Intramolecular kinetic isotope effect in hydride transfer from dihydroacridine to a quinolinium ion. Rejection of a proposed two-step mechanism with a kinetically significant intermediate

Perrin, Charles L.; Zhao, Chen

doi:10.1039/b806869k

Cited by 19 publications

(3 citation statements)

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“…We demonstrated that isotopic perturbation of resonance is real, in a series of metal complexes . We measured the intramolecular KIE for hydride transfer from an NADH model to a quinolinium ion and found that it is inconsistent with the intermolecular IEs that had been claimed as evidence for a two‐step mechanism.…”

Section: Researchmentioning

confidence: 91%

Half a century of research, teaching, service

Perrin

2014

J of Physical Organic Chem

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This is a summary of the research of Charles L. Perrin and his coworkers in the areas of aromatic mercuration, vibronic borrowing, ipso factors in electrophilic aromatic substitution, malonic anhydrides, mechanisms of proton exchange in amides, stereoelectronic control, the socalled reverse anomeric effect, an NMR titration method for highly accurate measurement of relative acidities, secondary deuterium isotope effects on acidity, symmetry of hydrogen bonds in solution, and nucleophilic addition to a para-benzyne diradical, along with Perrin's contributions to teaching and to service. Keywords:hydrogen bonds para-benzyne NMR titration isotope effects stereoelectronic control reverse anomeric effect vibronic borrowing electrophilic aromatic substitution malonic anhydrides proton exchange in amides Special thanks go to my dear wife Marilyn for her presence and support during these fifty years and for preparing a delicious dinner for the speakers and out-of-town guests the night before the symposium.After 50 years at UCSD I am still not retired but continue to enjoy teaching and research.

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Section: Researchmentioning

confidence: 91%

Half a century of research, teaching, service

Perrin

2014

J of Physical Organic Chem

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“…Since 1 H and 2 H are often used as good hydride donors, − 2 + and 7 (MeO) + are often used as good hydride acceptors, , and the corresponding KIE self values of the three hydride self-exchange reactions in acetonitrile at 298 K have been determined, it is not difficult to get the KIE self values of any another hydride self-exchange reactions XH + X + →X + + XH in acetonitrile at 298 K as long as the KIE value of the related hydride cross transfer reaction that one reactant is one of 1 H, 2 H, 2 + and 7 (MeO) + (eqs –) and their extension can be determined in acetonitrile at 298 K. In this work, the KIE self values of 68 hydride self-exchange reactions (XH/X + ) in acetonitrile at 298 K (see Table ) were obtained from the KIE values of the corresponding 68 hydride cross transfer reactions in acetonitrile at 298 K according to eq . All of the latter values can be determined using the stopped-flow UV–vis method in our laboratory, and the detailed results are listed in Table . …”

Section: Determination Of Kieselfmentioning

confidence: 99%

Prediction of Kinetic Isotope Effects for Various Hydride Transfer Reactions Using a New Kinetic Model

Shen

Xia

et al. 2016

J. Phys. Chem. A

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In this work, kinetic isotope effect (KIEself) values of 68 hydride self-exchange reactions, XH(D) + X(+) → X(+) + XH(D), in acetonitrile at 298 K were determined using a new experimental method. KIE values of 4556 hydride cross transfer reactions, XH(D) + Y(+) → X(+) + YH(D), in acetonitrile were estimated from the 68 determined KIEself values of hydride self-exchange reactions using a new KIE relation formula derived from Zhu's kinetic equation and the reliability of the estimations was verified using different experimental methods. A new KIE kinetic model to explain and predict KIE values was developed according to Zhu's kinetic model using two different Morse free energy curves instead of one Morse free energy curve in the traditional KIE theories to describe the free energy changes of X-H bond and X-D bond dissociation in chemical reactions. The most significant contribution of this paper to KIE theory is to build a new KIE kinetic model, which can be used to not only uniformly explain the various (normal, enormous and inverse) KIE values but also safely prodict KIE values of various chemical reactions.

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“…In connection with our interest in hydrogen tunneling, the intramolecular KIE for hydride transfer from 10-methyl-9,10-dihydroacridine- d ( 42 - d ) to 1-benzyl-3-cyanoquinolinium ion ( 43 ) (Scheme ) was measured by NMR (and by mass spectrometry) . The result, k H / k D = 5–6, is a very ordinary and anticlimactic KIE, inconsistent with the unusually high intermolecular KIEs, attributed to tunneling, that were derived by fitting the kinetics of reactions of 42 and 42 - d 2 with 43 to a two-step mechanism with an intermediate complex .…”

Section: Primary Kinetic Isotope Effectsmentioning

confidence: 99%

The Logic behind a Physical–Organic Chemist’s Research Topics

Perrin

2016

J. Org. Chem.

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Abstract. Although my research has no common theme or defining area, a coherence connects the diverse topics, insofar as one project leads logically to another. Thus studies on mechanisms of hydrogen exchange in amides and amidines led to the influence of hydrogenbonding and to NMR methods for chemical kinetics, including 2D-EXSY spectroscopy.Another connection was the OH --catalyzed NH exchange in amines that had supported the hypothesis of stereoelectronic control. We therefore analyzed that hypothesis critically, tested it, found counterexamples, and proposed an alternative hypothesis. We next addressed one-bond NMR coupling constants in ethers and the reverse anomeric effect. The latter studies required a highly accurate NMR titration method that we developed to measure the additional steric bulk resulting from protonation of a substituent. This method is also applicable to measuring secondary isotope effects on acidity, and we could demonstrate that they arise from n-* delocalization, not from an inductive effect. Other studies included kinetic isotope effects for both dissociation and H exchange of aqueous NH 4 + , for C-N rotation in amides, and for a hydride transfer. The role of hydrogen-bonding led us to the rotation of NH 4 + within its solvent cage and then to the symmetry of hydrogen bonds. This review article is based on an address presented at the 249th National Meeting of the American Chemical Society in Denver CO, on the occasion of the James Flack Norris Award in Physical-Organic Chemistry. 1 It demonstrates the ways whereby one physicalorganic chemist, and physical-organic chemists in general, have investigated how molecular structure affects chemical reactivity. It also seeks to confirm my claim that "In my opinion, 2 physical organic chemistry represents the intellectual basis of organic chemistry. It asks (and answers!) fundamental questions about how chemical substances behave, and it rationalizes that behavior." 2 The reason that I won the James Flack Norris Award was for my "insight, rigorous analysis, and understanding of mechanisms and reactive intermediates", rather than any distinctive area of research with which I am associated. Instead of choosing one area to review here, I have tried to describe the path of my research for the past 40 years, as an expansion of an earlier article on this topic. 3 Each area seems to have engendered additional questions, leading to additional areas. Often those questions are marked by an intense skepticism, and the answers to those questions are supported by a logical analysis that I am proud of. I hope that this article will be as interesting, informative, and enjoyable to the reader as the research described here has been for me. A Beginner's ResearchMy Ph.D. thesis research was on mercuration of benzene, an electrophilic aromatic substitution that is accelerated by strong acid, and where we measured the H/D kinetic isotope effect. 4 To understand the origin of the acceleration it was necessary to consider acidity functions, including a new one, H...

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Intramolecular kinetic isotope effect in hydride transfer from dihydroacridine to a quinolinium ion. Rejection of a proposed two-step mechanism with a kinetically significant intermediate

Cited by 19 publications

References 32 publications

Half a century of research, teaching, service

Half a century of research, teaching, service

Prediction of Kinetic Isotope Effects for Various Hydride Transfer Reactions Using a New Kinetic Model

The Logic behind a Physical–Organic Chemist’s Research Topics

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