In Spite of the Chemist's Belief: Carbonic Acid Is Surprisingly Stable

Ludwig, Ralf; Kornath, Andreas

doi:10.1002/(sici)1521-3773(20000417)39:8<1421::aid-anie1421>3.0.co;2-p

Cited by 39 publications

(25 citation statements)

References 12 publications

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“…2,3 Carbonic acid also attracted a significant amount of theoretical attention, but the question of whether bare carbonic acid can exist as a stable species remained a topic of discussion for many years. 2,3 Carbonic acid also attracted a significant amount of theoretical attention, but the question of whether bare carbonic acid can exist as a stable species remained a topic of discussion for many years.…”

Section: Introductionmentioning

confidence: 99%

Dissociation of carbonic acid: Gas phase energetics and mechanism from ab initio metadynamics simulations

Kumar

Kalinichev

Kirkpatrick

2007

The Journal of Chemical Physics

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A comprehensive metadynamics study of the energetics, stability, conformational changes, and mechanism of dissociation of gas phase carbonic acid, H2CO3, yields significant new insight into these reactions. The equilibrium geometries, vibrational frequencies, and conformer energies calculated using the density functional theory are in good agreement with the previous theoretical predictions. At 315 K, the cis-cis conformer has a very short life time and transforms easily to the cis-trans conformer through a change in the O=C-O-H dihedral angle. The energy difference between the trans-trans and cis-trans conformers is very small (approximately 1 kcal/mol), but the trans-trans conformer is resistant to dissociation to carbon dioxide and water. The cis-trans conformer has a relatively short path for one of its hydroxyl groups to accept the proton from the other end of the molecule, resulting in a lower activation barrier for dissociation. Comparison of the free and potential energies of dissociation shows that the entropic contribution to the dissociation energy is less than 10%. The potential energy barrier for dissociation of H2CO3 to CO2 and H2O from the metadynamics calculations is 5-6 kcal/mol lower than in previous 0 K studies, possibly due to a combination of a finite temperature and more efficient sampling of the energy landscape in the metadynamics calculations. Gas phase carbonic acid dissociation is triggered by the dehydroxylation of one of the hydroxyl groups, which reorients as it approaches the proton on the other end of the molecule, thus facilitating a favorable H-O-H angle for the formation of a product H2O molecule. The major atomic reorganization of the other part of the molecule is a gradual straightening of the O=C=O bond. The metadynamics results provide a basis for future simulation of the more challenging carbonic acid-water system.

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Section: Introductionmentioning

confidence: 99%

Dissociation of carbonic acid: Gas phase energetics and mechanism from ab initio metadynamics simulations

Kumar

Kalinichev

Kirkpatrick

2007

The Journal of Chemical Physics

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“…In many inorganic chemistry textbooks it is still reported that the molecules sulfurous acid (H 2 SO 3 ) and carbonic acid (H 2 CO 3 ) cannot be isolated in (water‐)free form 1–5. However, this picture has been partially revised in the last couple of years since it has become possible to prepare and isolate carbonic acid by several methods6–12 and to show its remarkable kinetic stability 11, 13…”

Section: Introductionmentioning

confidence: 99%

About the Stability of Sulfurous Acid (H2SO3) and Its Dimer

Voegele¹,

Tautermann²,

Loerting³

et al. 2002

Chem. Eur. J.

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A series of optically active helical polyphosphazene block copolymers of general formula R[NP(O2C20H12)]n‐b‐[NPMePh]m (R‐7 a–c) was synthesized and characterized. The polymers were prepared by sequential living cationic polycondensation of N‐silylphosphoranimines using the mono‐end‐capped initiator [Ph3PNPCl3][PCl6] (5) and exhibit a low polydispersity index (ca. 1.3). The temperature dependence of the specific optical activity ([α]D) of R‐7 a,b relative to that for the homopolymers R‐[NP(O2C20H12)]n (R‐8 a) and the R/S analogues (R/S‐7 a,b), revealed that the binaphthoxy–phosphazene segments induce a preferential helical conformation in the [NPMePh] blocks through a “sergeant‐and‐soldiers” mechanism, an effect that is unprecedented in polyphosphazenes. The self‐assembly of drop‐cast thin films of the chiral block copolymer R‐7 b (bearing a long chiral and rigid R[NP(O2C20H12)] segment) evidenced a transfer of helicity mechanism, leading to the formation of twisted morphologies (twisted “pearl necklace”), not observed in the nonchiral R/S‐7 b. The chiral R‐7 a and the nonchiral R/S‐7 a, self‐assemble by a nondirected morphology reconstruction process into regular‐shaped macroporous films with chiral‐rich areas close to edge of the pore. This is the first nontemplate self‐assembly route to chiral macroporous polymeric films with pore size larger than 50 nm. The solvent annealing (THF) of these films leads to the formation of regular spherical nanostructures (ca. 50 nm), a rare example of nanospheres exclusively formed by synthetic helical polymers.

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“…[1][2][3][4][5] Whereas H 2 O·CO 2 has been characterized by spectroscopy, [6,7] there is only indirect experimental evidence for the existence of H 2 CO 3 in the gas phase. [1][2][3][4][5] Whereas H 2 O·CO 2 has been characterized by spectroscopy, [6,7] there is only indirect experimental evidence for the existence of H 2 CO 3 in the gas phase.…”

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confidence: 99%

“…

Carbonic acid, H 2 CO 3 , and its isomeric weakly bound H 2 O·CO 2 complex are short-lived intermediates in the hydrolysis of CO 2 , a process of fundamental importance in geochemistry and biology. [1,3] Theoretical calculations predict that isolated H 2 CO 3 should be stable but that it decomposes into H 2 O and CO 2 in the presence of water. [1,3] Theoretical calculations predict that isolated H 2 CO 3 should be stable but that it decomposes into H 2 O and CO 2 in the presence of water.

…”

mentioning

confidence: 99%

IR Spectra of Protonated Carbonic Acid and Its Isomeric H₃O⁺⋅CO₂ Complex

Andrei¹,

Nizkorodov²,

Dopfer³

2007

Angew Chem Int Ed

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The authors of this Communication wish to correct a remark in their introductory paragraph: "There have been several unsuccessful attempts to generate and characterize gas-phase H 2 CO 3 by heating solid H 2 CO 3 [3] or NH 4 HCO 3. [12] " This statement is incorrect and misleading, and the authors apologize for their oversight. The sentence should read: "Although there have been several successful attempts to generate and identify gas-phase H 2 CO 3 by heating solid H 2 CO 3 [3] or NH 4 HCO 3 , [12] there is still a lack of detailed experimental information on its structural, spectroscopic, and thermochemical properties."

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In Spite of the Chemist's Belief: Carbonic Acid Is Surprisingly Stable

Cited by 39 publications

References 12 publications

Dissociation of carbonic acid: Gas phase energetics and mechanism from ab initio metadynamics simulations

Dissociation of carbonic acid: Gas phase energetics and mechanism from ab initio metadynamics simulations

About the Stability of Sulfurous Acid (H2SO3) and Its Dimer

IR Spectra of Protonated Carbonic Acid and Its Isomeric H₃O⁺⋅CO₂ Complex

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In Spite of the Chemist's Belief: Carbonic Acid Is Surprisingly Stable

Cited by 39 publications

References 12 publications

Dissociation of carbonic acid: Gas phase energetics and mechanism from ab initio metadynamics simulations

Dissociation of carbonic acid: Gas phase energetics and mechanism from ab initio metadynamics simulations

About the Stability of Sulfurous Acid (H2SO3) and Its Dimer

IR Spectra of Protonated Carbonic Acid and Its Isomeric H3O+⋅CO2 Complex

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IR Spectra of Protonated Carbonic Acid and Its Isomeric H₃O⁺⋅CO₂ Complex