Higher n-Alkanes

An /7-alkane of molecular formula C28H68 has been isolated from a certain fossil plant. Write a condensed structural formula for this alkane. 

Unbranched alkanes are sometimes referred to as straight-chain alkanes, but, as weTl see in Chapter 3, their chains are not straight but instead tend to adopt the zigzag shape as portrayed in their line formulas. 

Bond-line formula of n-pentane Bond-line formula of n-hexane 

Much of the communication between insects involves chemical messengers called pheromones. A species of cockroach secretes a substance from its mandibular glands that alerts other cockroaches to its presence and causes them to congregate. One of the principal components of this aggregation pheromone is the alkane shown. Give the molecular formula of this substance, and represent it by a condensed formula. 

22-Alkanes are alkanes that have an unbranched carbon chain. 22-Pentane and 22-hexane are 22-alkanes possessing five and six carbon atoms, respectively. 

22-Alkanes have the general formula CH3(CH2) cCH3 and eonstitute a homologous series of compounds. A homologous series is one in which successive members differ by a —CH2— group. 

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Solubility. Also involved in concentration of n-alkanes in the C27-C33 range may be the immobility of higher n-alkanes by reason of insolubility in mixed hydrocarbons underground. Immobility may be assisted by adsorptive forces involving minerals or such organic materials as kerogen. 

Peters, C. J., R. N. Lichtenthaler, and J. de Swaan Arons. 1986. Three-phase equilibria in binary mixtures of ethane and higher n-alkanes. J. Fluid Phase Equil. 29 495-504. 

However, the treatment used by Cameron and his co-workers is physically incorrect. Equations 10-2 and 10-6 apply to a Langmuir-type adsorption equilibrium in which the solvent is merely the inert carrier for the solute and does not compete with it for the surface of the adsorbent. We have examined evidence in this chapter that demonstrates this is not always the case, particularly if the solvent has the linear long-chain structure of the higher n-alkanes used by Cameron zt al. The equilibria for the two-component adsorption are given by... 

Fortimately, several hydrocarbon liquids which are of interest in the present discussion have been among those studied. Turnbull and Cormia [66] report a value of 9.6 dynes per cm. for the solid-liquid interfacial tension of n-octadecane and 7.2 dynes per cm. for n-hepta-decane. They suggest that these two values are characteristic of the higher n-alkanes with even and odd numbers of carbon atoms, respectively. That is, for each series, the solid-liquid tension is independent of the number of carbon atoms. Data for other hydrocarbons are given by Thomas and Stavely [64]. They report values of 20.4 dynes per cm. for benzene, 24.0 for biphenyl, and 30.1 for naphthalene. 

Scheraga, 1966). Nevertheless, the situation is very complicated for higher n-alkanes with many adopted conformations. 

The higher n-alkanes and polyethylene (PE) have been studied by Patterson and Latham (9). There is a general relation between V(d and relative free volume for all the homologs ... 

Most of the members of the series of w-alkanes evaporate in the DSC experiment at atmospheric as well as at 10 bar cell pressure due to the gas flow. Decrease of the gas flow rate from 5 to 1 or 2 cmVmin causes a true pyrolysis reaction for the higher n-alkanes, starting at about n-C Hg. This may recognized by the fact, that the peak maximum temperatures of the n- anes tested, from 1° " 60 122 longer differ at the... 

Isomeric Alkanes The Butanes 65 Higher n-Alkanes 66 The C5H,2 Isomers 66 lUPAC Nomenclature of Unbranched Alkanes 68... 

Einsele, A. Biomass from higher n-alkanes. In Biotechnology (Eds. Rehm, H.-J., Reed, G.), Vol. 3, p. 43, Verlag Chemie Weinheim. 1983 Faust, U., Prave. R Biomass from methane and methanol. In Biotechnology (Eds. Rehm, H.-J., Reed, G.), Vol. 3, p. 83, Verlag Chemie Weinheim. 1983... 

On the other hand, in the liquid state, the methyl carbons in the higher n-alkanes (n 4) resonate upheld at 13.2-14.1 ppoL [19] Of course in the liquid state the C—C bonds in n- kanes possess a sig cant gauche content, and this results in the shielding of for n-butane and the higher n-alkanes com-... 

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