Abstract: The present invention provides a method for producing ditrimethylolpropane which is characterized by the following (1) and (2): (1) a distillation still residue separated from purified trimethylolpropane is subjected to re-distillation under specific conditions to obtain a ditrimethylolpropane-containing solution having given contents of bis-TMP and tri-TMP; and (2) when subjecting the ditrimethylolpropane-containing solution to crystallization with an organic solvent, the crystallization is initiated under pressure at a temperature exceeding a boiling point of the organic solvent as measured under normal pressures, and the resulting crystallization product solution is cooled at a temperature drop rate of 2° C./min or less. According to the above method, it is possible to produce a high-purity ditrimethylolpropane from a distillation still residue obtained upon production of trimethylolpropane in a simple, industrially useful manner.

Abstract: In the production of spiroglycol by the reaction of pentaerythritol and hydroxypivalaldehyde in water in the presence of an acid catalyst, (A) a total content of amines and amine salts in hydroxypivalaldehyde is reduced to 1.5% by weight or lower; (B) seed crystals are added to the reaction system before initiating the reaction and/or during the reaction in an amount from 1.5 to 30% by weight on the basis of the total feed amount of pentaerythritol, hydroxypivalaldehyde, water, the acid catalyst and the seed crystals, each being fed into the reaction system; (C) the pH of the reaction system is kept from 0.1 to 4.

Abstract: The present invention provides a method for concentrating an aqueous solution containing at least 3-hydroxy-2,2-dimethyl propanal and/or a dimer thereof, which includes subjecting a mixed solution of an aqueous solution containing at least 3-hydroxy-2,2-dimethyl propanal and/or a dimer thereof and an azeotropic agent to azeotropic distillation in a distillation column to distil off water and the azeotropic agent from the mixed solution, wherein the mixed solution is prepared by adding, as the azeotropic agent, at least one selected from the group consisting of 1-butanol, 2-butanol, 2-methyl-1-propanol, 1-pentanol and 1-hexanol to the aqueous solution.

Abstract: The present invention provides a method for concentrating an aqueous solution containing at least 3-hydroxy-2,2-dimethyl propanal and/or a dimer thereof, which includes subjecting a mixed solution of an aqueous solution containing at least 3-hydroxy-2,2-dimethyl propanal and/or a dimer thereof and an azeotropic agent to azeotropic distillation in a distillation column to distil off water and the azeotropic agent from the mixed solution, wherein the mixed solution is prepared by adding, as the azeotropic agent, at least one selected from the group consisting of 1-butanol, 2-butanol, 2-methyl-1-propanol, 1-pentanol and 1-hexanol to the aqueous solution.

Abstract: The present invention provides a method for producing ditrimethylolpropane which is characterized by the following (1) and (2): (1) a distillation still residue separated from purified trimethylolpropane is subjected to re-distillation under specific conditions to obtain a ditrimethylolpropane-containing solution having given contents of bis-TMP and tri-TMP; and (2) when subjecting the ditrimethylolpropane-containing solution to crystallization with an organic solvent, the crystallization is initiated under pressure at a temperature exceeding a boiling point of the organic solvent as measured under normal pressures, and the resulting crystallization product solution is cooled at a temperature drop rate of 2° C./min or less. According to the above method, it is possible to produce a high-purity ditrimethylolpropane from a distillation still residue obtained upon production of trimethylolpropane in a simple, industrially useful manner.

Abstract: In the production of spiroglycol by the reaction of pentaerythritol and hydroxypivalaldehyde in water in the presence of an acid catalyst, (A) a total content of amines and amine salts in hydroxypivalaldehyde is reduced to 1.5% by weight or lower; (B) seed crystals are added to the reaction system before initiating the reaction and/or during the reaction in an amount from 1.5 to 30% by weight on the basis of the total feed amount of pentaerythritol, hydroxypivalaldehyde, water, the acid catalyst and the seed crystals, each being fed into the reaction system; (C) the pH of the reaction system is kept from 0.1 to 4.

Abstract: A method for producing flake-like dried DOG by making DOG containing from 10 to 50% by mass of a liquid go through a continuous melt-drying step of a specified condition and then making it go through, as a next step, a vacuum-drying step of a specified condition or a ventilation-drying step of a specified condition while holding a molten state thereof, to obtain DOG in which the liquid in DOG is reduced to not more than 0.5% by mass (dried DOG), and flaking the obtained dried DOG in a flake production step.

Abstract: A method for producing flake-like dried DOG by making DOG containing from 10 to 50% by mass of a liquid go through a continuous melt-drying step of a specified condition and then making it go through, as a next step, a vacuum-drying step of a specified condition or a ventilation-drying step of a specified condition while holding a molten state thereof, to obtain DOG in which the liquid in DOG is reduced to not more than 0.5% by mass (dried DOG), and flaking the obtained dried DOG in a flake production step.

Abstract: In the method of producing ditrimethylolpropane of the present invention, the distillation still residue obtained in the production of trimethylolpropane is subjected to crystallizing treatment while strictly regulating the amount of organic solvent to be used, the crystallization temperature and the crystallization time within the specific ranges. With the method of the present invention, a highly pure di-TMP is obtained only by a single operation of the crystallization.

Abstract: A process of producing 2-(5-ethyl-5-hydroxymethyl-1,3-dioxane-2-yl)-2-methylpropane-1-ol (DOG) by the acetalization of hydroxypivalaldehyde with trimethylolpropane in water in the presence of an acid catalyst and optional seed crystals. DOG crystals having an increased particle size and containing the trans isomer in a high content are produced by the process in which the reaction temperature, pH of the reaction system and concentration of DOG to be produced in the reaction system are controlled.

Abstract: A production method of 2-(5-ethyl-5-hydroxymethyl-1,3-dioxane-2-yl)-2-methylpropane-1-ol (DOG) which includes a step of acetalizing hydroxypivalaldehyde with trimethylolpropane in a solvent in the presence of an acid catalyst. After the acetalization, the reaction product liquid is neutralized and then heated to dissolve the deposited DOG crystals. Then, the reaction product liquid is cooled to recrystallize DOG. DOG produced in such manner has an adequately large particle size. Therefore, DOG is easy to handle and involves little danger of dust explosion.

Abstract: The present invention provides a method of producing high-purity hydroxypivalaldehyde and/or dimer thereof, including: reacting isobutyl aldehyde with formaldehyde in a presence of a basic catalyst; distilling a low boiling point component including unreacted isobutyl aldehyde to obtain an aqueous solution; adding a diluent to the aqueous solution; cooling the aqueous solution to crystallize the hydroxypivalaldehyde and/or the dimer thereof; and subjecting the aqueous solution to a solid-liquid separation, followed by washing with an organic solvent and/or water, in which the diluent and a basic compound are added to the aqueous solution containing the hydroxypivalaldehyde and/or the dimer thereof obtained by distilling the low boiling point component off so that a concentration of the hydroxypivalaldehyde and/or the dimer becomes 5 to 23% by mass, the concentration of formaldehyde becomes 0.2 to 2.5% by mass, and a pH value becomes 5.0 or more, the solution is crystallized at a temperature of 20 to 45° C.

Abstract: In the method of producing ditrimethylolpropane of the present invention, the distillation still residue obtained in the production of trimethylolpropane is subjected to crystallizing treatment while strictly regulating the amount of organic solvent to be used, the crystallization temperature and the crystallization time within the specific ranges. With the method of the present invention, a highly pure di-TMP is obtained only by a single operation of the crystallization.

Abstract: A process of producing 2-(5-ethyl-5-hydroxymethyl-1,3-dioxane-2-yl)-2-methylpropane-1-ol (DOG) by the acetalization of hydroxypivalaldehyde with trimethylolpropane in water in the presence of an acid catalyst and optional seed crystals. DOG crystals having an increased particle size and containing the trans isomer in a high content are produced by the process in which the reaction temperature, pH of the reaction system and concentration of DOG to be produced in the reaction system are controlled.

Abstract: A production method of 2-(5-ethyl-5-hydroxymethyl-1,3-dioxane-2-yl)-2-methylpropane-1-ol (DOG) which includes a step of acetalizing hydroxypivalaldehyde with trimethylolpropane in a solvent in the presence of an acid catalyst. After the acetalization, the reaction product liquid is neutralized and then heated to dissolve the deposited DOG crystals. Then, the reaction product liquid is cooled to recrystallize DOG. DOG produced in such manner has an adequately large particle size. Therefore, DOG is easy to handle and involves little danger of dust explosion.

Abstract: The present invention provides a method of producing high-purity hydroxypivalaldehyde and/or dimer thereof, including: reacting isobutyl aldehyde with formaldehyde in a presence of a basic catalyst; distilling a low boiling point component including unreacted isobutyl aldehyde to obtain an aqueous solution; adding a diluent to the aqueous solution; cooling the aqueous solution to crystallize the hydroxypivalaldehyde and/or the dimer thereof; and subjecting the aqueous solution to a solid-liquid separation, followed by washing with an organic solvent and/or water, in which the diluent and a basic compound are added to the aqueous solution containing the hydroxypivalaldehyde and/or the dimer thereof obtained by distilling the low boiling point component off so that a concentration of the hydroxypivalaldehyde and/or the dimer becomes 5 to 23% by mass, the concentration of formaldehyde becomes 0.2 to 2.5% by mass, and a pH value becomes 5.0 or more, the solution is crystallized at a temperature of 20 to 45° C.

Abstract: In the method of the invention, hydroxypivalaldehyde (3-hydroxy-2,2-dimethylpropanal) and/or its dimer is stored under solid conditions containing an amount of water. By storing such solid conditions, hydroxypivalaldehyde and/or its dimer is stored for a long period of time without reducing its purity.

Abstract: In the production of spiroglycol by the reaction of pentaerythritol and hydroxypivalaldehyde in water in the presence of an acid catalyst, (A) a total content of amines and amine salts in hydroxypivalaldehyde is reduced to 1.5% by weight or lower; (B) seed crystals are added to the reaction system before initiating the reaction and/or during the reaction in an amount from 1.5 to 30% by weight on the basis of the total feed amount of pentaerythritol, hydroxypivalaldehyde, water, the acid catalyst and the seed crystals, each being fed into the reaction system; (C) the pH of the reaction system is kept from 0.1 to 4.

Abstract: In the method of the invention, hydroxypivalaldehyde (3-hydroxy-2,2-dimethylpropanal) and/or its dimer is stored under solid conditions containing an amount of water. By storing such solid conditions, hydroxypivalaldehyde and/or its dimer is stored for a long period of time without reducing its purity.

Abstract: A process for producing trimellitic acid which comprises step A for oxidizing pseudocumene, thereby obtaining a reaction mixture comprising dimethyl benzoic acid, dimethyl benzyl alcohol, and dimethyl benzaldehyde, step B for separating dimethyl benzoic acid, dimethyl benzyl alcohol and dimethyl benzaldehyde from the reaction mixture obtained in step A, step C for oxidizing dimethyl benzyl alcohol separated in step B, thereby obtaining dimethyl benzoic acid and dimethyl benzyl aldehyde and then feeding dimethyl benzoic acid and dimethyl benzyl aldehyde thus obtained to step B, and step D for oxidizing dimethyl benzoic acid and/or dimethyl benzaldehyde separated in step B, thereby obtaining trimellitic acid.