On the gas-phase reactivity of complexed OH+ with halogenated alkanes

Adlhart, Christian; Sekiguchi, Osamu; Uggerud, Einar

doi:10.1002/chem.200400699

Publication type:	Article in scientific journal
Type of review:	Peer review (publication)
Title:	On the gas-phase reactivity of complexed OH+ with halogenated alkanes
Authors:	Adlhart, Christian Sekiguchi, Osamu Uggerud, Einar
DOI:	10.1002/chem.200400699
Published in:	Chemistry - A European Journal
Volume(Issue):	11
Issue:	1
Page(s):	152
Pages to:	159
Issue Date:	2005
Publisher / Ed. Institution:	Wiley
Publisher / Ed. Institution:	Weinheim
ISSN:	0947-6539 1521-3765
Language:	English
Subjects:	C-h activation; Proton affinities; Oxidation; Peroxide
Subject (DDC):	540: Chemistry
Abstract:	OH+ is an extraordinarily strong oxidant. Complexed forms (LOH+), such as H2OOH+, H3NOH+, or iron–porphyrin‐OH+ are the anticipated oxidants in many chemical reactions. While these molecules are typically not stable in solution, their isolation can be achieved in the gas phase. We report a systematic survey of the influence on L on the reactivity of LOH+ towards alkanes and halogenated alkanes, showing the tremendous influence of L on the reactivity of LOH+. With the help of with quantum chemical calculations, detailed mechanistic insights on these very general reactions are gained. The gas‐phase pseudo‐first‐order reaction rates of H2OOH+, H3NOH+, and protonated 4‐picoline‐N‐oxide towards isobutane and different halogenated alkanes CnH2n+1Cl (n=1–4), HCF3, CF4, and CF2Cl2 have been determined by means of Fourier transform ion cyclotron resonance meaurements. Reaction rates for H2OOH+ are generally fast (7.2×10−10–3.0×10−9 cm3 mol−1 s−1) and only in the cases HCF3 and CF4 no reactivity is observed. In contrast to this H3NOH+ only reacts with tC4H9Cl (kobs=9.2×10−10), while 4‐CH3‐C5H4N‐OH+ is completely unreactive. While H2OOH+ oxidizes alkanes by an initial hydride abstraction upon formation of a carbocation, it reacts with halogenated alkanes at the chlorine atom. Two mechanistic scenarios, namely oxidation at the halogen atom or proton transfer are found. Accurate proton affinities for HOOH, NH2OH, a series of alkanes CnH2n+2 (n=1–4), and halogenated alkanes CnH2n+1Cl (n=1–4), HCF3, CF4, and CF2Cl2, were calculated by using the G3 method and are in excellent agreement with experimental values, where available. The G3 enthalpies of reaction are also consistent with the observed products. The tendency for oxidation of alkanes by hydride abstraction is expressed in terms of G3 hydride affinities of the corresponding cationic products CnH2n+1+ (n=1–4) and CnH2nCl+ (n=1–4). The hypersurface for the reaction of H2OOH+ with CH3Cl and C2H5Cl was calculated at the B3 LYP, MP2, and G3m* level, underlining the three mechanistic scenarios in which the reaction is either induced by oxidation at the hydrogen or the halogen atom, or by proton transfer.
URI:	https://digitalcollection.zhaw.ch/handle/11475/2108
Fulltext version:	Published version
License (according to publishing contract):	Licence according to publishing contract
Departement:	Life Sciences and Facility Management
Organisational Unit:	Institute of Chemistry and Biotechnology (ICBT)
Appears in collections:	Publikationen Life Sciences und Facility Management

Files in This Item:

There are no files associated with this item.

Show full item record

Adlhart, C., Sekiguchi, O., & Uggerud, E. (2005). On the gas-phase reactivity of complexed OH+ with halogenated alkanes. Chemistry - A European Journal, 11(1), 152–159. https://doi.org/10.1002/chem.200400699

Adlhart, C., Sekiguchi, O. and Uggerud, E. (2005) ‘On the gas-phase reactivity of complexed OH+ with halogenated alkanes’, Chemistry - A European Journal, 11(1), pp. 152–159. Available at: https://doi.org/10.1002/chem.200400699.

C. Adlhart, O. Sekiguchi, and E. Uggerud, “On the gas-phase reactivity of complexed OH+ with halogenated alkanes,” Chemistry - A European Journal, vol. 11, no. 1, pp. 152–159, 2005, doi: 10.1002/chem.200400699.

ADLHART, Christian, Osamu SEKIGUCHI und Einar UGGERUD, 2005. On the gas-phase reactivity of complexed OH+ with halogenated alkanes. Chemistry - A European Journal. 2005. Bd. 11, Nr. 1, S. 152–159. DOI 10.1002/chem.200400699

Adlhart, Christian, Osamu Sekiguchi, and Einar Uggerud. 2005. “On the Gas-Phase Reactivity of Complexed OH+ with Halogenated Alkanes.” Chemistry - A European Journal 11 (1): 152–59. https://doi.org/10.1002/chem.200400699.

Adlhart, Christian, et al. “On the Gas-Phase Reactivity of Complexed OH+ with Halogenated Alkanes.” Chemistry - A European Journal, vol. 11, no. 1, 2005, pp. 152–59, https://doi.org/10.1002/chem.200400699.