- Preparation method of low-phosphorous corrosion and scale inhibitor PBTCA (2-phosphonobutane-1,2,4-tricarboxylic acid)
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The invention discloses a preparation method of low-phosphorous corrosion and scale inhibitor PBTCA (2-phosphonobutane-1,2,4-tricarboxylic acid). Certain amounts of diethyl phosphite and diethyl maleate are added to a reaction kettle, a condensation reflux device and a stirrer are started, a certain amount of a catalyst A is slowly dropwise added under the stirring condition that the revolving speed of the stirrer is 200 r/min, and the mixture reacts for 1 h after the temperature is increased to 100 DEG C; then the temperature is decreased to 50 DEG C, a certain amount of ethyl acrylate is added, and the mixture reacts for 8 h in the stirred state; then a certain amount of a catalyst B is added to the reaction kettle, the mixture is heated to 80 DEG C for hydrolysis for 0.5 h, and a finally obtained product, namely, PBTCA, is a yellowish-brown viscous liquid. The preparation method of PBTCA has the advantages of simple process route, convenience in operation, low three-waste emission and the like, and can be widely applied to corrosion and scale inhibition of industrial recirculating cooling water systems.
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Paragraph 0006; 0007; 0021; 0022
(2016/11/14)
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- Production of 2-phosphonobutane-1,2,4-tricarboxylic acid and the alkali metal salts thereof
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This invention relates to an improved process for the production of 2-phosphono-butane-1,2,4-tricarboxylic acid (PBTC) and the alkali metal salts thereof, in which process dialkyl phosphite, preferably dimethyl or diethyl phosphite, and ethene-1,2-dicarboxylic acid dialkyl ester, in particular the dimethyl or diethyl ester of maleic acid and/or fumaric acid, are initially reacted in the presence of a basic catalyst to yield a phosphonosuccinic acid tetraalkyl ester, the resultant ester is thereupon reacted without further working up with acrylic acid alkyl ester, preferably methyl or ethyl acrylate, in the presence of an alkaline catalyst and the reaction product obtained in this manner is saponified without further working up to yield PBTC or the alkali metal salts thereof. The product when mixed with bleaching lye exhibits reduced chlorine depletion.
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