74975-65-8Relevant academic research and scientific papers
Solvolysis-decomposition of N-1-adamantyl-N-p-tolylcarbamoyl chloride in hydroxylic solvents
Kevill, Dennis N.,Upadhyay, Veena
, p. 600 - 606 (2007/10/03)
In hydroxylic solvents, N-1-adamantyl-N-p-tolylcarbamoyl chloride undergoes a facile rate-determing ionization with very little assistance from nucleophilic solvation (very low sensitivity to changes in solvent nucleophilicity). In the relatively nucleophilic aqueous ethanol or aqueous acetone, the cation formed reacts directly with the solvent. In fluoroalcohols, the low nucleophilicity of the solvent allows an effective competition from a pathway involving disproportionation to the 1-adamantyl cation and p-tolyl isocyanate, followed by reaction of the new cation either with solvent or with the chloride ion formed in the initial ionization. Grunwald-Winstein plots against Ycl values show for different binary solvent systems a marked dispersion, which can be considerably reduced by incorporation into the analyses of a term governed by the aromatic ring parameter. (I).
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.
Solvolysis in 2,2,2-Trifluoroethanol-Water and 2,2,2-Trifluoroethanol-Etanol Mixtures. Selectivity of the Intermediates and N Values
Kaspi, Joseph,Rappoport, Zvi
, p. 3829 - 3837 (2007/10/02)
Solvolysis of 1-adamantyl bromide (1-Br) in eight TFE-EtOH mixtures gave a Grunwald-Winstein mGW value of 1.50, and the ethyl (1-OEt) and trifluoroethyl (1-OTFE) ethers.The selectivity ratios for reaction with the solvent components kTFE/kEtOH are medium dependent, being 2.60-0.83.In TFE-H2O, mGW = 0.56 and the kTFE/KH2O ratios increase with ΧH2O from 0.49 to 2.04.Solvolysis of 1-anisyl-2-methylpropen-1-yl tosylate (2-OTs) in TFE-EtOH gives mGW = 0.89 and an average kTFE/kEtOH value of 0.086.Methyl tosylate was solvolyzed in several TFE-EtOH and TFE- H2O mixtures and new values of the nucleophilic parameter N were determined.Products were derived from the free cation in the solvolysis of 2-OTs and from the solvent-separated ion pair in the solvolysis of 1-Br, and the selectivities of these species were analyzed.The nucleophilicities of TFE-H2O and TFE-EtOH mixtures and the recent use of the comparison od TFE-H2O and EtOH-H2O mixtures for evaluating solvent participation in solvolysis reactions were discussed.
