Cyclo paraffins

Selecting the naphtha type can be an important processing procedure. For example, a paraffinic-base naphtha is a better feedstock for steam cracking units because paraffins are cracked at relatively lower temperatures than cycloparaffins. Alternately, a naphtha rich in cycloparaffins would be a better feedstock to catalytic reforming units because cyclo-paraffins are easily dehydrogenated to aromatic compounds. Table 2-5 is a typical analysis of naphtha from two crude oil types. 

Naphthenes (cyclo-paraffins) cracked to olefins and smaller ring compounds... 

Concentrated sulphuric acid. The paraffin hydrocarbons, cyclo-paraffins, the less readily sulphonated aromatic hydrocarbons (benzene, toluene, xylenes, etc.) and their halogen derivatives, and the diaryl ethers are generally insoluble in cold concentrated sulphiuic acid. Unsaturated hydrocarbons, certain polyalkylated aromatic hydrocarbons (such as mesitylene) and most oxygen-containing compounds are soluble in the cold acid. 

Cyclo-paraffins, also referred to as naphthenes, are mainly produced by dehydrogenation of their equivalent aromatic compounds such as the production of cyclohexane by dehydrogenation of benzene. Cyclohexane is mostly used for the production of adipic acid and nylon manufacturing (Rudd et al., 1981). 

Figure 4.22 Entropies of hydrocarbons at 25 °C paraffins, olefins, alkynes, cyclo-paraffins, and aromatics...

Figure 5.4 Boiling points of the series of normal paraffins, iso-paraffins, cyclo-paraffins, olefins, and 1-alcohols...

Mononuclear aromatics, containing one aromatic ring, plus one, two, or three cyclo-paraffin rings, plus appropriate paraffin side or connecting groups, about 10%... 

Zeolite 12 7.5 n-paraffins, isoparaffins, simple aromatics and cyclo-paraffins... 

An interesting extension of the Friedel-Crafts reaction, by which paraffins are converted into cyclo-paraffins, is described in B., 66, 1892. The reaction is summarised in A., 510, 269. 

A further reaction then takes place in this particular instance (see Preparation 26), but in the general case the reaction goes no further. The compounds so obtained are all derivatives of cyclohexenone. These latter compounds may be transformed by various reactions into cyclo-paraffins on the one hand, and aromatic compounds on the other. This affords a method of passing from simple aliphatic to aromatic compounds (see Preparation 446). (A., 281, 25.)... 

Reaction XLVII. Condensation of an Ester with itself by the action of Iodine on its Sodio-derivative. (B., 23, R., 141 A., 201, 144 266, 88.) When iodine, usually in ethereal solution, acts on the sodio-derivatives of esters, such as malonic or acetoacetic esters, the metal is eliminated, and higher dibasic esters are obtained. As will be seen, the reaction is especially useful for preparing cyclo-paraffins by acting with iodine (or bromine) upon disodio-methylene- and disodio-ethylene-, etc., di-malonic esters. 

Results from both analyses were combined to give carbon distribution in the range 0-10 by several hydrocarbon types namely iso, normal and cyclo paraffins, iso, normal, and cyclo olefins, and mono-ring aromatics. For convenience these groups are abbreviated to IP, NP, CP, IO, NO, CO, and AR respectively, and suffixed by the relevant carbon number i.e. IP-5 equates to total C5 iso-paraffins. 

In both cases, there is little reaction with cyclo-paraffins but cyclo-olefins virtually disappear with REHY. ZSM-5 also reacts with cyclo-olefins, and a similar result has been observed with gas-oil cracking [6]. 

Cyclo-paraffins react more readily with REHY, presumably as a result of pore size differences between the 10 ring ZSM-5 and the 12 ring faujasite, resulting in size discrimination (reactant shape selectivity). Over both zeolites, C9-C10 cyclo-olefins are completely converted so that size discrimination is not observed. However, where conversion of cyclo-olefins is not complete (i.e. C6-C8) there is clear evidence for discrimination between the two zeolites (Figure 7). Presumably this high reactivity of C9/C10 cyclo-olefins over either zeolite can be explained by initial facile attack at outer surfaces. 

Cracking patterns for cyclo-paraffins over US-Y have recently been reported [9] where products from the conversion of methycyclohexane include C2-C6 compounds with C3 + C4 hydrocarbons as the major yields. The authors of this study have assumed that isomerisation of the initial carbenium ion is relatively facile and that a combination of hydrogen transfer, isomerisation, and beta scission generates the products. This is envisaged in Scheme 2 which uses the classification A, B, C for cracking, A, B for isomerisation f8,91 and which presumes that intramolecular hydrogen transfer is rapid [8]. 

The cracking of naphtha produces most of the world s ethylene. Naphtha is the crude oil fraction boiling Irom about 32°C to 192°C. The composition of naphtha made from crude oil comprises four basic components linear paraffins, branched paraffins, naphthenes (cyclo-paraffins) and aromatics. The relative amount of these in naphtha is dependent on the source crude oil and varies widely. 

In the first place, as already stated, when benzene is treated with bromine, substitution products are more readily formed than addition products, and the former are the stable compounds. While methane, because of its saturated character, does not form addition products, but only substitution products, benzene forms both, but the substitution products are the more stable. Evidently benzene is more like a saturated compound than an unsaturated one in spite of the fact that it has eight less hydrogen atoms than are sufficient to satisfy the six carbon atoms according to the open-chain structure, and six less than sufficient according to the cyclo-paraffin structure. 

Character of Center Nucleus.—As was stated in connection with anthracene itself we can not say positively as to the character of the center nucleus in either the hydrocarbon or the quinone. In anthracene the aliphatic character of this center nucleus is indicated by its formation from an ethane residue, by the tetra-brom ethane synthesis. This does not, however, preclude the possibility of its becoming a true benzene nucleus when condensed with two benzene rings, for benzene itself may be made from aliphatic hydrocarbons, from acetylene by polymerization (p. 478), and from hexane through hexa-methylene with the loss of hydrogen after the formation of the cyclo-paraffin (p. 469). Also naphthalene, in which there is no doubt of the benzene character of the two nuclei, may have one nucleus formed from an aliphatic chain as in the syntheses given (p. 767) from phenyl butylene bromide, from phenyl vinyl acetic acid and from tetra-carboxy ethane. In the same way the facts in regard to anthraquinone do not prove... 

The use of NMR for the compositional analysis of crude oils and fractionated products is routine in industrial production. Common analyses include the determination of saturated and aromatic hydrocarbon content, average structural parameters such as the percentages of n-paraffins, / 6>-paraffins, cyclo-paraffins, mono-, di-, and poly aromatics. These data are used for the development of correlations between the compositions and their characteristics.Spectral editing such as DEPT is routinely used for the unambiguous assignments of resonances in complex mixtures, and recent trends indicate the utility of 2D-correlation techniques for such purpose. " In addition, NMR is used to determine additive constituents... 

Mono-cyclopara f-fin and noncon-densed cyclo-paraffin... 

McAuliffe, C. D. Solubility in Water of Paraffin, Cyclo-Paraffin, Olefin,... 

Solvent (cyclo)paraffins Surface tension dyne/cm at 20°C Electrical conductivity pS/m... 

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