Hydrogenation to saturated hydrocarbons

Like chlorine, bromine can displace hydrogen from saturated hydrocarbons, though not as readily, and adds on to unsaturated ones. 

When applying this principle to replacement names generated from fusion nomenclature, it is essential to keep in mind that fusion names for hydrocarbons ending in -cycloalkene are for fully unsaturated skeletons the -ene ending implies whatever number of double bonds may be necessary, without a multiplier. Thus (117) has six double bonds in the twelve-membered ring, and one must add ten hydrogens to saturate it to the stage of a simple benzene derivative, compound (118). 

Because large quantities of unsaturated organic compounds are obtained by removing hydrogen from saturated hydrocarbons, these processes are also important in production of hydrogen commercially. In one of these processes, hexane is converted to cyclohexane by the reaction... 

In this behavior, sulfur resembles iodine, which reacts in an analogous way to form polyiodides. Sulfur will also remove hydrogen from saturated hydrocarbons to produce H2S with the formation of carbon-carbon double bonds. Sulfur dissolves in hot concentrated nitric acid as a result of being oxidized as shown in this reaction ... 

In contrast to saturated hydrocarbons, the unsaturated hydrocarbons react with atomic fluorine by two pathways, i.e. (atomic fluorine addition at >C=C< double bond and hydrogen substitution by fluorine atoms. The reaction of fluorine with aromatic hydrocarbons proceeds with the formation of F-derivatives and hydrogen atoms break off ... 

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. 

These ABA copolymers have an index of refraction of 1.5 and water absorption of about 0.2%. Unless hydrogenated to saturated block copolymers, these unsaturated unstabilized plastics are degraded in sunlight. The polybutadiene domains are attacked by aliphatic hydrocarbon solvents, such as hexane, and the polystyrene domains arc attacked by aromatic hydrocarbon... 

A further step towards optimised conditions in the catalytic transfer hydrogenation of alkenes was achieved with the introduction of the ionic liquid N-butyl-N -methylimidazolium hexafluorophosphate (BMIMPFg) as a solvent. The reduction of alkenes with formates and Pd/C in BMIMPF6 leads to saturated hydrocarbons in high yields. With an alkyne, a mixture of cis/trans alkenes and the saturated alkane was obtained (Scheme 4.5). Sufficiently pure products were isolated by a simple liquid-liquid... 

Cobalt catalysts have been shown to hydrogenate arenes to saturated hydrocarbons. The Co(acac)2-AlHBu 2-PBun3 system hydrogenates benzene to cyclohexene, but the presence of styrene was necessary, otherwise the reaction ceased. The styrene was also hydrogenated.72... 

Owing to the high affinity of the NH2- ion for the proton, potassium amide is an exceptionally effective catalyst of hydrogen exchange reactions in organic compounds. As was noted above, it can be used to extend the range in which the acidity of substances, including hydrocarbons (and even to saturated hydrocarbons), can be studied. 

The logarithms of the equilibrium constants for the reduction of sulfur compounds to saturated hydrocarbons over a wide temperature range (Table 4-1) are almost all positive, indicating that the reaction can virtually proceed to completion if hydrogen is present in the stoichiometric quantity. 

The methods for ji-electrons have been also applied to u-orbitals. Sandorfy and Daudel (1954), and later Sandorfy (1955), have applied the Hiickel treatment to saturated hydrocarbons, using sp3 hybrid orbitals for the carbon atoms and Is orbitals for the hydrogen atoms. These methods, improved by Yoshizumi (1957), have been used by Fukui, Kato, and Yonezawa (1960—1961) and Klopman (1962, 1963). More complete treatments have been developed by Hoffman (1963) and Pople and Santry (1963). 

Catalytic hydrogenation reduces alkenes to saturated hydrocarbons. 

The monomer, NOg, an odd-electron molecule, has many of the characteristics of a free radical since it (i) associates with other radicals, (ii) abstracts hydrogen from saturated hydrocarbons, (iii) adds to unsaturated hydro-... 

Some unsaturated hydrocarbons are converted to saturated hydrocarbons in the manufacture of high-octane gasoline and aviation fuels. Unsaturated vegetable oils can also be converted to solid cooking fats (shortening) by hydrogenation of most of the carbon-carbon double bonds present (Figure 27-21). Most of the double bonds that remain are the trans- isomer. 

Allylic conjugation stabilizes carbanions and pA values of 43 (in cyclohexy-lamine) and 47 8 (in THF-HMPA) have been determined for propene. On the basis of exehange rates with cesium cyclohexylamide, cyclohexene and cycloheptene have been found to have pAT values of about 45 in cyclohexylamine3 The hydrogens on the sp carbons in benzene and ethylene are more acidic than the hydrogens in saturated hydrocarbons. A pAT of 43 has been estimated for benzene on the basis of extrapolation from a series of fluorobenzenes. Electrochemical measurements have been used to establish a lower limit of about 46 for the pAT of ethylene. ... 

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