Abstract: In the method of the present invention, a dimethylolcarboxylic acid is produced by reacting a trimethylolalkane and formaldehyde to prepare a cyclic formal having a formal protecting group, followed by the oxidation of the cyclic formal by using nitric acid as an oxidizing agent to prepare a cyclic carboxylic acid which is then subjected to cleavage to remove the formal protecting group. The formal protecting group protects two of the methylol groups against the oxidation to enable the production of the dimethylolcarboxylic acid with a high selectivity.

Abstract: A process for producing a polyol by reacting an aliphatic aldehyde with formaldehyde in the presence of a basic catalyst, which comprises a step of concentration which comprises removing water and unreacted formaldehyde from a reaction liquid by distillation; a step of extraction which comprises extracting the polyol from a concentrated reaction liquid with an extracting reagent; a step of washing with water which comprises washing an extract liquid with water and separating the liquid into an oil layer containing the polyol and an aqueous layer; wherein by useing an specific aliphatic aldehyde as the extracting agent and recovering the extracting reagent from the oil layer containing the polyol after adjusting pH of the oil layer, a high purity polyhydric alcohol can be obtained at a high yield with suppressed formation of byproducts such as acetal compounds and aldol compounds.

Abstract: In the method of the present invention, a dimethylolcarboxylic acid is produced by reacting a trimethylolalkane and formaldehyde to prepare a cyclic formal having a formal protecting group, followed by the oxidation of the cyclic formal by using nitric acid as an oxidizing agent to prepare a cyclic carboxylic acid which is then subjected to cleavage to remove the formal protecting group. The formal protecting group protects two of the methylol groups against the oxidation to enable the production of the dimethylolcarboxylic acid with a high selectivity.

Abstract: The present invention provides a process for recovering ditrimethylolpropane from a still residue obtained by extracting and then distilling off trimethylolpropane from a reaction solution obtained by reacting n-butyraldelhyde with formaldehyde in the presence of a basic catalyst, wherein the still residue is distilled to remove high-boiling components therefrom, and the resultant distillate is subjected to crystallization. When the above process is combined with the acid decomposition, it becomes possible to decompose a linear formal compound obtained from 2 molecules of TMP contained in the still residue as crude TMP and one molecule of formaldehyde, so that di-TMP having a higher purity is obtained.

Abstract: A process for producing a polyol by reacting an aliphatic aldehyde with formaldehyde in the presence of a basic catalyst, which comprises a step of concentration which comprises removing water and unreacted formaldehyde from a reaction liquid by distillation; a step of extraction which comprises extracting the polyol from a concentrated reaction liquid with an extracting reagent; a step of washing with water which comprises washing an extract liquid with water and separating the liquid into an oil layer containing the polyol and an aqueous layer; wherein by useing an specific aliphatic aldehyde as the extracting agent and recovering the extracting reagent from the oil layer containing the polyol after adjusting pH of the oil layer, a high purity polyhydric alcohol can be obtained at a high yield with suppressed formation of byproducts such as acetal compounds and aldol compounds.