A method of forming a phenylene ether oligomer, the method comprising: reacting 2,6-dimethylphenol in the presence of toluene, oxygen, copper ion, bromide ion, and an alkylenediamine to form a first reaction mixture comprising 40 to 90 weight percent residual 2,6-dimethylphenol, and 10 to 60 weight percent 3,3',5,5'-tetramethyl-4,4'-dihydroxybiphenyl, 3,3',5,5'-tetramethyldiphenoquinone, or a combination thereof; wherein weight percent values are based on the weight of initial 2,6-dimethylphenol; and wherein the reaction of the 2,6-dimethylphenol is conducted at a mole ratio of 2,6-dimethylphenol to copper ion of 300:1 to 1000:1, at a mole ratio of alkylenediamine to copper ion of 2:1 to 8:1, in the presence of 0 to 0.2 weight percent of tertiary monoamine, based on the weight of toluene, and at a temperature of 50 to 110 °C; reacting the residual 2,6-dimethylphenol in the presence of toluene, oxygen, copper ion, bromide ion, and alkylenediamine to form a second reaction mixture comprising 40 to 90 weight percent poly(2,6-dimethyl-1,4-phenylene ether); wherein the reacting residual 2,6-dimethylphenol is conducted at a temperature of 25 to 60 °C; and wherein any 3,3',5,5'-tetramethyl-4,4'-dihydroxybiphenyl present in the first reaction mixture is substantially converted to 3,3',5,5'-tetramethyldiphenoquinone in the second reaction mixture; chelating the copper ion; and reacting the poly(2,6-dimethyl-1,4-phenylene ether) and the 3,3',5,5'-tetramethyldiphenoquinone to form a phenylene ether oligomer having the structure wherein x and y are independently 0 to 20, provided that the sum of x and y is at least 1 and no greater than 30; wherein the reacting the poly(2,6-dimethyl-1,4-phenylene ether) and the 3,3',5,5'-tetramethyldiphenoquinone is conducted at a temperature of 50 to 100 °C. reacting 2,6-dimethylphenol in the presence of toluene, oxygen, copper ion, bromide ion, and an alkylenediamine to form a first reaction mixture comprising 40 to 90 weight percent residual 2,6-dimethylphenol, and 10 to 60 weight percent 3,3',5,5'-tetramethyl-4,4'-dihydroxybiphenyl, 3,3',5,5'-tetramethyldiphenoquinone, or a combination thereof; wherein weight percent values are based on the weight of initial 2,6-dimethylphenol; and wherein the reaction of the 2,6-dimethylphenol is conducted at a mole ratio of 2,6-dimethylphenol to copper ion of 300:1 to 1000:1, at a mole ratio of alkylenediamine to copper ion of 2:1 to 8:1, in the presence of 0 to 0.2 weight percent of tertiary monoamine, based on the weight of toluene, and at a temperature of 50 to 110 °C; at a mole ratio of 2,6-dimethylphenol to copper ion of 300:1 to 1000:1, at a mole ratio of alkylenediamine to copper ion of 2:1 to 8:1, in the presence of 0 to 0.2 weight percent of tertiary monoamine, based on the weight of toluene, and at a temperature of 50 to 110 °C; reacting the residual 2,6-dimethylphenol in the presence of toluene, oxygen, copper ion, bromide ion, and alkylenediamine to form a second reaction mixture comprising 40 to 90 weight percent poly(2,6-dimethyl-1,4-phenylene ether); wherein the reacting residual 2,6-dimethylphenol is conducted at a temperature of 25 to 60 °C; and wherein any 3,3',5,5'-tetramethyl-4,4'-dihydroxybiphenyl present in the first reaction mixture is substantially converted to 3,3',5,5'-tetramethyldiphenoquinone in the second reaction mixture; chelating the copper ion; and reacting the poly(2,6-dimethyl-1,4-phenylene ether) and the 3,3',5,5'-tetramethyldiphenoquinone to form a phenylene ether oligomer having the structure wherein x and y are independently 0 to 20, provided that the sum of x and y is at least 1 and no greater than 30; wherein the reacting the poly(2,6-dimethyl-1,4-phenylene ether) and the 3,3',5,5'-tetramethyldiphenoquinone is conducted at a temperature of 50 to 100 °C.