Acetylene complexes decomposition

We note finally that in view of the apparent fragmentation of parent species, it seems somewhat surprising that the low temperature ethylene desorption peak is not accompanied by a partial decline in the intensity of the C2H2 ion. In fact, the intensity of this ion appears to increase slightly in this region. We suggest that this is due to the formation of additional acetylenic complexes by decomposition of adsorbed ethylene upon heating. 

An ethynylation reagent obtained by decomposition of lithium aluminum hydride in ethers saturated with acetylene gives a satisfactory yield of (64), Best results are obtained with the lithium acetylide-ethylene diamine complex in dioxane-ethylenediamine-dimethylacetamide. Ethynylation of (63) with lithium acetylide in pure ethylenediamine gives (64) in 95% yield. 

In contrast to the reaction of an i72-CS2-rhodium complex with dimethyl acetylenedicarboxylate which gives rise to a metallocycle,186 the iron complexes 103 are converted by activated acetylenes into air-sensitive carbene complexes 104. Decomposition of the latter in air provides an unusual synthetic route to substituted tetrathiofulvene derivatives (Scheme 121).187... 

Measurements of the enthalpy of thermal decomposition of five co-ordinate perfluoro-olefin and -acetylene-iridium(I) complexes according to the equation... 

Aramendia et al. (22) investigated three separate organic test reactions such as, 1-phenyl ethanol, 2-propanol, and 2-methyl-3-butyn-2-ol (MBOH) on acid-base oxide catalysts. They reached the same conclusions about the acid-base characteristics of the samples with each of the three reactions. However, they concluded that notwithstanding the greater complexity in the reactivity of MBOH, the fact that the different products could be unequivocally related to a given type of active site makes MBOH a preferred test reactant. Unfortunately, an important drawback of the decomposition of this alcohol is that these reactions suffer from a strong deactivation caused by the formation of heavy products by aldolization of the ketone (22) and polymerization of acetylene (95). The occurrence of this reaction can certainly complicate the comparison of basic catalysts that have different intrinsic rates of the test reaction and the reaction causing catalyst decay. 

Complexes containing three molecules of an acetylene give high yields of substituted benzenes on decomposition (117, 119). Possible structures of the more complicated complexes and intermediates have been discussed (117, 172, 200). 

Laboratory and industrial-scale processes show that acetylene is one intermediate in carbon formation in the combustion of petroleum hydrocarbons. This is not only a result of thermal decomposition but a part of the complex of reactions occurring in the oxidation system. Steps resulting in the immediate production of acetylene seem to be molecular decomposition of molecules, or free radicals, or dehydrogenation, followed by combination or addition of oxygen. Peroxide formation may occur also. These reactions may be a general source of the hydrocarbon flame bands. 

Thermal decomposition of Os3(CO),[Me2As(CH=CH2)] at 96°C gives a/i-vinyl complex Os3(/i-AsMe2)(u-CH=CH2)(CO),0 (82), which at higher temperatures affords successively the white / -vinylidene complex (83) and then the/t 3-alky ne derivative (84) (129). This sequence of reactions provides the first authenticated report of the interconversion of cluster-bound vinylidene to acetylene. 

Dicobalt octacarbonyl also reacts rapidly with acetylenes to give the (u-RCCR)Co2(C0)6 complexes. With 1, Co2(C0)8 reacts rapidly to give the products shown in eq. 49. These products may be the decomposition products of the desired metallatetrahedrane complex (6). 

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