A method for producing a diphosphite of Structure I, comprising the steps of: contacting a phosphorochloridite of Structure II, with a bisaryl compound selected from the group consisting of Structure III, Structure IV, and Structure V, and a tertiary organic amine, comprising a basic nitrogen atom or a plurality of nitrogen atoms, to produce a reaction mixture comprising a diphosphite of Structure I; wherein, the contacting step is carried out by at least one contacting method selected from the group consisting of, (i). feeding the bisaryl compound to a mixture of phosphorochloridite and tertiary organic amine, and (ii). feeding the bisaryl compound and the tertiary organic amine either separately or as a mixture to the phosphorochloridite; wherein and the contacting step is carried out by controlling the feeding such that: (a) a first mole ratio is at least 2.0 during all stages of the contacting step, wherein the first mole ratio is defined as moles of phosphorochloridite in the reaction mixture divided by moles of bisaryl compound fed to the reaction mixture; (b) a second mole ratio is at least 1.0 during all stages of the contacting step, wherein the second mole ratio is defined as moles of basic nitrogen atoms from the tertiary organic amine fed to the reaction mixture divided by moles of phosphorochloridite in the reaction mixture; (c) a phosphorochloridite concentration is greater than or equal to 0.02 moles per liter in the reaction mixture during the stage of the contacting wherein phosphorochloridite conversion is from 0% to 90%; and (d) the bisaryl compound is fed to the phosphorochloridite at a feed rate between 0.04 and 10 molar equivalents per hour, relative to total moles of phosphorochloridite undergoing the contacting step; wherein the bisaryl compound, the tertiary organic amine, or a combination of the bisaryl compound and the tertiary organic amine, contacting the phosphorochloridite further comprise a total of from 0 ppm to 300 ppm by weight of water; wherein the contacting occurs at a temperature from 10°C to 110°C to produce the diphosphite in the reaction mixture with a selectivity between 70% and 100% from the bisaryl compound, wherein the selectivity equals moles of diphosphite produced in the reaction mixture divided by total moles of the bisaryl compound contacting the phosphorochloridite; and wherein in Structures I to V, R 1 and R 2 are the same or different, substituted or unsubstituted, monovalent aryl groups; each of R 3, R 4, R 5, R 6, R 7, R 8, R 9, R 10, R 11, and R 12 is independently selected from the group consisting of hydrogen, alkyl, aryl, heteroaryl, aryloxy, heteroaryloxy, alkyloxy, alkoxyalkyl, acetal, carboaryloxy, carboalkoxy, arylcarbonyl, alkylcarbonyl, oxazole, amine, amide, nitrile, mercaptyl, and halogenyl groups; and O-Q-O is a dianion of the bisaryl compound. contacting a phosphorochloridite of Structure II, with a bisaryl compound selected from the group consisting of Structure III, Structure IV, and Structure V, and a tertiary organic amine, comprising a basic nitrogen atom or a plurality of nitrogen atoms, to produce a reaction mixture comprising a diphosphite of Structure I; the contacting step is carried out by at least one contacting method selected from the group consisting of, (i). feeding the bisaryl compound to a mixture of phosphorochloridite and tertiary organic amine, and (ii). feeding the bisaryl compound and the tertiary organic amine either separately or as a mixture to the phosphorochloridite; (i). feeding the bisaryl compound to a mixture of phosphorochloridite and tertiary organic amine, and (ii). feeding the bisaryl compound and the tertiary organic amine either separately or as a mixture to the phosphorochloridite; (a) a first mole ratio is at least 2.0 during all stages of the contacting step, wherein the first mole ratio is defined as moles of phosphorochloridite in the reaction mixture divided by moles of bisaryl compound fed to the reaction mixture; (b) a second mole ratio is at least 1.0 during all stages of the contacting step, wherein the second mole ratio is defined as moles of basic nitrogen atoms from the tertiary organic amine fed to the reaction mixture divided by moles of phosphorochloridite in the reaction mixture; (c) a phosphorochloridite concentration is greater than or equal to 0.02 moles per liter in the reaction mixture during the stage of the contacting wherein phosphorochloridite conversion is from 0% to 90%; and (d) the bisaryl compound is fed to the phosphorochloridite at a feed rate between 0.04 and 10 molar equivalents per hour, relative to total moles of phosphorochloridite undergoing the contacting step; R 1 and R 2 are the same or different, substituted or unsubstituted, monovalent aryl groups; each of R 3, R 4, R 5, R 6, R 7, R 8, R 9, R 10, R 11, and R 12 is independently selected from the group consisting of hydrogen, alkyl, aryl, heteroaryl, aryloxy, heteroaryloxy, alkyloxy, alkoxyalkyl, acetal, carboaryloxy, carboalkoxy, arylcarbonyl, alkylcarbonyl, oxazole, amine, amide, nitrile, mercaptyl, and halogenyl groups; and O-Q-O is a dianion of the bisaryl compound.