a solution of 39 . 2 g ( 0 . 4 moles ) of maleic anhydride in 40 ml of water were stirred at 25 °- 75 ° c . for 45 min to give a white slurry of maleic acid . to this slurry was added 42 g of 30 % aqueous ammonium hydroxide ( 0 . 36 moles nh 3 , 90 % of theoretical required ) with stirring and cooling . the resultant clear solution was then tumbled at 180 °- 200 ° c . ( salt bath temperature ) for 10 min to give a tan solid . the solids were pulverized and tumbled for 10 min at 200 °- 225 ° c . once again the solids were pulverized and then tumbled at 225 °- 240 ° c . for 10 min . finally , the solids were pulverized and tumbled for 10 min at 230 °- 240 ° c . to give 39 . 3 g of tan powder which was insoluble in water . the procedure of example 1 was repeated using 35 g of 30 % aqueous ammonium hydroxide ( 0 . 3 moles nh 3 , 75 % of theoretical required ) to give 39 . 3 g of pink - tan powder which was insoluble in water . the procedure of example 1 was repeated using 23 . 5 g of 30 % aqueous ammonium hydroxide ( 0 . 2 moles nh 3 , 50 % of theoretical required ) to give 37 . 8 g of pink - tan powder which was insoluble in water . the procedure of example 1 was repeated using 11 . 6 g of 30 % aqueous ammonium hydroxide ( 0 . 1 moles nh 3 , 25 % of theoretical required ) to give 36 . 3 g of pink - tan powder which was soluble in water . four gram portions of the solids from examples 1 - 4 were each dissolved 9 . 0 g of water containing 1 . 25 g of naoh to give clear red - brown solutions , ph 7 . 5 - 8 . 5 , estimated to contain 36 - 37 % solids . gel permeation chromatography ( gpc ) was run on a 1 cm × 18 cm , sephadex g - 50 column in a mobile phase of 0 . 02 m sodium phosphate buffer , ph 7 . 0 , running at 0 . 5 ml / min , with detection in the uv at 240 nm . table 1 shows the results which were obtained . table 1______________________________________sample residence time ( min ) ______________________________________example 1 21 . 5example 2 21 . 0example 3 23 . 0example 4 31 . 0______________________________________ to a solution of 4 . 6 g ( 0 . 025 moles ) of lysine in 40 g of water containing 1 . 0 g of naoh was added 39 . 2 g ( 0 . 4 moles ) of maleic anhydride while stirring at 70 °- 75 ° c . for 10 min to give a pale yellow slurry of maleic acid . to this slurry was added 5 . 0 g ( 0 . 29 moles ) of anhydrous ammonia with stirring and cooling . this solution was then treated with heat as in example 1 to give 44 . 0 g of pink - tan powder which was insoluble in water . a 4 . 0 g portion of the powder was dissolved in a solution of 9 . 0 g of water containing 1 . 3 g of naoh to give a clear red - brown solution , estimated to contain 36 % solids . addition of 0 . 55 g of 30 % h 2 o 2 gave a clear yellow solution after 16 hrs at 25 ° c . chromatography of this solution as in example 5 gave a peak centered at 13 min . to prepare a 100 % ammonia sample for comparison purposes , this experiment was carried out in the proportions above except that 1 equivalent of ammonia was used ( noted as 6a in the results ). the material to be tested as an inhibitor of calcium sulfate scale formation was added in the quantities indicated to a solution of 10 ml of calcium chloride solutions 17 . 3 g of cacl 2 dihydrate in 800 g of water containing 33 g of nacl ). to this solution was then added 10 ml of sulfate solution ( 16 . 8 g of na 2 so 4 and 33 g nacl in 800 ml of water ). the mixture was then sealed and maintained at 65 ° c . for 16 hours . finally the mixture was filtered through whatman # 2 paper and dried at 65 ° c . for 8 hours , after which the weight of precipitate was determined . the results in table 2 were obtained . table 2______________________________________ percent of caso . sub . 4 inhibition of precipitationsample from equivalence 1 . 25 ppm 2 . 5 ppmexample number of ammonia 0 ppm ( mg ppt ) ( mg ppt ) ______________________________________blank 79 . 51 90 23 102 75 4 . 5 13 50 48 04 25 51 35a 100 37 196 75 49 286a 100 52 14polyaspartic acid 38 10______________________________________ . sup . a prepared by the method of example 1 using 1 equivalent of ammonia in this assay a supersaturated solution of calcium carbonate is formed by adding 29 . 1 ml of 0 . 55 m nacl and 0 . 01 m kcl to 0 . 3 ml of 1 . 0 m cacl 2 , 5 microliter of sample ( 100 mg of the aqueous solution in 10 ml of water ) and 0 . 6 ml of 0 . 5 m nahco 3 . the reaction is initiated by adjusting the ph to 8 . 55 - 8 . 65 by titration with 0 . 5n naoh . at three minutes , 10 mg of caco 3 is added and the ph is recorded . the decrease in ph is directly correlated to the amount of caco 3 that precipitates . the additive concentration in the final test solution is 2 . 7 ppm . table 3______________________________________sample percent of caco . sub . 3from equivalence driftexample number of nh . sub . 3 ( ph units ) ______________________________________blank 1 . 051 90 0 . 602 75 0 . 633 50 0 . 534 25 1 . 05a 100 0 . 886a 100 0 . 60polyaspartate 0 . 442000 mol . wt . polyacrylate 0 . 374500 mol . wt . polyacrylate 0 . 20______________________________________ . sup . a prepared by the method of example 1 using 1 equivalent of ammonia kaolin dispersion was run by placing the sample ( final concentration of 20 ppm ) in a 12 × 100 mm test tube containing 5 ml of deionized water and adding 40 , 000 ppm kaolin clay . the height of the suspended solids was measured and compared to a control in which no dispersant had been added . a higher value indicates better dispersancy . table 4 gives the results . table 4______________________________________sample percent of kaolin clayfrom equivalence height ( mm ) example number of nh . sub . 3 suspension settled______________________________________blank 0 151 902 75 47 3 . 53 50 48 2 . 54 25 48 2 . 5a 100 50 36a 100polyaspartate2000 mol . wt . polyacrylate 48 24500 mol . wt . polyacrylate 48 3______________________________________ . sup . a prepared by the method of example 1 using 1 equivalent of ammonia a solution which is supersaturated with calcium phosphate was prepared by adding 0 . 1 ml of previously prepared aqueous solutions of 1 . 32 m cacl 2 dihydrate and 0 . 90 m na 2 po 4 to 29 . 8 ml of distilled water , resulting in 4 . 4 mm ca 2 + and 3 . 0 mm dissolved inorganic phosphorus . the reaction vessel is maintained at 25 ° c . there is considerable irregularity in the time necessary to begin precipitation . calcium phosphate begins to crystalize within a few minutes of initiation ( first drop in ph ) and is transformed to hydroxyapatite , ca 10 ( po 4 ) 6 ( oh ) 2 , with a consequent downward ph drift ( second drop in ph ). the reaction ceases when the reactants are depleted and the ph ceases its downward drift . the samples prepared in examples 1 - 4 and 6 were tested and the results ( the average of two separate runs ) are given in table 5 . table 5______________________________________sample from percent of inductionexample equivalence periodnumber of ammonia ( min ) ______________________________________blank 17 . 5 100 34 . 51 90 30 . 52 75 413 50 344 25 29 . 5a 100 26 . 56 75 34 . 56a 100 27polyaspartic acid 37______________________________________ . sup . a prepared by the method of example 1 using 1 equivalent of ammonia maleic anhydride , 39 . 2 g ( 0 . 4 moles ) dissolved in 40 g of water was added to 43 . 1 g of aqueous nh 4 oh ( 6 . 7 g nh 3 , 0 . 394 moles ) and tumbled at 180 °- 195 ° c . for 8 min to give a clear pink melt . it was then heated to 185 °- 200 ° c . for 10 min to give a pink foam . the pulverized foam was heated for 10 min at 200 °- 235 ° c . to give a pink powder and then heated at 235 °- 245 ° c . for 10 min to give 38 . 5 g of a pink tan powder . the material was hydrolyzed with aqueous naoh . the gpc gave a peak at 23 min . in the caso 4 assay of example 7 , the blank was 83 mg while the sample at 2 . 5 ppm gave a precipitate of 11 mg and at 1 . 25 ppm it gave a precipitate of 41 mg . in the kaolin dispersion test of example 9 , at 20 ppm the height of suspended solids was 48 mm whereas the blank was 0 mm . maleic anhydride , 39 . 2 g ( 0 . 4 moles ) dissolved in 40 g of water was added to 4 . 3 g of aqueous nh 4 oh ( 0 . 34 g nh 3 , 0 . 02 moles ) and tumbled at 180 °- 195 ° c . for 12 min to give a tan melt . it was then heated to 200 °- 225 ° c . for 10 min to give a tan melt . the melt was heated for 10 min at 220 °- 230 ° c . to give 18 . 1 g of brown solid . the material was hydrolyzed with aqueous naoh . in the caso 4 assay of example 7 , the blank was 80 mg while the sample at 2 . 5 ppm gave a precipitate of 50 mg and at 1 . 25 ppm it gave a precipitate of 78 mg . to a solution of 1 . 9 g ( 0 . 025 moles ) of ethylene diamine in 40 g of water containing 1 . 0 g of naoh was added 39 . 2 g ( 0 . 4 moles ) of maleic anhydride while stirring at 70 °- 25 ° c . for 10 min to give a white slurry of maleic acid . to this slurry was added 21 . 7 g of water containing 1 . 7 g ( 0 . 1 moles ) of ammonia with stirring and cooling . this solution was then heated for 15 min at 170 °- 200 ° c . to give a tan melt . the melt was heated at 200 °- 225 ° c . for 10 min to give 36 . 5 g of a tan melt . it was further heated at 225 °- 235 ° c . for 10 min to give 35 . 4 g of tan melt which was not soluble in water . the powder was dissolved in a solution of 9 . 0 g of water containing 1 . 3 g of naoh to give a clear red - brown solution , estimated to contain 36 % solids . in the caso 4 assay of example 7 , the blank was 80 mg while the sample at 2 . 5 ppm gave a precipitate of 22 mg and at 1 . 25 ppm it gave a precipitate of 66 mg . the gpc showed a peak at 29 . 5 min with a broad shoulder at 21 - 25 min . a solution of 9 . 8 g ( 0 . 1 mole ) maleic anhydride in 40 g of water was stirred 45 min at 75 °- 25 ° c . to this solution was added 34 . 5 g ( 0 . 3 mole ) of maleamic acid . the slurry was tumbled at 180 °- 195 ° c . for 10 min . all of the solids dissolved to give 39 . 9 g of a viscous red - tan syrup . upon further heating for six 10 min periods at 180 °- 245 ° c ., a tan powder , insoluble in water , was obtained . a 3 . 9 g portion was dissolved in 10 g of water containing 1 . 6 g of naoh . the gpc showed a peak at 22 . 5 min . in the caso 4 assay of example 7 , the blank was 86 mg while the sample at 2 . 5 ppm gave a precipitate of 11 mg . preparation of a maleic polymer with diethylene triamine and oleic acid a mixture of 2 . 0 g ( 0 . 0175 moles ) of diethylene triamine and 1 . 13 ( 0 . 0195 moles ) of oleic acid was heated with stirring for 10 min at 190 °- 210 ° c . the resulting oil was dissolved in 50 g of methanol . to this solution of 9 . 8 g ( 0 . 1 mole ) maleic anhydride in 40 g of water was stirred 45 min at 75 °- 25 ° c . to this solution was added 39 . 0 g ( 0 . 4 mole ) of maleic anhydride . the reactants were stirred 45 min , following which 4 . 3 g ( 0 . 25 mole ) of ammonia in 20 g of water was added ( 75 % of an equivalent ). the slurry was tumbled at 170 °- 185 ° c . for 10 min . upon further heating for four 10 min periods at 190 °- 245 ° c ., 42 . 3 g of a tan powder , insoluble in water , was obtained . a 4 . 0 g portion was dissolved in 10 g of water containing 1 . 6 g of naoh . the gpc showed two broad peaks at 14 and 24 min . in the caso 4 assay of example 7 , the blank was 86 mg while the sample at 2 . 5 ppm gave a precipitate of 8 mg . in the kaolin dispersion test of example 9 , at 20 ppm the height of suspended solids was 48 mm whereas the blank was 0 mm . to a solution of 2 . 67 g ( 0 . 01 mole ) oleyl amine in 50 g of methanol was added 39 . 2 g ( 0 . 4 mole ) maleic anhydride with stirring for 45 min at 25 ° c ., following which 5 . 0 g ( 0 . 29 mole ) of ammonia in 20 g of water was added ( 75 % of an equivalent ). the slurry was tumbled at 170 °- 195 ° c . for 10 min . upon further heating for four 10 min periods at 200 °- 235 ° c ., 41 . 4 g of a brittle glass , insoluble in water , was obtained . the material was dissolved in 100 g of water containing 16 g of naoh . to this solution was added 5 . 5 g of 30 % h 2 o 2 . after 16 hrs at 25 ° c ., the solution was a clear yellow color . the gpc showed a peak at 14 min . in the caso 4 assay of example 7 , the blank was 86 mg while the sample at 2 . 5 ppm gave a precipitate of 9 mg . it will be apparent to those skilled in the art that the examples and embodiments described herein are by way of illustration and not of limitation , and that other examples may be utilized without departing from the spirit and scope of the present invention , as set forth in the appended claims .
polymers of maleic acid may be prepared by thermally polymerizing malic acid , maleic acid or fumaric acid with less than one equivalent of ammonia . the polymers are modified by the incorporation of amines , carboxylic acids or combinations thereof . the polymers formed are excellent inhibitors of alkaline earth salt deposition , dispersants , tartar control additives , detergent additives , and water treatment agents .