Alkanes, addition alkenes

The butane-containing streams in petroleum refineries come from a variety of different process units consequently, varying amounts of butanes in mixtures containing other light alkanes and alkenes are obtained. The most common recovery techniques for these streams are lean oil absorption and fractionation. A typical scheme involves feeding the light hydrocarbon stream to an absorber-stripper where methane is separated from the other hydrocarbons. The heavier fraction is then debutanized, depropanized, and de-ethanized by distillation to produce C, C, and C2 streams, respectively. Most often the stream contains butylenes and other unsaturates which must be removed by additional separation techniques if pure butanes are desired. 

Alkane oxidation via a hydroperoxide was suggested many years ago, and seems to be operative in Acinetobacter sp. strain M-1 that has, in addition, a rather unusual range of substrates that include both n-alkanes and -alkenes. The purified enzyme contains FAD and requires copper for activity (Maeng et al. 1996). 

Contaminants in recycled plastic packaging waste (HDPE, PP) were identified by MAE followed by GC-MS analysis [290]. Fragrance and flavour constituents from first usage were detected. Recycled material also contained aliphatic hydrocarbons, branched alkanes and alkenes, which are also found in virgin resins at similar concentration levels. Moreover, aromatic hydrocarbons, probably derived from additives, were found. Postconsumer PET was also analysed by Soxhlet extraction and GC-MS most of the extracted compounds (30) were thermally degraded products of additives and polymers, whereas only a few derived from the original contents... 

In this chapter, we will study the elementary reaction steps of these mechanisms focusing primarily on the anthraphos systems. This chapter begins with a description of the impact of different methods (coupled cluster, configuration interaction and various DFT functionals), different basis sets, and phosphine substituents on the oxidative addition of methane to a related Ir system, [CpIr(III)(PH3)Me]+. Then, it compares the elementary reaction steps, including the effect of reaction conditions such as temperature, hydrogen pressure, alkane and alkene concentration, phosphine substituents and alternative metals (Rh). Finally, it considers how these elementary steps constitute the reaction mechanisms. Additional computational details are provided at the end of the chapter. 

Occasionally, the reactivity of ions with differing coordination numbers may be compared. Laser ablation of Mo02 or M0O3 produced the ions Mo+, [MoO]+, and [Mo02]+, which were reacted with alkanes, alkenes, and C6 hydrocarbons (183). None of the ions reacted with methane and Mo+ was generally less reactive than the other ions with the alkanes. Additions of the alkane to the Mo+, [MoO]+, and [Mo02]+ with loss of H2 or 2H2 were the major reaction products. 

In practice, short-chain alkanes and alkenes are normally used as feedstock for shape-selective catalytic formation of isooctanes at relatively low temperatures. Until the 1980s, lead alkyls (Section 18.1) were added to most automotive fuels to help suppress engine knock, but they have been phased out in North America because of the chronic toxicity of lead and lead compounds. The most commonly used nonlead antiknock additive is now methyl tert-butyl ether [MTBE CH30C(CH3)3], which is made by the reaction of methanol with 2-methylpropene, (CHs C—CH2 (see Section 7.4). The latter is obtained by catalytic cracking of petroleum fractions to give 1-butene, which is then shape-selectively isomerized on zeolitic catalysts. 

Chlorofluorination of alkenes and alkynes using the A -chlorosaccharin-hydrogen fluoride/ pyridine system (Method G)50 results in vicinal chlorofluoro-substituted alkanes or alkenes, respectively. Since this system is more reactive than with other A -chloroamides, its use allows shorter reaction times and milder reaction conditions to prepare chlorofluorinated products in higher yields. With phenyl-substituted alkenes, Markovnikov-type adducts are formed exclusively. The additions proceed predominantly anti, with varying degrees of stereoselectivity. 

Nirmalakhandan and Speece [36] introduced the polarizability factor,, as an additional molecular descriptor. They derived the following model for halogenated alkanes and alkenes, alkylbenzenes, halobenzenes, and alkanols ... 

Conducting the same experiment using tril-inolein produced volatiles unique to the trili-nolein substrate, with the major classes being alkanals, 2-alkenals, 2,4-alkadienals, and hydrocarbons. Those volatiles, produced uniquely from this substrate and attributable to the breakdown of 9- and 13-hydroperoxides, include pentane, pentanal, 1 -pentanol, hexanal, 2-hexenal, 3-hexenal, 2-heptenal, 2-octenal, 2,4-decadienal, and acrolein. Addition of triolein afforded the added production of volatiles previously identified in triolein alone, but ad-... 

ALKANE, ARENE, ALKENE AND ALKYNE ADDITIONS AND SUBSTITUTIONS... 

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