6221-75-6Relevant academic research and scientific papers
Solvolyis of 1-Adamantyl Nitrate. Y(ONO2) Scale and Product Partitioning in Aqueous Ethanol
Kevill, Dennis N.,Hawkinson, David C.
, p. 5394 - 5399 (1990)
The specific rate of solvolysis of 1-adamantyl nitrate has been measured for four solvents over a range of temperature, including 50.0 deg C, and for 30 additional solvents at 50.0 deg C.Autocatalysis is observed only in 100percent 2,2,2-trifluoroethanol, and this can be removed by addition of pyridine.A scale of solvent ionizing power values (YONO2) is developed in terms of Grunwald-Winstein equation.The YONO2 values correlate well with previously determined YOTs values, with a slope of close to unity.In aqueous ethanol, attack by water is favored.A selectivity value of 1.96 +/- 0.04 is observed in the 90-60percent ethanol range, falling slightly in value in more aqueous mixtures; possible explanations for this fall are discussed.
Essentially Solvent-Independent Rates of Solvolysis of the 1-Adamantyldimethylsulfonium Ion. Implications Regarding Nucleophilic Assistance in Solvolyses of tert-Butyl Derivatives and the NKL Solvent Nucleophilicity Scale
Kevill, Dennis N.,Anderson, Steven W.
, p. 1579 - 1585 (1986)
Rearside nucleophilic solvation of the developing carbocation is severely hindered during the solvolysis of the 1-adamantyldimethylsulfonium ion (1-AdSMe2+).For variation in the composition of binary solvent systems, the ion always shows a variation of the specific rate in the opposite direction to that observed for the tert-butyldimethylsulfonium ion (t-BuSMe2+); these observations are rationalized in terms of a dominanat nucleophilic solvation at the transition state for t-BuSMe2+ solvolysis and a dominanat nucleophilic stabilization of the reactant for 1-AdSMe2+ solvolysis.These systems are compared to the corresponding alkyl halides.Corrections applied in setting up the NKl scale of solvent nucleophilicities would be better based on 1-AdSMe2+ solvolyse.However, the intensitivity of 1-AdSMe2+ solvolyses to solvent variation (specific rates in 41 solventa, at 70.4 deg C, vary by less than a factor of seven) allows log (k/ko)Et3O+ values to be taken as a good measure of solvent nucleophilicity.For solvolyses of 1-AdSMe2+ in aqueous ethanol (ca. 60percent ethanol), the S value (favoring reaction with water) is 1.35 at both 70.6 and 100.1 deg C.
Multiple Pathways in the Solvolysis of 1-Adamantyl Fluoroformate
Kevill, Dennis N.,Kyong, Jin Burm
, p. 258 - 265 (2007/10/02)
Reactions of 1-adamantyl fluoroformate in hydroxylic solvents have been studied.In solvents of high ionizing power and relatively low nucleophilicity, such as 2,2,2-trifluoroethanol-water mixtures, the reactions parallel those of 1-adamantyl chloroformate, and only solvolysis-decomposition reaction is observed.However, differing from the reactions of the corresponding chloroformate, in other solvents appreciable amounts pf attack at acyl carbon occur, more than 90percent in 80percent aqueous ethanol.Entropies of activation for attack at acyl carbon are considerably more negative than for solvolysis-decomposition.For the solvolysis-decomposition, a Grunwald-Winstein m value of 0.70 is observed.The kCl/kF ratios for solvolysis-decomposition are in the range of 104-105, suggesting appreciable C-X bond breaking in the transition state of the rate-determining step and arguing against rate-determining formation of a 1-Ad(1+)(OCOX)(1-) ion pair.Attack at acyl carbon is analyzed in terms of the two-term Grunwald-Winstein equation, and sensitivities toward changes in nucleophilicity and ionizing power are identical to those for solvolyses of n-octyl fluoroformate, which are believed to proceed via a tetrahedral intermediate.For each of the major pathways, selectivities toward the components of binary hydroxylic solvents are reported and discussed.
Solvolysis-Decomposition of 1-Adamantyl Chloroformate: Evidence for Ion Pair Return in 1-Adamantyl Chloride Solvolysis
Kevill, Dennis N.,Kyong, Jin Burm,Weitl, Frederick L.
, p. 4304 - 4311 (2007/10/02)
In hydroxylic solvents, 1-adamantyl chloroformate reacts with loss of carbon dioxide and formation of both solvolysis and decomposition products.The rates of both processes are appreciably sensitive to solvent ionizing power, with the solvolysis slightly more so.The influence of anionic additives is discussed.For mixtures of hydroxylic solvents, the selectivities for the formation of solvolysis products are very similar to those observed in conventional solvolyses of 1-adamantyl derivatives.It is suggested that 1-Ad+Cl- ion pair intermediates are formed, and the observation of collapse requires that an identical collapse, corresponding to internal return, also occurs in 1-adamantyl chloride solvolysis.A comparison with solvolyses of other 1-AdOCOX compounds suggests that the initial ionization is not to 1-Ad+(OCOCl)- and that the 1-Ad+Cl- ion pair is formed either in a concerted process or via a very unstable (1-AdOCO)+Cl- ion pair.
Relative Reactivity of Bridgehead Adamantyl and Homoadamantyl Substrates from Solvolyses with Heptafluorobutyrate as a Highly Reactive Carboxylate Leaving Group. Absence of SN2 Character of Solvolysis of tert-Butyl Derivatives
Farcasiu, Dan,Jaehme, Joachim,Ruechardt, Christoph
, p. 5717 - 5722 (2007/10/02)
Heptafluorobutyrates, conveniently prepared from alcohols, possess a reactivity similar to that of halides in solvolysis reactions.A product and isotope distribution study for the reaction of 1-adamantyl heptafluorobutyrate (1a) in 80:20 ethanol-H2(18)O demonstrated exclusive alkyl-oxygen cleavage.The reactivities of 1a, 1-(2a), and 3-homoadamantyl heptafluorobutyrate (3a) increase with the flexibility of the hydrocarbon skeleton.The rate constants are linearly correlated with the strain increase upon ionization.No acceleration attributable to nucleophilic solvent assistance was evidenced for the tert-butyl ester, 4a.A literature proposal for such assistance in solvolyses of 4 is examined.The existing data are explained better by an SN1 process with electrophilic assistance of the leaving group in the solvents that can form very strong hydrogen bonds.
