Detail of "59123-41-0"

Reference

Influence of strain on chemical reactivity

Influence of strain on chemical reactivity. Relative reactivity of torsionally distorted double bonds in MCPBA epoxidations. Shea, Kenneth J.; Kim, Jang Seob (Dep. Chem., Univ. California, Irvine, CA 92717, USA). J. Am. 59123-41-0 and 110-82-7 are cas registry numbers. These chemicals are also mentioned in this article. Chem. Soc., 114(8), 3044-51 (English) 1992. CODEN: JACSAT. ISSN: 0002-7863. DOCUMENT TYPE: Journal CA Section: 22 (Physical Organic Chemistry) The second-order reaction rates were measured for the MCPBA epoxidn. in CH2Cl2 for cyclic olefins including bridgehead olefins and trans-cycloalkenes. As expected, strained bridgehead alkenes and trans-cycloalkenes showed faster reaction rates than nonstrained cis-cycloalkenes. The MM-2 steric energies of cycloalkenes, cycloalkanes, and their corresponding epoxides were calcd. to evaluate the strain energy released in each reaction (DSE). Plots of log krel vs. olefin strain did not show a good correlation. However, the plot of log krel vs. DSE (which is defined as the steric energy difference between olefin and the corresponding epoxide) showed a good correlation for each set of di- and trisubstituted olefins. This result means that DSE directly reflects strain energy relief in the transition state. The slope for the plot log krel vs. DSE shows that approx. 42% of strain (DSE) was released in the transition state for the MCPBA epoxidn. Also, trialkyl-substituted alkenes were about 50 times more reactive than dialkyl-substituted alkenes in cases where the strain energy relief (DSE) is the same. The reaction rate is also plotted vs. ionization potential of the olefin, assuming that the major orbital interaction lies between the LUMO of the peracid and the HOMO of the olefin. Although, in some cases, a rough correlation of the reaction rate with the ionization potential of the olefin exists, the frontier orbital interaction is not viewed as the dominant factor since conjugated alkenes, which have higher HOMO energies than simple olefins, are not more reactive in MCPBA epoxidn. .

Acid-catalyzed olefin-alcohol interconversion in the 1-methylcyclooctyl system

Acid-catalyzed olefin-alcohol interconversion in the 1-methylcyclooctyl system. Strain-relief acceleration of the hydration of 1-methyl-trans-cyclooctene. Chiang, Y.; Chwang, W. K.; Kresge, A. J.; Powell, M. F.; Szilagyi, S. (Dep. Chem., Univ. Toronto, Scarborough, ON M1C 1A4, Can.). J. Org. Chem., 49(26), 5218-24 (English) 1984. CODEN: JOCEAH. ISSN: 0022-3263. DOCUMENT TYPE: Journal CA Section: 22 (Physical Organic Chemistry) Rates of reaction with aq. HClO4 were measured for 1-methyl-cis- (I) and -trans-cyclooctene (II) and methylenecyclooctane (III). The only products formed to any significant extent in each of these reactions are 1-methylcyclooctanol and the cis-cycloalkene, but both II and III give these products in initially nonequil. proportions: [ROH]/[I] = 1.27 ± 0.05 at equil., 15.1 ± 0.9 from II and 0.44 ± 0.05 from III. This indicates the existence of 2 conformationally different 1-methylcyclooctyl carbocationic intermediates in these reactions, an unstable crown (or twist) cation formed by protonation of II and a (conformationally) stable boat-chair cation formed from I, III and the alc. The barrier for interconversion of these 2 cations is estd. as DGG = 5.3 ± 0.6 kcal mol-1. The barrier for hydration of either cation to the alc. is also estd., by 2 different methods, as DGG = 3.6 ± 0.6 or 4.3 ± 0.3 kcal mol-1. The smallness of these barriers suggests that the reaction of tertiary aliph.Chemical with cas number 59123-41-0 also plays role. carbocations with H2O is essentially an unactivated process. These ests., plus the rate and equil. consts. measured here, allow a nearly complete free-energy characterization of the 1-methylcyclooctyl system. The rates of reaction of I and III with H3O+ are normal, but strain relief accelerates the rate for II by a factor of 18,500. .