C2H5 dissociation

Fig. 28. Ion image of photofragment (a) m/e = 91, (b) m/e = 29, from photodissociation of ra-propylbenzene at 248 nm. The delay times between the pump and probe laser pulses are 20 /is and 5 /is, respectively. The image of m/e = 30 is the mass indicator. (c) The intensity decay of the disk-like image, a dissociation rate of 4.9 x 104 s-1 was obtained, (d) The translational momentum distributions of m/e = 29 (thin solid line) and 91 (thick solid line), (e) The fragment translational energy distribution for the reaction C6H5C3H7 - C6HbCH2 +C2H5.

Lead, like tin, forms only one hydride, plumbane. This hydride is very unstable, dissociating into lead and hydrogen with great rapidity. It has not been possible to analyse it rigorously or determine any of its physical properties, but it is probably PbH4. Although this hydride is unstable, some of its derivatives are stable thus, for example, tetraethyllead, Pb(C2H5)4, is one of the most stable compounds with lead in a formal oxidation state of + 4. It is used as an antiknock in petrol. 

Fig. 12 Bond dissociation energies (298 K) for compounds of the form H3MR, where M = C, Si, Ge, or Sn and R = CH3, C2H5, C3H7, C4H9. Data obtained from BAC-MP4 calculations, except for M = Ge, where the data are obtained from G2 calculations...

An alternate view regarding selectivity has been proposed for Si02-supported V2Os (20). In this proposal, ethane could be activated in two ways. One was by dissociative adsorption across a V=0 bond to form H—V—OC2H5. a- or -elimination of the ethoxide would result in acetaldehyde or ethene, respectively. The other way was by dissociative adsorption across a V—O— bond to form —OH and V—C2H5. The latter species would lead to combustion products. 

Similar to ethane, propane dissociates by breakage of a C-C bond, which is weaker than the C-H bonds. In molecules such as ethylene or acetylene, with double or triple bonds between carbon atoms, a hydrogen atom is released during thermal dissociation. The following reactions, in particular, thermal dissociation of the ethyl radical (C2H5),... 

Hiraoka and Kebarle748,830 studied the C3H9+ protonated propane cation in the gas phase and found two isomers (cations 455 and 456). The C-protonated cation 455 was shown to be of lower energy and also much more stable toward dissociation to C2H5+ + CH4 or tt>c-C3H7+ + H2 than the 2-//-protonated (456) cation. The energy barrier of the interconversion of the ions was calculated to be 9.1 kcal mol x. 

The only evidence for a dissociation process in BF3 adduct systems appears for BF3-N(C2H5)3, in which slow exchange was observed by Brownstein (18). The difference in mechanism for this system is thought to lie in the steric nature of the triethylamine ligand (13). The steric crowding... 

Comparison of Bond Dissociation Energy (BDE, in eV) of Zigzag Edge-X Bonds with Experimental BDE of C2H5-X... 

Table 1.1 shows one substituent effect that influences the stability of radicals. The dissociation enthalpies of reactions that lead to R—CH2 radicals are listed. The substituent R varies from C2H5 through H2C=CH—(vinyl substituent, vin) to C6H5— (phenyl substituent, Ph). The dissociation enthalpy is greatest for R = H. It can also be seen that a radical center is stabilized by 12 1 kcal/mol by the neighboring C=C double bond of an alkenyl or aryl sub-... 

Adsorptions of CS2 (102, 117), S02 (118), (CH3)2S (104, 119, 120), (C2H5)2S (105), n-propyl mercaptan (120, 121), thiophene (120), and isopropyl, n-butyl, isobutyl, and tert-butyl mercaptans (121) on Ni have also been investigated. It is speculated that CS2 adsorbs dissociatively on Ni surfaces at room temperature (117). The interaction of CS2 with Ni is limited to the surface at 193 K, but above 298 K bulk sulfidation is observed (102). Sulfur dioxide chemisorbs rapidly and irreversibly on Ni at 193 K, but extensive incorporation into the bulk is not observed below 373 K. 

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