Carbonation Reaction of Epoxidized Linseed Oil: Comparative Performance of TBABr and TBAI as Catalysts

Nieto-Alarcón, Juan F.; González, David A.; Vigueras-Santiago, Enrique; Hernández-López, Susana

doi:https://doi.org/10.1155/2023/3169663

Journal of Chemistry

On this page

Abstract Introduction Materials and Methods Results and Discussion Discussion Conclusions Data Availability Conflicts of Interest Acknowledgments Supplementary Materials References Copyright Related Articles

Research Article | Open Access

Volume 2023 | Article ID 3169663 | https://doi.org/10.1155/2023/3169663

Carbonation Reaction of Epoxidized Linseed Oil: Comparative Performance of TBABr and TBAI as Catalysts

Juan F. Nieto-Alarcón,¹David A. González,¹Enrique Vigueras-Santiago,¹and Susana Hernández-López¹

Academic Editor: Zhong-Wen Liu

Received09 Dec 2022

Revised31 Mar 2023

Accepted25 May 2023

Published28 Jun 2023

Abstract

Cyclic carbonates are considered to be green nontoxic intermediates with important applications in polymer synthesis and fuel additives and as polar solvents with high boiling points. The carbonation of epoxidized vegetable oils is a very important step in the synthesis of nonisocyanate polyurethane. This reaction is usually performed with carbon dioxide in the presence of an ionic liquid that acts both as solvent and catalyst, with the most studied catalyst being tetra-n-butylammonium bromide (TBABr). Most of the works have reported high yields and good carbonation conversions. In addition, studies with tetra-n-butylammonium iodide (TBAI) as the catalyst have shown it to improve the conversion in the carbonation of short-chain epoxides but not of fatty acid esters and in some vegetable oils. In the current study, the carbonation of epoxidized linseed oil (ELO) (5.8 epoxide group per molecule) was carried out in an autoclave-type reactor under a carbon dioxide atmosphere (60 psi) and the variables evaluated were the reaction temperature (110°C and 140°C), catalyst load (2.5 mol% and 5.0 mol%), reaction time (24 h and 48 h), and catalyst type (TBABr and TBAI). The results of the study showed that the temperature was the most important factor affecting the reaction. However, halohydrins and ketones were also found to have formed from side reactions promoted mainly by TBAI at 140°C and were identified and quantified using FTIR-HATR, ¹H-NMR, and ¹³C-NMR spectroscopy techniques. The best results namely, 100% conversion, 87.9% carbonation, and 87.9% selectivity, with relatively few side reactions (1.7% halohydrins and 1.7% ketones)were: 2.5 mol% of TBABr, a temperature of 110°C, and a reaction time of 24 h. The results also showed that using TBAI as the catalyst increased the frequency of undesirable side reactions during the carbonation of ELO.

1. Introduction

During the last two decades, there has been an increasing interest in using vegetable oils as raw materials in the synthesis of biopolymers as substitutes for materials derived from fossil fuels. Since vegetable oils are biodegradable, they could endow materials synthesized from them with biodegradability as well and could reduce the negative effects on the environment caused by synthetic petroleum polymers pollution. Vegetable oils are easy to modify due to the presence of carbon double bonds in their structure. Among the most common modifications is the oxidation of the double bonds to epoxy groups, which could be used as intermediates in the synthesis of 5-membered cyclic carbonates (CC5s). Cyclic carbonates are of a great interest because they display high polarity, excellent solubility in organic solvents, a high boiling points, low toxicity, and low volatility [1, 2]. Such features give cyclic carbonates a wide variety of applications, such as serving as green solvents and electrolytes and being used in enzyme immobilization and polymer synthesis [3]. In particular, the aminolysis reaction between CC5s and diamines [2, 4, 5] is employed in the synthesis of nonisocyanate polyurethanes (NIPUs) [2, 4, 6–11] as a green alternative to the traditional method of producing polyurethanes that uses hazardous diisocyanates.

While the potential applications of CC5s [3] have garnered considerable attention, the synthesis of CC5 functional groups [5, 12–15] still shows drawbacks. However, particular interest is the addition of CO₂ to epoxy groups due to the contribution of this reaction for reducing the atmospheric CO₂ concentration, due to the ability to have this reaction catalyzed by tetrabutylammonium bromide (TBABr), which is one of the simplest, most accessible, active, effective, and low-toxicity quaternary ammonium salt. Use of this catalyst has been shown to allow very good carbonation reactions to be carried out on short-chain molecules under mild conditions [12, 16, 17] and on epoxidized vegetable oils under mild conditions. Studies of carbonation of soybean oil [2, 6, 18–21], linseed oil [2, 11, 22], cotton oil [23–25], castor oil [26], and Vernonia oil [27] using TBABr have been carried out. Caló et al. and Sun et al. found better results when using TBAI that when using TBABr for catalyzing the epoxidation of short-chain molecules, attributed to the better nucleophilicity of the iodine ion [16, 28]. However, opposite results have been reported by some other authors [29–31], where an iodine-based catalyst was the nucleophile for the reaction of methyl oleate with CO₂ to produce cyclic carbonates but also formed ketones in a side reaction. Based on our interests, it would be relevant to study the carbonation of epoxidized linseed oil due to its relatively high number of internal epoxy groups and high steric hindrance around the epoxy groups, useful for further polymerizations reactions, and because from the chemical point of view, it is a challenge to functionalize these epoxy groups at high conversions and selectivity levels [31, 32]. The available methodology for carbonating epoxidized linseed oil and for investigating the activities of both TBAI and TBABr, allowed us in the current work to quantitatively evaluate and compare the efficiency levels of both catalysts not only in terms of the conversion, selectivity, and carbonation percentages but also in terms of the competitive reactions producing halohydrins, as recently shown by Martínez et al. [22], and ketones. These side reactions were found in the current work to be mainly formed when TBAI rather than TBABr was employed as the catalyst.

2. Materials and Methods

2.1. Materials

Reagent-grade linseed oil (LO), amberlite IR-120H (AIR-120H), chromatographic-grade α-alumina, hydrogen peroxide solution (50 wt.%), toluene, ethyl acetate, deuterated chloroform, tetrabutylammonium bromide (98%), and tetrabutylammonium iodide (98%) were supplied by the Sigma Aldrich Co (Mexico City, Mexico). Acetic acid and anhydrous magnesium sulphate were acquired from Fermont (Mexico City, Mexico). Sodium bicarbonate was purchased from J.T. Baker (Mexico City, Mexico). Industrial-grade carbon dioxide was supplied by Praxair (Toluca, Mexico). The LO used in the epoxidation reaction was determined to have 6.5 double bonds per molecule and a molecular weight of 900.61 g/mol, and the epoxidized linseed oil (ELO) used in the synthesis of 5-membered cyclic carbonates (CC5s) was determined to have 5.8 epoxides per molecule and a molecular weight of 982.33 g/mol. These values for LO and ELO were determined specifically from ¹H-NMR results according to an areas ratio discussed and used in other works [33–35]. Before been used, linseed oil was passed through a column of chromatographic alumina to remove lead naphthene.

2.2. Synthesis Methodology

2.2.1. Epoxidation of Linseed Oil

Epoxidized linseed oil (ELO) was prepared according to the methodology established by our group [32]. Into a two-neck reactor were first placed 20 g of LO with 6.5 double bonds per molecule and a molecular weight of 900.61 g/mol, 8.8 g of toluene as solvent, 5.0 g of amberlite IR-120H as the catalyst, and 4.7 g of acetic acid followed by 15.2 g of hydrogen peroxide being added dropwise. The reaction was carried out at 80°C for 50 minutes. Then, the reaction mixture was subjected to filtration to remove the catalyst. The product was washed with a saturated sodium bicarbonate solution until a neutral pH was achieved. After separating the oil phase from these mixtures, traces of moisture were removed using anhydrous magnesium sulphate and the solvents were removed by subjecting the remaining mixture to distillation under vacuum. Once the ELO was characterized, it was stored in a freezer at −10°C. The reaction was performed in duplicate, and the standard deviation of the numbers of epoxides groups formed per molecule was <0.1.

2.2.2. Carbonation of ELO

The carbonation reaction of ELO was studied in an autoclave-type reactor under a carbon dioxide atmosphere (60 psi). The general procedure used to perform the carbonation of ELO consisted of placing 2 g of ELO (5.8 epoxides per ELO molecule and MW = 982.3 g/mol), and 2.5 mol% or 5.0 mol% of catalyst (TBABr or TBAI) in the reactor and subjecting the resulting mixture to magnetic stirring until it became homogenized. The reactor was then pressurized and purged twice with carbon dioxide (60 psi) to ensure an oxygen-free atmosphere after which the reactor was heated until reaching the reaction temperature (110°C or 140°C). After completion of the reaction (24 h or 48 h), the products were extracted using 50 mL of ethyl acetate and the catalyst was removed by performing solvent extraction using 250 mL of water (at 50°C) in a separatory funnel. The oil phase was dried using anhydrous magnesium sulphate, and the solvents were distilled under vacuum. Finally, the resulting carbonated epoxidized linseed oil (CELO) was placed in a vacuum desiccator for further analysis.

2.3. Characterizations

Molecular structures of the products were analyzed by deploying proton nuclear magnetic resonance (¹H-NMR), ¹³C nuclear magnetic resonance (¹³C-NMR), and Fourier transform infrared spectroscopy with horizontal attenuated total reflectance (FTIR-HATR). The thermal stability of TBAI was studied using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA).

2.3.1. Nuclear Magnetic Resonance Spectroscopy

NMR spectra were recorded using a Bruker Avance III apparatus at 300 MHz with deuterated chloroform as the solvent and tetramethylsilane (TMS) as the internal standard. Chemical shifts (δ) are quoted in ppm. Samples for ¹H-NMR and ¹³C-NMR analyses were prepared by dissolving 10–20 mg of product in 0.5 mL of deuterated chloroform.

2.3.2. Fourier Transform Infrared Spectroscopy

FTIR spectra were recorded using an IRPrestige-21 SHIMADZU spectrometer with a diamond crystal and in horizontal attenuated total reflectance (HART) mode. All spectra were obtained in the absorbance mode with 64 scans and a resolution of 4 cm⁻¹ in the wavenumber range 560–4000 cm⁻¹. All of the spectra were normalized to the signal at 1739 cm⁻¹, corresponding to ester carbonyl groups (C=O) from the oil products.

2.3.3. Thermal Analysis

Thermal analyses were performed using a Perking Elmer, Inc. simultaneous thermal analyzer (STA 8000). First, a simultaneous DSC/TGA ramp for TBAI was determined from 30 to 600°C under an N₂ atmosphere at a heating rate of 20°C/min. Then, a 72-hour isothermal analysis at 140°C for 72 h under an N₂ atmosphere was carried out.

3. Results and Discussion

Scheme 1 summarizes the sequence of reactions carried out to obtain carbonated epoxidized linseed oil (CELO), and it shows the formations of halohydrins and ketones as competitive reactions to the CC5 formation under the studied conditions.

Table 1 shows the various conditions tested and the results of each of these experiments. Each reaction was performed in duplicate, and the standard deviations of the number of CC5, halohydrin, and ketone groups formed per molecule, as well as of the number of epoxy groups remaining per molecule, were <0.2 in all cases.

The conditions for the carbonation of epoxidized linseed oil in the current work were set based on those conditions determined by various research groups to be best or optimal for carbonation of epoxidized vegetable oils, including epoxidized linseed oil, employing TBABr as a catalyst. Table 2 summarizes some of the reaction conditions and results of those works. The carbonation reaction was found to be straightforward and could be conducted at both atmospheric and elevated pressures of CO₂ with high conversions (usually higher than 80%). Zheng et al. determined high pressures and temperatures below 140°C to be beneficial for the kinetics of the carbonation of cottonseed oil (with 130°C, 50 bar of CO₂, 3.5 mol% of TBABr, and 7 h yielding 85% conversion and 96% selectivity) [24]; Mann et al. reported the carbonation of Vernonia oil with supercritical CO₂ at 100°C (with 13.8 MPa and 46 h achieving a conversion of 95.3%) [27]; Bähr and Mülhaupt reported the conversion of epoxidized linseed oil at 140°C have a stronger influence on reaction kinetics between 1 bar and 10 bar than between 10 and 30 bar [2]. Reaction times have been found to depend on the pressure and temperature, and to range from 3 h (115°C, 0.5 MPa, and 93% conversion, [26]) to 70 h (under the continuous flux of CO₂, 140°C; 94% conversion, [6]). In a study of the carbonation of soybean oil (5 mol% TBABr, atmospheric CO₂ pressure, 120°C, and 70 h), Mazo & Rios, 2013 reportedly increased the activity of the TBABr catalyst by including in the reaction mixture a 1 : 3 molar ratio of water to epoxide [19].

On the basis of this information, we tested a set of mild conditions including a constant CO₂ pressure of 60 psi, intermediate relative amounts of catalyst, specifically (2.5 mol% and 5 mol%), temperatures of 110 and 140°C, and reaction times of 12 h and 24 h (Table 1).

4. Discussion

Temperature was the most significant variable affecting the conversion (η%), carbonation (Y%), and selectivity (S%), and its contribution to the ketonation percentage (K%) was significant as well. This effect of the temperature could be appreciated by comparing Y% for reactions with TBABr catalyst: upon comparing experiments CELO1 and CELO5 (Table 1), this value decreased from 87.9% to 27.6% while, K% increased from 1.7% to 3.4% as the temperature was increased from 110°C to 140°C. In the same way, for reactions with TBAI catalyst, comparing experiments CELO2 and CELO6 (Table 1) showed Y% having decreased from 53.4% to 3.4%, and K% having increased from 29.3% to 36.2% with this same temperature change. The most important observation was the great difference between the results for TBABr and those for TBAI. For example, comparing experiments CELO1 with CELO2, each conducted at 110°C, showed a decrease of 29% in Y% and an increase of 22% in K% upon replacing TBABr with TBAI.

The decreases in η%, Y%, and S% upon increasing the temperature from 110 to 140°C could be attributed to multiple effects of higher temperature acting simultaneously. One effect may have involved the mechanism of the formation of CC5. This mechanism has been indicated to start with the halide of the catalyst attacking the epoxy ring, resulting in a ring opening to form an alkoxide—with this alkoxide then carrying out a nucleophilic attack of the carbon dioxide to give a carboxylate, and with this carboxylate then involved in an intramolecular substitution of the halide to close the ring and form the CC5 [19]. However, deviations from this mechanism could take place due to a decomposition of the catalyst. Zheng et al. studied the thermal stability of TBABr using differential scanning calorimetry and thermogravimetric analysis, and they demonstrated that the maximum reaction temperature should not exceed 130°C, or otherwise the catalyst would decompose [24]. Martínez et al. reported a decomposition of TBABr to hydrogen bromide, CO₂, butene and tributylamine at a bit of a lower temperature, specifically at 120°C when the presence of CO₂ at 90 psi [22], given the high reactivity of hydrogen halides with epoxy rings. The high reactivity of hydrogen halides with epoxy groups [24] would be responsible for the opening of the epoxy ring and subsequent formation of halohydrin groups. Due to our being unaware of any published information about the thermostability of TBAI, we subjected in the current work to a simultaneous DSC/TGA scanning (30–600°C, at 20°C/min, under N₂ flux). Here, the first solid-state transition in the DSC scan occurred at 124°C and was attributed to a kink-block-type rearrangement of the alkyl groups within the quaternary ammonium cation [37]. The second phase transition occurred at 146°C, and corresponded to the fusion of salt crystals. The TGA indicated the onset of decomposition occurring at 209°C (The DSC and TGA thermograms are shown in Figure A1 in the supplementary material). In an isothermal run at 140°C for 72 h, TBAI showed a mas loss of 14.2 wt% (Figure A2 in the supplementary material). These results showed that TBAI underwent the same decomposition process (supplementary material, section A) as that described for TBABr [22] yielding the same volatile and toxics products.

The formation of ketones was reported as a side reaction during the polymerization of epoxides with fluorosulfonic acid [38]. Rios et al. studied the rearrangement of epoxidized vegetable oils to produce fatty ketones, catalyzed by acid resins [39]. They proposed a mechanism involving two steps: the first one being an acid-catalyzed rupture of the oxirane ring to produce a carbocation and the second being a hydride migration. Such acid conditions were not employed in our study, but it was described previously in [29, 30] that ketones during carbonation of EMO were formed as a result of Meinwald isomerization of the epoxide moiety in two steps: first halogen elimination (related to iodine being a good leaving group), and then hydride shift from the alkoxide intermediate of the cycloaddition reaction. It was recently posited in [31] that catalysts with halides that are good leaving groups (Br and I) would favor the formation of a ketone as by product in the carbonation of internal epoxides.

The catalyst type in our current work mainly affected the Y%, S%, and K%. Y% and S% decreased and K% increased, when TBAI was employed as the catalyst instead of TBABr. In contrast to the results reported by Sun et al., 2009, replacing TBABr with TBAI in our current work did not have a considerable impact on η%, which showed only a slight decrease of 2.4%. The described effects of TBAI activity versus TBABr activity can be appreciated by comparing experiments CELO1 and CELO2 (Table 1), where η% decreased only from 100% to 96.6%; while, Y% decreased from 87.9% to 58.6%; S% decreased from 87.9% to 60.7%; and the K% increased from 1.7% to 24.1%. When TBABr was replaced with TBAI, these results provided evidence for TBAI not being a better catalyst than TBABr for the carbonation of linseed oil, and for TBAI in fact promoting the formation of ketones as described above.

The catalyst load was the variable that impacted most of the carbonation parameters. Upon increasing the catalyst load, from 2.5 to 5.0 mol%, η% and K% increased. An increase in catalyst load here would be expected to favor the opening of the epoxy ring due to it increasing the probability of the ion of the catalyst attacking the epoxy group. However, there was a decrease in S%. S% is calculated with the relationship between carbonation percentage (Y%) and conversion percentage (η%). Then, an increase in η% and decrease in Y% with an increase in catalyst load would result in a decrease in S%. Thus, not all the open epoxides led to the formation of CC5. An “excess” of the catalyst appeared to have produced side reactions such as formation of ketones, especially at 140°C with TBAI as the catalyst. These effects were revealed by comparing reaction parameters for experiments CELO2 versus CELO3, and CELO6 versus CELO7.

The reaction time did have a significant effect on η%, Y%, S%, and K%. η%, Y%, and K% increased whereas, S% decreased when the reaction time was increased from 24 to 48 h. At 48 h, the opening of the epoxy ring was favored but so was the formation of ketones. Ketone formation as a competitive reaction to the CC5 synthesis in ELO was detected (from 1.7 to 36.2%) in the reaction products for all the experiments, but was mainly promoted when the reaction conditions were 5.0 mol% TBAI, reaction time of 48 h, and a temperature of 140°C (CELO7). Even with 5.0 mol% TBABr at 140°C and a reaction time of 48 h, K% was 32.8% (CELO8). With the variables studied, it was not possible to avoid the formation of ketones, but those conditions that can minimize their formation were identified to be a temperature of 110°C, TBABr as the catalyst, and a reaction time of either 24 or 48 h (CELO1 and CELO4).

4.1. Characterization: Structural Analysis

Here, we describe how the carbonation parameters and the detection/quantification of halohydrins and ketones, both formed from side reactions during the carbonation of ELO, were determined from the analysis of FTIR and NMR spectroscopy results. All of the signals of the LO, ELO, and CELO FTIR-HATR, ¹H-NMR and ¹³C-NMR spectra are described in the supplementary material (section B). Most importantly, the formation of epoxy groups in LO was corroborated by the vanishing of the FTIR-signals associated with carbon double bonds at 3009 cm⁻¹ and 1651 cm⁻¹ (Figure 1(a)) as well as the presence of the double band of the epoxides at 820 cm⁻¹ (Figure 1(b)). Additionally, the epoxidation of LO was confirmed by the disappearance of the ¹H-NMR signal at δ 5.60 ppm associated with carbon double bonds (Figure 2(a)), and the appearance of epoxy group signals at δ 3.25−2.85 ppm (Figure 2(b)). The LO epoxidation reaction showed a conversion of 92.7% ± 1.2, an epoxidation of 90.4% ± 1.0, and a selectivity of 97.5% ± 1.0, which corresponded to 5.8 ± 0.1 epoxides per molecule. The yield of the reaction was 93.0% ± 0.6.

4.2. Carbonation of Epoxidized Linseed oil

The decrease in intensity of the epoxy signal at 820 cm⁻¹ (Figure 1(b)), and the appearance of three new signals associated with CC5s at 1793 cm⁻¹, 1044 cm⁻¹, and 771 cm⁻¹ in the FTIR-HATR spectra validated the formation of CC5s (Figure 1(c)). Additionally, in some spectra where TBAI was used as the catalyst (CELO2, CELO3, CELO6, and CELO7), and at 140°C and 5.0 mol% of TBABr (CELO8), the ketone carbonyl signal at 1714 cm⁻¹ was observed (Figure 3).

Even at a relatively low temperature (110°C) and with TBABr as the catalyst, the samples presented a relatively wide ester carbonyl signal (Figure 3), attributed to the presence of the ketone and vibrations of hydrogen bonds to carbonyl groups as corroborated by a deconvolution analysis of the ester carbonyl signals (supplementary material, section C), and the results of ¹³C-NMR and ¹H-NMR.

The ¹³C-NMR results provided evidence for the presence of CC5s, halohydrins (bromohydrins or iodohydrins), and ketones in the CELO samples. Figure 4 shows the ¹³C-NMR spectrum of the CELO3 sample with the main functional groups of the CELO structure. Signals associated with ketones appeared at δ 212.00−208.50 ppm (carbonyl carbons of ketones (a) and δ 42.83−42.66 ppm (methylene carbons α to the carbonyls of ketones (b). These signals were found to be the same as those reported in other works [38, 41]. CC5s signals appeared at δ 154.40−152.80 ppm (carbonyl carbon of CC5s, (c), δ 83.00−79.00 ppm, and δ 75.22 ppm (methine carbons of CC5s, (d). An iodohydrins signal appeared at δ 62.07 ppm (methine carbons α to iodide of the iodohydrins, (e) but overlapped with the signals of the methylene carbon of the glycerol moiety at δ 74.49 ppm (methine carbon α to the hydroxyls of the iodohydrins, (f), δ 35.9 ppm (methylene carbons β to the hydroxyls of the iodohydrins, (g), and δ 29.35 ppm (methylene carbons β to the iodides of the iodohydrins, (h) (See details in B.1.2 from Section B in the supplementary material).

As illustrated in the ¹H-NMR spectrum acquired of CELO (Figure 5), the carbonation of ELO was corroborated by the disappearance of the epoxy group signals, with the appearance of the signals associated with CC5s at δ 5.10−4.40 ppm, and with the increase in the area of the δ 4.40−4.06 ppm signal from the CELO samples. All reports have considered that the signals associated with CC5s appear in the region from δ 4.40 ppm to δ 5.10 ppm. However, simulations of different possible structures of CELO, carried out using MestreNova 14.2.1 software, suggested the presence of CC5s in the δ 4.13−4.00 ppm region.

Table 3 shows a comparison of the number of CC5s per molecule obtained using data in the range δ 5.10−4. 40 ppm with that obtained using data in the range δ 5.10−4.06 ppm and its correlation with the area of the deconvoluted FTIR-HATR carbonyl signal of CC5s obtained at 1793 cm⁻¹. According to the Beer–Lambert law, absorbance is proportional to the concentration of the functional group; however, the CELO7 and CELO8 samples showed discrepancies. While the FTIR-HATR spectrum of the CELO7 sample (Figure 3) showed the presence of the carbonyl group of CC5s (with the area of the signal of the carbonyl group of CC5s equal to 6.7), the quantification of CC5s based on the ¹H-NMR signals at δ 5.10−4.40 ppm was zero.

The areas of the FTIR-HATR signal for the carbonyl group of CC5s of CELO8 was similar to that of CELO5 (27.9 and 28.3, respectively), but the number of CC5s groups per molecule determined from the ¹H-NMR signals at δ 5.10−4.40 ppm for CELO8 (0.2 CC5s) was very different from that for CELO5 (1.1 CC5s). The above discrepancies were overcome by quantifying the number of CC5 groups per molecule according to the signals at δ 5.10−4.06 ppm, in each case the numbers of CC5s groups per molecule for samples CELO5, CELO7, and CELO8 were determined to be 1.6, 0.2, and 1.1, respectively. A linear correlation coefficient of 0.95062 was obtained for the plot of the area of the FTIR-HATR signal for the carbonyl group of CC5s at 1793 cm⁻¹ versus the number of CC5s groups per molecule derived from the ¹H-NMR signals at δ 5.10−4.06 ppm (Figure 6), with this result indicating a strong correlation between the two techniques.

The formation of halohydrins and ketones during the carbonation reaction was corroborated by the increase in the areas of the signals at δ 3.95−3.60 ppm (hydroxyl hydrogens and methine hydrogens of the halohydrins), δ 2.58−2.23 ppm (methylene hydrogens α to the ester carbonyl groups and methylene hydrogens α to the carbonyls of the ketones), and δ 2.16−1.94 ppm (methylene hydrogens β to CC5s and methylene hydrogens α to the carbonyls of the ketones). The quantification of the remaining epoxides and the number of CC5s, halohydrins, and ketones groups were determined from ¹H-NMR results. The calculations are shown in the supplementary material, section D.

5. Conclusions

FTIR-HATR, ¹H, and ¹³C-NMR spectroscopic techniques were useful for characterizing the structure of carbonated epoxidized linseed oil (CELO). ¹H-NMR allowed us to quantify the number of remaining epoxides groups per molecules as well as the numbers of halohydrin, ketone, and CC5 groups formed per molecule in CELO under the conditions established. The studied variables were catalyst load, reaction temperature, catalyst type, and reaction time, all at 60 psi of CO₂. The results showed the opening of the epoxy ring to be influenced by the reaction temperature, catalyst load, and reaction time, with the highest values for η% obtained at 110°C, 5 mol% catalyst, and 48 hours of the reaction. On the other hand, the formation of CC5s was found to be highly influenced by the reaction temperature, with the best Y% results obtained at 110°C. Regarding the catalyst type, TBABr turned out to be better than TBAI in large part due to TBAI having promoted the formation of ketones under the conditions used in this work.

Data Availability

The data used to support the findings of this study are included within the article.

Conflicts of Interest

The authors declare that they have no conflicts of interest.

Acknowledgments

The authors thank M.C. María de las Nieves Zavala from CCIQS (SHL-2018), UAEM-UNAM, for providing technical support with NMR measurements. This work was supported by COMECyT (grant no. FICDTEM-2023-33) and by CONACyT (grant no. A1-S-33899), Mexico.

Supplementary Materials

Additional details of the spectra/thermograms/descriptions/calculations related to the characterization of LO, ELO, and TBAI, and the process for calculating all the percentages are discussed in this study. (Supplementary Materials)

References

J. H. Clements, “Reactive applications of cyclic alkylene carbonates,” Industrial & Engineering Chemistry Research, vol. 42, no. 4, pp. 663–674, 2003.
View at: Publisher Site | Google Scholar
M. Bähr and R. Mülhaupt, “Linseed and soybean oil-based polyurethanes prepared via the non-isocyanate route and catalytic carbon dioxide conversion,” Green Chemistry, vol. 14, no. 2, pp. 483–489, 2012.
View at: Publisher Site | Google Scholar
D. C. Webster, “Cyclic carbonate functional polymers and their applications,” Progress in Organic Coatings, vol. 47, no. 1, pp. 77–86, 2003.
View at: Publisher Site | Google Scholar
A. R. Mahendran, N. Aust, G. Wuzella, U. Müller, and A. Kandelbauer, “Bio-based non-isocyanate urethane derived from plant oil,” Journal of Polymers and the Environment, vol. 20, no. 4, pp. 926–931, 2012.
View at: Publisher Site | Google Scholar
W. Y. Pérez-Sena, X. Cai, N. Kebir et al., “Aminolysis of cyclic-carbonate vegetable oils as a non-isocyanate route for the synthesis of polyurethane: a kinetic and thermal study,” Chemical Engineering Journal, vol. 346, pp. 271–280, 2018.
View at: Publisher Site | Google Scholar
B. Tamami, S. Sohn, and G. L. Wilkes, “Incorporation of carbon dioxide into soybean oil and subsequent preparation and studies of nonisocyanate polyurethane networks,” Journal of Applied Polymer Science, vol. 92, no. 2, pp. 883–891, 2004.
View at: Publisher Site | Google Scholar
M. S. Kathalewar, P. B. Joshi, A. S. Sabnis, and V. C. Malshe, “Non-isocyanate polyurethanes: from chemistry to applications,” Royal Society of Chemistry Advances, vol. 3, no. 13, pp. 4110–4129, 2013.
View at: Publisher Site | Google Scholar
A. R. Mahendran, G. Wuzella, N. Aust, and U. Müller, “Synthesis, characterization, and properties of isocyanate-free urethane coatings from renewable resources,” Journal of Coatings Technology and Research, vol. 11, no. 3, pp. 329–339, 2014.
View at: Publisher Site | Google Scholar
Q. Chen, K. Gao, C. Peng, H. Xie, Z. K. Zhao, and M. Bao, “Preparation of lignin/glycerol-based bis(cyclic carbonate) for the synthesis of polyurethanes,” Green Chemistry, vol. 17, no. 9, pp. 4546–4551, 2015.
View at: Publisher Site | Google Scholar
A. F. Guzmán Agudelo, W. Y. Pérez-Sena, N. Kebir, T. Salmi, L. A. Ríos, and S. Leveneur, “Influence of steric effects on the kinetics of cyclic-carbonate vegetable oils aminolysis,” Chemical Engineering Science, vol. 228, Article ID 115954, 115958 pages, 2020.
View at: Publisher Site | Google Scholar
J. Pouladi, S. M. Mirabedini, H. E. Mohammadloo, and N. G. Rad, “Synthesis of novel plant oil-based isocyanate-free urethane coatings and study of their anti-corrosion properties,” European Polymer Journal, vol. 153, pp. 1–12, 2021.
View at: Publisher Site | Google Scholar
R. A. Holser, “Carbonation of epoxy methyl soyate at atmospheric pressure,” Journal of Oleo Science, vol. 56, no. 12, pp. 629–632, 2007.
View at: Publisher Site | Google Scholar
A. J. R. Amaral, J. F. J. Coelho, and A. C. Serra, “Synthesis of bifunctional cyclic carbonates from CO₂ catalysed by choline-based systems,” Tetrahedron Letters, vol. 54, no. 40, pp. 5518–5522, 2013.
View at: Publisher Site | Google Scholar
J. Kothandaraman, J. Zhang, V. A. Glezakou, M. T. Mock, and D. J. Heldebrant, “Chemical transformations of captured CO₂ into cyclic and polymeric carbonates,” Journal Of CO₂ Utilization, vol. 32, pp. 196–201, 2019.
View at: Publisher Site | Google Scholar
M. Vagnoni, C. Samorì, and P. Galletti, “Choline-based eutectic mixtures as catalysts for effective synthesis of cyclic carbonates from epoxides and CO₂,” Journal Of CO₂ Utilization, vol. 42, Article ID 101302, 101307 pages, 2020.
View at: Publisher Site | Google Scholar
V. Caló, A. Nacci, A. Monopoli, and A. Fanizzi, “Cyclic carbonate formation from carbon dioxide and oxiranes in tetrabutylammonium halides as solvents and catalysts,” Organic Letters, vol. 4, no. 15, pp. 2561–2563, 2002.
View at: Publisher Site | Google Scholar
R. Gérardy, J. Estager, P. Luis, D. P. Debecker, and J.-C. M. Monbaliu, “Versatile and scalable synthesis of cyclic organic carbonates under organocatalytic continuous flow conditions,” Catalysis Science and Technology, vol. 9, no. 24, pp. 6841–6851, 2019.
View at: Publisher Site | Google Scholar
K. M. Doll and S. Z. Erhan, “The improved synthesis of carbonated soybean oil using supercritical carbon dioxide at a reduced reaction time,” Green Chemistry, vol. 7, no. 12, pp. 849–854, 2005.
View at: Publisher Site | Google Scholar
P. Mazo and L. Rios, “Carbonation of epoxidized soybean oil improved by the addition of water,” Journal of the American Oil Chemists' Society, vol. 90, no. 5, pp. 725–730, 2013.
View at: Publisher Site | Google Scholar
M. A. Levina, D. G. Miloslavskii, M. L. Pridatchenko et al., “Green chemistry of polyurethanes: synthesis, structure, and functionality of triglycerides of soybean oil with epoxy and cyclocarbonate groups—renewable raw materials for new urethanes,” Polymer Science-Series B, vol. 57, no. 6, pp. 584–592, 2015.
View at: Publisher Site | Google Scholar
I. Javni, D. P. Hong, and Z. S. Petrović, “Soy-based polyurethanes by nonisocyanate route,” Journal of Applied Polymer Science, vol. 108, no. 6, pp. 3867–3875, 2008.
View at: Publisher Site | Google Scholar
D. A. G. Martínez, E. V. Santiago, and S. H. López, “Yield and selectivity improvement in the synthesis of carbonated linseed oil by catalytic conversion of carbon dioxide,” Polymers, vol. 13, no. 6, pp. 1–17, 2021.
View at: Publisher Site | Google Scholar
L. Zhang, Y. Luo, Z. Hou, Z. He, and W. Eli, “Synthesis of carbonated cotton seed oil and its application as lubricating base oil,” Journal of the American Oil Chemists' Society, vol. 91, no. 1, pp. 143–150, 2014.
View at: Publisher Site | Google Scholar
J. L. Zheng, F. Burel, T. Salmi, B. Taouk, and S. Leveneur, “Carbonation of vegetable oils: influence of mass transfer on reaction kinetics,” Industrial & Engineering Chemistry Research, vol. 54, no. 43, pp. 10935–10944, 2015.
View at: Publisher Site | Google Scholar
X. Cai, M. Matos, and S. Leveneur, “Structure-reactivity: comparison between the carbonation of epoxidized vegetable oils and the corresponding epoxidized fatty acid methyl ester,” Industrial & Engineering Chemistry Research, vol. 58, no. 4, pp. 1548–1560, 2019.
View at: Publisher Site | Google Scholar
A. F. Guzmán, D. A. Echeverri, and L. A. Rios, “Carbonation of epoxidized castor oil: a new bio-based building block for the chemical industry,” Journal of Chemical Technology and Biotechnology, vol. 92, no. 5, pp. 1104–1110, 2017.
View at: Publisher Site | Google Scholar
N. Mann, S. K. Mendon, J. W. Rawlins, and S. F. Thames, “Synthesis of carbonated vernonia oil,” Journal of the American Oil Chemists' Society, vol. 85, no. 8, pp. 791–796, 2008.
View at: Publisher Site | Google Scholar
J. Sun, J. Ren, S. Zhang, and W. Cheng, “Water as an efficient medium for the synthesis of cyclic carbonate,” Tetrahedron Letters, vol. 50, no. 4, pp. 423–426, 2009.
View at: Publisher Site | Google Scholar
N. Tenhumberg, H. Büttner, B. Schäffner, D. Kruse, M. Blumenstein, and T. Werner, “Cooperative catalyst system for the synthesis of oleochemical cyclic carbonates from CO₂ and renewables,” Green Chemistry, vol. 18, no. 13, pp. 3775–3788, 2016.
View at: Publisher Site | Google Scholar
W. Natongchai, S. Pornpraprom, and V. D’Elia, “Synthesis of bio-based cyclic carbonates using a bio-based hydrogen bond donor: application of ascorbic acid to the cycloaddition of CO₂ to oleochemicals,” Asian Journal of Organic Chemistry, vol. 9, no. 5, pp. 801–810, 2020.
View at: Publisher Site | Google Scholar
V. Aomchad, À. Cristòfol, F. della Monica, B. Limburg, V. D’Elia, and A. W. Kleij, “Recent progress in the catalytic transformation of carbon dioxide into biosourced organic carbonates,” Green Chemistry, vol. 23, no. 3, pp. 1077–1113, 2021.
View at: Publisher Site | Google Scholar
E. Dehonor-Márquez, J. Nieto-Alarcón, E. Vigueras-Santiago, and S. Hernández-López, “Effective and fast epoxidation reaction of linseed oil using 50 wt% hydrogen peroxyde,” American Journal of Chemistry, vol. 8, no. 5, pp. 99–106, 2018.
View at: Publisher Site | Google Scholar
P. Joshep-Nathan and E. Díaz, Introducción a la resonancia mágnetica nuclear, Wiley, Hoboken, NJ, USA, 1980.
E. Albarrán-Preza, D. Corona-Becerril, E. Vigueras-Santiago, and S. Hernández-López, “Sweet polymers: synthesis and characterization of xylitol-based epoxidized linseed oil resins,” European Polymer Journal, vol. 75, pp. 539–551, 2016.
View at: Publisher Site | Google Scholar
G. López Téllez, Modificación Química del Aceite de Linaza para la Obtención de Polímeros Procesables, Master’s thesis, Universidad Autónoma del Estado de México, Toluca, Mexico, 2008.
S. Doley and S. K. Dolui, “Solvent and catalyst-free synthesis of sunflower oil based polyurethane through non-isocyanate route and its coatings properties,” European Polymer Journal, vol. 102, pp. 161–168, 2018.
View at: Publisher Site | Google Scholar
N. N. Smirnova, L. Y. Tsvetkova, T. A. Bykova, V. A. Ruchenin, and Y. Marcus, “Thermodynamic properties of tetrabutylammonium iodide and tetrabutylammonium tetraphenylborate,” Thermochimica Acta, vol. 483, no. 1-2, pp. 15–20, Feb. 2009.
View at: Publisher Site | Google Scholar
A. Biswas, Z. Liu, and H. N. Cheng, “Polymerization of epoxidized triglycerides with fluorosulfonic acid,” International Journal of Polymer Analysis and Characterization, vol. 21, no. 1, pp. 85–93, 2016.
View at: Publisher Site | Google Scholar
L. A. Rios, B. A. Llano, and W. F. Hoelderich, “Fatty ketones from the rearrangement of epoxidized vegetable oils,” Applied Catalysis A: General, vol. 445-446, no. 446, pp. 346–350, 2012.
View at: Publisher Site | Google Scholar
J. F. Nieto Alarcón, “Estudio de la reacción de carbonatación del aceite de linaza epoxidado,” 2019, http://hdl.handle.net/20.500.11799/105654.
View at: Google Scholar
T. Eren and S. H. Küsefoğlu, “One step hydroxybromination of fatty acid derivatives,” European Journal of Lipid Science and Technology, vol. 106, no. 1, pp. 27–34, 2004.
View at: Publisher Site | Google Scholar

Copyright

Copyright © 2023 Juan F. Nieto-Alarcón et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

PDF Download Citation

Download other formats

Order printed copies