Aliphatic Olefins

Fischer-Tropsch. Caibon monoxide is catalyticaily hydrogenated to a mixtuie of straight-chain aliphatic, olefinic, and oxygenated hydrocarbon molecules in the Fischer-Tropsch reaction (eq. 11) (see Fuels, synthetic). 

The use of supported transition metal oxide and Ziegler-Natta-type catalysts for polymerising aliphatic olefins (alkenes) was extended in the 1960s and 1970s to the ring-opening polymerisation of cyclo-olefins. 

Evaporative emissions from vehicle fuel systems have been found to be a complex mixture of aliphatic, olefinic, and aromatic hydrocarbons [20,24,33]. However, the fuel vapor has been shown to consist primarily of five light paraffins with normal boiling points below 50 °C propane, isobutane, n-butane, isopentane, and n-pentane [33]. These five hydrocarbons represent the more volatile components of gasoline, and they constitute from 70 to 80 per cent mass of the total fuel vapor [24,33]. 

Fischer-Tropsch hydrogenation to a mixture of straight chain aliphatic, olefinic and oxygenated hydrocarbons. Despite an enormous amount of research during the past two decades, this is still not an economically viable process except in special circumstances, such as in South Africa. " ... 

Since the rate of aliphatic acylation is higher than that of aromatic acylation, the olefin may possess aromatic substituents yields are lower, however, than with aliphatic olefins. Tlie types of olefins with aliphatic or aromatic substituents, undergoing diacylation, are shown in Table I. Systematic variation of the structure of the olefin... 

Micellar catalysis to enhance or diminish the rate of chemical reactions is well known [97]. Of somewhat greater interest is the influence of micelles on competing reactions, e.g., proton-catalyzed reactions. An example related to the effect of alkanesulfonates is the epoxidation of simple aliphatic olefins. The reaction of olefins and hydrogen peroxide catalyzed by strongly acidic Mo(VI)... 

Lange CC, LP Wackett (1997) Oxidation of aliphatic olefins by toluene dioxygenase enzyme rates and product identification. J Bacterial 179 3858-3865. 

Although the Vilsmeier reaction is known best in aromatic systems, aliphatic olefins also undergo formylation. Synthesis of forwocortal (257) involves such a step. Formation of the monoketal of 255 involves the 3-ketone function with the familiar concomitant shift of the double bond to C-5,6. 

A similar set of experiments was carried out with the phosphine substituted derivative Co2(CO),L2 (L = PBu3). Again it was shown that Co(C0)3L radicals were not involved in the hydroformylation of aliphatic olefins /32/. It is quite clear now, however, that such radicals may play a role in the hydrogenation of aromatic olefins, like styrene, stilbene, etc. /34, 35/. 

The use of metal-catalyzed aziridination methods with chiral ligands has also been reported. The copper-based system paired with ligand 56 provides the expected cinnamyl aziridine in good yield and excellent ee <06MI4568>. It is interesting to note that the /-butyl ester is obtained with 99% ee while the smaller methyl ester is obtained in only 88% ee. The binaphthyl ruthenium catalyst 57 has been found to aziridinate a number of olefins with moderate enantioselectivity <06TL1571>. Both p-nitrophenyl (Ns) and trimethylsilyloxy (SES) sulfonamides work well with this catalytic system. As is usually seen, the aziridination of aliphatic olefins proceeds in only 32% yield and 56% ee. 

The C-H bond activation followed by addition to a double bond leads to the formation of alkylated compounds (Equation (1)). This reaction involves aromatic, aliphatic, olefinic, and acetylenic C-H bonds. 

Styrene derivatives show a higher tendency to polymerise under the action of protonic acid in comparison to aliphatic olefins, a-methyl styrene polymerises in ethyl chloride when catalysed by sulphuric acid at -78.5°C but isobutene does not polymerise. 

Af-Acyliminium ions are known to serve as electron-deficient 4n components and undergo [4+2] cycloaddition with alkenes and alkynes.15 The reaction has been utilized as a useftil method for the construction of heterocycles and acyclic amino alcohols. The reaction can be explained in terms of an inverse electron demand Diels-Alder type process that involves an electron-deficient hetero-diene with an electron-rich dienophile. Af-Acyliminium ions generated by the cation pool method were also found to undergo [4+2] cycloaddition reaction to give adduct 7 as shown in Scheme 7.16 The reaction with an aliphatic olefin seems to proceed by a concerted mechanism, whereas the reaction with styrene derivatives seems to proceed by a stepwise mechanism. In the latter case, significant amounts of polymeric products were obtained as byproducts. The formation of polymeric byproducts can be suppressed by micromixing. 

Isobutene is one of the very small number of aliphatic hydrocarbons which form linear high polymers by cationic catalysis (see Section 5). The reason for this is that only in these few among the lower aliphatic olefins is there found the right balance of those factors which determine the path of a cationic polymerisation. For the formation of linear high polymers it is necessary that the propagation reaction should be much faster than all alternative reactions of the growing end of the chain and for any appreciable numbers of chains to be formed at all, the initiation must be fast. ... 

The reasons for the peculiar reactivity of isobutene among the lower aliphatic olefins can be summarised thus ethylene is insufficiently basic ethylene, propene and the w-butenes offer reaction paths which can compete effectively with propagation and most of the more heavily substituted ethylenes are sterically inhibited. (See also Appendix to Chapter 5.)... 

A highly obscure feature of cationic polymerization is the great phenomenological difference between aliphatic and aromatic monomers. The survey by Brown and Mathieson [84] of the behaviour of a very wide range of monomers towards trichloroacetic acid is particularly illuminating in this respect. Unfortunately, there are so few studies with aliphatic olefins that detailed comparisons must be confined to isobutene. It is well known that isobutene cannot be polymerised by conventional acids, such as sulphuric, perchloric, hydrochloric, or by salt-like catalysts such as benzoyl perchlorate, whereas all these catalysts readily give at least oligomers from aromatic olefins. Even when the same catalytic system, (e.g., titanium... 

There remains, of course, the question why apparently isobutene (and perhaps other aliphatic olefins) do not polymerise by the pseudo-cationic mechanism - or do so much less readily than, say, styrene. Probably the short answer lies in the relative stabilities of the esters in the polymerisation conditions, (e.g., perchlorate stabilised by co-ordination of styrene). The long answer will have to be based on a detailed understanding of all the factors which determine this stability and thus govern the equilibrium between ester and ions. 

Conjugated arylalkenes undergo ally lie amination on treatment with /V-phcnylhydro-xylamine under the influence of iron phthalocyanin, e.g. equation 71. The yields from aliphatic olefins are very poor 1-octene gives only 3% of the amine 193198. 

Von Oettingen WF. 1955. The halogenated aliphatic, olefinic, cyclic, aromatic, and aliphatic-aromatic hydrocarbons including the halogenated insecticides, their toxicity and potential dangers. Washington, DC U.S. Public Health Service. PHS Publication No. 414, 15-28. 

The method described, which is the only one available for the direct preparation of 1,1,3-trichloroalkanes, is applicable to aliphatic olefins and gives good yields, especially with terminal olefins. With styrene or butadiene, yields are much lower. 

You may wonder why boch these processes produce isopropyl alcohol instead of (normal) propyl alcohoL With the exception of ethylene, direct or indirect hydration of an aliphatic olefin always produces an alcohol with the hydroxyl group preferentially attached to the double-bonded carbon with the least number of hydrogen atoms. 

Indeed, aliphatic olefins treated with equivalent amounts of diphenyl ditelluride and f-BuOOH in methanol in the presence of sulphuric acid give methoxytellurenylated adducts. ... 

In many manufacturing processes there exists the potential for aldehyde formation. Often these aldehydes occur in low concentrations in the presence of much higher levels of aliphatics, olefinics and aromatic hydrocarbons. Gas chromatography or combined gc/ms methods are often ineffective in determining aldehydes in such a matrix. Several wet chemical techniques have been devised for estimating the total aldehyde concentration in these streams, but quantitation of the individual aldehydes has remained a difficult task. 

Fig. 21. Products from reactions of chelating aliphatic olefin complexes of platinnm-(II) with acetate and methoxide...

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