 370°C 2. H OH Phenol Cl Chlorobenzene O2 CH(CH3)2 Isopropylbenzene (cumene) C(CH3)2 OOH 1-Methyl-1-phenylethyl hydroperoxide Acetone OH (CH3)2C O Phenol C(CH3)2 OOH 1-Methyl-1-phenylethyl hydroperoxide H2O H2SO4 CH(CH3)2 (CH2)4CH3 CH(CH3)2 CH(CH3)2 CH3 CH3 CH3 CH3 OH Thymol (major constituent of oil of thyme) Cl Cl OH 2,5-Dichlorophenol (isolated from defensive secretion of a species of grasshopper) O 9 -Tetrahydrocannabinol (active component of marijuana) HC OH OH OH O HC O HO HO HO HO CH3 CH3 Gossypol (About 109 lb of this material is obtained each year in the United States as a byproduct of cotton-oil production.) FIGURE 24.2 Some naturally occurring phenols. Back Forward Main Menu TOC Study Guide TOC Student OLC MHHE Website