Acetone model structure

Formal intramolecular hydrogen abstraction (proceeding through coupled electron and proton transfer) occurs in the titi triplet excited state of furanone derivatives, upon acetone photosensitization. After hydrogen transfer from the tetrahydropyran to the (I position of the furanone moiety, radical recombination leads to the final products (18). The results of computational studies on model structures are in accordance with experimental observations and reveal that the reactivity and selectivity are mainly determined by the hydrogen-abstraction step. ... 

The more extensive problem of correlating substituent effects in electrophilic substitution by a two-parameter equation has been examined by Brown and his co-workers. In order to define a new set of substituent constants. Brown chose as a model reaction the solvolysis of substituted dimethylphenylcarbinyl chlorides in 90% aq. acetone. In the case ofp-substituted compounds, the transition state, represented by the following resonance structures, is stabilized by direct resonance interaction between the substituent and the site of reaction. 

Figure 4. Models of IL s showing optimized positions of HCl sited in the structures and the calculated H-NMR chemical shifts from TMS along with C-NMR chemical shifts observed in 2- C-Acetone in IL reported in parentheses...

Fig. 7. Energy-minimized structures of acetone and mesityl oxide adsorption complexes on a cluster model of HZSM-5 using DFT calculation. Note that in the case of the acetone complex, the proton remains bonded to the bridging oxygen, while in the case of the mesityl oxide complex, the proton is more fully transferred to the ketone. (Reprinted with permission from Haw et al. (7). Copyright 1996 American Chemical Society.)...

Another approach attempts to explain the different effect of the ester structure in different reaction media simply by the changing ability of the esters to be absorbed by the resin. Qualitatively, this approach was used [476] to interpret the results for water and aqueous acetone and a similar idea was suggested for the hydrolysis of dicarboxylic acid esters in water—dioxan mixtures [482,483]. Quantitative interpretation was based [481,489] on Helfferich s model [427]. It follows from eqn. (30) and from the relation... 

The calculation of the electro-optical parameters describing Raman intensities is not yet very advanced, because of the paucity of data. Nevertheless, some success was achieved in calculations of the intensity of infrared absorption. The results on trans and gauche bond-rotation in ethylene glycol146 could be taken as a model for carbohydrates. Indeed, similar electro-optical parameters (/aCH, /aOH, /aCC, and /aCO) were calculated. This leads to the expectation that calculations of the intensity of the vibrational spectra of carbohydrates may be accomplished in the near future. In addition, the delicate problem of accounting for molecular interactions in calculating infrared intensities could be approached as it was for v(CCC) and i CO) vibrations in acetone.149 This will allow interpretation of weak, as well as strong, i.r. bands, in order to determine the structural properties of molecules. 

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