25319-53-3Relevant academic research and scientific papers
The application of resolution enhancement techniques to the study of factors affecting group frequencies - I. Coupling of symmetric methyl deformation frequencies in o-xylene
Mayo, D. W.,Bellamy, L. J.,Merklin, G. T.
, p. 355 - 358 (1985)
Deconvolution of methyl symmetric deformation frequencies of o-, m- and p-xylene yields a fully resolved doublet with 10 cm-1 spacing in o-xylene, but singlets in m- and p-xylene.Resolution enhancement of the methyl bending mode of 1-methyl-2--benzene yields a single band near 1380 cm-1.The relative intensity of the heavy to light band systems is 0.4.The data indicate that spatial coupling exists between the symmetric methyl deformation modes of o-xylene.
Evidence for an intermediate in the methylation of CB11H 12- with methyl triflate: Comparison of electrophilic substitution in cage boranes and in arenes
Kaleta, Jiri,Akdag, Akin,Crespo, Rauel,Piqueras, Mari-Carmen,Michl, Josef
, p. 1174 - 1183 (2013)
The trideuteriomethylation of BH vertices in CB11H 12- and its derivatives with CD3OTf (OTf=triflate, trifluoromethanesulfonate) yields a mixture of B-CD3 and B-CHD2 substitution products, thus demonstrating the intermediacy of a species with a long enough lifetime for hydrogen scrambling between the boron vertex and the methyl substituent. No such scrambling is observed if CD3OTf is used to methylate toluene. According to density functional theory calculations, the intermediate in BH vertex methylation is a three-center bonded σadduct of a methyl cation to the BH bond and the proton scrambling occurs via a transition structure containing a distorted square-pyramidal methane attached axially to a naked boron vertex. The subsequent proton or deuteron loss is presently not understood in detail. A general comparison of electrophilic substitution on closo-boranes and arenes is provided and similarities as well as differences are discussed. A recalculation of the optimized geometry of the CB11Me12. radical produced a second Jahn-Teller distorted minimum and resulted in a somewhat improved agreement between calculated and measured proton hyperfine coupling constants. Scrambled protons: Methylation of HCB11H 12- and similar anions with deuterated methyl triflate (CD3OTf) produces a mixture of CD3- and CHD 2-substituted anions (see scheme), thus demonstrating that the reaction mechanism involves an intermediate in which protons can scramble. A comparison with electrophilic substitution on arenes shows similarities and differences. Copyright
