- Open Access
A novel Brönsted–Lewis acidic heteropoly organic–inorganic salt: preparation and catalysis for rosin dimerization
© Yuan et al. 2016
- Received: 17 November 2015
- Accepted: 4 April 2016
- Published: 14 April 2016
A novel Brönsted–Lewis acidic heteropoly organic–inorganic salt has been prepared via the replacement of protons in neat phosphotungstic acid with both organic and metal cations. This hybrid catalyst, Sm0.33[TEAPS]2PW12O40, exhibited satisfactory performance in the dimerization of rosin to prepare polymerized rosin Under optimum conditions (15.0 g rosin and 5.0 g Sm0.33[TEAPS]2PW12O40 catalyst in 18.0 mL toluene at 90 °C for 10 h), a polymerized rosin product with a softening point of 120.1 °C was obtained. In addition, the Sm0.33[TEAPS]2PW12O40 catalyst maintains excellent catalytic performance over five recycles.
- Ionic Liquid
- Organic Cation
- Lewis Acid Site
- Resin Acid
- Softening Point
Polymerized rosin has a higher softening point, lighter color, and better stability than rosin, and is harder to oxidize. It is a key ingredient in oil paints, printing ink, adhesives, perfume, and more (Cheng et al. 1996; Chen 1992). The industrial preparation of polymerized rosin, employing aqueous mineral acids such as H2SO4 or ZnCl2/HCl, suffers from various shortcomings, including corrosion, pollution, and difficult recovery. Some environmentally friendly catalysts, such as solid superacids (Luo and Wu 1999; Gao et al. 2007), have been used to realize the clean polymerization of rosin. However, despite their superior separation, solid superacids exhibit insufficient recycling performance due to their uneven and vulnerable active components.
For the past few years, types of heteropoly organic salt catalytic materials have called attention for their potential water tolerance, acidity and self-separation performance (Leng et al. 2009a, b, 2012; Li et al. 2011, 2014; Shimizu et al. 2009; Sun et al. 2012; Zhou et al. 2014). It has been found that heteropoly anions with high charge numbers in these materials lead to higher melting points than conventional ionic liquids (Yuan et al. 2014). Furthermore, based on the high charge numbers of heteropoly anions, sulfated organic cations with Brönsted acidity and metal cations with Lewis acidity can act together as counterions to heteropoly anions, establishing novel Brönsted–Lewis acidic heteropoly organic–inorganic salts (Yu ST 2013). Herein, we report a heteropoly organic–inorganic catalyst, Sm0.33[TEAPS]2PW12O40, with Brönsted–Lewis acidity, which has different performances for melting point, solubility and acidity with both heteropoly compounds and ionic liquids. Moreover, the dimerization of rosin catalyzed by Sm0.33[TEAPS]2PW12O40 as a solid acid has been carried out to achieve an environmentally friendly process for polymerized rosin.
Materials and methods
Analytical grade H3PW12O40 was dried at 180 °C. All other chemicals were of analytical grade and used without further purification. The 1H-NMR spectra of the catalyst and intermediates were recorded with a 500 MHz Bruker spectrometer in D2O. FT-IR spectra for catalyst samples (the Py-IR sample was mixed with pyridine (2:1, v/v) for 24 h prior to measurement) on KBr discs were recorded on a Nicolet iS10 FT-IR instrument. Melting points were measured using a conventional method on an X-4 type micro melting point apparatus. TG analysis was performed with a NETZSCH-TG 209 F1 Libra instruments in dry N2 at a heating rate of 20 °C/min from 30 to 800 °C.
The acidity of the prepared catalysts was determined by potentiometric titration (Shi and Pan 2008; Vazquez et al. 2000). A mixture containing the sample (0.5 g) and acetonitrile (30 mL) was mixed at the stable potential before being titrated with n-C4H9NH2 solution (0.05 mol/L in acetonitrile). The initial and jump potential values were measured by a pH meter to identify the acid strength and total acid amount in catalyst samples.
Contrastive catalyst, [TEAPS]3PW12O40 and H2[TEAPS]PW12O40, were prepared according to the literature (Leng et al. 2009b). Analogously, equimolar triethylamine and 1,3-propanesultone (0.10 mol) were dissolved in 80 mL ethyl acetate and stirred at 50 °C for 24 h under nitrogen atmosphere. The obtained white precipitate, 3-(triethylammonio)propane sulfonate, was filtered, washed with ethyl acetate and dried at 100 °C for 6 h. Next, a solution of intermediate 3-(triethylammonio)propane sulfonate (0.008 mol) and Sm(NO3)3·6H2O (0.0013 mol) in water was dropped into another aqueous solution of H3PW12O40 (0.004 mol). The mixture was stirred at room temperature for 24 h, distilled to remove water, and washed with ethyl acetate. Finally, the obtained Sm0.33[TEAPS]2PW12O40 solid was dried in a vacuum at 80 °C for 6 h (Leng et al. 2009b; Ramesh Kumar et al. 2012). Catalyst Sm0.66[TEAPS]PW12O40 was prepared by a similar method to that outlined above, using alternative materials proportion.
Dimerization of rosin
In batch experiments, heteropoly organic–inorganic salt catalyst (5.0 g) was added to a round-bottomed flask contained toluene (18.0 mL) and dissolved rosin (15.0 g). The resulting reaction mixture was stirred vigorously at 90 °C for 10 h and then cooled to room temperature. The solid catalyst was removed by centrifugation and directly reused without further treatment. The reaction solution, from which the toluene solvent had been separated, was distilled under low pressure (2 mmHg) at 260–270 °C (system temperature) and 180–210 °C (steam outlet temperature) for 30 min to remove low softening point materials, such as rosinol and some unpolymerized rosin, and obtain the polymerized rosin product. The ring and ball softening points of the products were determined by SYD-2806G numerical control asphalt softening point tester.
Characterization of hybrid catalysts
Properties of hybrid catalysts
Melting point (°C)
Solubility (25 °C)
Acid strength (mV)
Total acid amount (mmol/g)
Faint yellow/white crystal
Catalytic performances of Sm0.33[TEAPS]2PW12O40 in the dimerization of rosin
Catalytic dimerization performance of hybrid catalysts
Softening point (°C)
Acid value (mg/g)
Catalytic reusability of Sm0.33[TEAPS]2PW12O40 for the rosin dimerization
Catalyst recycle times
Softening point (°C)
Acid value (mg/g)
A novel heteropoly organic–inorganic salt with Brönsted–Lewis double acidity, Sm0.33[TEAPS]2PW12O40, was prepared via the replacement of protons in neat phosphotungstic acid with both organic cations containing sulfonic acid groups and metal Sm3+ cations. As a solid acid catalyst, this environmentally benign Brönsted–Lewis double acidic hybrid enables an effective catalytic performance in the dimerization of rosin to afford polymerized rosin products with a softening point above 115 °C. Moreover, the catalyst also exhibited reasonable reuseability, demonstrated by a five-run recycling test.
BY made the study desighs, did the data analysis, and drafted the manuscript. CXX, FLY, STY and JLZ participated in the design and coordination of the study and helped to draft the manuscript, XYY and XBC participated in the acquisition of data. All authors read and approved the final manuscript.
The financial support provided for this research by the “National Natural Science Foundation of China” (31470595, 31270615 and 21106074), “Opening Foundation of Beijing National Laboratory for Molecular Sciences” (20140141) and “The Taishan Scholar Program of Shandong” is gratefully acknowledged.
The authors declare that they have no competing interests.
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- Chen GF (1992) Development in the field of rosin chemistry and its implications in coatings. Prog Org Coat 20:139–167View ArticleGoogle Scholar
- Cheng Z, Zhang JK, Jin Q (1996) Natural resin production technology. China Forestry Publishing House, Beijing, pp 20–25Google Scholar
- Fang D, Cheng J, Gong K, Shi QR, Liu ZL (2008) Synthesis of coumarins via bechmann reaction in water catalyzed by acyclic acidic ionic liquids. Catal Lett 121:255–259View ArticleGoogle Scholar
- Gao HC, Yu ST, Liu FS, Xie CX, Li L (2007) Studies on synthesis of polymerized rosin catalyzed by mesoporous molecular sieves under supercritical carbon dioxide conditions. Chem Ind For Prod 27:72–76Google Scholar
- Hoang P, Samira Z, Michel B (2005) An improved greener esterification of fatty alcohols using a renewable acid-ionic liquid cuple as catalyst-solvent. Synth Commun 34:2085–2093Google Scholar
- Leng Y, Wang J, Zhu DR, Ren XQ, Ge HQ, Shen L (2009a) Heteropolyanion-based ionic liquids: reaction-induced self-separation catalysts for esterification. Angew Chem Int Ed 48:168–171View ArticleGoogle Scholar
- Leng Y, Wang J, Zhu DR, Wu YJ, Zhao PP (2009b) Sulfonated organic heteropolyacid salts: recyclable green solid catalysts for esterifications. J Mol Catal A 313:1–6View ArticleGoogle Scholar
- Leng Y, Jiang PP, Wang J (2012) A novel Brønsted acidic heteropolyanion-based polymeric hybrid catalyst for esterification. Catal Commun 25:41–44View ArticleGoogle Scholar
- Li KX, Chen L, Wang HL, Lin WB, Yang ZC (2011) Heteropolyacid salts as self-separation and recyclable catalysts for transesterification of trimethylolpropane. Appl Catal A 392:233–237View ArticleGoogle Scholar
- Li YY, Wu XF, Wu QY, Ding H, Yan WF (2014) Ammonium- and phosphonium-based temperature control-type polyoxometalate ionic liquids. Dalton Trans 43:13591–13595View ArticleGoogle Scholar
- Liu SW, Yu ST, Liu FS, Xie CX, Mao CM (2005) Studies on synthesis of polymerized rosin catalyzed by sulfuric acid-ionic liquid. Chem Ind For Prod 25:65Google Scholar
- Liu SW, Xie CX, Yu ST, Liu FS (2008) Dimerization of rosin using Brønsted–Lewis acidic ionic liquid as catalyst. Catal Commun 9:2030–2034View ArticleGoogle Scholar
- Liu SW, Xie CX, Yu ST, Xian M, Liu FS (2009) Brønsted–Lewis acidic ionic liquid: its synthesis and use as the catalyst in rosin dimerization. Chin J Catal 30:401–406View ArticleGoogle Scholar
- Luo JY, Wu ZM (1999) Studies on synthesis of polymeric rosin catalyzed by solid superacids. Chem Ind For Prod 19:57–62Google Scholar
- Paun C, Stere C, Coman SM, Parvulescu VI, Goodrich P, Hardacre C (2008) Acylation of sulfonamines using silica grafted 1-butyl-3-(3-triethoxysilylpropyl)-4,5-dihydroimidazolium ionic liquids as catalysts. Catal Today 131:98–103View ArticleGoogle Scholar
- Ramesh Kumar Ch, Jagadeeswaraiah K, Sai Prasad PS, Lingaiah N (2012) Samarium-exchanged heteropoly tungstate: an efficient solid acid catalyst for the synthesis of glycerol carbonate from glycerol and benzylation of anisole. ChemCatChem 4:1360–1367View ArticleGoogle Scholar
- Shi J, Pan G (2008) Preparation of 1-butyl-3-methylimidazolium dodecatungstophosphate and its catalytic performance for esterification of ethanol and acetic acid. Chin J Catal 29:629–632Google Scholar
- Shimizu K, Furukawa H, Kobayashi N, Itaya Y, Satsuma A (2009) Effects of Brønsted and Lewis acidities on activity and selectivity of heteropolyacid-based catalysts for hydrolysis of cellobiose and cellulose. Green Chem 11:1627–1632View ArticleGoogle Scholar
- Sun Z, Cheng MX, Li HC, Shi T, Yuan MJ, Wang XH, Jiang ZJ (2012) One-pot depolymerization of cellulose into glucose and levulinic acid by heteropolyacid ionic liquid catalysis. RSC Adv 2:9058–9065View ArticleGoogle Scholar
- Vazquez P, Pizzio L, Caceres C, Blanco M, Thomas H, Alesso E, Finkielsztein L, Lantano B, Moltrasio G, Aguirre J (2000) Silica-supported heteropolyacids as catalysts in alcohol dehydration reactions. J Mol Catal A 161:223–232View ArticleGoogle Scholar
- Yuan B, Xie CX, Yu FL, Zhao WS, Liu ZQ, Yu ST, A sort of heteropoly ionic liquid catalysts with both Brönsted and Lewis acidity. ZL 201310299872.8 CNGoogle Scholar
- Yuan B, Zhao WS, Yu FL, Xie CX (2014) Clean benzylation of anisole with benzyl alcohol over recyclable partially sulfonated imidazole-exchanged heteropoly phosphotungstates. Catal Commun 57:89–93View ArticleGoogle Scholar
- Zhou Y, Chen GJ, Long ZY, Wang J (2014) Recent advances in polyoxometalate-based heterogeneous catalytic materials for liquid-phase organic transformations. RSC Adv 4:42092–42113View ArticleGoogle Scholar