Kinetic Study of the Nitrolysis of Haloadamantanes
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tic Study of the Nitrolysis of Haloadamantanes Yu. N. Klimochkina, E. A. Ivlevaa,*, and M. Yu. Skomorokhovb a
Samara State Technical University, Samara, 443100 Russia b
Olainfarm Joint Stock Company, Olaine, 2114 Latvia *e-mail: [email protected]
Received April 30, 2020; revised May 3, 2020; accepted May 16, 2020
Abstract—The kinetics of nitrolysis of haloadamantanes containing halogen atoms in the bridging and bridgehead positions with fuming nitric acid have been studied. The effective nitrolysis constants of eight haloadamantane derivatives have been determined. The reaction is described by pseudo-first-order kinetic equation, and the reactivity decreases as the number of halogen atoms in the substrate molecule increases. Haloadamantanes with less electronegative halogens show higher reactivity. Keywords: kinetics, haloadamantanes, nitrolysis, mechanism, fuming nitric acid, reactivity
DOI: 10.1134/S1070428020090043 Polyfunctional adamantane derivatives are key starting materials in the synthesis of biologically active compounds and advanced materials [1–5]. Among them, polyhalogenated adamantanes are most synthetically accessible. For example, 1,3-dibromoadamantane is used as a molecular scaffold in the design of metal– organic frameworks [6] and polymeric materials [7, 8] and synthesis of biologically active compounds [9–11] and alkylboronic acid esters for cross-coupling reactions and medicinal chemistry [12, 13]. 1,3-Dibromoadamantane was reported to undergo transformations accompanied by change of the molecular skeleton [14–17]. The synthetic potential of 1,3-dichloroand 1,3-difluoroadamantanes has been explored to a lesser extent [18, 19]. 1,3,5-Tribromoadamantane is the basic structural unit of tripod systems [20, 21] and is used to obtain other polyfunctionalized adamantane derivatives [22]. Until present, nucleophilic substitution in the haloadamantane series [23–29] and anodic oxidation of these compounds [30–33] have been well documented. On the other hand, only a few data are available on reactions of haloadamantanes involving oxidative cleavage of the C–Hlg bond [34]. In continuation of our studies on the mechanisms of oxidation of cage substrates [35–37], herein we report some kinetic data for the nitrolysis of polyhaloadamantanes. The nitrolysis of haloalkanes with nitric acid was studied in [38]. It was presumed that heterolytic dissociation of the C–Hlg bond in nitric acid gives the
corresponding carbocation which is then stabilized by nitrate ion to form alkyl nitrate as a final product. Treatment of 1-haloadamantanes with fuming nitric acid was reported to afford adamantan-1-yl nitrate and adamantane-1,3-diyl dinitrate [39]; in the reaction of 2-haloadamantanes with nitric acid, the nytrolysis of the C–Hlg bond was accompanied by oxidation to adamantan-2-one [40]. Cleavage of the C–Hlg bond is likely to involve one-electron transfer with the formation of adamantyl radical cation which then decomposes to adamantyl cation and halogen atom. This was confirmed by photoelectron spectra o
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