Modeling of the Chemico-Physical Process of Protonation of Molecules Entailing Some Quantum Chemical Descriptors

Sandip K. Rajak, Nazmul Islam, Dulal C. Ghosh

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DOI: 10.4236/jqis.2011.12012                

Abstract

Relying upon the basic tenets of scientific modeling, an ansatz for the evaluation of proton affinity of mole-cules are evolved in terms of a four component model. The components of the model chosen are global de-scriptors like ionization energies, global softness, electronegativity and electrophilicity index. These akin quantum mechanical descriptors of atoms and molecules are linked with the charge rearrangement and polarization that occur during the physico-chemical process of protonation of molecules. The suggested ansatz is invoked to compute the protonation energy of as many as 43 compounds of diverse physico-chemical nature viz, hydrocarbons, alcohols, carbonyls, carboxylic acids, esters, aliphatic amines and aromatic amines. A detailed comparative study of theoretically evaluated protonation energies of the above mentioned molecules vis-à-vis their corresponding experimental counterparts reveals that there is a close agreement between the theory and experiment. Thus the results strongly suggest that the proposed modeling and the ansatz for computing PA, the proton affinity, of molecules for studying the physico-chemical process of protonation may be valid proposition.

Keywords

Physico-Chemical Process of Protonation, Proton Affinity, Conceptual Density Functional Descriptors, Commonality between Density Functional Descriptors and Proton Affinity, Muliti-Linear Regression Model

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	R. Stewart, “The Proton: Appellation to Organic Chemistry,” Academic Press, New York, 1985.
[2]	F. A. Carrol, “Per-spectives on Structure and Mechanism in Organic Chemistry,” Brooks-Cole, New York, 1998.
[3]	J. Zhao and R. Zhang, “Proton Transfer Reaction Rate Constants between Hydronium Ion (H3O+) Andvolatile Organic Compounds,” Atmospheric Environment, Vol. 38, No. 14, 2004, pp. 2177-2185. doi:10.1016/j.atmosenv.2004.01.019
[4]	R. A. Kennedy, Ch. A. Mayhew, R. Thomas and P. Watts, “Reactions of H3O+ with a Number of Bromine Containing Fully and Partially Halo-genated Hydrocarbons,” International Journal of Mass Spec-trometry, Vol. 223-224, 2003, pp. 627-637. doi:10.1016/S1387-3806(02)00934-X
[5]	G. Bouchoux, “Gas-Phase Basicities of Polyfunctional molecules Part 1: Theory and Methods,” Mass Spectrometry Reviews, Vol. 26, No. 6, 2007, pp. 775-835. doi:10.1002/mas.20151
[6]	C. A. Deakyne, “Proton Affinities and Gas-Phase Basicities: Theoretical Methods and Structural Effects,” International Journal of Mass Spectrometry, Vol. 227, No. 3, 2003, pp. 601-616. doi:10.1016/S1387-3806(03)00094-0
[7]	S. G. Lias, J. F. Liebman and R. D. Levine, “Evaluated Gas Phase Basicties and Proton Affinityies of Molecules; Heat of Formation of Protonated Molecules,” Journal of Physical and Chemical Reference Data, Vol. 13, No. 3, 1984, pp. 695-808. doi:10.1063/1.555719
[8]	A. Hansel, N. Oberhofer, W. Lindinger, V. A. Zenevich and G. B. Billing, “Vibrational Re-laxation of NO+ (v) in Collisions with CH4: Experimental and Theoretical Studies,” International Journal of Mass Spec-trometry, Vol. 185-187, 1999, pp. 559-563. doi:10.1016/S1387-3806(98)14156-8
[9]	J. N. Bronsted, “Einige Bemerkungen üBer den Begriff der saüRen und Basen,” Recl Trav chim Pays-Bas, Vol. 42, 1923, pp. 718-728.
[10]	G. N. Lewis, “Valence and the Structure of Atoms and Molecules,” Chemical Catalog, New York, 1923.
[11]	M. Meot-Ner, “Ion Thermochemistry of Low-Volatility Com-pounds in the Gas Phase. 2. Intrinsic Basicities and Hydro-gen-Bonded Dimers of Nitrogen Heterocyclics and Nucleic Bases,” Journal of the American Chemical Society, Vol. 101, 1979, pp. 2396-2403. doi:10.1021/ja00503a027
[12]	D. A. Dixon and S. G. Lias, In: J. F. Liebman and A. Greenberg, Eds., Molecular Structure and Energetics, Vol. 2, Physical Measurements, VCH, Deereld Beach, FL, 1987.
[13]	L. A. Curtiss, K. Raghavachari and P. A. Pople, “Gaussian-2 Theory Using Reduced Moller-Plesset Or-ders,” Journal of Chemical Physics, Vol. 98, No. 2, 1993, pp. 1293-1298. doi:10.1063/1.464297
[14]	J. E. Del Bene, “Molecular Orbital Study of the Protonation of DNA Bases,” The Journal of Physical Chemistry, Vol. 87, 1983, pp. 367-371. doi:10.1021/j100225a040
[15]	B. J. Smith and L. Radom, “Calculation of Proton Affinities Using the G2(MP2,SVP) Procedure,” The Journal of Physical Chemistry, Vol. 99, No. 17, 1995,pp. 6468-6471. doi:10.1021/j100017a028
[16]	B. S. Jursic, “Density Functional Theory and Complete Basis Set Ab Initio Evaluation of Proton Affinity for Some Selected Chemical Systems,” Journal of Molecular Structure: THEOCHEM, Vol. 487, No. 1, 1999, pp. 193- 203. doi:10.1016/S0166-1280(99)00154-2
[17]	S. Hammerum, “Heats of Formation and Proton Affinities by the G3 Method,” Chemical Physics Letters, Vol. 300, No. 3-4, 1999, pp. 529-532. doi:10.1016/S0009-2614(98)01439-0
[18]	W. J. Hehre, L. Radom, P. V. R. Schleyer and J. A. Pople, “Ab Initio Molecular Orbital Theory,” John Willey and Sons, New York, 1986.
[19]	J. K. Labanowskiy, R. A. Hill, D. J. Heisterbergy, D. D. Miller, C. F. Bender and J. W. Andzelm, “Proton Affinities Calculated by Traditional Ab Initio Approaches and by Density Functional Methods,” http://www.ccl.net/cca/documents/proton-affinity/affinities.pdf
[20]	J. L. Ozment and A. M. Schmiedekamp, “Proton Affinities of Molecules Containing Nitrogen and Oxygen: Comparing Ab Initio and Semiempirical Results to Experiments,” International Journal of Quantum Chemistry, Vol. 43, No. 6, 1992, pp. 783-800. doi:10.1002/qua.560430606
[21]	M. Eckert-Maksic, M. Klessinger and Z. B. Maksic, “Theoretical Calculations of Proton Affinities in Phenol,” Chemical Physics Letters, Vol. 232, No. 5, 1995, pp. 472- 478. doi:10.1016/0009-2614(94)01383-7
[22]	N. Russo, M. Toscano, A. Grand and T. Mineva, “Proton Affinity and Protonation Sites of Aniline. Energetic Behavior and Density Functional Reactivity Indices,” The Journal of Physical Chemistry A, Vol. 104, No. 17, 2000, pp. 4017-4021. doi:10.1021/jp991949e
[23]	R. Margabandu and K. Subramani, “Comparative Study of Various Quantum Mechanical Descriptors for Prediction of Ionization Constant (pKa) of Substituted Anilines,” International Journal of ChemTech Research, Vol. 2, No. 3, 2010, pp. 1507-1513.
[24]	R. W. Taft, M. Taagepera, J. L. M. Abboud, J. F. Wolf, D. J. DeFrees, W. J. Hehre, J. E. Bartmess and Jr. R. T. McIver, “The Separation of Polarizability and Inductive Effects in Gas- and Solution-Phase Proton-Transfer Equilibriums,” Journal of the American Chemical Society, Vol. 100, No. 24, 1978, pp. 7765-7767. doi:10.1021/ja00492a075
[25]	Z. B. Maksic and R. Vianello, “Quest for the Origin of basicity: Initial vs Final State Effect in Natural Nitrogen Bases,” The Journal of Physical Chemistry A, Vol. 106, No. 2, 2002, pp. 419-430. doi:10.1021/jp013296j
[26]	P. Perez, A. Toro-Labbe and R. Contreras, “A Semiquantitative Description of Electrostatics and Polarization Substituent Effects: Gas-Phase Acid-Base Equilibria as Test Cases,” The Journal of Physical Chemistry A, Vol. 104, No. 51, 2000, pp. 11993-11998. doi:10.1021/jp0025734
[27]	P. Geerlings, F. De Proft and W. Langenaeker, “Conceptual Density Functional Theory,” Chemical Reviews, Vol. 103, 2003, pp. 1793-1873. doi:10.1021/cr990029p
[28]	M. Berkowitz, S. K. Ghosh and R. G. Parr, “On the Concept of Local Hardness in Chemistry,” Journal of the American Chemical Society, Vol. 107, 1985, pp. 6811- 6814. doi:10.1021/ja00310a011
[29]	S. K. Ghosh, M. Berkowitz and R. G. Parr, “Transcription of Ground-State Density-Functional Theory into a Local Thermodynamic,” Proceedings of the National Academy of Sciences, Vol. 81, No. 24, 1984, pp. 8028- 8031. doi:10.1073/pnas.81.24.8028
[30]	C. Hansch and A. Leo, “Substituent Constants for Correlation Analysis in Chemistry and Biology,” John Wiley & Sons, New York, 1979.
[31]	M. V Putz, N. Russo and E. Sicilia, “Atomic Radii Scale and Related Size Properties from Density Functional Electronegativity Formulation,” The Journal of Physical Chemistry A, Vol. 107, 2003, pp. 5461-5465. doi:10.1021/jp027492h
[32]	M. V. Putz, N. Russo and E. Sicilia, “About the Mulliken Electronegativity in DFT,” Theoret Chim Acta, Vol. 114, 2005, pp. 38-45. doi:10.1007/s00214-005-0641-4
[33]	M. V. Putz, “Systematic Formulations for Electronegativity and Hardness and Their Atomic Scales within Density Functional Softness Theory,” International Journal of Quantum Chemistry, Vol. 106, No. 2, 2006, pp. 361-389. doi:10.1002/qua.20787
[34]	M. V. Putz, “Semi Classical Electronegativity and Che- mical Hardness,” Journal of Theoretical and Computational Chemistry, Vol. 6, No. 1, 2007, pp. 33-47.
[35]	M. V. Putz, “Density Functionals of Chemical Bonding,” International Journal of Molecular Sciences, Vol. 9, No. 6, 2008, pp. 1050-1095.
[36]	M. V. Putz, “Electronegativity: Quantum Observable,” International Journal of Quantum Chemistry, Vol. 109, No. 4, 2009, pp. 733-738. doi:10.1002/qua.21957
[37]	L. Tarko and M. V. Putz, “On Electronegativity and Chemical Hardness Relationships with Aromaticity,” Journal of Mathematical Chemistry, Vol. 47, No. 1, 2010, pp. 487-495. doi:10.1007/s10910-009-9585-6
[38]	M. V. Putz, “Chemical Action and Chemical Bonding,” Journal of Molecular Structure: THEOCHEM, Vol. 900, No. 1-3, 2009, pp. 64-70. doi:10.1016/j.theochem.2008.12.026
[39]	R. G. Parr, R. A. Donnelly, M. Levy and W. E. Palke, “Electronegativity: The Density Functional Viewpoint,” Journal of Chemical Physics, Vol. 68, No. 8, 1978, pp. 3801-3807. doi:10.1063/1.436185
[40]	R. G. Parr and R. G. Pearson, “Absolute Hardness: Companion Parameter to Absolute Electronegativity,” Journal of the American Chemical Society, Vol. 105, No. 26, 1983, pp. 7512-7516. doi:10.1021/ja00364a005
[41]	R.G. Parr and W. Yang, “Density Functional Approach to the Frontier-Electron Theory of Chemical Reactivity,” Journal of the American Chemical Society, Vol. 106, No. 14, 1984, pp. 4049-4050. doi:10.1021/ja00326a036
[42]	W. Yang and R. G. Parr, “Hardness, Softness, and the Fukui Function in the Electronic Theory of Metals and Catalysis,” Proceedings of the National Academy of Sciences, Vol. 82, No. 20, 1985, pp. 6723-6726. doi:10.1073/pnas.82.20.6723
[43]	R. G. Parr and W. Yang, “Density Functional Theory of Atoms and Molecules,” Oxford University Press, New York, 1989.
[44]	R. G. Parr, L. V. Szentpaly and S. Liu, “Electrophilicity Index,” Journal of the American Chemical Society, Vol. 121, No. 9, 1999, pp. 1922-1924. doi:10.1021/ja983494x
[45]	D. C. Ghosh, “A Theorrtical Study of Some Selected Molecules and Their Protonation by the Application of CNDO Method,” Premchand Roychand Research Studentship Award, University of Calcutta, 1976.
[46]	T. Chakraborty and D. C. Ghosh, “Computation of the Atomic Radii through the Conjoint Action of the Effective Nuclear Charge and the Ionization Energy,” Molecular Physics, Vol. 108, No. 16, 2010, pp. 2081-2092.
[47]	B. E. Mills, R. L. Martin and D. A. Shirley, “Further Studies of the Core Binding Energy-Proton Affinity Correlation in Molecules,” Journal of the American Chemical Society, Vol. 98, No. 9, 1976, pp. 2380-2385. doi:10.1021/ja00425a002
[48]	L. L. Lohr, “Protonic Counterpart of Electronegativity as an Organizing Principle for Acidity and Basicity,” The Journal of Physical Chemistry, Vol. 88, 1984, pp. 3607- 3611. doi:10.1021/j150660a046
[49]	R. G. Pearson, “Absolute Electronegativity and Hardness Correlated with Molecular Orbital Theory,” Proceedings of the National Academy of Sciences, Vol. 83, No. 22, 1986, pp. 8440-8441. doi:10.1073/pnas.83.22.8440
[50]	P. Chaquin, “Absolute Electronegativity and Hardness: An Analogy with Classical Electrostatics Suggests an Interpretation of the Parr ‘Electrophilicity Index’ as a ‘Global Energy Index’ Leading to the ‘Minimum Electrophilicity Principle,” Chemical Physics Letters, Vol. 458, 2008, pp. 1439-1444.
[51]	S. Noorizadeh, “Is There a Minimum Electrophilicity Principle in Chemical Reactions?” Chinese Journal of Chemistry, Vol. 27, 2007, pp. 1439-1444. doi:10.1002/cjoc.200790266
[52]	N. Islam and D. C. Ghosh, “A New Algorithm for the Evaluation of Equilibrium Inter nuclear Bond Distance of Heteronuclear diatomic Molecule Based on the Hardness Equalization Principle,” The European Physical Journal D—Atomic, Molecular, Optical and Plasma Physics, Vol. 61, No. 2, 2010, pp. 341-348.
[53]	N. Islam and D. C. Ghosh, “A New Radial Dependent Electrostatic Algorithm for the Evaluation of the Electrophilicity Indices of the Atoms,” International Journal of Quantum Chemistry, Vol. 111, No. 14, 2010, pp. 3556- 3564. doi:10.1002/qua.22861
[54]	N. Islam and D. C. Ghosh, “Determination of Some Descriptors of the Real World Working on the Fundamental Identity of the Basic Concept and the Origin of the Electronegativity and the Global Hardness of Atoms. Part 2: Computation of the Dipole Moments of Some Heteronuclear Diatomics,” International Journal of Quantum Chemistry, Vol. 111, No. 12, 2010, pp. 2802-2810. doi:10.1002/qua.22651
[55]	N. Islam and D. C. Ghosh, “Evaluation of Global Hardness of Atoms Based on the Commonality in the Basic Philosophy of the Origin and the Operational Significance of the Electronegativity and the Hardness. Part I. The Gordy’s Scale of Electronegativity and the Global Hardness,” European Journal of Chemistry, Vol. 1, No. 2, 2010, pp. 83-89.
[56]	N. Islam and D. C. Ghosh, “Charge transfer associated with the physical process of hardness equalization and the chemical event of the molecule formation and the dipole moments,” International Journal of Quantum Chemistry, 111, No. 12, 2010, pp. 2811-2819.
[57]	N. Islam and D. C. Ghosh, “Determination of Some Descriptors of the Real World Working on the Fundamental Identity of the Basic Concept and the Origin of the Electronegativity and the Global Hardness of Atoms, Part 1: Evaluation of Internuclear Bond Distance of Some Heteronuclear Diatomics,” International Journal of Quantum Chemistry, 2010, in Press. doi:10.1002/qua.22500
[58]	N. Islam and D. C. Ghosh, “A Quest for the Algorithm for Evaluating the Molecular Hardness,” International Journal of Quantum Chemistry, Vol. 111, No. 9, 2010, pp. 1931-1941. doi:10.1002/qua
[59]	N. Islam and D. C. Ghosh, “Whether There Is a Hardness Equalization Principle Analogous to the Electronegativity qualization Principle—A Quest,” International Journal of Quantum Chemistry, Vol. 111, No. 9, 2010, pp. 1961- 1969. doi:10.1002/qua.22508
[60]	N. Islam and D. C. Ghosh, “Whether Electronegativity and Hardness Are Manifest Two Different Descriptors of the One and the Same Fundamental Property of Atoms— A Quest,” International Journal of Quantum Chemistry, Vol. 111, No. 1, 2009, pp. 40-51. doi:10.1002/qua.22415
[61]	N. Islam and D. C. Ghosh, “A New Algorithm for the Evaluation of the Global Hardness of Poly Atomic Molecules,” Molecular Physics, 2011, Accepted.
[62]	E. P. L. Hunter and S. G. Lias, “Evaluated Gas Phase Basicities and Proton Affinities of Molecules: An update,” Journal of Physical and Chemical Reference Data, Vol. 27, No. 3, 1998, pp. 413-656. doi:10.1063/1.556018
[63]	National Institute of Standards and Technology. http://webbook.nist.gov/chemistry/pa-ser.html.
[64]	T. Wróblewski, L. Ziemczonek, A. M. Alhasan and G. P. Karwasz. http://www.fizyka.umk.pl/~karwasz/.../2007_Ab_initio_and_density_functional.pdf.
[65]	S. G. Lias, J. E. Bartmess, J. F. Liebman, J. L. Holmes, R. D. Levin and W. G. Mallard, “Gas-Phase Ion and Neutral Thermochemistry,” Journal of Physical and Chemical Reference Data, Vol. 17, Suppl. 1, 1988, pp. 1-861. doi:10.1063/1.555819
[66]	PQSMol 1.2-20-win, Parallel Quantum Solutions, LLC. http://www.pqs-chem.com.
[67]	C. Nantasenamat, C. Isarankura-Na-Ayudhya, T. Naenna and V.Prachayasittikul, “A Practical Overview of Quantitative Structure—Activity Relationship,” EXCLI Journal, Vol. 8, 2009, pp. 74-88.
[68]	MINITAB, a Statistical Software of STATSOFT Inc U.S.A.