Saturated hydrocarbons reactivity

The high acidity of superacids makes them extremely effective pro-tonating agents and catalysts. They also can activate a wide variety of extremely weakly basic compounds (nucleophiles) that previously could not be considered reactive in any practical way. Superacids such as fluoroantimonic or magic acid are capable of protonating not only TT-donor systems (aromatics, olefins, and acetylenes) but also what are called (T-donors, such as saturated hydrocarbons, including methane (CH4), the simplest parent saturated hydrocarbon. 

The lack of reactivity of acyl cations such as the acetyl cation with deactivated aromatics or saturated hydrocarbons is therefore not un-... 

Protonation of formic acid similarly leads, after the formation at low temperature of the parent carboxonium ion, to the formyl cation. The persistent formyl cation was observed by high-pressure NMR only recently (Horvath and Gladysz). An equilibrium with diprotonated carbon monoxide causing rapid exchange can be involved, which also explains the observed high reactivity of carbon monoxide in supera-cidic media. Not only aromatic but also saturated hydrocarbons (such as isoalkanes and adamantanes) can be readily formylated. 

Aliphatic Chemicals. The primary aliphatic hydrocarbons used in chemical manufacture are ethylene (qv), propjiene (qv), butadiene (qv), acetylene, and / -paraffins (see Hydrocarbons, acetylene). In order to be useflil as an intermediate, a hydrocarbon must have some reactivity. In practice, this means that those paraffins lighter than hexane have Httle use as intermediates. Table 5 gives 1991 production and sales from petroleum and natural gas. Information on uses of the C —C saturated hydrocarbons are available in the Hterature (see Hydrocarbons, C —C ). 

Compounds that contain only hydrogen and carbon are called hydrocarbons. The hydrocarbons that have only single bonds all have similar chemistry and they are called, as a family, the saturated hydrocarbons. If there are carbon-carbon double bonds, the reactivity is much enhanced. Hence hydrocarbons containing one or more double bonds are named as a distinct family, unsaturated hydrocarbons. Both saturated and unsaturated hydrocarbons can occur in chain-like structures or in cyclic structures. Each of these families will be considered. 

In a sense, the absence of reactivity of saturated hydrocarbons, whether cyclic or not, is a crucial aspect of their chemistry. This inertness accounts for the fact that the chemistry of... 

Unsaturated hydrocarbons are quite reactive —in contrast to the relatively inert saturated hydrocarbons. This reactivity is associated with the double bond. In the most characteristic reaction, called addition, one of the bonds of the double bond opens and a new atom becomes bonded to each of the carbon atoms. Some of the reagents that will add to the double bond are... 

The nature of dangerous reactions involving organic chemicals depends on the saturated, unsaturated or aromatic structures of a particular compound. Saturated hydrocarbons are hardly reactive, especially when they are linear. Branched or cyclic hydrocarbons (especially polycyclic condensed ones) are more reactive, in particular as with oxidation reactions. With ethylenic or acetylenic unsaturated compounds, the products are endothermic . 

Because of their limited reactivity, the saturated hydrocarbons are also called the paraffins. This term is derived from the Latin words meaning little affinity. ... 

Cyclopentane has the low chemical reactivity which is typical of saturated hydrocarbons, while 2-pentene is much more reactive. Similarly, ring structures containing double bonds, called cyclo-alkenes, can be shown to be isomeric with alkynes. 

The saturated hydrocarbon moieties give lipids an aliphatic character, and thus hydro-phobic properties, which limit their loss from artefacts by water leaching. However, they are subject to chemical and microbiological alterations since they have a limited number of reactive sites, they are relatively less susceptible to structural modification and degradation than polysaccharides, proteins and nucleotides. 

The reactions of hydrocarbons with [LnO]+ and [ AcO]+ (where Ln = Ce and Nd and Ac = Th and U) have been compared (101) and indicate that the [AcO]+ ions are more reactive than the [LnO]+ ions. In the ions [LnO]+, the metals are in their stable oxidation state but are coordinately unsaturated. None of the [MO]+ ions react with H2, saturated hydrocarbons, ethene, propene, or benzene but they all react with 1,4-cyclohexadiene. The [AcO]+ ions gave benzene addition product ions AcOC6H6]+ as the sole product, whereas the [LnO]+ ions gave the cyclohexadiene and benzene addition product ions, [LnOC6H8]+ and [LnOC6H6]+. 

Saturable dye absorber, 14 677 Saturated aqueous salt solution, 9 34 Saturated calomel electrode (SCE), 9 571 Saturated fatty acids, 10 829, 830 Saturated hydrocarbons adsorbent affinity, 1 674 adsorption by zeolites, 1 624 fluorine reactivity with, 11 831 isomerization of, 12 172—173 Saturated polyester resins, based on trimethylpentanediol, 12 673 Saturated polyesters, 10 7 Saturated synthetic rubber, 10 705 Saturation and coating processes, 10 12-13 Saturation bonding, 17 509-510 Saturation color, 19 262 Saturation concentration, 15 677 Saturation index... 

Heterocycles with conjugated jr-systems have a propensity to react by substitution, similarly to saturated hydrocarbons, rather than by addition, which is characteristic of most unsaturated hydrocarbons. This reflects the strong tendency to return to the initial electronic structure after a reaction. Electrophilic substitutions of heteroaromatic systems are the most common qualitative expression of their aromaticity. However, the presence of one or more electronegative heteroatoms disturbs the symmetry of aromatic rings pyridine-like heteroatoms (=N—, =N+R—, =0+—, and =S+—) decrease the availability of jr-electrons and the tendency toward electrophilic substitution, allowing for addition and/or nucleophilic substitution in yr-deficient heteroatoms , as classified by Albert.63 By contrast, pyrrole-like heteroatoms (—NR—, —O—, and — S—) in the jr-excessive heteroatoms induce the tendency toward electrophilic substitution (see Scheme 19). The quantitative expression of aromaticity in terms of chemical reactivity is difficult and is especially complicated by the interplay of thermodynamic and kinetic factors. Nevertheless, a number of chemical techniques have been applied which are discussed elsewhere.66... 

This chapter deals with anodic oxidation of saturated hydrocarbons, olefins, and aromatic compounds. Substituted hydrocarbons are included, when the substituents strongly influence the reactivity. Anodic functional group interconversions (FGI) of the substituents are covered in Chapters 6, 8-10 and 15. 

The hydrogenation step following hydroformylation serves two important purposes. It reduces the aldehyde intermediate product to the desired primary alcohol functional group, which is the primary site of reactivity of the polyol with isocyanates. It also reduces the residual olefins in the FAMEs to saturated hydrocarbons, thus eliminating the pathway to Hock degradation and odor development, which is inherent to other processes that leave fatty acid unsaturation in the polyols. This step eliminates the typical vegetable oil odor from the final namral oil polyols of this process. 

While it is well established that HO—ONO can be involved in such two-electron processes as alkene epoxidation and the oxidation of amines, sulfides and phosphines, the controversy remains concerning the mechanism of HO-ONO oxidation of saturated hydrocarbons. Rank and coworkers advanced the hypothesis that the reactive species in hydrocarbon oxidations by peroxynitrous acid, and in lipid peroxidation in the presence of air, is the discrete hydroxyl radical formed in the homolysis of HO—ONO. The HO—ONO oxidation of methane (equation 7) on the restricted surface with the B3LYP and QCISD methods gave about the same activation energy (31 3 kcalmol" ) irrespective of basis set size . ... 

Part of the mystique surrounding the often assumed high reactivity of dioxiranes stems from the observation that dioxiranes such as methyl(trifluoromethyl)dioxirane (TFDO) are capable of oxidizing saturated hydrocarbons to their alcohols at relatively low temperatures in high yields and with impressive stereoselectivities (equation 8). 

Short-Lived Species in Fluid Solution. - In fluid solution, radical cations derived from saturated hydrocarbons are highly reactive oxidizing species and the rates of their bimolecular reactions are often determined by the frequency of diffusion collisions in solutions. It is known that the reactions of primary radical... 

The reactivity of surface methoxy species was further investigated with various probe molecules that were thought to possibly be involved in the MTO process, including water, toluene (representing aromatics), and cyclohexane (representing saturated hydrocarbons) (263). It was found that surface methoxy species react at room temperature with water to form methanol, which indicates the occurrence of a chemical equilibrium between these species at low reaction temperatures (Scheme 15) (263). 

Protolytic reactions of saturated hydrocarbons in superacid media21 were interpreted by Olah as proceeding through the protonation (protolysis) of the covalent C—H and C—C single bonds. The reactivity is due to the electron donor ability of the <7 bonds via two-electron, three-center bond formation. Protolysis of C—H bonds leads via five-coordinate carbocations with subsequent cleavage of H2 to trivalent ions, which then themselves can further react in a similar fashion ... 

Many of the characteristic features of hydroalanation of alkenes (reactivities, selectivities) are very similar to those of hydrosilylation. Terminal alkenes react readily in hydroalumination, whereas internal alkenes are much less reactive. Aluminum usually adds selectively to the terminal carbon. Hydroalumination of styrene, however, leads to a mixture of regioisomers.392 When hydroalumination of alkenes is followed by protolysis, saturated hydrocarbons are formed that is, net hydrogenation of the carbon-carbon double bond may be achieved. The difference in reactivity of different double bonds allows selective hydroalumination of the less hindered bond in dienes 393... 

Ozone reacts slowly with saturated hydrocarbons usually to give alcohols.92 93 The reactivity of alkanes toward ozone is several orders of magnitude less than that of alkenes. Oxidation of saturated hydrocarbons takes place preferentially at the tertiary carbon. In liquid-phase ozonation94 the order of reactivity of the primary, secondary and tertiary C—H bonds is 1 13 110. The formation of tertiary alcohols occurs with high degree (60-94%) of stereoselectivity.94-96... 

Information of the Gif system has been summarized,1055 1123 and new results, including new oxidants such as bis(trimethylsilyl) peroxide,1124 the synergistic oxidation of saturated hydrocarbons and H2S,1125 studies with the Fe3+-picolinate complex encapsulated within zeolites,1126 and the use of Udenfriend s system under Gif conditions1127 were disclosed. Gif-type oxidations were found to be moderately stereoselective.1128 Iron/zinc-containing species involved in Gif-type chemistry were synthesized, and their reactivity and catalytic behavior were studied.1129... 

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