阅读说明：本技术 一种提取异丙烯膦酸和丙烯酰胺共聚反应产物的方法 (Method for extracting copolymerization reaction product of isopropenylphosphonic acid and acrylamide ) 是由 孟丽艳 苏雪霞 徐生婧 孙举 梁庆磊 李保慧 于 2020-03-23 设计创作，主要内容包括：本发明提供了一种提取异丙烯膦酸和丙烯酰胺共聚反应产物的方法,包括：将异丙烯膦酸和水混合制备异丙烯膦酸溶液后放置,再用碱液调节放置后的溶液的pH值,然后将调节pH值后的溶液和丙烯酰胺混合,得到反应前溶液；将所述反应前溶液升温后和引发剂混合引发反应；引发反应后将得到的反应溶液多次滴入乙醇溶液中,直至乙醇溶液产生浑浊现象,停止反应,得到反应后溶液；将所述反应后溶液和无水乙醇混合后放置,析出聚合物；将所述聚合物用无水乙醇浸洗,得到共聚反应产物。本发明将配制的异丙烯膦酸水溶液放置一段时间,将酸酐水解转变回异丙烯膦酸,能够减少试验误差,使得到的共聚反应产物具有更高的准确性和可靠性。(The invention provides a method for extracting a copolymerization reaction product of isopropenylphosphonic acid and acrylamide, which comprises the following steps: mixing isopropenylphosphonic acid and water to prepare an isopropenylphosphonic acid solution, standing, adjusting the pH value of the solution after standing by using an alkali liquor, and mixing the solution after adjusting the pH value with acrylamide to obtain a solution before reaction; heating the solution before reaction, and mixing the solution with an initiator to initiate reaction; after the initiation reaction, dripping the obtained reaction solution into an ethanol solution for many times until the ethanol solution generates a turbid phenomenon, and stopping the reaction to obtain a solution after the reaction; mixing the reacted solution with absolute ethyl alcohol, and then standing to precipitate a polymer; and (3) soaking and washing the polymer by using absolute ethyl alcohol to obtain a copolymerization reaction product. The prepared isopropenylphosphonic acid aqueous solution is placed for a period of time, and the anhydride is hydrolyzed and converted back to isopropenylphosphonic acid, so that the test error can be reduced, and the obtained copolymerization reaction product has higher accuracy and reliability.)

1. A method for extracting a copolymerization product of isopropenylphosphonic acid and acrylamide, comprising:

mixing isopropenylphosphonic acid and water to prepare an isopropenylphosphonic acid solution, standing, adjusting the pH value of the solution after standing by using an alkali liquor, and mixing the solution after adjusting the pH value with acrylamide to obtain a solution before reaction;

heating the solution before reaction, and mixing the solution with an initiator to initiate reaction;

after the initiation reaction, dripping the obtained reaction solution into an ethanol solution for many times until the ethanol solution generates a turbid phenomenon, and stopping the reaction to obtain a solution after the reaction;

mixing the reacted solution with absolute ethyl alcohol, and then standing to precipitate a polymer;

and (3) soaking and washing the polymer by using absolute ethyl alcohol to obtain a copolymerization reaction product.

2. The method of claim 1, wherein the isopropenylphosphonic acid is added in an amount of: the ratio of the theoretical amount of isopropenylphosphonic acid added to the double bond content of isopropenylphosphonic acid.

3. The method according to claim 1, wherein the time for standing after the preparation of the isopropenylphosphonic acid solution is 8-10 hours.

4. The method according to claim 1, wherein the mass concentration of the ethanol solution is 95-98%.

5. The method of claim 1, wherein after the polymer is soaked with the absolute ethanol, the method further comprises:

and (3) measuring the double bond content in the washing filtrate after the soaking to judge whether the unreacted raw materials in the polymer are completely removed by the soaking.

6. The method of claim 1, wherein obtaining the pre-reaction solution further comprises:

the double bond content in the solution before the reaction was determined.

7. The method of claim 1, wherein obtaining the post-reaction solution further comprises:

and (4) measuring the double bond content in the solution after the reaction.

8. The method of claim 1, wherein obtaining the copolymerization reaction product further comprises:

the conversion of the copolymerization product was measured.

9. The method of claim 8, wherein the conversion of the copolymerization reaction product is determined by: and (4) determining according to the change of the double bond content in the solution after the reaction and the double bond content in the solution before the reaction.

10. The method of claim 1, wherein the pH is 5.0 to 9.0.

Technical Field

The invention relates to the technical field of organic chemistry, in particular to a method for extracting a copolymerization reaction product of isopropenylphosphonic acid and acrylamide.

Background

The excellent chemical properties of the polymerizable organic phosphonic acid monomer have attracted wide attention of researchers at home and abroad, and the research on phosphonic acid polymers by taking the polymerizable organic phosphonic acid monomer as a raw material relates to the aspects of scale inhibitors for industrial circulating water treatment, drilling fluid treatment agents, oil well cement additives and the like. Isopropenylphosphonic acid has unsaturated carbon-carbon double bonds and phosphonic acid groups in the molecule, so that the isopropenylphosphonic acid is easy to polymerize with other monomers. The phosphonic acid group-containing polymer has good temperature resistance and salt calcium resistance. The copolymerization reaction between isopropenylphosphonic acid and the common monomer acrylamide is researched, wherein the most important parameter is reactivity ratio, and the method provides guidance and reference for the design and synthesis of the phosphonic acid group-containing polymer. And the polymerization rate between the two is considered, firstly, a research object is subjected to copolymerization reaction under a fixed synthesis condition according to a certain monomer ratio to obtain an early-stage product of the copolymerization reaction, and the conversion rate must be ensured to be less than 10%. Domestic patents on the aspects of the polymerization rate and the extraction of copolymerization reaction products are not reported.

Disclosure of Invention

In view of the above, the present invention provides a method for extracting a copolymerization product of isopropenylphosphonic acid and acrylamide, and the extraction method provided by the present invention has higher accuracy and reliability, and provides more accurate data for the calculation of the late-stage polymerization rate.

The invention provides a method for extracting a copolymerization reaction product of isopropenylphosphonic acid and acrylamide, which comprises the following steps:

mixing isopropenylphosphonic acid and water to prepare an isopropenylphosphonic acid solution, standing, adjusting the pH value of the solution after standing by using an alkali liquor, and mixing the solution after adjusting the pH value with acrylamide to obtain a solution before reaction;

heating the solution before reaction, and mixing the solution with an initiator to initiate reaction;

after the initiation reaction, dripping the obtained reaction solution into an ethanol solution for many times until the ethanol solution generates a turbid phenomenon, and stopping the reaction to obtain a solution after the reaction;

mixing the reacted solution with absolute ethyl alcohol, and then standing to precipitate a polymer;

and (3) soaking and washing the polymer by using absolute ethyl alcohol to obtain a copolymerization reaction product.

In the present invention, the method for preparing isopropenylphosphonic acid (IPPA) preferably comprises:

mixing phosphorous acid and acetic anhydride, and dropwise adding acetone into the obtained mixture to react;

and carrying out reduced pressure distillation on the obtained reaction product to obtain the isopropenylphosphonic acid.

In the present invention, acetone is preferably added dropwise using a constant pressure dropping funnel. In the present invention, the reduced pressure distillation is preferably carried out using a circulating water pump. In the invention, the reduced pressure distillation is preferably stopped after no fraction is distilled at 180 ℃ to obtain the isopropenylphosphonic acid.

In the present invention, the purity of the isopropenylphosphonic acid (IPPA) is preferably 95% or more, and cannot reach 100%, and the purity of IPPA is preferably reflected by the double bond content. In the present invention, it is preferred to accurately calculate and remove the actual mass of isopropenylphosphonic acid as an addition amount to the nearest 0.0001g, based on the theoretical mass of IPPA to be added and its double bond content, said addition amount (actual mass) of isopropenylphosphonic acid being:

MIPPA (actual) ═ MIPPA (theoretical)/IPPA double bond content.

The method for measuring the double bond content of the isopropenylphosphonic acid is not particularly limited, and the double bond content in the isopropenylphosphonic acid can be measured by a method well known to those skilled in the art, for example, a bromination method can be used for measuring the double bond content of the isopropenylphosphonic acid, the principle is that the amount of bromine added to the double bond is measured, the amount of bromine added to the double bond is usually expressed by a bromine number, the bromine number refers to the gram number of bromine used for adding 100g of a substance to be measured, and the purity of the unsaturated compound can be determined by comparing the measured bromine number with a theoretical bromine number. The brominating method is that bromine liquid or bromine-generating substance-brominating reagent is added into the tested sample, the commonly used brominating reagent is bromine-carbon tetrachloride solution, bromine-ethyl alcohol solution and potassium bromide-potassium bromate solution, the former is strong brominating agent and is accompanied with substitution reaction at the same time of bromine addition, especially the unsaturated compound with side chain is more easily substituted, the latter is made into bromine by oxidation-reduction reaction in acid medium, said brominating agent can greatly reduce substitution reaction, bromine is added with double bond, excess bromine makes potassium iodide separate out iodine, then sodium thiosulfate is used to titrate iodine so as to obtain bromine value and purity in the sample. In the present invention, the double bond content in isopropenylphosphonic acid is preferably determined by potassium bromide-potassium bromate titration.

In the invention, the mass concentration of the isopropenylphosphonic acid solution is preferably 30-50%, which is beneficial to the hydrolysis of anhydride.

In the invention, the time for standing the prepared isopropenylphosphonic acid solution is 8-10 hours, and a small amount of anhydride contained in the isopropenylphosphonic acid is completely hydrolyzed and reduced into phosphoric acid.

In the present invention, the alkali solution is preferably a sodium hydroxide solution. In the present invention, the pH is preferably 5.0 to 9.0, more preferably 5.0, 7.0 or 9.0.

In the present invention, the Acrylamide (AM) is preferably analytical grade acrylamide.

In the invention, the molar ratio of the isopropenylphosphonic acid to the acrylamide is preferably (1-2): (1-4), more preferably (1-2): (2-3).

In the present invention, after obtaining the solution before reaction, preferably determining the content of double bonds in the solution before reaction, more preferably determining the content of double bonds in the solution before reaction by using a bromination method, wherein the determination of the content of double bonds in the solution before reaction by using the bromination method is consistent with the determination of the content of double bonds in isopropenylphosphonic acid by using the bromination method described in the above technical scheme, more preferably determining the content of double bonds in the solution before reaction by using a potassium bromide-potassium bromate titration method:

adding water into the solution before reaction, dissolving, adding dilute hydrochloric acid and a potassium bromate-potassium bromide solution, and standing to obtain a mixed solution;

and adding the mixed solution into a potassium iodide solution, then titrating by using a sodium thiosulfate solution, adding a starch indicator when the end point is approached, and taking the titration end point when the solution is colorless.

In the present invention, the amount of the pre-reaction solution used in the determination of the double bond content in the pre-reaction solution is preferably in accordance with the total mass concentration C of the two monomers IPPA and AM_SheetAccurate mass m₁To the nearest 0.0001 g:

m₁＝0.1/C_sheet

In the invention, the molar concentration of the potassium bromate-potassium bromide solution is preferably 0.1 mol/L.

In the invention, the time for placing the solution after adding the dilute hydrochloric acid and the potassium bromate-potassium bromide solution is preferably 15-30 min, and more preferably 20-25 min.

In the invention, the mass concentration of the potassium iodide solution is preferably 35-45%, and more preferably 40%.

In the present invention, the sodium thiosulfate solution is preferably a calibrated sodium thiosulfate standard solution.

In the present invention, it is preferable that the solution before reaction is obtained by further including:

the solution before reaction is dripped into the ethanol solution to observe the state of the ethanol solution.

In the invention, the mass concentration of the ethanol solution is preferably 95-98%, and more preferably 96-97%. In the present invention, the state of the ethanol solution dropped into the ethanol solution before the reaction is preferably a clear state without becoming turbid.

In the invention, the temperature rise is preferably carried out in a constant-temperature water bath, and the temperature rise is preferably 60-70 ℃, and more preferably 65 ℃.

In the present invention, it is preferable that the temperature rise further includes:

introducing nitrogen to remove oxygen, and adding an initiator to initiate reaction.

In the invention, the time for introducing the nitrogen is preferably 25-35 min, and more preferably 30 min.

In the present invention, the initiator is preferably selected from (NH4)₂S₂O₈Or K₂S₂O₈. In the invention, the dosage of the initiator is preferably 0.15-0.25%, more preferably 0.2% of the total mass of the IPPA and AM monomers.

In the present invention, the reaction solution obtained after initiation of the reaction is taken out at intervals and added dropwise to an ethanol solution until turbidity is found in the ethanol solution, and the reaction is stopped. In the present invention, the ethanol solution is the same as the ethanol solution described in the above technical solution, and is not described herein again.

In the present invention, it is preferable to further include, after obtaining the post-reaction solution:

and (3) measuring the content of the double bonds in the solution after the reaction, preferably measuring the content of the double bonds in the solution after the reaction by adopting a bromination method, wherein the method for measuring the content of the double bonds in the solution after the reaction by adopting the bromination method is consistent with the method for measuring the content of the double bonds in the solution before the reaction by adopting the bromination method in the technical scheme, and details are not repeated.

In the present invention, the volume ratio of the solution after the reaction to the absolute ethyl alcohol is preferably 1: (2-3). In the invention, the time for the mixture of the reacted solution and the absolute ethyl alcohol solution to stand is preferably 6-12 hours, more preferably 8-10 hours, and the polymer is separated out or a thin layer of polymer appears at the bottom of the beaker.

In the invention, the immersion cleaning is preferably repeated immersion cleaning, the immersion cleaning frequency is preferably 2-4 times, more preferably 3 times, and the reaction product is extracted to remove unreacted monomers.

In the present invention, after the immersion cleaning, it is preferable to further include:

the double bond content in the washing filtrate after the leaching was measured to judge whether or not the unreacted monomer (raw material) in the polymer was completely leached and removed.

In the invention, the double bond content in the washing filtrate is preferably determined by adopting a bromination method, and the determination of the double bond content in the washing filtrate by adopting the bromination method is consistent with the determination of the double bond content in the solution before the reaction by adopting the bromination method in the technical scheme, and is not repeated herein. In the present invention, if the volume of the titration solution consumed by measuring the double bond content in the washing filtrate is close to the volume of the titration solution consumed by the blank solution, it is indicated that the polymer has been completely washed to remove the unreacted monomer. In the present invention, the amount of the washing filtrate (ethanol filtrate) used in the measurement of the double bond content in the washing filtrate after the leaching is preferably 0.1g to the accuracy of 0.0001 g.

In the present invention, it is preferable to further include, after obtaining the copolymerization reaction product:

the conversion of the copolymerization product was measured.

In the present invention, the conversion rate is preferably calculated according to the change of the double bond content in the solution after the reaction and the double bond content in the solution before the reaction, and if the conversion rate is less than 10%, the copolymerization reaction product after extraction can be further analyzed and detected to calculate the polymerization rate. In the present invention, the conversion of the copolymerization reaction product is:

the conversion rate of the copolymerization reaction product is (double bond content of the solution before reaction-double bond content of the solution after reaction)/double bond content of the solution before reaction.

According to the method provided by the invention, the actual input amount of the IPPA is accurately quantified and the calculation error is reduced by measuring the double bond content of the reaction raw material IPPA; and because a small amount of phosphoric acid anhydride exists in IPPA, the prepared isopropenylphosphonic acid aqueous solution is fully and uniformly stirred in advance, and is placed for a period of time to hydrolyze the anhydride and convert the anhydride into the isopropenylphosphonic acid, so that the test error is reduced; because IPPA-Na in the solution before reaction is in a semitransparent state in absolute ethyl alcohol, if the reaction is ended, the phenomenon that the solution is dripped into the absolute ethyl alcohol after the reaction is in a weak turbid state, which can interfere with the judgment of the time for ending the reaction, so the absolute ethyl alcohol cannot be used when the time for ending the reaction is judged, but in order to ensure that the solution before the reaction is in a semitransparent state in the absolute ethyl alcohol solution, an ethanol aqueous solution with low water content of 95-98% is adopted; the conversion rate is judged by measuring the change of double bond content in the solution before and after the reaction by adopting a bromination method, the conversion rate is convenient and quick, the accuracy rate is higher than that obtained by a weighing method for extracting a reaction product, the operation steps of purifying, drying and weighing for many times are complicated for the conversion rate obtained by the weighing method, and the introduced system error is correspondingly increased, so that the accuracy of the conversion rate is reduced; and judging whether the unreacted monomers in the polymer solution are completely removed by washing according to the condition of measuring the content of double bonds in the ethanol washing solution after the soaking.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other examples, which may be modified or appreciated by those of ordinary skill in the art based on the examples given herein, are intended to be within the scope of the present invention.

An isopropenylphosphonic acid sample was prepared as follows:

mixing 41g of phosphorous acid and 105ml of acetic anhydride, uniformly stirring, dropwise adding 35ml of acetone by using a constant-pressure dropping funnel, continuously stirring and reacting for a period of time, carrying out reduced pressure distillation by using a circulating water pump, and stopping the experiment after no fraction is distilled out at 180 ℃ to obtain the isopropenylphosphonic acid.

Example 1

Two isopropenylphosphonic acid samples (0.1 g, to the nearest 0.0001g) were measured and placed in a clean iodine flask, the double bond content of the samples was measured according to the bromination method (potassium bromide-potassium bromate titration method), the average double bond content was then calculated, and 9.4245g (ippa 9.0240g theoretically required) of a predetermined isopropenylphosphonic acid sample was measured based on the double bond content. IPPA is prepared into 50 percent aqueous solution, stirred and placed for 10 hours, when a small amount of anhydride contained in isopropenylphosphonic acid is completely hydrolyzed and reduced into phosphoric acid, a proper amount of NaOH solution is used for adjusting the pH value to 7.0, and then 21.0314g of analytical grade acrylamide is added, and 120ml of solution before reaction is prepared by fully dissolving. 0.4g (to the nearest 0.0001g) of the pre-reaction solution was measured in a dry iodometric vial according to a total monomer mass concentration of 25% and the double bond content was determined by the bromination method (potassium bromide-potassium bromate titration method). Preparing 97% ethanol water solution, and dripping 1-2 drops of the pre-reaction solution to ensure that the ethanol water solution is clear and does not become turbid.

Placing the solution before reaction in a reaction kettle, heating to 65 ℃, introducing nitrogen for 30min to remove oxygen, adding initiator ammonium peroxide (NH) accounting for 0.2 percent of the total mass of the two monomers₄)₂S₂O₈0.0601g initiated the reaction.

Taking out the reaction solution at intervals after initiating the reaction, sampling the reaction solution for multiple times, dripping the reaction solution into 97% ethanol water solution, stopping the reaction immediately if the reaction is turbid, taking out the reaction solution to obtain a solution after the reaction, measuring 0.4g (accurate to 0.0001g) of the solution after the reaction in a dry iodometric flask, measuring the content of double bonds by adopting a bromination method (a potassium bromide-potassium bromate titration method), slowly pouring the rest solution after the reaction into 250ml of absolute ethanol while stirring, and precipitating a polymer after standing for 10 hours.

Repeatedly washing with anhydrous ethanol, extracting polymer for 3 times, and removing unreacted monomer to obtain polymerization reaction product. Weighing 0.1g (accurate to 0.0001g) of ethanol filtrate after being soaked, measuring the double bond content by a bromination method (potassium bromide-potassium bromate titration method), and determining that the double bond content in the ethanol filtrate is close to a blank solution, which indicates that unreacted monomers contained in the polymer solution are thoroughly washed and removed.

The polymerization product obtained by the extraction was dried in a vacuum oven at 60 ℃, and m (to the accuracy of 0.0001g) was weighed and the conversion was calculated. The dried polymerization product was milled and powdered into a sample bottle for instrumental analysis.

(1) Conversion rate calculated by titration method for double bond content:

solution before reaction: m is 0.4260g, V is 9.38 ml;

the double bond content a is 1/2(33.4-9.38) × 0.1015 × 10^-3/(0.426×25％)＝11.45mmol/g；

Solution after reaction: 0.4460g for m and 10.27ml for V

Double bond content B ═ 1/2(33.4-10.27) x 0.1015 x 10^-3/(0.446×25％)＝10.53mmol/g；

Conversion (double bond content a-double bond content B)/double bond content a (11.45-10.53)/11.45 × 100% ═ 8.03%

(2) Calculating the conversion rate by a gravimetric method:

the conversion rate (mass of polymerization product after drying/total mass of monomer before reaction) is 2.6449/(9.0240+ 21.0314). times.100%

By comparing the two methods described above, the gravimetric method yields higher conversions than the titration method. The reason for the analysis may be: multiple ethanol extraction processes may elute low molecular weight byproduct polymers; drying is not thorough, and moisture is brought into the quality. This may lead to the possibility that if the conversion obtained by gravimetric method is greater than 10%, the product is mistakenly rejected as unsatisfactory.

(3) The titration method judges whether the unreacted monomers are completely removed:

the mass m of the ethanol filtrate is 0.1663g, and V is 32.7ml and is approximately equal to 32.8ml (the blank solution consumes the volume of the titration solution);

from this, it can be shown that the double bond content in the ethanol filtrate is close to that of the blank solution, which indicates that the unreacted monomers contained in the polymer solution were completely removed by washing.

Examples 2 to 7

The polymerization product was obtained by extraction according to the method of example 1, the reaction conditions and parameters being shown in Table 1:

TABLE 1 reaction conditions and parameters for examples 2-7

Note: the average double bond content in the IPPA samples of examples 1-4 was 95.5%; the average double bond content in the IPPA samples of examples 5-6 was 96.2%; the average double bond content in the IPPA sample in example 7 was 96.6%.

As can be seen from table 1 above, in general cases, the conversion rate obtained by the titration method is slightly lower than that calculated by the weighing method, the conversion rate obtained by the weighing method in example 5 is greater than 10%, and the conversion rate obtained by the titration method is less than 10%, and if the conversion rate is calculated by the conventional weighing method, the polymer product obtained by the test is mistakenly considered to be not in compliance with the test requirements. Therefore, the conversion rate obtained by titrating the change of the double bond content is more accurate and reliable, and the calculation of the polymerization rate between the monomers at the later stage is facilitated to provide more accurate data.

As can be seen from the above examples, the present invention provides a method for extracting a copolymerization product of isopropenylphosphonic acid and acrylamide, comprising: mixing isopropenylphosphonic acid and water to prepare an isopropenylphosphonic acid solution, standing, adjusting the pH value of the solution after standing by using an alkali liquor, and mixing the solution after adjusting the pH value with acrylamide to obtain a solution before reaction; heating the solution before reaction, and mixing the solution with an initiator to initiate reaction; after the initiation reaction, dripping the obtained reaction solution into an ethanol solution for many times until the ethanol solution generates a turbid phenomenon, and stopping the reaction to obtain a solution after the reaction; mixing the reacted solution with absolute ethyl alcohol, and then standing to precipitate a polymer; and (3) soaking and washing the polymer by using absolute ethyl alcohol to obtain a copolymerization reaction product. The prepared isopropenylphosphonic acid aqueous solution is placed for a period of time, and the anhydride is hydrolyzed and converted back to isopropenylphosphonic acid, so that the test error can be reduced, and the obtained copolymerization reaction product has higher accuracy and reliability.

While only the preferred embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.