Name: Synthesis of High Purity Nonsymmetric Dialkylphosphinic Acid Extractants (Video) | JoVE Journal
Uploaded: 2017-10-19T12:30:00.000+00:00
Duration: 12 min 6 s
Description: Learn a universal synthetic method for high-purity nonsymmetric dialkylphosphinic acid extractants using sodium hypophosphite. This protocol enables safer, scalable production for hydrometallurgy applications.

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5 minutes

This work was supported by the National Nature Science Foundation of China (21301104), the Fundamental Research Funds for the Central Universities (FRF-TP-16-019A3), and the State Key Laboratory of Chemical Engineering (SKL-ChE-14A04).

1. Synthesis of Mono-(2,3-dimethylbutyl)phosphinic acid 18,19
<ol>
	<li>Reaction
	<ol>
		<li>Weigh 31.80 g sodium hypophosphite hydrate, 16.00 g acetic acid, 8.42 g 2,3-dimethyl-1-butene, 0.73 g di-tert-butylnperoxide (DTBP), and 25.00 g tetrahydrofuran (THF) into a 100 mL Teflon-lined stainless steel autoclave, put a magnetic stirrer into the autoclave, and seal it.</li>
		<li>Put the autoclave in a vertical tube furnace under which is a magnetic stirringapparatus.Start the magnetic stirring apparatus and set the speed at 800 rpm.</li>
		<li>Set the heating program of the temperature controller connected to the autoclave: heat from room temperature to 120 &#176;C during 90 min, maintain at 120 &#176;C for 8 h, then cool down to room temperature naturally. Start the heating program.</li>
	</ol>
	</li>
	<li>Post-treatment
	<ol>
		<li>Transfer the products into a 250 mL one-neck round-bottom flask, wash the Teflon-lining with 50 mL THF, and add it into the same flask to ensure that all the products are transferred.</li>
		<li>Remove the THF and unreacted olefins using a rotary evaporator.</li>
		<li>Transfer the residua into a 250 mL separating funnel, wash the flask with 80 mL ethyl ether and 30 mL deionized water respectively, and add them into the same separating funnel to ensure that all the products are transferred.</li>
		<li>Add 50 mL 4% NaOH solution into the above separating funnel, shake it vigorously, and separate the aqueous phase. Extract the organic phase with 20 mL 4% NaOH solutions for three times (20 mL &#215; 3) to ensure that the aqueous phase exceeds pH 10.</li>
		<li>Combine the aqueous solutions in the above step, and transfer them into a 500 mL separating funnel.</li>
		<li>Add 90 mL of 10% H2SO4 solution and 50 mL of ethyl ether, shake vigorously, and separate the organic phase; then extract the aqueous phase with 30 mL of ethyl ether for three times (30 mL &#215; 3).</li>
		<li>Combine the ethyl ether solutions in step 1.2.6, and transfer them into another 500 mL separating funnel.</li>
		<li>Wash it with 100 mL of saturated NaCl solutions four times (100 mL &#215; 4).</li>
		<li>Add 4 g of anhydrous MgSO4 to remove any soluble water. Filter to remove the solid, and collect the liquid in a clean 250 mL one-neck round-bottom flask.</li>
		<li>Remove the ethyl ether using the rotary evaporator to obtain 17.92 g of the crude product.</li>
	</ol>
	</li>
</ol>
2. Purification of Mono-(2,3-dimethylbutyl)phosphinic Acid
<ol>
	<li>Preparation of amantadine solution
	<ol>
		<li>Dissolve 22.28 g of amantadine hydrochloride in 100 mL of deionized water in a 500 mL beaker.</li>
		<li>Add 100 mL of saturated NaOH solution, and stir for 5 min.</li>
		<li>Add 150 mL of ethyl ether, and stir until the white precipitate generated in step 2.1.2 disappears.</li>
		<li>Transfer the solutions into a 500 mL separating funnel, wash the beaker with ethyl ether for three times (50 mL &#215; 3), and combine them into the same separating funnel.</li>
		<li>Separate the aqueous phase, and wash the organic phase with saturated NaCl solutions five times (100 mL &#215; 5).</li>
		<li>Add 4 g of anhydrous MgSO4 to remove any soluble water. Filter to obtain the amantadine ethyl ether solution.</li>
	</ol>
	</li>
	<li>Preparation of amantadine &#8729; mono-(2,3-dimethylbutyl)phosphinic acid salt
	<ol>
		<li>Add drop-wise the crude mono-(2,3-dimethylbutyl)phosphinic acid product to the amantadine solution. During dropping add 150 mL of ethyl ether to ensure that it can stir properly.</li>
		<li>Wash the one-neck round-bottom flask containing the mono-(2,3-dimethylbutyl)phosphinic acid product with 50 mL of ethyl ether to ensure that all the product is transferred to the amantadine solution. Stir for 30 min, and let it sit overnight.</li>
		<li>Filter under reduced pressure, and wash the filter cake with 200 mL ethyl ether.</li>
	</ol>
	</li>
	<li>Release the mono-(2,3-dimethylbutyl)phosphinic acid
	<ol>
		<li>Transfer the filtered cake into a 500 mL beaker, add 80 mL of 1 M HCl, and stir for 5 min.</li>
		<li>Add 70 mL ethyl acetate, and stir for another 5 min.</li>
		<li>Transfer the solutions into a 250 mL separating funnel and separate the aqueous phase.</li>
		<li>Extract the aqueous phase with 40 mL ethyl acetate again and combine the ethyl acetate solutions.</li>
		<li>Wash the ethyl acetate solution with 30 mL of 1 M HCl twice (30 mL &#215; 2) and saturated NaCl three times (80 mL &#215; 3), sequentially.</li>
		<li>Add 4 g anhydrous MgSO4 to remove any soluble water. Filter and collect the liquid in a 250 mL one-neck round-bottom flask.</li>
		<li>Remove the ethyl acetate using the rotary evaporator, and obtain 12.45 g of the pure mono-(2,3-dimethylbutyl)phosphinic acid (Yield: 82.9%).</li>
	</ol>
	</li>
</ol>
3. Synthesis of (2,3-dimethylbutyl)(2,4,4&#39;-trimethylpentyl)phosphinic Acid
<ol>
	<li>Reaction
	<ol>
		<li>Transfer all of the pure mono-(2,3-dimethylbutyl)phosphinic acid product into a 100 mL Teflon-lined stainless steel autoclave, add 4.95 g of acetic acid, 25.39 g of diisobutylene, 0.30 g of DTBP, put a magnetic stirrer into the autoclave, and seal it.</li>
		<li>Put the autoclave in a vertical tube furnace under which is a magnetic stirring apparatus, and start the magnetic stirring apparatus.</li>
		<li>Set the heating program of the temperature controller: heat from room temperature to 135 &#176;C during 90 min, maintain at 135 &#176;C for 8 h, then cool down to room temperature naturally. Start the heating program.</li>
		<li>When the reaction system cools down to room temperature, add another 0.30 g of DTBP, and restart the heating program.</li>
		<li>Repeat step 3.1.4 once.</li>
	</ol>
	</li>
	<li>Post-treatment
	<ol>
		<li>Dilute the product with 100 mL ethyl ether, and then transfer to a 250 mL separating funnel.</li>
		<li>Wash it with 30 mL of 4% NaOH three times (30 mL &#215; 3) to ensure that aqueous phase exceeds pH 10.</li>
		<li>Add 70 mL of 10% H2SO4 solution to acidify the product.</li>
		<li>Wash it with saturated NaCl solution several times (80 mL each) until the aqueous phase pH equals pH 6-7.</li>
		<li>Add 4 g of anhydrous MgSO4 to remove any soluble water. Filter to remove the solid, and collect the liquid in a clean 250 mL one-neck round-bottom flask.</li>
		<li>Remove the ethyl ether and unreacted olefins using the rotary evaporator to obtain 15.10 g of crude product.</li>
	</ol>
	</li>
</ol>
4. Purification of (2,3-dimethylbutyl)(2,4,4&#39;-trimethylpentyl)phosphinic Acid
<ol>
	<li>Obtain pure co-(2,3-dimethylbutyl)(2,4,4&#39;-trimethylpentyl)phosphinic acid complex
	<ol>
		<li>Dissolve 2.30 g of NaOH in 40 mL deionized water. Add the NaOH solution to the flask containing the crude (2,3-dimethylbutyl)(2,4,4&#39;-trimethylpentyl)phosphinic acid product, and shake it vigorously for 5 min.</li>
		<li>Add 0.5 M CoCl2 solution dropwise while shaking until no more blue precipitate is generated and the solution in the flask is pink.</li>
		<li>Filter and wash the blue precipitate with deionized water until the filter cake is colorless.</li>
		<li>Transfer the filter cake into a 250 mL beaker, add 100 mL of acetone, seal it with preservative film, and then refrigerate it at 4 &#176;C for one night.</li>
		<li>Pulverize the blue precipitate to release any impurities trapped in the bulk.</li>
		<li>Filter and wash it with 100 mL of fresh acetone. Dry the filter cake at room temperature, and then transfer it into a 250 mL separating funnel.</li>
	</ol>
	</li>
	<li>Regenerate the (2,3-dimethylbutyl)(2,4,4&#39;-trimethylpentyl)phosphinic acid
	<ol>
		<li>Add 120 mL ethyl ether and 80 mL 10% H2SO4, and shake vigorously until the blue precipitate disappears.</li>
		<li>Separate the aqueous phase,wash the organic phase sequentially with 30 mL of 10% H2SO4 once and saturated NaCl solutions several times (80 mL each) until the aqueous phase pH equals pH 6-7.</li>
		<li>Add 4 g of anhydrous MgSO4 to remove any soluble water. Filter to remove the solid and collect the liquid in a clean 250 mL one-neck round-bottom flask.</li>
		<li>Remove the ethyl ether using the rotary evaporator, and obtain 11.46 g of the pure product (Yield: 52.8%).</li>
	</ol>
	</li>
</ol>

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<li>Hereijgers, J., et al. <a target="_blank" href="http://www.sciencedirect.com/science/article/pii/S0263876216301095">Separation of Co(II)/Ni(II) with Cyanex 272 using a flat membrane microcontactor: Stripping kinetics study, upscaling and continuous operation.</a> Chem Eng Res Des. 111, 305-315 (2016).</li>
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<li>Li, X. B., et al. <a target="_blank" href="http://www.sciencedirect.com/science/article/pii/S1003632611611990">Thermodynamics and mechanism of vanadium(IV) extraction from sulphate medium with D2EHPA, EHEHPA and CYANEX 272 in kerosene.</a> Trans Nonferrous Met Soc China. 22 (2), 461-466 (2012).</li>
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<li>Baba, A. A., et al. <a target="_blank" href="http://br.123dok.com/document/enq73ky6-extraction-of-copper-from-leach-liquor-of-metallic-component-in-discarded-cell-phone-by-cyanex-272.html">Extraction of copper from leach liquor of metallic component in discarded cell phone by Cyanex (R) 272.</a> JESTEC. 11 (6), 861-871 (2016).</li>
<li>Du, R. B., et al. <a target="_blank" href="http://pubs.rsc.org/en/content/articlelanding/2015/ra/c5ra23483b#!divAbstract">Microwave-assisted synthesis of dialkylphosphinic acids and a structure-reactivity study in rare earth metal extraction.</a> RSC Adv. 5 (126), 104258-104262 (2015).</li>
<li>Du, R. B., et al. alpha, beta-Substituent effect of dialkylphosphinic acids on anthanide extraction. RSC Adv. 6 (61), 56004-56008 (2016).</li>
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<li>Hino, A., Nishihama, S., Hirai, T., Komasawa, I. <a target="_blank" href="https://www.researchgate.net/publication/244736570_Practical_Study_of_Liquid-Liquid_Extraction_Process_for_Separation_of_Rare_Earth_Elements_with_BIS2-_ETHYLHExy1phosphinic_Acid">Practical study of liquid-liquid extraction process for separation of rare earth elements with bis (2-ethylhexyl) phosphinic acid.</a> J Chem Eng Jpn. 30 (6), 1040-1046 (1997).</li>
<li>Ju, Z. J., et al. <a target="_blank" href="http://jglobal.jst.go.jp/en/public/201602250422742738">Synthesis and extraction performance of di-decylphosphinic acid.</a> Chin J Nonferrous Met. 20 (11), 2254-2259 (2010).</li>
<li>Li, L. Y., et al. <a target="_blank" href="http://www.sciencedirect.com/science/article/pii/S1003632610600404">Dialkyl phosphinic acids: Synthesis and applications as extractant for nickel and cobalt separation.</a> Trans Nonferrous Met Soc China. 20, 205-210 (2010).</li>
<li>Wang, J. L., et al. <a target="_blank" href="http://www.sciencedirect.com/science/article/pii/S1002072116600881">Solvent extraction of rare earth ions from nitrate media with new extractant di-(2,3-dimethylbutyl)-phosphinic acid.</a> J Rare Earths. 34 (7), 724-730 (2016).</li>
<li>Hu, W. X. <a target="_blank" href="http://www.cjcu.jlu.edu.cn/EN/abstract/abstract19918.shtml">Synthesis and properties of di-tertiary alkylphosphinic acids.</a> Chem J Chin Univ-Chin. 15 (6), 849-853 (1994).</li>
<li>Wang, J. L., Chen, G., Xu, S. M., Li, L. Y. <a target="_blank" href="http://www.sciencedirect.com/science/article/pii/S0304386X15000687">Synthesis of novel nonsymmetric dialkylphosphinic acid extractants and studies on their extraction-separation performance for heavy rare earths.</a> Hydrometallurgy. 154, 129-136 (2015).</li>
<li>Wang, J. L., Xie, M. Y., Wang, H. J., Xu, S. M. <a target="_blank" href="http://www.sciencedirect.com/science/article/pii/S0304386X16303590">Solvent extraction and separation of heavy rare earths from chloride media using nonsymmetric (2,3-dimethylbutyl)(2,4,4'-trimethylpentyl)phosphinic acid.</a> Hydrometallurgy. 167, 39-47 (2017).</li>
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The authors have nothing to disclose.

The most critical step within the protocol is the mono-alkylphosphinic acid synthesis (Figure 1a). In this reaction, a higher yield and less dialkylphosphinic acid by-product is better. Increasing the molar ratio of NaH2PO2/olefin A will improve the yield and inhibit the generation of dialkylphosphinic acid by-product. However, a large NaH2PO2 dosage will also increase the cost and cause a stirring problem. The preferred molar rati...

Acidic organophosphorus extractants are widely used in the traditional hydrometallurgy field for extraction and separation of rare earth ions1,2, non-ferrous metals (like Co/Ni3,4), rare metals (such as Hf/Zr5, V6,7), actinides8, etc. In recent years, they have also attracted more attention in the fields of secondary resource recycling and high-level liquid waste disposal9. Di-(2-ethylhexyl)phosphoric acid (D2EHPA or P204), 2-ethylhexylphosphoric acid mono-2-ethylhexyl ester (EHEHPA, PC 88A, or P507), and Di-(2,4,4&#39;-trimethylpentyl)-phosphinic acid (Cyanex272), which are representatives of dialkylphosphoric acids, alkylphosphoric acid mono-alkyl esters, and dialkylphosphinic acids respectively, are the most commonly used extractants. Their acidity decreases in the following sequence: P204 &#62; P507 &#62; Cyanex 272. The corresponding extraction ability, extraction capacity, and stripping acidity are all in the order of P204 &#62; P507 &#62; Cyanex 272, and the separation performance is in the opposite order. These three extractants are effective in most cases. However, there are still some conditions where they are not so efficient: in heavy rare earths separation, of which the existing main problems are the poor selectivity and high stripping acidity for P204 and P507, low extraction capacity, and emulsion tendency during extraction for Cyanex 272. Thus, the development of novel extractants has drawn greater attention in recent years.
The class of dialkylphosphinic acid extractants is considered to be one of the most important research aspects to develop new extractants. Recent research showed that the extraction ability of dialkylphosphinic acids depends largely on the structure of the alkyl substituent10,11. It can be a wide range from significantly higher than that of P507 to lower than that of Cyanex 27212. However, the exploration of novel dialkylphosphinic acid extractants is restricted to the commercial olefin structure10,12,13,14,15,16. Though dialkylphosphinic acid extractants can also be synthesized by the Grignard-reaction method, the reaction conditions are rigorous12,17.
NSDAPA, of which the two alkyls are different, opens a door to the exploration of new extractants. It makes the structures of dialkylphosphinic acid more diverse, and its extraction and separation performance can be fine-tuned by modifying both of its alkyl structures. The traditional synthetic method of NSDAPA used PH3 as a phosphorus source, which has many drawbacks like high toxicity, rigorous reaction conditions, and difficult purification. Recently we reported a new method to synthesize NSDAPA using sodium hypophosphite as a phosphorus source (see Figure 1) and successfully synthesized three NSDAPAs18. This detailed protocol can help new practitioners repeat the experiments and master the synthetic method of NSDAPA extractants. We take (2,3-dimethylbutyl)(2,4,4&#39;-trimethylpentyl)phosphinic acid as an example. The names and structures of olefin A, the mono-alkylphosphinic acid intermediate, olefin B, and the corresponding NSDAPA are shown in Table 1.

<table><tbody><tr><td>2,3-dimethyl-1-butene</td><td>Adamas Reagent Co., Ltd.</td><td></td><td>Molecular formula: C&lt;span class=&quot;font8&quot;&gt;&lt;sub&gt;6&lt;/sub&gt;&lt;/span&gt;&lt;span class=&quot;font7&quot;&gt;H&lt;/span&gt;&lt;span class=&quot;font8&quot;&gt;&lt;sub&gt;12&lt;/sub&gt;&lt;/span&gt;&lt;span class=&quot;font7&quot;&gt;, purity &amp;ge;99%&lt;/span&gt;</td></tr><tr><td>diisobutylene</td><td>Shanghai&amp;nbsp;Aladdin&amp;nbsp;Bio-Chem&amp;nbsp;Technology&amp;nbsp;Co.,&amp;nbsp;LTD</td><td></td><td>Molecular formula: C&lt;span class=&quot;font8&quot;&gt;&lt;sub&gt;8&lt;/sub&gt;&lt;/span&gt;&lt;span class=&quot;font7&quot;&gt;H&lt;/span&gt;&lt;span class=&quot;font8&quot;&gt;&lt;sub&gt;16&lt;/sub&gt;&lt;/span&gt;&lt;span class=&quot;font7&quot;&gt;, purity 97%&lt;/span&gt;</td></tr><tr><td>acetic acid</td><td>Sinopharm Chemical Reagent Co., Ltd.</td><td></td><td>Molecular formula: C&lt;span class=&quot;font8&quot;&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;/span&gt;&lt;span class=&quot;font7&quot;&gt;H&lt;/span&gt;&lt;span class=&quot;font8&quot;&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;/span&gt;&lt;span class=&quot;font7&quot;&gt;O&lt;/span&gt;&lt;span class=&quot;font8&quot;&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;/span&gt;&lt;span class=&quot;font7&quot;&gt;, purity &amp;ge;99.5%&lt;/span&gt;</td></tr><tr><td>di-&lt;span class=&quot;font9&quot;&gt;tert&lt;/span&gt;&lt;span class=&quot;font7&quot;&gt;-butylnperoxide&lt;/span&gt;</td><td>Sinopharm Chemical Reagent Co., Ltd.</td><td></td><td>Molecular formula: C&lt;span class=&quot;font8&quot;&gt;&lt;sub&gt;8&lt;/sub&gt;&lt;/span&gt;&lt;span class=&quot;font7&quot;&gt;H&lt;/span&gt;&lt;span class=&quot;font8&quot;&gt;&lt;sub&gt;18&lt;/sub&gt;&lt;/span&gt;&lt;span class=&quot;font7&quot;&gt;O&lt;/span&gt;&lt;span class=&quot;font8&quot;&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;/span&gt;&lt;span class=&quot;font7&quot;&gt;, purity &amp;ge;97.0%&lt;/span&gt;</td></tr><tr><td>tetrahydrofuran</td><td>Beijing Chemical Works</td><td></td><td>Molecular formula: C&lt;span class=&quot;font8&quot;&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;/span&gt;&lt;span class=&quot;font7&quot;&gt;H&lt;/span&gt;&lt;span class=&quot;font8&quot;&gt;&lt;sub&gt;8&lt;/sub&gt;&lt;/span&gt;&lt;span class=&quot;font7&quot;&gt;O, purity A.R.&lt;/span&gt;</td></tr><tr><td>ethyl ether</td><td>Sinopharm Chemical Reagent Co., Ltd.</td><td></td><td>Molecular formula: C&lt;span class=&quot;font8&quot;&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;/span&gt;&lt;span class=&quot;font7&quot;&gt;H&lt;/span&gt;&lt;span class=&quot;font8&quot;&gt;&lt;sub&gt;10&lt;/sub&gt;&lt;/span&gt;&lt;span class=&quot;font7&quot;&gt;O, purity &amp;ge;99.7%&lt;/span&gt;</td></tr><tr><td>ethyl acetate</td><td>Xilong Chemical Co., Ltd.</td><td></td><td>Molecular formula: C&lt;span class=&quot;font8&quot;&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;/span&gt;&lt;span class=&quot;font7&quot;&gt;H&lt;/span&gt;&lt;span class=&quot;font8&quot;&gt;&lt;sub&gt;8&lt;/sub&gt;&lt;/span&gt;&lt;span class=&quot;font7&quot;&gt;O&lt;/span&gt;&lt;span class=&quot;font8&quot;&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;/span&gt;&lt;span class=&quot;font7&quot;&gt;, purity &amp;ge;99.5%&lt;/span&gt;</td></tr><tr><td>acetone</td><td>Beijing Chemical Works</td><td></td><td>Molecular formula: C&lt;span class=&quot;font8&quot;&gt;&lt;sub&gt;3&lt;/sub&gt;&lt;/span&gt;&lt;span class=&quot;font7&quot;&gt;H&lt;/span&gt;&lt;span class=&quot;font8&quot;&gt;&lt;sub&gt;6&lt;/sub&gt;&lt;/span&gt;&lt;span class=&quot;font7&quot;&gt;O, purity &amp;ge;99.5%&lt;/span&gt;</td></tr><tr><td>sodium hydroxide</td><td>Xilong Chemical Co., Ltd.</td><td></td><td>Molecular formula: NaOH, purity &amp;ge;96.0%</td></tr><tr><td>concentrated sulfuric acid</td><td>Sinopharm Chemical Reagent Co., Ltd.</td><td></td><td>Molecular formula: H&lt;span class=&quot;font8&quot;&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;/span&gt;&lt;span class=&quot;font7&quot;&gt;SO&lt;/span&gt;&lt;span class=&quot;font8&quot;&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;/span&gt;&lt;span class=&quot;font7&quot;&gt;, purity 95-98%&lt;/span&gt;</td></tr><tr><td>hydrochloric acid</td><td>Beijing Chemical Works</td><td></td><td>Molecular formula: HCl, purity 36-38%</td></tr><tr><td>sodium chloride</td><td>Sinopharm Chemical Reagent Co., Ltd.</td><td></td><td>Molecular formula: NaCl, purity &amp;ge;99.5%</td></tr><tr><td>anhydrous magnesium sulfate</td><td>Tianjin Jinke Institute of Fine Chemical Industry</td><td></td><td>Molecular formula: MgSO&lt;span class=&quot;font8&quot;&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;/span&gt;&lt;span class=&quot;font7&quot;&gt;, purity &amp;ge;99.0%&lt;/span&gt;</td></tr></tbody></table>

synthesis of high purity nonsymmetric dialkylphosphinic acid extractants

Synthesis of High Purity Nonsymmetric Dialkylphosphinic Acid Extractants

We present the synthesis of (2,3-dimethylbutyl)(2,4,4&#39;-trimethylpentyl)phosphinic acid as an example to demonstrate a method for the synthesis of high purity nonsymmetric dialkylphosphinic acid extractants. Low toxic sodium hypophosphite was chosen as the phosphorus source to react with olefin A (2,3-dimethyl-1-butene) to generate a monoalkylphosphinic acid intermediate. Amantadine was adopted to remove the dialkylphosphinic acid byproduct, as only the monoalkylphosphinic acid can react with amantadine to form an amantadine&#8729;mono-alkylphosphinic acid salt, while the dialkylphosphinic acid cannot react with amantadine due to its large steric hindrance. The purified monoalkylphosphinic acid was then reacted with olefin B (diisobutylene) to yield nonsymmetric dialkylphosphinic acid (NSDAPA). The unreacted monoalkylphosphinic acid can be easily removed by a simple base-acid post-treatment and other organic impurities can be separated out through the precipitation of the cobalt salt. The structure of the (2,3-dimethylbutyl)(2,4,4&#39;-trimethylpentyl)phosphinic acid was confirmed by 31P NMR, 1H NMR, ESI-MS, and FT-IR. The purity was determined by a potentiometric titration method, and the results indicate that the purity can exceed 96%.

31P NMR spectra were collected for the mono-(2,3-dimethylbutyl)phosphinic acid before and after purification by the amantadine method (Figure 1a-b). 31P NMR spectra, 1H NMR spectra, MS spectra, and FT-IR spectra were collected for (2,3-dimethylbutyl)(2,4,4'-trimethylpentyl)phosphinic acid (see Figure 3, Figure 4, Figure 5...

A protocol for the synthesis of high purity nonsymmetric dialkylphosphinic acid extractants is presented, taking (2,3-dimethylbutyl)(2,4,4&#39;-trimethylpentyl)phosphinic acid as an example.

We present the synthesis of (2,3-dimethylbutyl)(2,4,4&#39;-trimethylpentyl)phosphinic acid as an example to demonstrate a method for the synthesis of high ...

The overall goal of this protocol, is to introduce a universal synthetic method for nonsymmetric dialkylphosphinic acid extractants to a free radical addition reaction using sodium hypophosphite as a phosphorus source. The method can for a potential in the hydrometallurgy to develop a new dialkylphosphinic acid extractants. And novel potential extraction and separation with class of extractants.Compared to the traditional method, which use phosphate as a phosphorus source, this method had the advantages of low toxicity, reaction conditions, easy purification, and potential for larger-scale production. The video takes two, three-dimethylbutyl-two, four, four-trimethylpentylphosphinic acid as an example, to demonstrate the synthesis of high-purity NSDAPA extractants. First, sodium hypophosphite reacted with two-three dimethyl-one-butene, mono-DMBPA.Amantadine was adopted to remove the byproduct di-DMBPA, since only the mono-DMBPA can react with amantadine to form an amantadine mono-DMBPA salt, while the di-DMBPA cannot due to its large steric hindrance. The purified mono-DMBPA was then reacted with di-isobutylene to yield two, three-dimethylbutyl-two, four, four-trimethylpentylphosphinic acid. The unreacted mono-DMBPA can be easily removed by a simple base-acid post treatment, and other organic impurities can be separated out through the precipitation of the cobalt salt.First, weigh the appropriate reagents into a 100 milliliter teflon-lined stainless steel autoclave. Place a magnetic stirrer into the autoclave and seal it. Place the autoclave in a vertical tube furnace placed on a magnetic stirring apparatus.Start the magnetic stirring apparatus, and set the speed to 800 RPM. Then, start the heating program of the temperature controller connected to the autoclave. After the reaction is complete, transfer the mixture containing the product to a 250 milliliter one neck round bottom flask.Remove the solvent and unreacted oliphants using a rotary evaporator. Following this, transfer the residues to a 250 milliliter separating funnel. Add 50 milliliters of four percent sodium hydroxide solution to the separating funnel, and shake vigorously.After the phases have separated, transfer the bottom aqueous phase into a 500 milliliter separating funnel. Wash the organic phase three times with 20 milliliters of four percent sodium hydroxide solution to ensure that the aqueous phase exceeds pH 10. Then transfer the aqueous phases into the 500 milliliter separating funnel containing the first aqueous phase.Add 90 milliliters of 10%sulfuric acid solution and 50 milliliters of ethyl ether to the separating funnel containing the combined aqueous phases, and shake vigorously. After the phases have separated, transfer the top organic phase into another 500 milliliter separating funnel. Extract the aqueous phase three times with 30 milliliters of ethyl ether.Then transfer the organic phase into the 500 milliliter separating funnel containing the first organic phase. Wash the combined ethyl ether solution four times with 100 milliliters of saturated sodium chloride solution. After transferring the ethyl ether solution to a round bottom flask, add four grams of anhydrous magnesium sulfate to remove any soluble water.Filter it to remove the solid, and collect the liquid in a clean 250 milliliter one neck round bottom flask. Then remove the ethyl ether using the rotary evaporator to obtain the crude product. Add the crude product dropwise to a previously prepared amantadine solution.After allowing the solution to sit overnight, filter it under reduced pressure. Then wash the filter cake with 200 milliliters of ethyl ether. Transfer the filter cake to a 500 milliliter beaker.Add 80 milliliters of one molar hydrochloric acid, and stir the mixture for five minutes. Then add 70 milliliters of ethyl acetate, and stir the mixture for another five minutes. Now add the mixture to a 250 milliliter separating funnel, and transfer the bottom aqueous phase into a 250 milliliter separating funnel.After extracting the aqueous phase with ethyl acetate, wash the ethyl acetate solution twice with 30 milliliters of one molar hydrochloric acid and three times with 80 milliliters of saturated sodium chloride. After transferring the ethyl acetate solution to a round bottom flask, add four grams of anhydrous magnesium sulfate to remove any soluble water. Filter to remove the solid, and collect the liquid in a clean 250 milliliter one neck round bottom flask.Then remove the ethyl acetate using a rotary evaporator to obtain the pure product. Transfer the purified product to a 100 milliliter teflon-lined stainless steel autoclave. Add the appropriate reagents and a magnetic stirrer to the autoclave, and seal it.Place the autoclave in a vertical tube furnace placed on a magnetic stirring apparatus. Start the magnetic stirring apparatus and set the speed to 800 RPM. Start the heating program of the temperature controller connected to the autoclave.When the reaction system cools down to room temperature, add another 0.3 grams of DTBP to the autoclave and restart the heating program. After the reaction is complete, dilute the product with 100 milliliters of ethyl ether, and transfer the solution to a 250 milliliter separating funnel. Wash the ethyl ether solution three times with 30 milliliters of four percent sodium hydroxide solution to ensure that the aqueous phase exceeds pH 10.After removing the bottom aqueous phase, add 70 milliliters of 10%sulfuric acid solution to acidify the product. Wash the acidified ethyl ether solution several times with 80 milliliters of saturated sodium chloride solution until the aqueous phase pH is six to seven. After transferring the ethyl ether solution to a round bottom flask, add four grams of anhydrous magnesium sulfate to remove any soluble water.Filter to remove the solid, and collect the liquid in a clean 250 milliliter one neck round bottom flask. Then remove the ethyl ether and unreacted oliphants using the rotary evaporator to obtain the crude product. Dissolve 2.3 grams of sodium hydroxide in 40 milliliters of deionized water.Add the previously prepared sodium hydroxide solution to the flask containing the crude product, and shake vigorously for five minutes. Following this, add 0.5 molar cobalt chloride solution dropwise while shaking until no more blue precipitate is generated and the solution is pink. Filter the pink solution, and wash the blue precipitate with deionized water until the filtrate is colorless.Then transfer the filter cake back to the flask, and add 100 milliliters of acetone. On the following day, pulverize the blue filter cake using a stainless steel spoon to release any impurities trapped in the bulk. Filter the solid and wash it with 100 milliliters of acetone.After drying the filter cake at room temperature, add 120 milliliters of ethyl ether and 80 milliliters of 10%sulfuric acid solution to the filter cake. Transfer the resulting solution into a 250 milliliter separating funnel, and shake vigorously until the blue precipitate disappears. After removing the bottom aqueous phase, wash the ethyl ether solution several times with 30 milliliters of 10%sulfuric acid solution until the aqueous phase is colorless.Then wash with 80 milliliters of saturated sodium chloride solution until the aqueous phase pH is six to seven. After transferring the ethyl ether solution to a round bottom flask, add four grams of anhydrous magnesium sulfate to remove any soluble water. Filter to remove the solid, and collect the liquid in a clean 250-milliliter one neck round bottom flask.Finally, remove the ethyl ether using the rotary evaporator to obtain the pure product. Phosphorus NMR spectra were collected for the intermediate monoalkylphosphinic acid before and after purification by the amantadine method. During the monoalkylphosphinic acid synthesis, it is difficult to avoid the generation of the dialkylphosphinic acid byproduct, which is the reason for the peak at 62.507 PPM in the spectra.Phosphorus NMR spectra, proton NMR spectra, MS spectra, and FTIR spectra, were collected for the acid product after purification by the cobalt salt precipitation method. Potentiometric titration curves of the acid product indicate that the purity of the product can exceed 96%High-purity nonsymmetric dialkylphosphinic acid can be obtained through this method, which allows exploration of new extractants. This class of extractants can be used to aid the extraction and the separation of rare earth irons, nonferrous metals, rare metals, et cetera.The separation and extraction performance can be fine-tuned by modifying the alkyl chains.

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Learn a universal synthetic method for high-purity nonsymmetric dialkylphosphinic acid extractants using sodium hypophosphite. This protocol enables safer, scalable production for hydrometallurgy applications.

Synthesis of High Purity Nonsymmetric Dialkylphosphinic Acid Extractants

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