Paraffin isomerization

Kjj = number of structurally isomeric paraffins of molecular formula without asymmetric carbon atoms ... 

The curious combinatorial number p, that is, the number of the structurally isomeric paraffins CjjHjjj.j, which intrigued Cayley, is asymptotically given by (4.81). 

Characteristic fragment ions Aliphatic ketones also give abundant McLafferty rearrangement ions at m/z 58, 72, 86, and so forth. Methyl ketones produce an abundant ion at m/z 43. Low-intensity ions at m/z 31, 45, 59, 73, and so on reveal oxygen in the unknown ketone and are especially useful in distinguishing ketone spectra from isomeric paraffin spectra. Subtract 43 from the mass of the rearrangement ion to determine R. 

Isomerize paraffins to a more highly branched product. 

Several years ago, one of the authors found that nickel, platinum, and some other hydrogenating agents, when deposited on fresh synthetic silica-alumina cracking catalyst, made a new catalyst that would isomerize paraffin and naphthene hydrocarbons in the presence of hydrogen at elevated pressures and nominal temperatures. Table I shows some early typical results calculated from mass spectrometer analyses of the products obtained by passing methyl cyclopentane, cyclohexane, and n-hexane over a catalyst composed of 5% nickel in silica-alumina at the indicated reaction conditions. Isomerization of a number of other hydrocarbons has also been studied and reported elsewhere (2). 

Fig. 2-8. Vapor pressures of isomeric paraffins. (From Handbook of Natural Gas Engineering by Katz et al. Copyright 1959 by McGraw-Hill Book Co. Used with permission of McGraw-Hill Book Co.)...

Over 25 plants are operating the total isomerization process (TIP) and this number is growing continuously. Many millions of tons of isomerized paraffins are produced annually by this process. 

Hexanes occur as a clear, colorless, flammable liquid. It is composed predominantly of C6, with some C5 and C7, isomeric paraffins. The relative proportion of isomers varies with the producer and the production lot. It is soluble in alcohol, in acetone, and in ether and is insoluble in water. 

When no reforming process is carried out in the pyrolysis of PP, 90.50% of the gasoline fraction in the products is olefin, and the yield fractions of isomerized paraffins, cycloalkanes and aromatics are very low. The gasoline has a RON of no more than 80 and is very unstable [99]. However, after reforming and fractionation [100], the results improved significantly, as shown in Table 28.11. Two kinds of molecular sieve catalysts were adopted for the process. 

If the assumption of constancy held exactly, it would be possible to deduce jE (CH) from methane and jF(G - G) from ethane, and to use these values to give the heats of formation of all paraffins. This is not in fact possible. The increment per GH2 group to the heat of formation is not constant for the lower n-paraffins, but becomes so only at -pentane 6. Moreover, if the assumption of constancy held exactly, all isomeric paraffins should have the same heat of formation. This is not so. For example, the heats of formation ( - A// ) at 298-16 K of n-butane and wo-butane are 29kcal and 31 45 respectively, and those of n-pentane and neo-pentane are 35-Oq and 39 67 kcal. This effect persists at 0 428, jf the... 

In all commercial processes for isomerizing paraffins and naphthenes, the catalyst is essentially aluminum chloride plus hydrogen chloride. The... 

In these, as in other isomeric paraffins, the isomer containing the quaternary carbon atom has the lowest enthalpy. This is in contrast with the isomeric polysulphones, where it is that of isobutene which has the highest enthalpy, presumably because of steric hindrance between the oxygen atoms and the methyl groups. 

Isomerization (Paraffin) Fast Exothermic (Mild) None None... 

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