Dissociation of acetone

Vinylcyclopropane to cyclopentene rearrangement 184 Dissociation of acetone radical cation 186 The wolff rearrangement 187... 

In conclusion, on anatase, photo-oxidation of acetone limits the total oxidation, whereas on rutile, formate does so. The latter is attributed to a combination of thermal dissociation of acetone on defect sites, which aids acetone oxidation, and the strong bonding of p-formate to the (110) surface facets on rutile. A synergetic effect between anatase and rutile particles is observed, where the measured photooxidation rate from either quadrupole mass spectrometry (QMS) or DRIFTS exceeds than that for the individual constituent particles. 

One example is the dissociation of laser-excited iron pentacarbonyl Fe(CO)5, where the ratio Fe(CO)5/Fe can be varied between 0.06 to 4.8 by coherent control [15.37]. Another example is the photodissociation of C5H5Fe(CO)2Cl into selected fragments. Optimum shaped femtosecond pulses can alter the ratio C5H5COCl/FeCl from 1 to 5 [15.38], or the selected bond dissociation of acetone (CH3)2CO or acetophenone C6H5COCH3 [15.39]. More examples and a detailed description of the technique can be found in [15.40] and [15.41]. 

According to the Stark-Einstein law, (p should be equal to 1. In practice, in most cases, it is less than 1. For instance, if the quantum yield is 0.01, then only one hundredth of the molecules that are excited undergo photochemical reaction. In chain reactions, secondary processes occur and hence their cp is greater than 1. For example, in the photo dissociation of acetone, quantum yield of the reaction may be 1 or 2 depending on the number of bonds broken. 

Qian, K., A. Shnkla, and J. FntreU. 1990. CoUision-induced intramolecular energy transfer and dissociation of acetone molecular ioa J. Chem. Phys. 92 5988-5997. 

Apparent non-RRKM dynamics has also been observed in time-resolved femtosecond (fs) experiments in a collision-free enviromnent [117], An experimental study of acetone illustrates this work. Acetone is dissociated to the CH and CH CO (acetyl) radicals by a fs laser pulse. The latter which dissociates by the channel... 

Five-coordinate Ni111 complexes (89) have been prepared by oxidation of the square planar Ni11 precursor complexes [Ni(L)X] with either X2 or CuX2, and the crystal structure of the iodo derivative has been determined. The geometry at Ni is best described as square pyramidal, with the Ni atom displaced approximately 0.34 A out of the basal plane towards the apical I atom. EPR confirms the Ni111 oxidation state, in which the unpaired electron of the low-spin d1 system is situated in the dz2 orbital.308,309 In aqueous solution full dissociation of both X anions occurs, while in acetone solution dissociation is not significant. The redox couple [Nin NCN (H20)]+/ [Ni111 NCN (H20)ra]2+ in water is +0.14V (vs. SCE). 

An explanation not easily distinguishable from the one involving resonance with a carbonium ion structure in the transition state is that the reactive species is an ion pair in equilibrium with the covalent molecule. This is quite likely in a solvent insufficiently polar to cause dissociation of the ion pairs. Examples of second order nucleophilic displacements accelerated by the sort of structural change that would stabilize a carbonium ion are of fairly frequent occurrence. Allyl chloride reacts with potassium iodide in acetone at 50° seventy-nine times as fast as does -butyl chloride.209 Another example is the reaction of 3,4-epoxy-1 -butene with methoxide ion.210... 

Dissociation of 1,1,4,4-tetrapheny 1-2,3- dibenzoyl-tetrazane into radicals in chloroform, acetone, ether, and toluene.464 90s... 

Electric conductance measurements have been widely used in the study of lanthanide complexes to determine the nature of the anions in the complexes and hence to indicate the possible coordination number of the lanthanide ion. Water is a strong donor toward the lanthanides and is seldom used for the purpose of measuring electric conductance, since the complex is completely dissociated on dissolution in water. The complete dissociation of lanthanide complexes in water has been shown by molecular weight determinations in water as in the case of the complexes of DMSO (246,249, 250), PyO (147,157,158), and DMF (41, 43). Most useful data are obtained in non-aqueous solvents like nitromethane, acetonitrile, nitrobenzene, and acetone (317). 

The fundamental method of calculating AG is from equilibrium measurements, primarily from measurement of the equilibrium constant of a chemical reaction. As an example, we shall consider the dissociation of isopropyl alcohol to form acetone and hydrogen ... 

If we start with o moles of isopropyl alcohol, a no mole each of acetone and hydrogen are formed, where a is the degree of dissociation. The quantity of... 

In order to assess the validity of such an approach, within the assumptions of the model outlined, we have recently undertaken an examination of deuterium isotope effects on both the radiative and unimolecular dissociation rates. One such case is that of the protonated dimer of acetone in which either the methyl groups, the protonated oxygen, or both, are deuterium substituted. Results for these four systems are shown in Figure 14 and the rate data derived are summarized in Table 1. 

Figure 15. Variation of the ratio of intensities of protonated acetone-c4 and pro-tonated acetone, [(CD3)2CO]H [(CH3)2CO]H arising from the unimolecular dissociation of the mass-selected mixed protonated dimer of acetone and acetone-ds (MIKES) as a function of the reciprocal ion source temperature.

Generation and Dissociation of the Acetone Radicai Cation. It has been known for some time, and verified by a number of research groups, that the... 

Despite this fact and the low (CH3-CO) bond dissociation energy in the acetyl radical, the products of photolysis of acetone with light of wavelength 3130 A. have been shown to contain substantial amounts of diacetyl, which could only arise from the combination of acetyl radicals. 

The energy required to dissociate the acetone molecule into two methyl radicals and a molecule of carbon monoxide may be calculated from thermocheinical data and amounts to 89 kcal. mol.-1. It would be energetically possible, therefore, for a photodecomposition of type B to occur,... 

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