Thermodynamic Calculations for Reactions Involving Hydrogen Halide Polymers, Ions, and Lewis Acid Adducts. 3. Systems Constituted from Al³⁺, H⁺, and Cl^-

Abstract

Semiempirical (MNDO, AM1 and PM3), ab initio (HF/3-21+G(d,p), MP2/3-21+G(d,p), HF/6-311+G(d,p), and MP2/6-311+G(d,p)), and density functional (BVWN/3-21+G(d,p) and BVWN/6-311+G(d,p)) energy minimization and frequency calculations have been carried out on AlCl(3), AlCl(4)(-), AlCl(2)(+), HAlCl(4), HAlCl(3)(+), and ClHAlCl(4)(-). The same computational set, except for MP2/6-311+G(d,p) frequency calculations, was performed on Al(2)Cl(6) and Al(2)Cl(7)(-). For ClHAl(2)Cl(7)(-), only semiempirical calculations, as well as Hartree-Fock and BVWN optimizations using the 3-21+G(d,p) and 6-311+G(d,p) basis sets, were carried out along with Hartree-Fock frequency determinations. DeltaG degrees, DeltaH degrees, and DeltaS degrees values have been calculated for a number of reactions involving these species along with a variety of ions derived from HCl. Thermodynamic data and equilibrium constants at 298 K are presented for 22 reactions using calculations at the best level, along with a comparison of DeltaG degrees values obtained from all molecular orbital methods used.

Catalyzed β scission of a carbenium ion — Mechanistic differences from varying catalyst basicity

“…Second, the 1998 FKRS study (24) with pentenium ion and AlH 2 (OH) 2 G was incomplete, and we wished to make use of the stationary points they had. Third, the AlHCl 3 G catalyst was chosen from our exploratory ionic liquid calculations (33), which suggest that the active Al 2 Cl 7 G Lewis acid anion (34,35) will create AlHCl 3 G upon hydride abstraction from an alkane.…”

Once‐a‐Day Controlled‐Release Dosage Form of Divalproex Sodium II: Development of a Predictive In Vitro Drug Release Method

“…In this article, equilibrium thermodynamics were used to predict the composition of an EMIM‐Cl/chloroaluminate IL as a function of HCl partial pressure above the mixture at room‐temperature. Chandler and Johnson2 modeled basic, neutral, and Lewis acidic chloroaluminate IL's using a collection of 22 elementary reactions to describe the species present in these materials. They predicted the free energies of formation for species appearing in the elementary reactions using semiempirical and higher‐level quantum mechanical calculations.…”

“…Subsets were used of these six reactions and the corresponding equilibrium constants2 to model the IL under the desired conditions. For example, when no HCl was added to the system, then only the first three reactions were used when [AlCl 3 /𝒪 + ]° ratio was >2, and only the first two reactions were needed for the case when 1 < [AlCl 3 /𝒪 + ]° < 2.…”

Predicting the composition of acidic, ionic liquids in contact with HCl gas

“…This equilibrium would explain the decrease in the NMR signal attributed to the Lewis acid, Al 2 Cl 7 Ϫ , but it would not explain the existence of the superacidic activity documented by the toluene carbonylation reaction since H ϩ AlCl 4 Ϫ is said to exhibit an acidity similar to HF. 2 The acidity of HF alone is not sufficient to catalyze the arene carbonylation reaction. The predictions shown here and the results of the carbonylation reaction suggest that a reexamination is necessary of the NMR assignments reported by Nara et al 6 The calculations completed here assumed one structure existed for the dimeric, Bronsted acidic, anionic species: ClHAl 2 Cl 7 Ϫ (Figure 11a).…”

“…Given the uncertainty in the model predictions for these energy functions, we must admit that both new structures are possible and they may exist in equilibrium with the structure proposed by Chandler and Johnson. 2 Additionally, we can examine the effect of these free energies of formation upon the equilibrium constant for reaction 6 in the manuscript Each structure is shown with the ethyl-methyl imidazolium cation. The new equilibrium constants are different by only 1-2% from that reported by Chandler and Johnson, 2 depending on the model used to determine the free energy of formation.…”