Preparation Of The New Kind Multifunctional Monomer 2, 2-Dimethylol Butanoic Acid

2, 2-Dimethylol butanoic acid (DMBA), also known as 2, 2-bis (hydroxymethyl) butyric acid, is a new kind of multifunctional monomer which contains several functional groups. It can be used in preparation of water-borne polyurethane, water-soluble polyester, water-borne epoxy resin, adhesive and coating agents. In this work, the preparation of DMBA and analytical methods were investigated.2,2-dihydroxymethylbutanal (DMB) was prepared by aldol condensation with formaldehyde (FA) and butyraldehyde (BA) under the action of alkaline catalysts. Gas chromatography (GC) method was established and applied to monitor the chemical compositions of the reaction mixture. It has been found that when triethylamine (TEA) was used as the catalyst, the best molar ratio of FA to BA was 2.2:1 and the optimal TEA to BA molar ratio was 0.05:1. The molar yield of DMB was up to 74.7% on the basis of BA when the reaction was conducted at 40℃for 4 h under the optimal ratios.DMBA was synthesized by oxidation of DMB with hydrogen peroxide to give white crystalline. It has been found that the best molar ratio of hydrogen peroxide to DMB was 1.2:1 and the optimal volume ratio of water (as solvent) to reactants was 1:1. When the oxidation reaction was conducted at 70℃for 6 h under the optimal conditions, the yield of DMBA reached 65.5% on the basis of DMB.The suitable solvents for crystallization and re-crystallization of DMBA were screened and the structure of DMBA was characterized by IR and NMR. High pressure liquid chromatography (HPLC) was used for analyzing the content of DMBA. Some properties of the DMBA product, including acidity, hydroxyl value, melting point and ash content, were measured.