Thermochemistry of amineborane adduct formation of pyridine and picoline isomers

Flores, Henoc; Torres, Lizeth

doi:10.1007/bf02275162

Cited by 3 publications

(4 citation statements)

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“…would slowly decompose after prolonged storage at room temperature in ambient atmosphere. Enthalpies for forming adducts are listed in Table together with data from Flores-Segura and Torres , to complement/supplement our determinations for NH 3 and other Lewis bases.…”

Section: Resultsmentioning

confidence: 99%

“… a Conditions: 5 vol % Lewis base/THF and 0.5 M THFBH 3 at 25 °C, unless noted. b Δ H 1 (THF) − Δ H 1 (L) from Table using G3MP2 results. c Values for reaction of 0.1 M THFBH 3 with dilute solutions of amine d Run in 50 vol% Lewis base/THF solution. e Value for pyridine in dilute solution …”

Section: Resultsmentioning

confidence: 99%

“…Calculated gas phase B−N bond energies in methyl substituted NH 3 BH 3 are in semiquantitative agreement with the experimental gas phase values. − Solution-phase calculations have received less attention despite the possibility of differential solvation energies between products and reactants and the wealth of solution-phase measurements available for comparison. For example, Flores-Segura and Torres , measured the enthalpies for forming pyridine and alkyl amine boranes in tetrahydrofuran (THF). The thermochemistry and kinetics of reactions in THF are particularly important because of the wide variety of chemical reactions that can be conducted in this solvent.…”

Section: Introductionmentioning

confidence: 99%

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Thermochemistry of Lewis Adducts of BH₃ and Nucleophilic Substitution of Triethylamine on NH₃BH₃ in Tetrahydrofuran

Potter¹,

Camaioni²,

Vasiliu³

et al. 2010

Inorg. Chem.

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The thermochemistry of the formation of Lewis base adducts of BH(3) in tetrahydrofuran (THF) solution and the gas phase and the kinetics of substitution on ammonia borane by triethylamine are reported. The dative bond energy of Lewis adducts were predicted using density functional theory at the B3LYP/DZVP2 and B3LYP/6-311+G** levels and correlated ab initio molecular orbital theories, including MP2, G3(MP2), and G3(MP2)B3LYP, and compared with available experimental data and accurate CCSD(T)/CBS theory results. The analysis showed that the G3 methods using either the MP2 or the B3LYP geometries reproduce the benchmark results usually to within ~1 kcal/mol. Energies calculated at the MP2/aug-cc-pVTZ level for geometries optimized at the B3LYP/DZVP2 or B3LYP/6-311+G** levels give dative bond energies 2-4 kcal/mol larger than benchmark values. The enthalpies for forming adducts in THF were determined by calorimetry and compared with the calculated energies for the gas phase reaction: THFBH(3) + L → LBH(3) + THF. The formation of NH(3)BH(3) in THF was observed to yield significantly more heat than gas phase dative bond energies predict, consistent with strong solvation of NH(3)BH(3). Substitution of NEt(3) on NH(3)BH(3) is an equilibrium process in THF solution (K ≈ 0.2 at 25 °C). The reaction obeys a reversible bimolecular kinetic rate law with the Arrhenius parameters: log A = 14.7 ± 1.1 and E(a) = 28.1 ± 1.5 kcal/mol. Simulation of the mechanism using the SM8 continuum solvation model shows the reaction most likely proceeds primarily by a classical S(N)2 mechanism.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Thermochemistry of Lewis Adducts of BH₃ and Nucleophilic Substitution of Triethylamine on NH₃BH₃ in Tetrahydrofuran

Potter¹,

Camaioni²,

Vasiliu³

et al. 2010

Inorg. Chem.

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“…For these reasons we are interested in the thermochemistry of amineborane adducts. Recently, the adduct formation enthalpies in THF solution of four amineboranes of pyridine and picoline isomers have been experimentally determined [4]. The thermochemical data show that the coordination bond is more effective in 3-picoline than in the cases of 2-picoline and 4-picoline and this is consistent with the pKa values determined in the same solvent, In order to learn more about the influence of the steric effect and chain length on the enthalpy of formation of amineborane adducts, the current work reports the experimental determination of the enthalpy for the reaction between borane and primary, secondary, and tertiary amines in THF solution.…”

Section: Introductionmentioning

confidence: 99%

Enthalpies of formation of primary, secondary, and tertiary amineborane adducts in tetrahydrofuran solution

Flores

Torres

1997

Struct Chem

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The enthalpies of solution of primary, secondary, and tertiary amines in THF were determined from calorimetric experiments for five primary, five secondary, and three tertiary amines. The enthalpies of formation of amineborane adducts from borane and the corresponding amines in THF solution were also determined. The differences in adduct formation enthalpies from borane and the corresponding amines can be explained by taking into account steric effects and the chain length of the substituents on the amine. In general, as the alkyl chain length, branching, or the number of chains increases, the formation enthalpy of amineborane adducts is less exothermic. That is to say, the steric effect is more important in tertiary and secondary amines than in primary ones. The enthalpy of solution of linear primary amines in THF was more endothermic as the alkyl chain increased and a similar behavior was observed with linear secondary and tertiary ones. An analysis is made of the amine structural factors which affect the amineborane adduct formation.

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Enthalpy of solvation correlations for organic solutes and gases dissolved in 1-propanol and tetrahydrofuran

et al. 2011

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Data have been assembled from the published literature on the enthalpies of solvation for 103 organic vapors and gaseous solutes in 1-propanol and for 86 gaseous compounds in tetrahydrofuran. It is shown that an Abraham solvation equation with five descriptors can be used to correlate the experimental solvation enthalpies to within standard deviations of 2.35 kJ/mole and 2.10 kJ/mole for 1-propanol and tetrahydrofuran, respectively. The derived correlations provide very accurate mathematical descriptions of the measured enthalpy of solvation data at 298 K, which in the case of 1-propanol span a range of 119 kJ/mole. Division of the experimental values into a training set and a test set shows that there is no bias in predictions, and that the predictive capability of the correlations is better than 3.5 kJ/mole.

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Thermochemistry of amineborane adduct formation of pyridine and picoline isomers

Cited by 3 publications

References 6 publications

Thermochemistry of Lewis Adducts of BH₃ and Nucleophilic Substitution of Triethylamine on NH₃BH₃ in Tetrahydrofuran

Thermochemistry of Lewis Adducts of BH₃ and Nucleophilic Substitution of Triethylamine on NH₃BH₃ in Tetrahydrofuran

Enthalpies of formation of primary, secondary, and tertiary amineborane adducts in tetrahydrofuran solution

Enthalpy of solvation correlations for organic solutes and gases dissolved in 1-propanol and tetrahydrofuran

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Thermochemistry of amineborane adduct formation of pyridine and picoline isomers

Cited by 3 publications

References 6 publications

Thermochemistry of Lewis Adducts of BH3 and Nucleophilic Substitution of Triethylamine on NH3BH3 in Tetrahydrofuran

Thermochemistry of Lewis Adducts of BH3 and Nucleophilic Substitution of Triethylamine on NH3BH3 in Tetrahydrofuran

Enthalpies of formation of primary, secondary, and tertiary amineborane adducts in tetrahydrofuran solution

Enthalpy of solvation correlations for organic solutes and gases dissolved in 1-propanol and tetrahydrofuran

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Thermochemistry of Lewis Adducts of BH₃ and Nucleophilic Substitution of Triethylamine on NH₃BH₃ in Tetrahydrofuran

Thermochemistry of Lewis Adducts of BH₃ and Nucleophilic Substitution of Triethylamine on NH₃BH₃ in Tetrahydrofuran