HMPA Research Articles

Ultra-Mild Fabrication of Highly Concentrated SWCNT Dispersion Using Spontaneous Charging in Solvated Electron System.

The efficient dispersion of single-walled carbon nanotubes (SWCNTs) has been the subject of extensive research over the past decade. Despite these efforts, achieving individually dispersed SWCNTs at high concentrations remains challenging. In this study, we address the limitations associated with conventional methods, such as defect formation, excessive surfactant use, and the use of corrosive solvents. Our novel dispersion method utilizes the spontaneous charging of SWCNTs in a solvated electron system created by dissolving potassium in hexamethyl phosphoramide (HMPA). The resulting charged SWCNTs (c-SWCNTs) can be directly dispersed in the charging medium using only magnetic stirring, leading to defect-free c-SWCNT dispersions with high concentrations of up to 20 mg/mL. The successful dispersion of individual c-SWCNT strands is confirmed by their liquid-crystalline behavior. Importantly, the dispersion medium for c-SWCNTs exhibits no reactivity with metals, polymers, or other organic solvents. This versatility enables a wide range of applications, including electrically conductive free-standing films produced via conventional blade coating, wet-spun fibers, membrane electrodes, thermal composites, and core-shell hybrid microparticles.

Direct alcoholysis of furfuryl alcohol to alkyl levulinates using nano-crystalline polyoxometalate-hexamethylphosphoramide salt as a defined solid Brønsted acid catalyst

A nano-crystalline cubic-type, organo-polyoxometalate salts prepared in a single step via quaternization of phosphotungstic acid (PWA) and hexamethylphosphoramide (HMPA) with different rations PWA-HMPA (1:1 to 1:3). The catalysts preserved their solid forms without hydrolysis of HMPA as verified through FT-IR and XRD analyses. A cubic nano-crystalline structure of the catalyst PWA-HMPA (1:3) was revealed by HR-TEM and FE-SEM and defined with moderate and strong Brønsted acid sites (1.19 mmols/g) remarkably provided 99 % conversion of FAL with 98 % selectivity for isopropyl levulinate (IPL) in one hour at 145 °C using isopropanol (IPA) as solvent. Two distinct reaction pathways over PWA-HMPA (1:3) observed with linear alcohols via 1,2 addition/tri-alkoxy intermediate showed lower AKLs selectivity while favouring high selectivity in IPA through 1,4 addition/furan ring opening. PWA-HMPA (1:3) exhibited notable stability over six recycling runs without leaching HMPA or PWA components, indicating its environmental compatibility.

Exploring Unconventional σ-Hole Interactions: Computational Insights into the Interaction of XeO3 with Non-Aromatic Coordinating Solvents.

In order to control the explosiveness and shock sensitivity of XeO3 , we have investigated its plausible interaction with various non-aromatic coordinating solvents, serving as potential Lewis base donors, through density functional theory (DFT) calculations. Out of twenty six such solvents, the top ten were thus identified and then thoroughly examined by employing various computational tools such as the mapping of the electrostatic potential surface (MESP), Wiberg bond indices (WBIs), non-covalent interaction (NCI) plots, Bader's theory of atoms-in-molecules (AIM), natural bond orbital (NBO) analysis, and the energy decomposition analysis (EDA). The amphoteric nature of XeO3 was also explored by investigating the extent of back donation from the lone pair of Xe to the antibonding orbital of the donating atom/group of the solvent molecules. The C-H…O interactions were also found to be a contributing factor in the stabilization of these adducts. Although these aerogen-bonding interactions were found to be predominantly electrostatic, significant contributions from the orbital contributions, as well as dispersion interactions, were observed. The top three non-aromatic solvents (among the twenty six studied) which form the strongest adducts with XeO3 are proposed to be hexamethylphosphoramide (HMPA), N,N'-dimethylpropyleneurea (DMPU) and tetramethylethylenediamine (TMEDA).

Aminophosphine Based Lewis Pair for the Controlled Polymerization of Methyl Methacrylate

AbstractLewis pair polymerization (LPP) has made significant progress in recent decades as a powerful method to synthesize polymers. The matching of electronic and steric properties of Lewis base/acid plays a decisive role in the activity, controlled behavior, and initiation efficiency (I*) of the polymerization. However, exploration of aminophosphine based Lewis base for polymer synthesis has been limited. Herein, commercially available aminophosphine, namely hexamethylphosphorous triamide (HMPT) in combination with common organoaluminum for the polymerization of methyl methacrylate (MMA), is presented. HMPT/iBu3Al shows controlled behavior in MMA polymerization with polymerization degree from 48 to 800, affording defined polymethyl methacrylate (PMMA) with molecular weight (Mn = 15.1–110.7 kg mol−1) with relatively narrow molecular weight distributions (Ð = 1.11–1.37). Matrix‐assisted laser desorption/ionization time of flight mass spectroscopy (MALDI‐TOF‐MS) affirmed the chain‐end fidelity of PMMA. The interaction mode between Lewis pair affects the in situ generated fraction of active species. The basicity and the cone angle of the aminophosphine determine the activity of the formed active species and I*. The successful application highlights the benefits of introducing P─N bonds into Lewis bases, thereby expanding the variety of Lewis base categories.

Structure, dynamic, and free energy analyses of 5-hydroxymethylfurfural in aprotic solvents and imidazolium ionic liquids using all-atom molecular dynamics simulations.

5-Hydroxymethylfurfural (5-HMF) is an important chemical generated from lignocellulosic biomass (LCB) to produce a wide variety of value-added chemicals, biofuels, and biochemicals. Different forms of ionic liquids (ILs) have been utilized for the formation of 5-HMF from LCB. However, 5-HMF is highly soluble in imidazolium-based ionic liquids (IMILs), which makes it difficult to separate after its formation from LCB. In this manuscript, we perform all-atom molecular dynamics simulations to investigate the performance of several aprotic solvents in the extraction of 5-HMF from various IMILs. We consider twelve aprotic solvents with different physicochemical properties, such as acetonitrile (AN), acetone (AT), 1,4-dioxane (DI), N,N-dimethyl acetamide (DMA), N,N-dimethyl formamide (DMF), dimethyl sulfoxide (DMSO), gamma-butyrolactone (GBL), gamma-valerolactone (GVL), hexamethylphosphoramide (HMPA), N-methyl pyrrolidone (NMP), propylene carbonate (PC), and sulfolane (SF). We analyze various structures and dynamics and perform a detailed thermodynamic analysis to understand the underlying molecular behavior. The results indicate that solvents AT and DI showed the least favorable interactions with 5-HMF, whereas HMPA showed the most favorable interactions with 5-HMF. Based on the detailed structural insights, HMPA enhances the separation of 5-HMF from the ILs. Furthermore, different anion combinations were tested to benchmark their separation capability. Overall, the results presented in this manuscript guide the selection of solvent and IL combinations for the effective separation of 5-HMF.

Al- driven deoxydehydration (DODH) of glycols in the presence of pincer type mo-catalyst

This study demonstrates that the zero-valent elements aluminum, zinc, iron, manganese, copper, and carbon are effective reductants for the ONO-pincer ligated molybdenum dioxo catalyzed deoxydehydration (DODH) of polyols. The reductants (elements) and their oxidized products remain insoluble during the reaction and can be easily separated. The cis-MoO2(dipic)L (dipic = pyridine-2,6-dicarboxylate); L=HMPA (Hexamethylphosphoramide), THF), and cis-MoO2(4-Chloro-dipic) HMPA catalysts (1) were found to be effective for the DODH of polyols. The stoichiometric experiments indicate a probable transition from Mo (VI) to Mo (IV) in the redox cycle for the DODH of polyols.

Light in SmI2‐mediated chemistry: Synthetic applications and mechanistic studies

AbstractSmI2 is a versatile reagent in single electron transfer‐mediated reductive transformations. Photoexcitation of SmI2 generates a reactive excited state capable of transferring an electron to substrates that are recalcitrant towards accepting electrons. Synthetic results unequivocally indicate light as a green and sustainable promoter of SmI2‐mediated chemistry, with the potential to replace the suspected carcinogen hexamethylphosphoramide (HMPA). Rate constants of photoinduced electron transfer from SmI2 are in the range of 107–109 M−1 s−1, which are an order of magnitude higher in comparison with the ground state process. Recent advancement in EuII‐ and CeIII‐based photo‐redox catalysis rejuvenated the area of photo‐catalyzed reactions of low‐valent lanthanides. This review article aims to illustrate the role of photoexcitation on SmI2‐mediated reductive transformations.

Solvation Modulation Enhances Anion‐Derived Solid Electrolyte Interphase for Deep Cycling of Aqueous Zinc Metal Batteries

AbstractStable Zn anodes with a high utilization efficiency pose a challenge due to notorious dendrite growth and severe side reactions. Therefore, electrolyte additives are developed to address these issues. However, the additives are always consumed by the electrochemical reactions over cycling, affecting the cycling stability. Here, hexamethylphosphoric triamide (HMPA) is reported as an electrolyte additive for achieving stable cycling of Zn anodes. HMPA reshapes the solvation structures and promotes anion decomposition, leading to the in situ formation of inorganic‐rich solid‐electrolyte‐interphase. More interestingly, this anion decomposition does not involve HMPA, preserving its long‐term impact on the electrolyte. Thus, the symmetric cells with HMPA in the electrolyte survive ≈500 h at 10 mA cm−2 for 10 mAh cm−2 or ≈200 h at 40 mA cm−2 for 10 mAh cm−2 with a Zn utilization rate of 85.6 %. The full cells of Zn||V2O5 exhibit a record‐high cumulative capacity even under a lean electrolyte condition (E/C ratio=12 μL mAh−1), a limited Zn supply (N/P ratio=1.8) and a high areal capacity (6.6 mAh cm−2).

Solvation Modulation Enhances Anion-Derived Solid Electrolyte Interphase for Deep Cycling of Aqueous Zinc Metal Batteries.

Stable Zn anodes with a high utilization efficiency pose a challenge due to notorious dendrite growth and severe side reactions. Therefore, electrolyte additives are developed to address these issues. However, the additives are always consumed by the electrochemical reactions over cycling, affecting the cycling stability. Here, hexamethylphosphoric triamide (HMPA) is reported as an electrolyte additive for achieving stable cycling of Zn anodes. HMPA reshapes the solvation structures and promotes anion decomposition, leading to the in situ formation of inorganic-rich solid-electrolyte-interphase. More interestingly, this anion decomposition does not involve HMPA, preserving its long-term impact on the electrolyte. Thus, the symmetric cells with HMPA in the electrolyte survive ≈500 h at 10 mA cm-2 for 10 mAh cm-2 or ≈200 h at 40 mA cm-2 for 10 mAh cm-2 with a Zn utilization rate of 85.6 %. The full cells of Zn||V2 O5 exhibit a record-high cumulative capacity even under a lean electrolyte condition (E/C ratio=12 μL mAh-1 ), a limited Zn supply (N/P ratio=1.8) and a high areal capacity (6.6 mAh cm-2 ).

Study on synthesis of ursodeoxycholic acid by reduction of 7-ketolithocholic acid in double aprotic solvents and molecular simulations

Ursodeoxycholic acid (UDCA) is not only safer than chenodeoxycholic acid in the treatment of hepatobiliary diseases, but also has a wide range of applications in Acute Kidney Injury and Parkinson’s Disease. The purpose of this experiment is to improve the conversion rate of 7-ketocholic acid (7K-LCA) and the yield of ursodeoxycholic acid in aprotic solvents during electrochemical reduction process. Three aprotic solvents were investigated as electrolytes. 1,3-Dimethyl-2-imidazolidinone (DMI) has a stable five-membered ring structure, and 7K-LCA has undergone two nucleophilic reactions and “Walden” inversion, the 7K-LCK was stereoselectively reduced to UDCA. Hexamethylphosphoramide (HMPA) and 1,3-methyl-3,4,5,6-Tetrahydro-2(1H)-pyrimidinone (DMPU) can be attacked by chloride ions to produce by-products. Molecular orbital theory-based simulations were conducted to study the reducibility of three aprotic solvents [hexamethylphosphoramide (HMPA), 1,3-methyl-3,4,5,6-Tetrahydro-2(1H)-pyrimidinone (DMPU), and 1,3-Dimethyl-2-imidazolidinone (DMI)] in combination with experiments. Choose the best solvent based on the simulation results, the electrolysis reaction can be carried out by applying current and voltage when lithium chloride is used as electrolytes. Calculations using Materials Studio showed that Cu, Pb, Hg–Cu, and Ni exhibited the highest binding energies to the substrate in this system. Using Cu as the electrode when the solvent is a 1:1 mix of DMI and HMPA, the conversion rate of 7-ketocholic acid (could reach 98%, the yield of ursodeoxycholic acid was up to 80%. Under the same conditions, linear voltammetry was performed on the electrochemical workstation to study the electrolysis behavior, and the obtained results were consistent with the experiment.Graphical

Surface Overpotential as a Key Metric for the Discharge-Charge Reversibility of Aqueous Zinc-Ion Batteries.

Aqueous zinc-ion batteries (AZIBs) are receiving increasing attention for power-grid energy storage systems. Nevertheless, warranting long-term reversible operation is not trivial owing to uncontrolled interfacial phenomena related to zinc dendritic growth and parasitic reactions. Herein, the addition of hexamethylphosphoramide (HMPA) to the electrolyte revealed the surface overpotential (|ηs|) to be a key metric of the reversibility. HMPA adsorbs onto active sites on the zinc metal surface, raising the surface overpotential toward lowering the nucleation energy barrier and decreasing the critical size (rcrit) of nuclei. We also correlated the observed interface-to-bulk properties by the Wagner (Wa) dimensionless number. The controlled interface enables a Zn|V6O13 full cell to retain 75.97% capacity for 2000 cycles, with a capacity loss of only 1.5% after 72 h resting. Our study not only delivers AZIBs with unparalleled cycling and storage performance but also proposes surface overpotential as a key descriptor regarding the sustainability of AZIB cycling and storage.

The Role of Non-Covalent Interactions in the Reactions between Palladium Hydrido Complex with Amidoarylphosphine Pincer Ligand and Brønsted Acids

The interaction between (PNP)PdH (1); PNP = bis(2-diisopropylphosphino-4-methylphenyl)amide and different acids (CF3SO3H, HBF4∙Et2O, fluorinated alcohols and formic acid) was studied in benzene or toluene as well as in neat alcohols by IR and NMR spectroscopies. The structures of hydrogen-bonded complexes were also optimized at the DFT/ωB97-XD/def2-TZVP level. The nitrogen atom of the amidophosphine pincer ligand readily accepts proton not only from strong Brønsted acids but from relatively weak fluorinated alcohols. That suggests that binding to palladium(II) increases the diarylamine basicity, making it a strong base. Nevertheless, H+ can be taken from [(PN(H)P)PdH]+ (2) by pyridine or hexamethylphosphoramide (HMPA). These observations confirm the need for a shuttle base to form [(PN(H)P)PdH]+ (2) as the result of the heterolytic splitting of H2 by [(PNP)Pd]+. At that, a stoichiometric amount of formic acid protonates a hydride ligand yielding an unstable η2-H2 complex that rapidly converts into formate (PNP)Pd(OCHO), which loses CO2 to restore (PNP)PdH, whereas the relatively high acid excess hampers this reaction through competitive protonation at nitrogen atom.

Hexamethylphosphoramide-Assisted Structure and Morphology Regulation of a PbI2 Film for Air-Processed Efficient Perovskite Solar Cells via a Two-Step Deposition Method

The two-step deposited method with the advantages of high reproducibility and controllability is widely used in fabricating highly efficient perovskite solar cells (PSCs). However, it is still a challenge to fabricate air-processed PSCs through this method due to the existing techniques with glove box circumstance that are not well extended to the ambient air-condition fabrication process. Here, hexamethylphosphoramide (HMPA) used as a solvent additive is incorporated into the first-step PbI2 precursor solution, which can effectively modify the morphology and crystallinity of the PbI2 layer, thereby creating more opportunities for the infiltration of the second-step organic salt. This two-step coating leads to the full conversion from PbI2 to the perovskite crystal and large grains, reduced defects, and enhanced uniformity for the final perovskite film. Consequently, a champion efficiency of 20.84% of the HMPA-based device fabricated using this procedure is achieved. The HMPA-based device shows long-term stability of the remaining 85.7% of the initial efficiency after 1000 h of storage in an ambient air environment. This method demonstrates the great potential toward air-processed efficient PSCs.

Breaking the tert-Butyllithium Contact Ion Pair: A Gateway to Alternate Selectivity in Lithiation Reactions.

The effects of Lewis basic phosphoramides on the aggregate structure of t-BuLi have been investigated in detail by NMR and DFT methods. It was determined that hexamethylphosphoramide (HMPA) can shift the equilibrium of t-BuLi to include the triple ion pair (t-Bu-Li-t-Bu)-/HMPA4Li+ which serves as a reservoir for the highly reactive separated ion pair t-Bu-/HMPA4Li+. Because the Li-atom's valences are saturated in this ion pair, the Lewis acidity is significantly decreased; in turn, the basicity is maximized which allowed for the typical directing effects within oxygen heterocycles to be overridden and for remote sp3 C-H bonds to be deprotonated. Furthermore, these newly accessed lithium aggregation states were leveraged to develop a simple γ-lithiation and capture protocol of chromane heterocycles with a variety of alkyl halide electrophiles in good yields.

Financial Performance and Valuation Assessment of PT Gudang Garam Tbk in Comparison to PT. Hm Sampoerna and PT. Wismilak Inti Makmur

Financial Performance and Valuation Assessment of PT Gudang Garam Tbk in Comparison to PT. Hm Sampoerna and PT. Wismilak Inti Makmur

Financial Performance and Valuation Assessment of PT Gudang Garam Tbk in Comparison to PT. Hm Sampoerna and PT. Wismilak Inti Makmur

The Tobacco Products Industry (IHT) remains the primary sector as one of the largest contributors to the national economy through excise. The tobacco or cigarette processing industry amounted to IDR 21.96 trillion in the first quarter of 2022. This value grew 0.98% compared to the same period the previous year (year on year/yoy) of IDR 21.75 trillion. This final task will aim to assess the performance finance PT. Gudang Garam Tbk for the last five years has provided recommendations to PT. Gudang Garam tbk in increasing company profits and sales. Ultimately to achieve management goals and provide optimal returns to investors. Financial ratio analysis carried out in this project includes profitability ratios, liquidity ratios, solvency ratios, market ratio, activity ratio, and intrinsic value of GGRM companies using the free cash flow to the firm (FCFF) method. The study results show that GGRM has good performance and the valuation results using the FCC method show that the intrinsic value of the shares is IDR 112,775, while the stock market price is IDR 17,100 (As of January 16, 2023), so the value of the shares is stated to be undervalued.

On the interpretation of the unusual behavior of aqueous-organic mixtures in concentration regions with intersecting isotherms of heat capacity properties

Based on our own and some literature results, we have carried out a detailed analysis of concentration regions of the aqueous-organic mixture in which the temperature dependences of both excess molar heat capacity, CpE, and apparent molar heat capacity of each component, Cp,ϕ,i, are intersected. It is established that the ∂CpE/∂T and ∂Cp,ϕ,w/∂Tderivatives (W is water) for the {(W + hexamethylphosphoramide (HMPA)} and {(W + tert‑butanol (t-BuOH)} mixtures intersect in a rather narrow concentration interval between (0.30 and 0.35) and (0.35 and 0.40) mole fractions of the organic component, respectively. This fact we have interpreted as evidence that the decisive role in the mutually overlapping heat-capacity contributions to CpEresulting in such a situation plays the abnormal change in the isobaric molar heat capacity of W (Cp,w), which has a minimum at T ≈ 308 K, when the temperature increases.

Regulating Zn(002) Deposition toward Long Cycle Life for Zn Metal Batteries

Regulating the Zn deposition orientation is an efficient way to suppress Zn dendrites and stabilize Zn anodes in aqueous Zn ion batteries (ZIBs). Few studies have been conducted to control Zn(002) deposition by altering the Zn2+ solvation structure with a cosolvent. Herein, the bifunctional high-polarity cosolvent hexamethylphosphoramide (HMPA) is proposed in an aqueous electrolyte. It not only suppresses the H2 evolution reaction via the reshaped Zn2+ solvation structure with decreased H2O activity but also induces Zn(002) deposition with a hexagonal-close-packed morphology due to the strong absorption ability of HMPA to Zn(002). With the optimized electrolyte, Zn dendrites and the HER are suppressed and an ultralong cycle life of 1500 cycles with 99.6% Coulombic efficiency is achieved in Zn||Cu cells. Zn||NH4V5O10 and Zn||polyaniline full cells exhibit improved cycling performances compared to that of the bare electrolyte. Our finding provides a feasible and promising way to stabilize Zn anodes and promote the commercial application of ZIBs.

Effects of four chemosterilants on Bactrocera tau

Bactrocera tau (Walker) is a fly pest species mainly distributed in Southeast Asia and the South Pacific; it causes substantial ecological and economic issues because of its destructiveness and rapid reproduction. Chemical sterilization technology can reduce the use of insecticides and is widely applied for insect pest control. In this study, the sterilization efficacy of varying concentrations of four chemosterilants, namely, hexamethylphosphoramide (HMPA), CSII Aqua, 5-fluorouracil (5-FU), and colchicine, on adult pumpkin flies was investigated. The results indicated that a solution of 0.03% HMPA had the highest sterilization efficacy. When the number of sterile males was equal to or exceeded 20 times that of untreated males, the hatching rate of offspring eggs was less than 10%. Chemosterilant treatment significantly altered the levels of acid phosphatase (ACP), alkaline phosphatase (AKP), and B. tau vitellogenin (BtVg); these substances have an important impact on reproductive development. The treatment also decreased the size of the reproductive organs (i.e., testes and ovaries). Our results suggest that 0.03% HMPA has unique sterilization properties and may represent a new chemical agent for the control of B. tau populations in agricultural settings.

Determination of ribose and phosphorus contents in Haemophilus influenzae type b capsular polysaccharide by a quantitative NMR method using a single internal standard.

The ribose and phosphorus contents in Haemophilus influenzae type b (Hib) capsular polysaccharide (CPS) are two important chemical indexes for the development and quality control of Hib conjugate vaccine. A quantitative 1H- and 31P-NMR method using a single internal standard was developed for simultaneous determination of ribose and phosphorus contents in Hib CPS. Hexamethylphosphoramide (HMPA) was successfully utilized as an internal standard in quantitative 1H-NMR method for ribose content determination. The ribose and phosphorus contents were found to be affected by the concentration of polysaccharide solution. Thus, 15-20 mg·L-1 was the optimal concentration range of Hib CPS in D2O solution for determination of ribose and phosphorus contents by this method. The ribose and phosphorus contents obtained by the quantitative NMR were consistent with those obtained by traditional chemical methods. In conclusion, this quantitative 1H- and 31P-NMR method using a single internal standard shows good specificity, accuracy and precision, providing a valuable approach for the quality control of Hib glycoconjugate vaccines.