Group IIA Metal Research Articles

Potassium Carbonate as a Low-Cost and Highly Active Solid Base Catalyst for Low-Temperature Methanolysis of Polycarbonate.

As the demand for polycarbonate (PC) plastic increases over the years, the development of a chemical recycling system to produce virgin-like-quality monomers is indispensable not only to attain completely sustainable cycles but also to contribute to the decrease in global plastic pollution. Herein, potassium carbonate (K2CO3) was used as a low-cost, readily available, and highly active solid base catalyst for low-temperature PC methanolysis in the presence of THF as a solvent, producing highly pure and crystalline bisphenol A (BPA) and with a catalytic performance higher than group IIA metal oxides (MgO, CaO, and SrO) and some group IA metal carbonates (NaHCO3, KHCO3, and Na2CO3). THF was the best solvent in aiding the reaction owing to it having a similar polar parameter (δp) to that of PC according to Hansen solubility parameters. By the reaction over the catalyst, 100% PC conversion, 97% BPA yield, and 86% dimethyl carbonate yield were achieved within just 20 min at 60 °C. The catalyst possessed an apparent activation energy (Ea) of 52.3 kJ mol-1, which is the lowest value so far for heterogeneous catalysts, while the mechanistic study revealed that the reaction proceeded via the methoxide pathway. The reusability test demonstrated that the catalyst was reusable at least four times. Furthermore, this catalytic system was successfully applied to actual post-consumerPC wastes and polyesters, including polyethylene terephthalate (PET) and polylactic acid (PLA).

Zigzag boron nitride nanotube functionalization as a sensor for the recognition of group IIA (Mg2+, Ca2+) metal ions, quasi-metal (Si2+, Ge2+) ions, and transition metal (Cu2+, Zn2+) ions: a computational study.

Boron nitride nanotubes (BNNTs) provide an exceptional and sophisticated platform for detecting metal ions with high surface area and remarkable chemical stability. Metal cations tend to bind to the surface of BNNTs, which leads to significant changes in the electrical properties of nanotubes. BNNT-based metal ion sensors have shown promising results in various applications, including water quality monitoring, biomedical research, industrial quality control, and environmental monitoring. In the present study, we have explored the electronic sensitivity of the BNNT to metal ions (Si2+, Ge2+, Cu2+, Zn2+, Mg2+, and Ca2+). The interaction between the ions with the pristine BNNT is performed in the solution phase. The results show that ion adsorption on the nanotube surface is exothermic and favorable. The density of states calculation is presented to investigate the electronic properties of the nanotube during the adsorption process. The results display that an increase in the electrical conductivity of the complexes accompanies the reduction in the energy gap. Based on the obtained data, the Si2+ and Ge2+ cations adsorbed on the BNNT with satisfactory Eg changes (%ΔE) can be promising candidates for better sensing ability. All calculations are conducted within the density functional theory (DFT) using the ωB97XD functional and 6-31G(d,p) basis set. The present approach incorporates the utilization of empirical atom-atom dispersion in conjunction with long-range correction. The calculations are performed using the quantum chemistry package GAMESS, and the obtained results are visualized by employing the GaussView 6.0.16 program.

Theoretical investigation of the carbonyl-ene reaction between encapsulated formaldehyde and propylene over M-Cu-BTC paddlewheels (M= Be, Mg, and Ca): A DFT study

Formaldehyde is a VOC gas that plays a key role in air pollution. To limit emissions into the environment, the utilization of this waste as a raw material is a promising way. In this work, the M06-L functional calculation was used to investigate the structure, electronic properties, and catalytic activity of group IIA metals (Be, Mg, and Ca) partial substitution on Cu-BTC paddlewheels for formaldehyde encapsulation and carbonyl-ene reaction with propylene. Formaldehyde is absorbed by the metal center of the paddlewheel via its oxygen atom. The adsorption of formaldehyde on the substituted metal sites increased as compared to the parent Cu-BTC which can facilitate formaldehyde to react with propylene. The adsorption free energies are predicted to be −15.1 (Be–Cu-BTC), −14.7 (Mg–Cu-BTC), and −14.5 (Ca–Cu-BTC) kcal mol−1, respectively. The substituted metal has a slight effect on the Lewis acidity of the Cu ion in the paddlewheel. The adsorption free energy of formaldehyde, similar to that found in the pristine Cu-BTC, is observed. For the carbonyl-ene reaction, the reaction is proposed via a single step involving the C–C bond formation between two reactants and one hydrogen of propylene methyl group moves to formaldehyde oxygen, simultaneously. It was found that the substituted metals do not affect the catalytic performance of the Cu center for this reaction. The activation energies for the reaction at the Cu center are in the range of 22.0–23.4 kcal mol−1, which are slightly different from Cu-BTC (21.5 kcal mol−1). Interestingly, the catalytic activity of this reaction on the substituted metal is greater than that on the Cu center. The catalytic activities are in the order Be–Cu-BTC (13.3 kcal mol−1) > Mg–Cu-BTC (15.9 kcal mol−1) > Ca–Cu-BTC (17.8 kcal mol−1). Among them, the Be site of the bimetallic Be–Cu-BTC paddlewheel is predicted as a promising candidate catalyst.

First principle calculation of structural, electronic, optical, elastic and thermodynamic properties of group IIA metal iodides: Structure-property correlation

The Structural, Electronic, Optical, Elastic and Thermodynamic Properties of Group IIA Metal Iodides were investigated using DFT calculations employing full potential linearized augmented plane wave plus local orbitals with Perdew Burke Ernzerhof-Generalized Gradient Approximation (PBE-GGA). We have also carried out band structure calculations using some other exchange-correlation functionals such as LSDA, PBEsol-GGA,WC-GGA and TB-mBJ for all the compounds. Among these iodides, MgI2 and CaI2 have same trigonal structure while SrI2 and BaI2 follow same orthorhombic structure with BeI2 having orthorhombic structure of entirely different space group. All the calculated properties show consistently the similarity for the iodides of same structure following the structure-property correlation. Bands are fewer and less dense for MgI2 and CaI2 in contrast with many and denser bands of SrI2 and BaI2 in comparison to altogether different moderately dense bands of BeI2. The band structure reveals an indirect band gap of 4.08 eV, 3.5 eV, 3.58 eV for BeI2, MgI2, CaI2 respectively and a direct band gap of 3.79, 3.35 for SrI2, BaI2 respectively. The optical anisotropy with excitonic features exhibited by BeI2, MgI2 and CaI2 is clearly absent in SrI2 and BaI2. The calculated elastic constants show that all these compounds are quite mechanically stable having the magnitude of elastic anisotropy in the order: BeI2>CaI2>BaI2>MgI2>SrI2. All the thermodynamic properties show bunching according to their structure consistent with structure-property correlation. Debye temperatures were calculated for BeI2, MgI2, CaI2, SrI2 and BaI2 at room temperature and zero pressure as 183.53 K, 188.51 K, 166.98 K, 151.12 K and 135.55 K respectively. Many parameters of these properties are new in the literature. A reasonable agreement between our calculated and available theoretical/experimental band gaps of these iodides in the literature justifies the accuracy of the calculations of other properties. All the properties of these iodides are explained consistently and comprehensively in terms of their structure-property correlation.

Inhibition of sintering and coking by post-coating group IIA metal oxides on trace-Rh-promoted Ni-based catalysts for high-temperature steam reforming

Liquid hydrocarbon steam reforming (SR) faces the challenges of sintering and carbon deposition induced deactivation of catalysts. Herein, the strategy for stabilizing trace Rh-promoted Ni-based catalysts by post-coating group IIA metal oxide is proposed. The stabilities for catalytic n-dodecane SR are as followed: Mg–Rh–Ni–CZO > Sr–Rh–Ni–CZO > Ba–Rh–Ni–CZO ∼ Ca–Rh–Ni–CZO ∼ Rh–Ni–CZO. The reduction suppression of Rh–Ni by alkaline-earth metal oxide and the formation of Mg–O–Ni bonds in Mg–Rh–Ni–CZO are demonstrated by TPR and EXAFS techniques. The TEM and TGA characterization results confirm that IIA metal oxide inhibit Ni sintering, in turn decreasing the carbon deposition amount and graphitic carbon proportion. Negligible Ni sintering and low carbon deposition (0.7 mg/g-cat.·mmol-C12H26) occurs in Mg–Rh–Ni–CZO after SR at 700 °C for 50 h. Contrarily, the MgO-precoated Rh–Ni–Mg–CZO do not exhibit improved catalytic performance owing to the correlation between sintering and coking behaviors with interfacial structures.

Synthesis and structural characterizations of tris(hydroxymethyl)aminomethane complexes with group IIA metals

Herein, this article aimed to investigate the tendency of tris(hydroxymethyl) aminomethane (THAM) to form stable complexes with group IIA metals. Four new colorless solid complexes of group IIA metals [Ba(II), Ca(II), Sr(II) and Mg(II)] with THAM were prepared and well characterized. The chemical reactions between group IIA metals and THAM were conducted by stoichiometry of 2:1 (Ligand: Metal ion) at 65 °C and pH of ~ 8.5. Under these conditions, the THAM molecule (C4H11NO3) was deprotonated and converted to the (C4H10NO3-; L-) chelate with the metal ions. The structures of these complexes were suggested by UV-visible, IR, Raman and 1H NMR spectroscopies and other physicochemical and analytical methods (elemental analysis, thermogravimetry, and SEM). The results shows that the general composition of the complexes obtained with Ba(II), Ca(II), Sr(II) and Mg(II) ions are [BaL2(H2O)2], [CaL2(H2O)2]·2H2O, [SrL2(H2O)2], and [MgL2(H2O)2]·4H2O, respectively, and in all complexes, the geometry was octahedral.

Effect of delocalization of nonbonding electron density on the stability of the M–Ccarbene bond in main group metal-imidazol-2-ylidene complexes: a computational and structural database study

Abstract The M–Ccarbene bond in metal (M) complexes involving the imidazol-2-ylidene (Im) ligand has largely been described using the σ-donor only model with donation of σ electrons from the sp-hybridized orbital of the carbene carbon into vacant orbitals on the metal centre. Analyses of the M–Ccarbene bond in a series of group IA, IIA and IIIA main group metal complexes show that the M-Im interactions are mostly electrostatic with the M–Ccarbene bond distances greater than the sum of the respective covalent radii. Estimation of the binding energies of a series of metal hydride/fluoride/chloride imidazol-2-ylidene complexes revealed that the stability of the M–Ccarbene bond in these complexes is not always commensurate with the σ-only electrostatic model. Further natural bond orbital (NBO) analyses at the DFT/B3LYP level of theory revealed substantial covalency in the M–Ccarbene bond with minor delocalization of electron density from the lone pair electrons on the halide ligands into antibonding molecular orbitals on the Im ligand. Calculation of the thermodynamic stability of the M–Ccarbene bond showed that these interactions are mostly endothermic in the gas phase with reduced entropies giving an overall ΔG > 0.

Host-guest interactions between p-sulfonatocalix[4]arene and p-sulfonatothiacalix[4]arene and group IA, IIA and f-block metal cations: a DFT/SMD study.

The molecular recognition in aqueous solution is extremely important because most biological processes occur in aqueous solution. Water-soluble members of the calix[n]arene family (e.g., p-sulfonato substituted) can serve as model systems for studying the nature and manner of interactions between biological receptors and small ions. The complex formation behavior of water-soluble p-sulfonatocalix[4]arene and thiacalix[4]arene and group IA, IIA and f-block metal cations has been investigated computationally by means of density functional theory computations in the gas phase and in aqueous environment. The calculated Gibbs free energy values of the complex formation reaction of these ligands with the bare metal cations suggest a spontaneous and energy-favorable process for all metal cations in the gas phase and only for Na+, Mg2+, Lu3+ cations in water environment. For one of the studied cations (La3+) a supramolecular approach with explicit solvent treatment has been applied in the study of the effect of metal hydration on the complexation process. The La3+ binding to the p-sulfonatocalix[4]arene host molecule (now in the metal’s second coordination shell) is still exergonic as evidenced by the negative Gibbs free energy values (ΔG1 and ΔG78). The combination of implicit/explicit solvent treatment seems useful in the modeling of the p-sulfonatocalix[4]arene (and thiacalix[4]arene) complexes with metal cations and in the prediction of the thermodynamic parameters of the complex formation reactions.

Determination of Dynamically Stable Electrenes toward Ultrafast Charging Battery Applications

Electrenes, an atomically thin form of layered electrides, are very recent members of the 2D materials family. In this work, we employed first-principle calculations to determine stable, exfoliatable, and application-promising 2D electrene materials among possible M2X compounds, where M is a group II-A metal and X is a nonmetal element (C, N, P, As, and Sb). The promise of stable electrene compounds for battery applications is assessed via their exfoliation energy, adsorption properties, and migration energy barriers toward relevant Li, Na, K, and Ca atoms. Our calculations revealed five new stable electrene candidates in addition to previously known Ca2N and Sr2N. Among these seven dynamically stable electrenes, Ba2As, Ba2P, Ba2Sb, Ca2N, Sr2N, and Sr2P are found to be very promising for either K or Na ion batteries due to their extremely low migration energy barriers (5-16 meV), which roughly demonstrates 105 times higher mobility than graphene and two to four times higher mobility than other promising 2D materials such as MXene (Mo2C).

Theoretical Study of Addition Reactions of L4M(M = Rh, Ir) and L2M(M = Pd, Pt) to Li+@C60

The addition reaction of M(Cl)(CO)(PPh3)2 (M = Rh, Ir) and M(PPh3)2 (M = Pd, Pt) fragments with X@C60 (X = 0, Li+) were characterized by density functional theory (DFT) and the artificial force-induced reaction (AFIR) method. The calculated free energy profiles suggested that the η2[6:6]-addition is the most favorable reaction, which is consistent with the experimental observations. In the presence of Li+ ion, the reaction is highly exothermic, leading to η2[6:6] product of L4IrLi+@C60. In contrast, an endothermic reaction was observed in the absence of a Li+ ion. The encapsulated Li+ ion can enhance the thermodynamic stability of the η2[6:6] product. The energy decomposition analysis showed that the interaction between metal fragment and X@C60 fragment is the key for the thermodynamic stability. Among the group IA and IIA metal cations, Be2+ encapsulation is the best candidate for the development of new fullerene-transition metal complexes, which will be useful for future potential applications such as solar cells, catalysts, and electronic devices.

A Practical and General Base-Catalyzed Carbonylation of Amines for the Synthesis of N-Formamides.

A highly practical and general base-catalyzed carbonylation of amines to the corresponding N-formamides has been realized. Cheap inorganic bases, including Group IA and IIA metal hydroxides, alkoxides, carbonates, and phosphates, were effective catalysts for the transformation. In the presence of 10-40 mol % of KOH or K2 CO3 , various amines were converted into the corresponding N-formamides in good-to-excellent yields using CO as the formylation reagents.

The van der Waals potentials of MgCa, MgSr, MgBa, CaSr, CaBa, and SrBa

Based on the facts that the potential energy curves of the homo-nuclear group 2 dimers (group IIA metal), except Be2, are conformal, and they can be described by the Tang–Toennies potential model, a set of simple combining rules are proposed for the parameters of the reduced potentials of the hetero-nuclear dimers. Together with the well-established combining rules of the range parameters of the exponential repulsion and the known dispersion coefficients, these rules enable us to determine the ground state potential energy curves of MgCa, MgSr, MgBa, CaSr, CaBa, and SrBa from those of Mg2, Ca2, Sr2, and Ba2. The determined potentials are comparable to some ab initio calculations and in excellent agreement with the experiment.

Formation of nanostructured Group IIA metal activated sensors: The transformation of Group IIA metal compound sites

Trends in the Group IIA metal oxides and hydroxides of magnesium, calcium, and barium are unique in the periodic table. In this study we find that they display novel trends as decorating nanostructures for extrinsic semiconductor interfaces. The Group IIA metal ions are strong Lewis acids. We form these M2+ ions in aqueous solution and bring these solutions in contact with a porous silicon interface to form interfaces for conductometric measurements. Observed responses are consistent with the formation of MgO whereas the heavier elements display behaviors which suggest the effect of their more basic nature. Mg(OH)2, when formed, represents a weak base whereas the heavier metal hydroxides of Ca, Sr, and Ba are strong bases. However, the hydroxides tend to give up hydrogen and act as Brönsted acids. For the latter elements, the reversible interaction response of nanostructures deposited to the porous silicon (PS) interface is modified, as the formation of more basic sites appears to compete with M2+ Lewis acidity and hydroxide Brönsted acidity. Mg2+ forms an interface whose response to the analytes NH3 and NO is consistent with MgO and well explained by the recently developing Inverse Hard/Soft Acid/Base model. The behavior of the Ca2+ and Ba2+ decorated interfaces as they interact with the hard base NH3 follows a reversal of the model, indicating a decrease in acidic character as the observed conductometric response suggests the interaction with hydroxyl groups. A change from oxide-like to hydroxide-like constituents is supported by XPS studies. The changes in conductometric response is easily monitored in contrast to changes associated with the Group IIA oxides and hydroxides observed in XPS, EDAX, IR, and NMR measurements.

Theoretical study on the interaction of glutathione with group IA (Li+, Na+, K+), IIA (Be2+, Mg2+, Ca2+), and IIIA (Al3+) metal cations

The structures and energies of complexes obtained upon interaction between glutathione (GSH) and alkali (Li+, Na+, K+), or alkaline earth metal (Be2+, Mg2+, Ca2+), or group IIIA (Al3+) cations were studied using quantum chemical density functional theory. The characteristics of the interactions between GSH and the metal cations at different nucleophilic sites of GSH were examined selecting systematically, both mono- and multi-coordinating were taken into account. The results indicated that the heteroatom of GSH, the radius and charge of metal ion, and the coordination number of the metal cation with the ligand played important roles in determining the stability of these complexes. Moreover, the intramolecular hydrogen migration in GSH could be promoted by the metal cations during coordination reaction. Furthermore, the Al3+ cation might catalyze the decarboxylation reaction and stimulate the formation of covalent bond between S atom and adjacent O atom of GSH.

Nanoporous Carbohydrate Metal–Organic Frameworks

The binding of alkali and alkaline earth metal cations by macrocyclic and diazamacrobicyclic polyethers, composed of ordered arrays of hard oxygen (and nitrogen) donor atoms, underpinned the development of host-guest supramolecular chemistry in the 1970s and 1980s. The arrangement of -OCCO- and -OCCN- chelating units in these preorganized receptors, including, but not limited to, crown ethers and cryptands, is responsible for the very high binding constants observed for their complexes with Group IA and IIA cations. The cyclodextrins (CDs), cyclic oligosaccharides derived microbiologically from starch, also display this -OCCO- bidentate motif on both their primary and secondary faces. The self-assembly, in aqueous alcohol, of infinite networks of extended structures, which have been termed CD-MOFs, wherein γ-cyclodextrin (γ-CD) is linked by coordination to Group IA and IIA metal cations to form metal-organic frameworks (MOFs), is reported. CD-MOF-1 and CD-MOF-2, prepared on the gram-scale from KOH and RbOH, respectively, form body-centered cubic arrangements of (γ-CD)(6) cubes linked by eight-coordinate alkali metal cations. These cubic CD-MOFs are (i) stable to the removal of solvents, (ii) permanently porous, with surface areas of ~1200 m(2) g(-1), and (iii) capable of storing gases and small molecules within their pores. The fact that the -OCCO- moieties of γ-CD are not prearranged in a manner conducive to encapsulating single metal cations has led to our isolating other infinite frameworks, with different topologies, from salts of Na(+), Cs(+), and Sr(2+). This lack of preorganization is expressed emphatically in the case of Cs(+), where two polymorphs assemble under identical conditions. CD-MOF-3 has the cubic topology observed for CD-MOFs 1 and 2, while CD-MOF-4 displays a channel structure wherein γ-CD tori are perfectly stacked in one dimension in a manner reminiscent of the structures of some γ-CD solvates, but with added crystal stability imparted by metal-ion coordination. These new MOFs demonstrate that the CDs can indeed function as ligands for alkali and alkaline earth metal cations in a manner similar to that found with crown ethers. These inexpensive, green, nanoporous materials exhibit absorption properties which make them realistic candidates for commercial development, not least of all because edible derivatives, fit for human consumption, can be prepared entirely from food-grade ingredients.

Calculation of the hydration energy of polyvalent metal ions by the RISM method

The energy of hydration of Group Ia, IIa, and IIIb metals has been calculated on the basis of the integral equation theory of molecular liquids. Calculations were performed in the RISM approximation with hypernetted chain closure, partial inclusion of the orientation effect, and semiempirical corrections for excluded volume and for the existence of hydrogen bonding with the solute molecule. The analysis of calculation data made it possible to apply a correction to the computation method used, which ensured better convergence between calculation results and experimental data.

The unique bonding characteristics of beryllium and the Group IIA metals

Having closed valence sub-shells, the alkaline earth atoms participate in covalent bonding via orbital hybridization and exchange interactions, with additional contributions from dispersion interactions. Starting from a closed ns2 configuration imparts different characteristics to the chemistry of this group, as compared to metals that have open-shell atomic ground states. Theoretical studies of the bonding of the Group IIA metals have been pursued for many years, and they are known to be challenging for ab initio electronic structure methods. The bonding motifs have been examined, and the differences between beryllium and the remainder of the group explored. Experimental studies that probe the bonding, particularly for beryllium, have lagged behind the theoretical work. In the present Letter we describe our recent spectroscopic and theoretical investigations of simple beryllium compounds, and discuss these results in terms of their relationship to the properties of the heavier Group IIA elements.

ChemInform Abstract: Metal-Ion NMR Studies of Ion Binding

Publisher Summary This chapter covers the studies, where nuclear magnetic resonance (NMR) is used as a tool to investigate the interaction between an ion and another ion or a molecule or an aggregate. The work dealing with ion binding is discussed in the chapter. NMR studies of ion binding correspond to the alkali and alkaline-earth ions. Thus, the chapter describes the small ligands, such as alkali metals, alkaline-earth metals, transition metals, and group IIA and IIIA metals. A number of macromolecules have been studied, using a limited number of NMR sensitive nuclei, owing to the size and complexity of the systems. However, of the available nuclei, both the alkali and the alkaline-earth metals have been used extensively. The metal ions that bind to the macromolecules are alkali metals (23Na and 7Li), alkaline-earth metals (25Mg and 43Ca), transition metals (51V), and thallium (205Tl). The ion binding to aggregates and cells occurs through Gramicidin channels. Finally, the chapter gives an account of the whole-cell studies.

A Study of the Variation of Monovacancy Formation Energy with the Parameter of Ashcroft's Potential and Different Exchange and Correlation Functions for Some Group-IIa and Group-VIII FCC Metals in the Active Divalent State

Graphs of monovacancy formation energy ( ) versus the parameter, , of Ashcroft's empty-core model potential (AECMP) and nine different exchange and correlation functions (ECF) are shown for two different group-IIa divalent fcc metals (Ca and Sr) and seven group-VIII divalent fcc metals in an active valence state (γ-Fe, β-Co, Rh, Ir, Ni, Pd and Pt). The criterion used is that is greater than the Bohr radius. There is a systematic increase and decrease in the fitted value of , and the calculated value of , respectively, in going from one ECF to other, as follows: Sham<K-K<G-V<Kle<Harr<V-S<Hub<Tay<M-D for group-IIa face-centered cubic metals and K-K<G-V<Sham<…..<Tay<Hub<M-D for group-VIII face-centered cubic metals; with a slight variation in between. It should be noted that the inherent simplicity of AECMP makes it difficult to have a universal parameter for all types of atomic property calculations.

Selective conversion of cis-2-butene-1,4-diol to 2-hydroxytetrahydrofuran over K, Ca and Ba metals-promoted Ru/SiO2 catalysts: Role of the promoter

Abstract The effect of K, Ca and Ba metals addition on the catalytic properties of SiO2 supported ruthenium catalysts in the selective liquid phase conversion of cis-2-butene-1,4-diol affording, when hydrogenated, 2-hydroxytetrahydrofuran has been investigated. Catalysts containing 5 wt% Ru and promoted with a different amount of selected first and second group metals salts have been prepared and characterized by TPR, XRD, TEM, FT-IR of adsorbed pyridine and CO. It has been found that promoters modify the microstructural and electronic properties of Ru particles compared with those of the undoped Ru/SiO2 sample, depending on the metal nature and loading. Consequently, the catalytic activity and selectivity towards reaction products, in cis-2-butene-1,4-diol hydrogenation, is strongly affected by the presence of promoters. In particular, K-promoted systems give an excellent selectivity to 2-hydroxytetrahydrofuran but a poor activity; whereas group IIA metals salts addition leads to an enhancement of activity and a slight increase of selectivity to the desired product with respect to the bare Ru sample. The promoted Ru catalysts behaviour is discussed in terms of charge/ionic radius ratio effect of doping cations. Finally, the salient result is the maximum yield to 2-hydroxytetrahydrofuran of 80%, so far obtained, over the sample promoted with the highest potassium loading and mainly attributed to kinetic factors.