HMPA Research Articles

Probing interactions within liquid media via a model H-bond donor-acceptor mixture.

Understanding interactions within liquids so as to obtain desired physicochemical properties is of utmost importance in chemistry. Solute-solvent and solvent-solvent interactions within mixtures of hexamethylphosphoramide (HMPA) and 2,2,2-trifluoroethanol (TFE) are assessed using various invasive and non-invasive techniques. HMPA and TFE possess similar static dielectric constants. While HMPA has high H-bond accepting basicity (β ∼ 1) and no H-bond donating acidity (α ∼ 0), TFE has high H-bond donating acidity (α ∼ 1) and almost no H-bond accepting basicity (β ∼ 0). Kamlet-Taft parameters obtained using solvatochromic UV-Vis molecular absorbance probes suggest α and β of the (HMPA + TFE) mixture to be higher than those expected from mole-fraction weighted ideal-additive values with α and β exhibiting synergism in TFE-rich and HMPA-rich regions where α > 1 and β > 1, respectively. HMPA has lower dipolarity/polarizability (π*) than TFE, however, the addition of TFE to HMPA results in even further lowering of π* implying significant non-polar nature of the (HMPA + TFE) mixture as compared to its neat constituents. Photoinduced charge-transfer (neutral and anionic) and ratiometric solvatochromic fluorescence polarity probes also confirm the mixture dipolarity to be significantly lower than that expected. FTIR absorbance and Raman spectroscopic measurements hint at the weakening of the strong H-bonds among TFE and/or HMPA as the two solvents are mixed. Positive excess molar volumes (VE) and excess logarithmic viscosities [(ln η)E] indicate weakened interactions in the (HMPA + TFE) mixtures as compared to the interactions within neat TFE and neat HMPA. Microfluidity of the mixture obtained from an intramolecular excimer-forming fluorescence probe further supports these outcomes. Formation of a low polarity liquid milieu upon mixing of two higher polarity solvents is amply highlighted.

Synthesis of hydrosilanes via Lewis-base-catalysed reduction of alkoxy silanes with NaBH4.

Hydrosilanes were synthesized by reduction of alkoxy silanes with BH3 in the presence of hexamethylphosphoric triamide (HMPA) as a Lewis-base catalyst. The reaction was also achieved using an inexpensive and easily handled hydride source NaBH4, which reacted with EtBr as a sacrificial reagent to form BH3in situ.

Talent Management and Financial Performance: Does Organization Learning Mediate That Relationship?

This research has a purpose to identify the impact of the talent management through organization learning towards the financial performance of the listed consumer goods sector in Indonesia. Indonesia costumer goods sector has faced significant growth during the recent year, the companies are enforced to establish competitive strategy to maintain their position in the market. Talent management should be paid attention more since it helps the company to attract, acquire, and retain the best employees that may help maintaining their position in the market as well as enhancing the performance. Based on the hypothesis test, it is true that talent management influences organization learning and financial performance. The companies such as PT HM Sampoerna Tbk and PT Unilever Tbk who obtain high score in the talent management variable most likely to be followed by high score in the organization learning as well. The results also reveal that some companies still need to improve the attraction activities and system to capture learning which are the first indicator of talent management and forth indicator of organization learning. In addition, it was found that organization learning as a mediator can strengthen the relationship between talent management and financial performance.

Phase Diagram of an Ethylene Glycol–Hexamethylphosphorotriamide System

The phase diagram of an ethylene glycol (EG)–hexamethylphosphorotriamide (HMPT) system is studied over two wide temperature intervals (+25°С…−90°С…+40°С) and (−150°С…+40°С) by means of differential scanning calorimetry using INTERTECH DSC Q100 and METTLER TA4000 DSC instruments (Switzerland) in the DSC30 mode with variable cooling/heating rates. Substantial overcooling of the liquid phase, a glass transition, and different types of interaction are observed in the system. No thermal effects are observed in intermediate range of concentrations during the slow cooling/heating processes, and the system remains liquid until the glass transition. The presence of such a metastable phase is attributed to a sharp rise in the viscosity of the system due to different kinds of interaction between the components. HMPT: 2EG and HMPT: EG compounds with crystallization temperatures of +5 and −0.5°С, respectively, are observed upon rapid cooling and slow heating. Changes in enthalpy are calculated for all of the observed thermal effects. The distinction from the phase diagram of H2O–HMFT (literary data) is explained by the difference in the interactions between system components and by the structural differences between EG and H2O.

Synthesis and Crystal Structure of Dinitratotetra(hexamethylphosphoric Triamide)-Lanthanum(III)Tetra(Isothiocyanato)Diammine Chromate(III)

A new coordination compound having the formula [La(HMPA)4(NO3)2][Cr(NH3)2(NCS)4] (I), where HMPA is ((CH3)2N)3PO, has been synthesized and studied by X-ray diffraction. Studied crystals of compound I are monoclinic, space group P21/n, a = 15.0360(3) A, b = 15.1214(3) A, c = 26.7529(7) A, β = 100.6610(10)°, V = 5977.7(9) A3, Z = 2, ρcalc = 1.442 g/cm3, and R1 = 0.0453 for 7344 reflections with Fo ≥ 4σ(Fo).

HMPA-Catalyzed One-Pot Multistep Hydrogenation Method for the Synthesis of 1,2,3-Trisubstituted Indolines

A convenient and facile method was developed for the synthesis of 1,2,3-trisubstituted indolines. Starting from indole derivatives and ketones/aldehydes, the corresponding indoline products could be obtained with high yield by the hexamethylphosphoramide (HMPA) catalyzed indole Friedel–Crafts reaction, reduction and direct reductive amination process.

Self-diffusion of molecules in ethylene glycol solutions of dimethyl sulfoxide

The self-diffusion coefficients of dimethylsulfoxide (DMSO) and ethylene glycol (EG) are measured using spin-echo approach on protons in a wide concentration range of ethylene glycol DMSO solution in the temperature range 30°C–70°C. The activation energies of the corresponding self-diffusion processes are calculated. The results are discussed as interactions and structural changes in the system EG-DMSO and compared with similar results on the study of the EG - hexamethylphosphoric triamide (HMPA) system.

Self-diffusion coefficients of hexamethylphosphoric triamide and ethylene glycol molecules in ethylene glycol solutions

The self-diffusion coefficients of the molecules of hexamethylphosphoric triamide (HMPT) and ethylene glycol (EG) in ethylene glycol solutions in the concentration range 0-16 mol % HMPT and molecules of pure HMPT in the temperature range 30–60°С are measured by the spin-echo method on protons. Activation energies for the corresponding processes of self-diffusion were calculated. The obtained data are discussed in terms of solvophobic effects in the EG–HMPT system. The self-diffusion coefficient of pure HMPT was 0.344 × 10−5 cm2/s at 33.2°C, and the self-diffusion activation energy was 3.86 kcal/mol.

Synthesis and characterization of trinuclear and mononuclear rare-earth metal aryloxides supported by Salpn ligand and their application for the polymerization of rac-lactide

Four rare-earth metal complexes supported by Salpn ligand were synthesized, and their catalytic behaviors for the polymerization of rac-lactide (rac-LA) were explored. The amine elimination reactions of Salpn ligand LH2 (LH2=(CH2)3[N=CH(C6H4-2-OH)]2) with RE[N(SiMe3)2]3 (RE=Y, Yb, Sm, Nd) in a 1:1M ratio, and then with 1 equiv. of phenol ArOH (ArO=2,6-But2-4-MeC6H2O) in THF gave the trinuclear rare-earth metal aryloxo complexes [LRE(OAr)(HMPA)]3 (RE=Y (1), Yb (2), Sm (3)), and the mononuclear neodymium complex LNd(OAr)(HMPA)2 (4), respectively, in good yields in the presence of HMPA (HMPA=hexamethylphosphoric triamide). Complexes 1 and 2 can also be prepared by the phenol elimination reactions of (ArO)3RE(THF) with LH2 in a 1:1M ratio or salt metathesis reaction of LLi2(THF)x with anhydrous RECl3, then with NaOAr in THF. Complexes 1–4 were well characterized by elemental analyses and IR, as well as NMR spectroscopy in the case of complex 1. The definitive molecular structures of complexes 1–4 were determined by single-crystal X-ray analysis. The catalytic behaviors of these complexes for rac-LA polymerization were investigated. It was found that complexes 1–4 can initiate efficiently this polymerization and gave hetero-rich PLA. Kinetics study demonstrated that rac-LA polymerization initiated by complexes 1–3 has a first order relationship between polymerization rate and monomer concentration. A comparative kinetics study in THF and CHCl3 revealed that polymerization media have significant influence on the activity order of complexes 1–3 for rac-LA polymerization. The observed activity-increasing order of these complexes in THF is in agreement with the increasing order of their ionic radii, whereas it is in reverse order in CHCl3. A mechanism study demonstrated that the polymerization proceeded via a coordination-insertion mechanism, and the aryloxo group in these complexes acted as the initiating group.

A High-Performance Li-O2 Battery with a Strongly Solvating Hexamethylphosphoramide Electrolyte and a LiPON-Protected Lithium Anode.

The aprotic Li-O2 battery has attracted a great deal of interest because theoretically it can store more energy than today's Li-ion batteries. However, current Li-O2 batteries suffer from passivation/clogging of the cathode by discharged Li2 O2 , high charging voltage for its subsequent oxidation, and accumulation of side reaction products (particularly Li2 CO3 and LiOH) upon cycling. Here, an advanced Li-O2 battery with a hexamethylphosphoramide (HMPA) electrolyte is reported that can dissolve Li2 O2 , Li2 CO3 , and LiOH up to 0.35, 0.36, and 1.11 × 10-3 m, respectively, and a LiPON-protected lithium anode that can be reversibly cycled in the HMPA electrolyte. Compared to the benchmark of ether-based Li-O2 batteries, improved capacity, rate capability, voltaic efficiency, and cycle life are achieved for the HMPA-based Li-O2 cells. More importantly, a combination of advanced research techniques provide compelling evidence that operation of the HMPA-based Li-O2 battery is backed by nearly reversible formation/decomposition of Li2 O2 with negligible side reactions.

Hydrogen Bond Donor/Acceptor Cosolvent-Modified Choline Chloride-Based Deep Eutectic Solvents.

Deep eutectic solvents (DESs) have emerged as nontoxic and inexpensive alternatives not only to the common organic solvents but to the ionic liquids as well. Some of the common and popular, and perhaps the most investigated, DESs are the ones comprising an ammonium salt and an appropriate hydrogen bond (HB) donor in a predetermined mole ratio. The formation of the DES is attributed to the H-bonding interaction(s) present between the salt and the HB donor. Consequently, addition of a predominantly HB donor or a predominantly HB acceptor cosolvent to such DESs may result in intriguing features and properties. We present investigation of two DESs constituted of salt choline chloride along with HB donors urea and glycerol, respectively, in 1:2 mol ratio, named reline and glyceline as the cosolvent of very high HB donating acidity and no HB accepting basicity 2,2,2-trifluoroethanol (TFE) and of very high HB accepting basicity and no HB donating acidity hexamethylphosphoramide (HMPA), respectively, is added. TFE shows up to 0.25 mole fraction miscibility with both reline and glyceline. While up to 0.25 mole fraction HMPA in glyceline results in transparent mixtures, this cosolvent is found to be completely immiscible with reline. From the perspective of the solvatochromic absorbance and fluorescence probes, it is established that the cybotactic region dipolarity within up to 0.25 mole fraction TFE/HMPA-added DES strongly depends on the functionalities present on the solute. Fourier transform infrared absorbance and Raman spectroscopic investigations reveal no major shifts in vibrational transitions as TFE/HMPA is added to the DES; spectral band broadening, albeit small, is observed nonetheless. Excess molar volumes and excess logarithmic viscosities of the mixtures indicate that while TFE may interstitially accommodate itself within H-bonded network of reline, it does appear to form H-bonds with the constituents of the glyceline. Increase in overall net repulsive interactions as HMPA is added to glyceline is suggested by both positive excess molar volumes and excess logarithmic viscosities. The addition of HB donor/acceptor cosolvent appears to disturb the salt-HB donor equilibria within DES via complex interplay of interactions within the system.

Tetra(hexamethylphosphoric triamide) solvate with ammonium tetrakis(isothiocyanato)diamminechromate(III): Synthesis and crystal structure

Ammonium tetrakis(isothiocyanato)diamminechromate(III) crystalline solvate (NH4)[Cr(NH3)2(NCS)4] ∙ 4((CH3)2N)3PO (I) has been synthesized and structurally characterized. Crystals of solvate I are tetragonal, space group P $$\overline{4}$$ 21 c, a = 15.8594(3) A, c = 11.1675(2) Ǻ, V = 2808.86(9) Ǻ3, Z = 2, ρcalcd = 1.245 g/cm3, ρmeas = 1.21 g/cm3. Cations, solvate molecules, and anions form chains in a crystal by means of intermolecular hydrogen bonds.

Cu(I)-promoted one-pot synthesis of 1,4-disubstituted 1,2,3-triazoles from anti-3-aryl-2,3-dibromopropanoic acids and nitrobenzaldehydes

ABSTRACTA series of 1,4-disubstituted 1,2,3-triazoles were synthesized through a one-pot process from easily available anti-3-aryl-2,3-dibromopropanoic acids and nitrobenzaldehydes in hexamethylphosphoric triamide. Inexpensive copper(I) iodide was the catalyst.

ChemInform Abstract: Cu(I)‐Promoted One‐Pot Click‐SNAr Reaction of Nitrobenzaldehydes.

ABSTRACTA series of 1,4-disubstituted 1,2,3-triazoles containing formyl was synthesized from a variety of readily available nitrobenzaldehydes and alkynes via a convenient one-pot, click-SNAr reaction with moderate to excellent yields. The reactions were easily carried out in hexamethyl phosphoramide in the absence of a base at 60 °C.

ChemInform Abstract: Diastereoselective Synthesis of Functionalized Spiro[cyclopropane‐1,3′‐indolines] and Spiro[indoline‐3,1′‐cyclopropane‐2′,3′′‐indolines

In the presence of hexamethylphosphorous triamide, the reaction of isatin with arylidene pivaloylacetonitriles in dry methylene dichloride afforded functionalized spiro[cyclopropane-1,3′-indolines] in good yields and with high diastereoselectivity. Moreover, the similar reaction of isatins with isatylidene malononitriles predominately gave spiro[indoline-3,1′-cyclopropane-2′,3″-indolines] in very high yields with two indoline moieties in trans-configuration.

Cu(I)-promoted one-pot click-SNAr reaction of nitrobenzaldehydes

ABSTRACTA series of 1,4-disubstituted 1,2,3-triazoles containing formyl was synthesized from a variety of readily available nitrobenzaldehydes and alkynes via a convenient one-pot, click-SNAr reaction with moderate to excellent yields. The reactions were easily carried out in hexamethyl phosphoramide in the absence of a base at 60 °C.

Diastereoselective synthesis of functionalized spiro[cyclopropane-1,3′-indolines] and spiro[indoline-3,1′-cyclopropane-2′,3″-indolines

In the presence of hexamethylphosphorous triamide, the reaction of isatin with arylidene pivaloylacetonitriles in dry methylene dichloride afforded functionalized spiro[cyclopropane-1,3′-indolines] in good yields and with high diastereoselectivity. Moreover, the similar reaction of isatins with isatylidene malononitriles predominately gave spiro[indoline-3,1′-cyclopropane-2′,3″-indolines] in very high yields with two indoline moieties in trans-configuration.

Reductive Hydrazination with Trichlorosilane: A Method for the Preparation of 1,1-Disubstituted Hydrazines.

A straightforward and facile method has been developed to prepare 1,1-disubstituted hydrazines via Lewis base promoted direct reductive hydrazination. Under the catalysis of hexamethylphosphoramide (HMPA) and N,N-dimethylacetamide (DMAc), respectively, various ketones and aldehydes could react with phenylhdrazines to prepare 1,1-disubstituted hydrazines with good to high yields.

Efficient synthesis of novel 2,3-dihydro-1,3,5,4-thiadiazaphosphole derivatives

ABSTRACTThe condensation of various thiosemicarbazones with methyl thiophene-2-carboximidate afforded the corresponding intermediates 2a–2h. Subsequent cyclization of the latter compounds with hexamethylphosphorous triamide constitutes a new route to the synthesis of novel highly functionalized thiadiazaphosphole derivatives 4a–4h. This method offers significant advantages such as efficiency, high yields and mild reaction conditions.

Relationship of the solvation enthalpies of n-alkanes in a methanol–hexamethylphosphortriamide mixture to its thermal and bulk properties

Enthalpies of dissolution are determined thermochemically under standard conditions, and the solvation enthalpies of n-hexane, n-decane, and n-hexadecane in a mixed methanol–hexamethylphosphor-triamide (HMPT) solvent are calculated. Experimental data are compared to values obtained from model calculations. It is shown that positive deviations of the enthalpies of dissolution of alkanes in a МеОН–HMPT mixture from additivity in the range enriched with methanol are due to changes in the bulk properties of the mixed solvent, while negative deviations of enthalpies of dissolution from additivity in the range enriched with HMPT are due to the selective solvation of alkanes by HMPT.