C3H7 decomposition

Decomposition of chromium dicumene Cr[(C6H5)C3H7]2 at 300-550°C and 0.5-50 Torr. 

A common deposition reaction combines the metal chloride with a hydrocarbon, such as butane, at an optimum deposition temperature of 1000°C.9 1 Other hydrocarbons can also be used. Another useful reaction is the decomposition of the chromium di cumene Cr[(C6H5)C3H7]2 in atemperature range of 300-550°C and at pressures of 0.5-50 Torr.0 1... 

Besides the increased reactivity, formation of species like 6a may also produce a change in the rate-determing step in substitutions of ortho-derivatives when compared with the para-isomers. For example, it has been recently demonstrated that the formation of 1 (L = F R1 = n-C H7, i-C3H7 R2 = H) is rate-limiting in the reaction of n-propylamine and isopropylamine with o-fluoronitrobenzene in toluene, while it is the decomposition of the corresponding zwitterionic intermediate that is rate-determining in the same reactions... 

In these experiments hydroxyl was obtained by photochemical decomposition of H202. Analysis of reaction products was also made. Hydroxyl concentrations were too low to be measured by the spectroscopic method, but were sufficient for detecting the reaction products such as acetone, which was apparently formed by the reaction of the iso-C3H7 radical with the O2 molecule. 

Chilton and Gowenlock85,87 pyrolyzed (z -C3H7)2Hg with NO and N2 as a carrier gas in a flow system at 230-280°C. They found (CH3)2 CHN=0 and (CH3)2C=NOH as products,85 the latter arising from the isomerization of the former. Woodall and Gunning454 studied the sensitized [Hg 6(3.Pi) plus NO Ilj)] decomposition of propane and its deuterated analogs at room temperature. Both n-propyl and isopropyl radicals were produced and added to NO. The product isomers, i.e., the respective oximes, were the principal products. An unusual feature of this study was that the oximes were formed readily at room temperature. The authors suggested that the reactant radicals might have been hot, and this coupled with the heat of addition could have facilitated the isomerization. 

Here it should be noted that secondary C-H bond rupture is only slightly more probable than the scission of primary bonds, despite the fact that D(iso-C3H7—H) is 5-6 kcal./mole lower than D(m-C3Ht—H) (70,71). Hence, the bond-dissociation energy does not appear to be the major determining factor in the primary mode of decomposition. However, the results obtained by Palmer and Lossing (73) for the isobutane reaction do indicate that methyl substitution on the secondary position in propane causes C-H bond cleavage to occur preponderately at the tertiary site. 

The elegant evaluations of Co—C BDEs from the Halpem and the Finke laboratories require exhaustive and extensive experimental studies. The rates of decomposition of many alkyl Cbls have been evaluated in earlier, less rigorous studies in Schrauzer s and Pratt s laboratories [77], The general features appear to be correct and the effects of steric factors on Co—C bond cleavage have been reviewed [77], An abbreviated series relevant to our discussion is CH3 < 5 -deoxyadenosyl < C2H5 < /-C3H7, CH2CMe3. 

From a study of metastable ion decompositions of [C2(H, D)sS] + ions, the average isotope effect, i, for acetylene loss was reported as 1.6 [137]. Isotope effects on metastable ion decompositions of (C3H7S)+ ions have proved difficult to study, because of hydrogen randomisation and facile isomerisation of ion structures. Nevertheless, the metastable ion abundances for H2S and HDS loss from [CH3(CD3)C = SH]+ have been shown to be in the ratio 2.2 1 [136]. 

The study of (C3H7)+ losing H2 found the transition state to be cyclic, (CH2CH2CH3)+, with both of the hydrogen atoms to be eliminated attached to the same (penta-coordinated) carbon atom [744]. The loss of H2 from the transition state resembled a 1, 1 elimination this decomposition has been observed to release most of its reverse critical energy as translational energy. This paper also contains a careful examination of the isotope effects /Hj //Hd/ d2 on metastable ion abundances. 

Avrahami and Kebarle47 also determined a rate constant for decomposition of C3H8, formed by the reaction, H + w-C3H7, which was 5-fold higher than that for the H + iso-C3Hj activation process the ratio agreed with a value deduced by them from some calculations of Marcus. 14 The ratio given by Table XIII at 25°C. is 6, at similar pressures. 

As the chain length of the primary alcohols increases, thermal decomposition through fracture of C—C bonds becomes more prevalent. In the pyrolysis of n-butanol, following the rupture of the C3H7—CH2OH bond, the species found are primarily formaldehyde and small hydrocarbons. However, because of the relative weakness of the C—OH bond at a tertiary site, r-butyl alcohol loses its OH group quite readily. In fact, the reaction... 

The TMB studies, and related investigations of the decomposition of tri-methylbutane and 2,3-dimethylbutane, have given accurate values for the heats of formation of 2-C3H7 [34] and t-C4H9 radicals [31] in excellent agreement with those given in Table 1.1. 

Fig. 2.16. Typical experimental traces for the decomposition of the neo pentyl (C5H11) and isopropyl (C3H7) radicals and production of the corresponding products, CH3 and propene (C3H6). For neopentyl decay, [He] = 2.40 x 10 molecules cm , [C5H12] = 7.84 x 10 molecules cm, [CCI4] = 4.70 x lO molecules cm , T=600K. For isopropyl decay [He] = 3.0 X 10 molecules cm , [isopropylketone] = 9.4 x 10 molecules cm, T =...

There appears to be some discrepancy in the literature as to the reasons for the instability of [Mn(C2H.s)(CO)5] and, presumably, [Mn(n-C3H7)(C0)5]. Several reports attribute the instability to a very facile /3-hydride transfer/alkene elimination process (1,34,43,44). Thus, the observation that [Mn(CH2SiMe3)(CO)5] is more stable than [Mn(C2Hj)(CO)5] was attributed to the lack of /3-hydrogens in the former complex (45). However, a )8-elimination reaction from [Mn(C2H5)(C05] would be expected to result in the formation of ethylene and [Mn(H)(CO)s] (which could decompose to [Mn2(CO)io]). However, neither ethylene nor [Mn(H)(CO)5] have been observed in the decomposition of [Mn(C2H5)(CO)s]. Propionyl manganesepentacarbonyl and [Mn2(CO)io] (which could derive from any source of [Mn(R)(CO)5]) are the observed decomposition products (12,16,37,46). 

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