Tetradecyl Trihexyl Phosphonium Chloride Research Articles

Solvation Environments in Porous Ionic Liquids Determine Selectivity in CO2 Conversion to Cyclic Carbonates.

Porous ionic liquids, which are suspensions of nanoporous particles in ionic liquids that maintain permanent porosity, are effective and selective media for the conversion of styrene oxide into styrene carbonate, absorbing CO2 [Zhou et al. Chem. Commun. 2021, 57, 7922-7925]. Here we elucidate the mechanism of selectivity using polarizable molecular dynamics simulations, which provide a detailed view on the structure of the porous ionic liquid and on the local solvation environments of the reacting species. The porous ionic liquids studied are composed of tetradecyltrihexylphosphonium chloride, or [P66614]Cl, and the ZIF-8 zinc-methylimidazolate metal-organic framework (MOF). The CL&Pol polarizable force field was extended to represent epoxide and cyclic carbonate functional groups, allowing the ionic liquid, the reactants, and the MOF to be all represented by fully flexible, polarizable force fields, providing a detailed description of interactions. The presence of reactant and product molecules leads to changes in the structure of the ionic liquid, revealed by domain analysis. The structure of local solvation environments, namely, the arrangement of charged moieties and CO2 around the epoxide ring of the reactant molecules, clearly indicate ring-opening the reaction mechanism. The MOF acts as a reservoir of CO2 through its free volume. The solute molecules are found in the accessible outer cavities of the MOF, which promotes reaction of the epoxide with CO2 excluding other epoxide molecules, thereby preventing the formation of oligomers, which explains the selectivity toward conversion to cyclic carbonates.

A kaolinite-tetrabutylphosphonium bromide intercalation compound as an effective intermediate for intercalation of bulky organophosphonium salts

A kaolinite-tetrabutylphosphonium bromide (TBPBr) intercalation compound (Kaol-TBPBr) underwent intercalation of dodecyltributylphosphonium bromide (C12TriBPBr), while a kaolinite-dimethyl sulfoxide (DMSO) intercalation compound (Kaol-DMSO) and methoxy-modified kaolinite (MeO-Kaol) showed no such capability. As for the reaction of Kaol-TBPBr and C12TriBPBr, the X-ray diffraction (XRD) patterns revealed expansion of the basal spacing from 1.53 nm of Kaol-TBPBr to 2.10 nm. Fourier transform infrared, solid-state 13C nuclear magnetic resonance (NMR) with cross polarization and magic angle spinning (13C CP/MAS NMR) spectroscopies and the C/P and the Br/P molar ratios indicated intercalation of C12TriBPBr between the layers of kaolinite upon removal of the pre-intercalated TBPBr. As concerns the reactions of Kaol-DMSO and C12TriBPBr, the XRD patterns exhibited no difference as compared to that of Kaol-DMSO or the decrease in basal spacing from the 1.12 nm of Kaol-DMSO to the 0.72 nm of pristine kaolinite. With respect to the reactions of MeO-Kaol with C12TriBPBr, the XRD patterns displayed no expansion of the basal spacing from 0.86 nm of MeO-Kaol. Kaol-TBPBr was also used as an intermediate for successful intercalation of relatively bulk organophosphonium salts, hexadecyltributylphosphonium bromide, tetradecyltrihexylphosphonium chloride and tetraoctylphosphonium bromide. These results clearly reveal the versatility of Kaol-TBPBr as an effective intermediate for use in kaolinite intercalation chemistry.

Structure and properties of nanocomposites based on poly(butylene succinate) and supercritical carbon dioxide-processed montmorillonite

Montmorillonite is intercalated with different amounts of tetradecyltrihexylphosphonium chloride in supercritical carbon dioxide and poly(butylene succinate)-based nanocomposites are prepared with the organically modified or commercial organoclay via melt-mixing. The effect of amount of tetradecyltrihexylphosphonium chloride on the structure of organically modified montmorillonite tactoids, organically modified montmorillonite dispersion and finally on properties of nanocomposites is systematically investigated. Different from the compact spherical structure for pristine montmorillonite tactoids, flexible expanded structure with large cavities on the surface can be obtained for organically modified montmorillonites, and their structure show slight difference with the tetradecyltrihexylphosphonium chloride amount. It is interesting to find that, despite almost no polymer molecule being intercalated into the interlayer, significant dispersion can be achieved for the scCO2-processed organically modified montmorillonite in polymer matrix, due to the easily broken tactoid structure. It is noteworthy, montmorillonite-tetradecyltrihexylphosphonium chloride 08, which is modified with 0.8 CEC tetradecyltrihexylphosphonium chloride, less than in most of the literature, shows almost the same degree of dispersion in poly(butylene succinate) matrix as commercial montmorillonite, which has a stronger interaction with the polymer. Differential scanning calorimetry and dynamic modulus analysis results demonstrate that the crystallization temperature and storage modulus of poly(butylene succinate)-based nanocomposites increase with the amount of tetradecyltrihexylphosphonium chloride, and montmorillonite-tetradecyltrihexylphosphonium chloride08/poly(butylene succinate) shows even higher crystallization temperature and low-temperature storage modulus compared to commercial montmorillonite/poly(butylene succinate).

Influence of physical state of intercalating agents on intercalation process of high speed airflow pretreated montmorillonite in supercritical carbon dioxide

The work aimed at studying the effect of scCO2 processing technology on basal spacing, surface morphology and thermal stability of sodium montmorillonite (MMT) that were pretreated with high speed airflow pulverization method and then modified using myristyltrimethylammonium bromide (MTAB) and tetradecyltrihexylphosphonium chloride (TDTHP) with scCO2 as the medium. X-ray diffraction (XRD) showed that physical state of intercalating agents played an important role on the intercalation process in scCO2. Solid-state MTAB could hardly intercalate into the interlayer of pretreated MMT (PMMT), though addition of co-solvent benefited the intercalation to some extent. However, liquid TDTHP could intercalate into the interlayer of PMMT easily even without co-solvent and the basal spacing of TDTHP-modified PMMT was larger than that of MTAB-modified PMMT. Scanning electron micrographic (SEM) showed the large compact structure for MMT broke into small random structures after airflow processing and some smaller tactoids and more dispersed structures can be observed for both MTAB-modified PMMT and TDTHP-modified PMMT compared to unprocessed MMT. For TDTHP–PMMT, many clay platelets that were separated from the tactoidal structure and more dispersed structure were observed, which may be helpful for MMT exfoliation and dispersion in polymers. Thermogravimetric analysis (TG) demonstrated that TDTHP-modified PMMT was up to 100°C more stable than MTAB-modified PMMT. These results are very important and relevant to the preparation and application of MMT/polymer nanocomposites.

Effect of Intercalation Method and Intercalating Agent Type on the Structure of Silane-Grafted Montmorillonite

AbstractSupercritical carbon dioxide (scCO2) processing has been proven as a method for preparing polymer/montmorillonite (MMT) nanocomposites with improved platelet dispersion. The influence of scCO2 processing on the shape and size of the MMT tactoid/platelet, which is of great importance to the final platelet dispersion in the polymer matrix, is scarcely reported in the literature. In the present study, the pristine MMT was first surface modified with 3-glycidoxypropyltrimethoxysilane (the grafted MMT is labeled as GMMT), and then intercalated using three kinds of intercalating agents, myristyltrimethyl-ammonium bromide (MTAB), tetradecyltrihexylphosphonium chloride (TDTHP), and ethoxyltriphenyl-phosphonium chloride (ETPC), in water or scCO2, to study the effect of intercalating agent type and intercalation method on the morphology and thermal properties of GMMT, as a part of a program devoted to the synthesis of polymer/MMT nanocomposites. The structure of intercalated GMMT was characterized by thermogravimetric analysis, X-ray powder diffraction, and scanning electron microscopy (SEM). The optimum intercalation conditions in scCO2 were established by trying a range of reaction times and pressures. The structures of intercalated GMMT obtained under optimum scCO2 conditions and water were compared. The basal spacing of GMMT intercalated in scCO2 was almost the same as that in water, and both were obviously larger than that of GMMT. The GMMT exhibited a compact spherical morphology (examined using SEM), and the surface structures (including surface morphology, surface roughness, and surface compactness) of samples intercalated in water became ‘less compact’ and the degree of the ‘compactness’ of samples intercalated in scCO2 decreased further. Whether in water or scCO2, samples intercalated with TDTHP exhibited a larger basal spacing and the extent of disorder increased compared to that for samples intercalated with MTAB. The pristine MMT was also intercalated for comparison and silane grafting was proven to contribute to the increased basal spacing and ‘less compact’ surface structure.

Liquid Structure of Trihexyltetradecylphosphonium Chloride at Ambient Temperature: An X-ray Scattering and Simulation Study

We report on an experimental and simulation study done on a representative room temperature ionic liquid, namely tetradecyltrihexylphosphonium chloride, at ambient conditions. The study was conducted using small and wide angle X-ray scattering and molecular dynamics simulations. Both approaches converge in indicating that this material is characterized by the existence of strong P-Cl interactions (with characteristic distances between 3.5 and 5.0 A) and by the occurrence of nanoscale segregation, despite the symmetric nature of the cation and similarly to other room temperature ionic liquids. A good agreement is found between the structure factor and pair correlation functions obtained from MD simulations and the corresponding experimental observables, thus strongly validating the interaction potential used in the simulations.

Suzuki Cross‐Coupling Reactions of Aryl Halides in Phosphonium Salt Ionic Liquid under Mild Conditions.

The Suzuki cross-coupling of aryl boronic acids with aryl halides, including aryl chlorides, proceeds in the phosphonium salt ionic liquid tetradecyltrihexylphosphonium chloride under mild conditions.

Suzuki cross-coupling reactions of aryl halides in phosphonium salt ionic liquid under mild conditions.

The Suzuki cross-coupling of aryl boronic acids with aryl halides, including aryl chlorides, proceeds in the phosphonium salt ionic liquid tetradecyltrihexylphosphonium chloride under mild conditions.