Comparison of gas-phase acidities of some carbon acids with their rates of hydron exchange in methanolic methoxide

Vincent F. DeTuri; Heinz F. Koch; Judith G. Koch; Gerrit Lodder; Masaaki Mishima; Han Zuilhof; Neal M. Abrams; Cecily E. Anders; Justin C. Biffinger; Patrick Han; Adam R. Kurland; Jason M. Nichols; Anne M. Ruminski; Patricia R. Smith; Karen D. Vasey

doi:10.1002/poc.1057

Comparison of gas-phase acidities of some carbon acids with their rates of hydron exchange in methanolic methoxide

Vincent F. DeTuri, Heinz F. Koch, Judith G. Koch, Gerrit Lodder, Masaaki Mishima, Han Zuilhof, Neal M. Abrams, Cecily E. Anders, Justin C. Biffinger, Patrick Han, Adam R. Kurland, Jason M. Nichols, Anne M. Ruminski, Patricia R. Smith, Karen D. Vasey

Research output: Contribution to journal › Article › peer-review

8 Citations (Scopus)

Abstract

Hydron exchange reaction rates, k_exch M^-1s ^-1, using methanolic sodium methoxide are compared with gas-phase acidities, ΔG_Acid⁰ kcal/mol, for four 9-YPhenylfluorenes-9-ⁱH, seven YC₆H₄C ⁱH(CF₃)₂, seven YC₆H ₄-CⁱHClCF₃, and C₆F₅ ⁱH. Fourteen of the fluorinated benzylic compounds and pentafluorobenzene result in near unity experimental hydrogen isotope effects that suggest substantial amounts of internal return associated with the exchange process. Although the reactions of 9-phenylfluorene have experimental isotope effects that appear to be normal in value, they do not obey the Swain-Schaad relationship. This suggests that they occur with small amounts of internal return. The entropies of activation, ΔS‡, are +12 to +14 eu, for the benzylic compounds and different significantly from those for the 9-YPhenylfluorenes, ΔS‡ of -8 to -12 eu. The ΔS‡ ∼ 1 eu for the reactions of pentafluorobenzene falls between the other compounds. Density functional calculations using B3LYP/6-31+G(d,p) are reported for the reactions of CH₃O^-(HOCH₃)₃ with C₆F₅H, C₆H₅CH(CF₃) ₂, C₆H₅CHlCF₃, and 9-phenylfluorene.

Original language	English
Pages (from-to)	308-317
Number of pages	10
Journal	Journal of Physical Organic Chemistry
Volume	19
Issue number	5
DOIs	https://doi.org/10.1002/poc.1057
Publication status	Published - 2006 May

Keywords

B3LYP/6-31+G(d,p) calculations
Kinetic acidities
Methanolic sodium methoxide
ΔG (gas phase)

ASJC Scopus subject areas

Physical and Theoretical Chemistry
Organic Chemistry

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10.1002/poc.1057

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DeTuri, V. F., Koch, H. F., Koch, J. G., Lodder, G., Mishima, M., Zuilhof, H., Abrams, N. M., Anders, C. E., Biffinger, J. C., Han, P., Kurland, A. R., Nichols, J. M., Ruminski, A. M., Smith, P. R., & Vasey, K. D. (2006). Comparison of gas-phase acidities of some carbon acids with their rates of hydron exchange in methanolic methoxide. Journal of Physical Organic Chemistry, 19(5), 308-317. https://doi.org/10.1002/poc.1057

DeTuri, VF, Koch, HF, Koch, JG, Lodder, G, Mishima, M, Zuilhof, H, Abrams, NM, Anders, CE, Biffinger, JC, Han, P, Kurland, AR, Nichols, JM, Ruminski, AM, Smith, PR & Vasey, KD 2006, 'Comparison of gas-phase acidities of some carbon acids with their rates of hydron exchange in methanolic methoxide', Journal of Physical Organic Chemistry, vol. 19, no. 5, pp. 308-317. https://doi.org/10.1002/poc.1057

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title = "Comparison of gas-phase acidities of some carbon acids with their rates of hydron exchange in methanolic methoxide",

abstract = "Hydron exchange reaction rates, kexch M-1s -1, using methanolic sodium methoxide are compared with gas-phase acidities, ΔGAcid0 kcal/mol, for four 9-YPhenylfluorenes-9-iH, seven YC6H4C iH(CF3)2, seven YC6H 4-CiHClCF3, and C6F5 iH. Fourteen of the fluorinated benzylic compounds and pentafluorobenzene result in near unity experimental hydrogen isotope effects that suggest substantial amounts of internal return associated with the exchange process. Although the reactions of 9-phenylfluorene have experimental isotope effects that appear to be normal in value, they do not obey the Swain-Schaad relationship. This suggests that they occur with small amounts of internal return. The entropies of activation, ΔS‡, are +12 to +14 eu, for the benzylic compounds and different significantly from those for the 9-YPhenylfluorenes, ΔS‡ of -8 to -12 eu. The ΔS‡ ∼ 1 eu for the reactions of pentafluorobenzene falls between the other compounds. Density functional calculations using B3LYP/6-31+G(d,p) are reported for the reactions of CH3O-(HOCH3)3 with C6F5H, C6H5CH(CF3) 2, C6H5CHlCF3, and 9-phenylfluorene.",

keywords = "B3LYP/6-31+G(d,p) calculations, Kinetic acidities, Methanolic sodium methoxide, ΔG (gas phase)",

author = "DeTuri, {Vincent F.} and Koch, {Heinz F.} and Koch, {Judith G.} and Gerrit Lodder and Masaaki Mishima and Han Zuilhof and Abrams, {Neal M.} and Anders, {Cecily E.} and Biffinger, {Justin C.} and Patrick Han and Kurland, {Adam R.} and Nichols, {Jason M.} and Ruminski, {Anne M.} and Smith, {Patricia R.} and Vasey, {Karen D.}",

year = "2006",

month = may,

doi = "10.1002/poc.1057",

language = "English",

volume = "19",

pages = "308--317",

journal = "Journal of Physical Organic Chemistry",

issn = "0894-3230",

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TY - JOUR

T1 - Comparison of gas-phase acidities of some carbon acids with their rates of hydron exchange in methanolic methoxide

AU - DeTuri, Vincent F.

AU - Koch, Heinz F.

AU - Koch, Judith G.

AU - Lodder, Gerrit

AU - Mishima, Masaaki

AU - Zuilhof, Han

AU - Abrams, Neal M.

AU - Anders, Cecily E.

AU - Biffinger, Justin C.

AU - Han, Patrick

AU - Kurland, Adam R.

AU - Nichols, Jason M.

AU - Ruminski, Anne M.

AU - Smith, Patricia R.

AU - Vasey, Karen D.

PY - 2006/5

Y1 - 2006/5

N2 - Hydron exchange reaction rates, kexch M-1s -1, using methanolic sodium methoxide are compared with gas-phase acidities, ΔGAcid0 kcal/mol, for four 9-YPhenylfluorenes-9-iH, seven YC6H4C iH(CF3)2, seven YC6H 4-CiHClCF3, and C6F5 iH. Fourteen of the fluorinated benzylic compounds and pentafluorobenzene result in near unity experimental hydrogen isotope effects that suggest substantial amounts of internal return associated with the exchange process. Although the reactions of 9-phenylfluorene have experimental isotope effects that appear to be normal in value, they do not obey the Swain-Schaad relationship. This suggests that they occur with small amounts of internal return. The entropies of activation, ΔS‡, are +12 to +14 eu, for the benzylic compounds and different significantly from those for the 9-YPhenylfluorenes, ΔS‡ of -8 to -12 eu. The ΔS‡ ∼ 1 eu for the reactions of pentafluorobenzene falls between the other compounds. Density functional calculations using B3LYP/6-31+G(d,p) are reported for the reactions of CH3O-(HOCH3)3 with C6F5H, C6H5CH(CF3) 2, C6H5CHlCF3, and 9-phenylfluorene.

AB - Hydron exchange reaction rates, kexch M-1s -1, using methanolic sodium methoxide are compared with gas-phase acidities, ΔGAcid0 kcal/mol, for four 9-YPhenylfluorenes-9-iH, seven YC6H4C iH(CF3)2, seven YC6H 4-CiHClCF3, and C6F5 iH. Fourteen of the fluorinated benzylic compounds and pentafluorobenzene result in near unity experimental hydrogen isotope effects that suggest substantial amounts of internal return associated with the exchange process. Although the reactions of 9-phenylfluorene have experimental isotope effects that appear to be normal in value, they do not obey the Swain-Schaad relationship. This suggests that they occur with small amounts of internal return. The entropies of activation, ΔS‡, are +12 to +14 eu, for the benzylic compounds and different significantly from those for the 9-YPhenylfluorenes, ΔS‡ of -8 to -12 eu. The ΔS‡ ∼ 1 eu for the reactions of pentafluorobenzene falls between the other compounds. Density functional calculations using B3LYP/6-31+G(d,p) are reported for the reactions of CH3O-(HOCH3)3 with C6F5H, C6H5CH(CF3) 2, C6H5CHlCF3, and 9-phenylfluorene.

KW - B3LYP/6-31+G(d,p) calculations

KW - Kinetic acidities

KW - Methanolic sodium methoxide

KW - ΔG (gas phase)

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U2 - 10.1002/poc.1057

DO - 10.1002/poc.1057

M3 - Article

AN - SCOPUS:33746151728

SN - 0894-3230

VL - 19

SP - 308

EP - 317

JO - Journal of Physical Organic Chemistry

JF - Journal of Physical Organic Chemistry

IS - 5

ER -

Comparison of gas-phase acidities of some carbon acids with their rates of hydron exchange in methanolic methoxide

Abstract

Keywords

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