The method of obtaining acrylamide polymer containing hydroxamic group


C08F8C08F220/58 -
C08F220/58 - containing oxygen in addition to the carbonamido oxygen

 

(57) Abstract:

Usage: obtain polymers with hydroxamic groups, used as flocculants. The inventive interaction of an aqueous solution acrylamide polymer with a concentration of at least 2 wt.% with a hydroxylamine salt at a molar ratio of hydroxylamine and amide groups in acrylamides the polymer is 0.1 to 2.0 : 1. The reaction is carried out at a pH value of at least 11, a temperature of 40 - 80oC for 1 - 4 h Molecular weight of the original polymer, which can be used acrylamide, 5 104- 15 106. 1 C. p. F.-ly, 7 PL.

The invention relates to the synthesis from hydroxamic groups used in the formation of iron complexes; they show a beneficial effect on drilling muds.

These polymers are used as flocculants.

A method of obtaining these polymers by reacting hydroxylamine with polyacrylamide in aqueous solution at a temperature of 50-80aboutC and the pH value of 6.2 to 6.8. It is noted that this temperature range is optimal for minimizing the decomposition of hydroxylamine while maintaining the reaction rate in a reasonable dinnie examples have a molecular weight in the range 1000-20000.

A method of obtaining hydroxamate polymers interaction of hydroxylamine with polyacrylamide at a temperature of 90aboutWith the use of sodium acetate as a buffer.

Closest to the claimed is a method for polyacrylamide with hydroxamic groups interaction polyacrylamide (PAA) with hydrochloric acid hydroxylamine in aqueous medium in the presence of sodium hydroxide in an amount to provide a degree of neutralization of hydroxylamine (HA) 80% (the molar ratio of alkali and HA 0,4:0,5-0,7) [3] the Method allows to obtain PAA content hydroxamate groups of up to 31% In the known methods for decreasing the concentration of hydroxylamine is proportional decrease the reaction rate and efficiency of conversion of hydroxylamine in hydroxamate group. Thus, at low concentrations of hydroxylamine, which was tested by hydroxamate polymers, especially in the case of high-molecular compounds, the reaction rate and efficiency of hydroxylamine are critical parameters for determining the commercial success of the process.

The aim of the invention is to provide a process in which the reaction rate and efficiency of use the steps acrylamide polymer with hydroxylamine is the pH value, close to the pKa of the latter. This is because when the pH is equal to pKa, the concentration of hydroxylamine and hydroxylamine salt serving as a catalyst for the reaction, the same.

Applicants have found that in the case of polymers the reaction rate suddenly increases with increasing pH and, moreover, there is an optimization of the efficiency of use of hydroxylamine. In accordance with the proposed applicants in a new way, thus, achieved an increase of hydroxamate per unit used hydroxylamine.

The invention consists in the fact that interact aqueous solution acrylamide polymer with a molecular weight of 15 10415 106with a salt of hydroxylamine at pH of at least 11. When the molar ratio of hydroxylamine and amide groups in acrylamides the polymer is about 0.1 to 2.0. The reaction temperature 40-80aboutWith time 1-4 hours and the concentration of the polymer solution, at least 2 wt.

In this process, the feedstock may be used any water-soluble or water-dispersible acrylamide polymer. Preferred are such compounds as polyacrylamide, polymethacrylamide, etc. but what of iMER, triple polymer, etc., up to 90%, preferably 50% including monoethylene unsaturated comonomer capable copolymerisate with the specified acrylamide. Suitable for these purposes, the copolymers include acrylic acid, methacrylic acid, 2-acrylamide-2-methylpropanesulfonic acid, alkalemia esters of acrylic and methacrylic acids such as methyl acrylate, acrylate, methyl methacrylate, butyl acrylate, telemetries, etc., sodium acrylate, vinyl acetate, vinyl pyrrolidone, styrene, Acrylonitrile, etc. due To the fact that these polymers are used in aqueous solution, then with increasing molecular weight of the polymer is required and a greater dilution of the solution.

Among the suitable hydroxylamine salts include phosphate, perchlorate, sulfate, sulfite, hydrochloride, acetate, propionate, etc., is Preferred sulfate.

At low reaction time, the degree of hydroxamate in the polymer is relatively low. The increase in time of the interaction leads to a slight increase.

The effectiveness of the interaction from the point of view of the degree of hydroxamate increases at lower temperatures, however, the reaction rate decreases. Preferred temperaturregler.

As mentioned above, the most important condition for carrying out this process is the pH value.

The excess of ammonia formed during the reaction, can be eliminated by heat, vacuum or pumping system with an inert gas.

Below are examples illustrating the invention.

P R I m e R s 1 and 2. A number of reactions to determine the influence of pH on the interaction of hydroxylamine with polyacrylamide. Used polyacrylamide has a molecular weight of 50000-60000. It was obtained by the polymerization of acrylamide in aqueous solution in the presence of ammonium sulfate or metabisulfite sodium as a catalyst. The reaction with hydroxylamine is carried out at concentrations of polyacrylamide 2.8 mol/l hydroxylamine of 1.27 mol/l (added as hydroxylamine sulphate) at a temperature of 80aboutC. hydroxylamine Sulfate is dissolved in water and treated with an appropriate base upon cooling. The resulting solution is added to a solution of polyacrylamide with stirring and the corresponding temperature. At equal intervals of time selected multiples of the amount of the mixture and analyzed in order to establish unreacted hydroxyl is trated acid with subsequent ion chromatographic analysis released by the hydroxylamine or13WITH NMR. The content of carboxylate define method13WITH NMR. Unreacted hydroxylamine determined by iodometric titration. In table. 1 shows that the highest rates are achieved with high initial pH values (examples 1 and 2). The value of hydroxamate in such experiments is also higher.

P R I m e R s 3-6. Polyacrylamide of example 1 and 2 the concentration of 1.41 mol/l (10 wt.) subjected to interaction with NH2HE (in the form of hydroxylamine sulphate concentration was 0.63 mol/l at a temperature of 80aboutC). Add enough NaOH to neutralize the sulfate hydroxylamine and additionally excess Paon, as indicated in the table. 2, which presents the results of kinetic studies. Despite the fact that even the lowest pH value (or the concentration of the base) are quite significant, however, there is still a rapid increase in velocity with increasing concentration.

P R I m e R s 7-11. The polymers of examples 1 and 2 are subjected to interaction similar to that described in examples 3-6 except that the concentration of polymer is 0.70 mol/l (5 wt.), and Na2OH 0.32 mol/L. the Results are shown in table. 3.

In this case, the end

Levels of hydroxamate usually lower than in examples 3-6, where the concentration of the polymer was higher.

P R I m e R s 12-15. To obtain the results shown in the table. 4, the polymers of examples 1 and 2 are subjected to interaction similar to examples 3-6 except that the concentration of the polymer is of 0.28 mol/l (2 wt.) Na2OH 0.13 mol/L.

P R I m e R s 16-19. Follow the procedure in examples 12-15, with the peculiarity that the concentration of polyacrylamide is 2 wt. and the reaction is carried out at a temperature of 60aboutC. the Results are shown in table. 5.

P R I m e R s 20-23. Repeat the procedure of examples 12-15, with the peculiarity that the reaction is carried out at a temperature of 40aboutC. the Results are shown in table. 4. Increases the reaction rate and the level of final hydroxamate when the concentration of NaOH with 2.0 mol/l to 4.0 mol/L. Thus, when the temperature of the 40aboutWith the speed of hydroxamate great at high pH values.

P R I m e R s 24-30. Follow the procedure described in examples 1 and 2, with the peculiarity that the polyacrylamide has a molecular weight of about 15 million, using different concentrations of polymer and hydroxylamine in the feedstock, and the reaction is carried out at different meant the ri same ratio polymerizability, there is a growing adoption of hydroxamate with increasing pH values. Comparing the data for examples 27-30 those shown in the table. 5 for a polymer with a lower molecular weight suggests that when conducting the reaction in substantially the same conditions, there is almost the same sensitivity to hydroxamate.

P R I m e R 31. Follow the procedure as described in examples 1, 2, but using salt and hydrochloride. Similar ndings.

P R I m e R 32. Follow the procedure in examples 1 and 2, with the peculiarity that the polymer is a copolymer (molecular weight 72000) acrylamide and acrylic acid (90:10), with similar ndings.

P R I m e R s 33-37. Follow the procedure described in example 32, but instead of the copolymer using the following polymers:

P R I m e R 33 acrylamide (sodium acrylate (60:40), molecular weight of 120,000.

P R I m e R 34 polymethacrylamide, molecular weight 2000000.

P R I m e R 35 acrylamide/Acrylonitrile (70:30), molecular weight of 8000.

P R I m e R 36 acrylamide (acrylate (80:20), molecular weight 8000000.

P R I m e R 37 acrylamide/acrylic acid/styrene (80:10:10), a molecular weight of 800000.

In each case obtained almost equivalent results.

doxylamin in example 40 on phenylhydroxylamine led to the achievement of similar hydroxamate polymer in all cases.

1. The METHOD of OBTAINING ACRYLAMIDE POLYMER CONTAINING HYDROXAMIC GROUP, by treatment of an aqueous solution acrylamide polymer salt of hydroxylamine in the presence of sodium hydroxide at a molar ratio of hydroxylamine salt and an amide group in the original polymer, 0.1 - 2 : 1, characterized in that use acrylamide polymer (mol.m. 5 104- 15 106and the treatment is carried out at a pH of at least 11, at a temperature of 40 - 80oC for 1 to 4 h and the solution concentration of the polymer is at least 2 wt.%:

2. The method according to p. 1, characterized in that as acrylamides of polyacrylamide polymer used.

 

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