Methanol - computational studie

In conclusion, the computational study of ternary Pt-Ru-X alloys suggests that future strategies toward more active electrocatalysts for the oxidation of methanol should be based on a modification of the CO adsorption energy of Pt (ligand effect), rather than on the enhancement of the oxophilic properties of alloy components (enhanced bifunctional effect). 

Cyclobutyl, substituted cyclobutyl, and related carbocations were reviewed.23 A study of the photophysical properties and photochemistry of 1-adamantyl aryl ethers in methanol solvent showed that, although the majority of the ethers underwent photolysis by homolytic pathways, irradiation of the 4-cyanophenol ether resulted, in part, in the methyl ether, implicating an ionic mechanism with the 1-adamantyl cation as an intermediate.24 Labelling experiments demonstrated that the fragmentation of 7-norbomyloxychlorocarbene to 7-norbornyl chloride proceeds with both retention and inversion.25 While an ion pair [Cl CO R+] is a possible intermediate, computational studies suggest that the fragmentations proceed via transition states that lead to either retention or inversion. 

CD spectra can be used for an exploration of intermolecular interactions. For example, flavanpentol, a dmg for different protein related diseases, has a benzene moiety and three chiral centers. Capelli et al. [293] studied the conformers that this molecule adopts when in close proximity to a proline-rich peptide in aqueous solution. The authors compared ECD spectra of conformers in gas phase and methanol computed with TDDFT at the B3LYP/6-31+G(d) level of theory. Solvent effects were modeled by an integral equation formalism of PCM. The authors noted... 

Enzymatic Methanol Electro-Oxidation A Computational Study... 

We shall concentrate on computational studies of the interaction between the methanol molecule and the acidic proton of the bridging (A1 0-H Si) hydroxyl group in zeolites to exemplify the contribution of simulation techniques in understanding chemical reactivity of zeolites. This interaction is the initial step of the industrially important conversion of methanol to gasoline. Therefore, understanding this primary step at the microscopic level has a direct impact on our understanding (and possibly rationalization) of the process. Before considering the results of calculations, let us outline the experimental information available for these systems. 

Stubbs and Marx reported Car-Parrinello ab initio molecular dynamics studies for the specific-acid-catalyzed glycosidic bond formation between a-D-glucopyranose and methanol (which corresponds to the cleavage reaction by microscopic reversibility)61,62 (Scheme 32). In this work, particular attention was paid to the role of the aqueous solvent, and as a computational study is particularly noteworthy for explicit consideration of solvent molecules. The dynamics simulations required constraints on the reaction coordinate (the methanol oxygen/oxocarbenium ion carbon distance) to ensure driving it along a productive pathway over the short time-course of the dynamics simulation, over a time period of approximately 15 ps. 

The first suggestion that ligand loss was important in reductive eliminatimi reactions from Pt(lV) complexes dates back more than 40 years. In 1969, Ettore observed that added iodide inhibited the reductive elimination of Phi from L2PtPh2l2 in methanol and suggested iodide loss to form a six-coordinate solvento intermediate [13]. Several years later, a five-coordinate intermediate was proposed by Puddephatt in studies of C-C reductive eliminations from Pt(IV) complexes (see Sect. 2.1.1) [15]. Since then, the involvement of five-coordinate intermediates has been supported so consistently in both experimental (e.g., [10,13-42]) and computational studies (e.g., [29, 30, 43 8]) of alkyl C-C, C-H, and C-X reductive elimination that it is now accepted as the norm in mechanistic schemes for reductive elimination from Pt(IV). 

Primary and sequential reactions of four small uranium oxide/hydroxide anions, U02, UO3, U04, and U03(0H), with methanol, were studied the experimental observations were evaluated by DFT, with the validity of the computational results—structures and reaction mechanisms—confirmed by isotopic labeling experiments (Michelini et al., 2010). The U02 ion was inert, whereas the other three oxoanions reacted with three methanol molecules via the addition or elimination of formaldehyde, water, or dihydrogen to ultimately produce inert uranyl methoxide anion complexes, [U 02(0CH3)2] or [U 02(0CH3)3] . The structure of the U04 ion reveals four discrete U—O bonds with no O—O bonding. Another notable feature of the DFT results that was verified by isotopic labeling is that the stmcture of... 

Zhang, X., L. P. Filho, C. Torras, and R. Gracia-Vails, Experimental and computational study of proton and methanol permeabilities through composite membranes , J. Power Sources, 145 (2005) 223-230. 

To further the mechanistic understanding, computational studies have been conducted by Bock and co-workers, who analysed a range of possible transition states in the formation of the B-O bond. In these studies the reaction was studied on the basis that a molecule of water was eliminated in each step, trigonal geometry was therefore restored to boron in each step. The binding of methanol, 1,2-ethanediol and o-glucose at boron were examined. Where the reactions were simulated in vacuo or in acetonitrile the activation barriers were significant. On the other hand, if water, ammonia or NaOH were used in... 

By a combined NMR spectroscopic and computational study, Wang and coworkers have demonstrated that the lone pair of the heteroatom of common solvents, e.g., acetonitrile, acetone, DMSO, and methanol, may donate electron... 

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