Cyclic Alkanes and Alkane Properties

One of the reasons that such a variety of organic compounds exists is that carbon atoms can form ring structures. An organic compound that contains a hydrocarbon ring is called a cyclic hydrocarbon. 

You are given a structure. To determine the parent cyclic structure and the iocation of branches, follow the lUPAC rules. 

The parent ring structure is numbered to give the branches the lowest possible set of numbers. The prefix tri- indicates that three methyl groups are present. No alphabetization is necessary because all branches are methyl groups. 

Stains and varnishes used to refinish wood often use cyclohexane as a solvent. 

For more practice with naming cycloalkanes go to Supplemental Practice Problems in Appendix A. 

Carbon atoms can bond with each other to form ring structures. A hydrocarbon ring contains three or more carbon atoms. An alkane that contains a hydrocarbon ring is called a cycloalkane. Cycloalkanes have the general molecular formula C H2 . 

The name of a cycloalkane reveals the number of carbon atoms in the ring. For example, cyclopropane (CjHg) is the smallest cycloalkane, with three carbon atoms in the ring. Cyclobutane (C4Hg) has a ring with four carbon atoms. A cyclic hydrocarbon can be represented by condensed, skeletal, and line structures. These structures are illustrated below for cyclobutane. Chemists usually use line structures to depict cycloalkanes. 

The ring has five carbon atoms, so the parent name is 

Solving Problems A Chemistry Handbook Chemistry Matter and Change 225 

---

With comprehensive GC, we can now choose a rational set of columns that should be able to tune the separation. If we accept that each column has an approximate isovolatility property at the time when solutes are transferred from one column to the other, then separation on the second column will largely arise due to the selective phase interactions. We need only then select a second column that is able to resolve the compound classes of interest, such as a phase that separates aromatic from aliphatic compounds. If it can also separate normal and isoalkanes from cyclic alkanes, then we should be able to achieve second-dimension resolution of all major classes of compounds in petroleum samples. A useful column set is a low polarity 5 % phenyl polysiloxane first column, coupled to a higher phenyl-substituted polysiloxane, such as a 50 % phenyl-type phase. The latter column has the ability to selectively retain aromatic components. 

Vanadium atom depositions were further studied in alkane matrices 109) in an effort to observe the influence of other low-temperature, matrix environments on the optical spectra and clustering properties of metal atoms. Thus, vanadium atoms were deposited with a series of normal, branched, and cyclic alkanes over a wide range of temperature. The atomic spectra were somewhat broadened compared to those in argon, but the matrix-induced, frequency shifts from gas-phase values were smaller. As shown in Fig. 3, these shifts decrease with in-... 

Petroleum is a complex mixture, mostly of alkanes and cyclic alkanes. Products we get from petroleum include gasoline, jet fuel, kerosene, diesel fuel, fuel oil, asphalt, and lubricating oil. To use these organic products, they have to be separated from one another. What properties of hydrocarbons might allow them to be separated ... 

Tables 2.4 and 2.6 show some physical properties of straight-chain and cyclic alkanes. Why do the boiling points increase as the number of carbons in the...

TABLE 2 Summary of structure-activity regressions of measured acute toxicity of PAH s, alkyl halides, cyclic alkanes, and heterocyclic nitrogens to Daphnia pulex (EC50) with several QSAR calculated properties of the chemicals where QSAR LC50 = calculated toxicity to Daphnia - watersolubility MV == molecular volume and the units are indicated as fM or mg L s = the square root of the mean square error for regression. 

Semiempirical modification SUPERTRAPP As will be shown in the next section, the modified TRAPP is very successful for the majority of fluids tested the exception is that the viscosity prediction for cyclic compounds and some highly branched alkanes is not satisfactory. To correct this and slightly improve the overall representation of the data, a further modification is proposed. It is semiempirical and requires thermophysical property data as input. If these data are not available, however, the modified procedure will revert to TRAPP. The modifications are implemented in a computer program SUPERTRAPP (Ely Huber 1990) and are as follows ... 

Suslick et al found that the porphyrinic MOF, PIZA-3, is capable to heterogeneously oxidize a range of linear and cyclic alkanes and epoxidize cyclic alkenes. The oxidation performance is moderate, which is similar to the homogeneous or heterogeneous Mffi Lporphyrin catalysts. Since PIZA-3 did not have shape-selective property in the reaction, the authors concluded that the catalysis occurred on the exterior surface instead of inside the pores. Their hypothesis was proved by subsequent control experiment. They added the bases that are too peripherally bulky to... 

It is of great value to know which types of sulphur compounds are present in a crude oil, because the various types may behave quite differently in respect to the properties of the crude and of the products that can be obtained from it by physical or chemical methods. According to recent investigations, in lower molecular oil fractions sulphur appears mainly in the form of alkane-thiols, cyclohexane-thiols and thio-alkanes in higher molecular fractions cyclic sulphur compounds of the thiophen type predominate. 

---