A method for the cleavage of a C 8-12 alkylbenzene hydroperoxide into phenol and a C 3-6 ketone, comprising: a method for the manufacture of a sulfonated phenol for use as a cumene hydroperoxide decomposition catalyst, preferably conducted in a plug-flow reactor, comprising, combining phenol and a sulfonating agent at a first temperature that is 1 °C to 15 °C higher than a melting temperature of the phenol, to form a reaction mixture at the first temperature, preferably wherein at least one of: the phenol and the sulfonating agent are combined in a molar ratio of 50:1 to 1:3, preferably a molar ratio of 4:1 to 1:1; the sulfonating agent comprises sulfuric acid, acetyl sulfate, sulfur trioxide, fuming sulfuric acid, or a combination comprising at least one of the foregoing; and the combining comprises adding the sulfonating agent to the phenol, reducing the first temperature of the reaction mixture to a second temperature that is 10 to 40°C lower than the first temperature, and forming the sulfonated phenol at the second temperature, preferably forming o-sulfonated phenol and p-sulfonated phenol in a weight ratio of o-sulfonated phenol to p-sulfonated phenol greater than or equal to 1; contacting the C 8-12 alkylbenzene hydroperoxide with a catalytically sufficient amount of the sulfonated phenol under conditions effective to cleave the C 8-12 alkylbenzene hydroperoxide to form the phenol, the C 3-6 ketone, a C 2 -C 6 alkylaldehyde, or a combination comprising at least one of the foregoing; and maintaining a concentration of hydroxyacetone of less than or equal to 400 ppmw, or less than or equal to 300 ppmw. a method for the manufacture of a sulfonated phenol for use as a cumene hydroperoxide decomposition catalyst, preferably conducted in a plug-flow reactor, comprising, combining phenol and a sulfonating agent at a first temperature that is 1 °C to 15 °C higher than a melting temperature of the phenol, to form a reaction mixture at the first temperature, preferably wherein at least one of: the phenol and the sulfonating agent are combined in a molar ratio of 50:1 to 1:3, preferably a molar ratio of 4:1 to 1:1; the sulfonating agent comprises sulfuric acid, acetyl sulfate, sulfur trioxide, fuming sulfuric acid, or a combination comprising at least one of the foregoing; and the combining comprises adding the sulfonating agent to the phenol, reducing the first temperature of the reaction mixture to a second temperature that is 10 to 40°C lower than the first temperature, and forming the sulfonated phenol at the second temperature, preferably forming o-sulfonated phenol and p-sulfonated phenol in a weight ratio of o-sulfonated phenol to p-sulfonated phenol greater than or equal to 1; combining phenol and a sulfonating agent at a first temperature that is 1 °C to 15 °C higher than a melting temperature of the phenol, to form a reaction mixture at the first temperature, preferably wherein at least one of: the phenol and the sulfonating agent are combined in a molar ratio of 50:1 to 1:3, preferably a molar ratio of 4:1 to 1:1; the sulfonating agent comprises sulfuric acid, acetyl sulfate, sulfur trioxide, fuming sulfuric acid, or a combination comprising at least one of the foregoing; and the combining comprises adding the sulfonating agent to the phenol, the phenol and the sulfonating agent are combined in a molar ratio of 50:1 to 1:3, preferably a molar ratio of 4:1 to 1:1; the sulfonating agent comprises sulfuric acid, acetyl sulfate, sulfur trioxide, fuming sulfuric acid, or a combination comprising at least one of the foregoing; and the combining comprises adding the sulfonating agent to the phenol, reducing the first temperature of the reaction mixture to a second temperature that is 10 to 40°C lower than the first temperature, and forming the sulfonated phenol at the second temperature, preferably forming o-sulfonated phenol and p-sulfonated phenol in a weight ratio of o-sulfonated phenol to p-sulfonated phenol greater than or equal to 1; contacting the C 8-12 alkylbenzene hydroperoxide with a catalytically sufficient amount of the sulfonated phenol under conditions effective to cleave the C 8-12 alkylbenzene hydroperoxide to form the phenol, the C 3-6 ketone, a C 2 -C 6 alkylaldehyde, or a combination comprising at least one of the foregoing; and maintaining a concentration of hydroxyacetone of less than or equal to 400 ppmw, or less than or equal to 300 ppmw.