Saturated Hydrocarbons The Alkanes and Cycloalkanes

3 Distinguish between saturated and unsaturated hydrocarbons (or other 

4 Distinguish between alkanes, alkenes, and alkynes (Sections 21.3 and 21.4). 

The simplest organic compounds are the hydrocarbons, binary compounds of carbon and hydrogen. Hydrocarbons are divided into two major classes, the aliphatic hydrocarbons and the aromatic hydrocarbons. We will examine three groups of aliphatic hydrocarbons, the alkanes, the alkenes, and the alkynes. The features that distinguish aliphatic and aromatic hydrocarbons will be identified when we study the latter group. As you will see shortly, these classifications are all based on molecular structure. 

5 Given a formula of a hydrocarbon or information from which it can be written, determine whether the compound can be a normal alkane or a cycloalkane. 

6 Given the name (or structural diagram) of a normal, branched, or halogen-substimted alkane, write the structural diagram (or name). 

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As compounds which consist of carbon and hydrogen atoms only, the hydrocarbons can be divided in two main categories, saturated, which comprises alkanes and cycloalkanes, and unsaturated, which comprises of alkenes, alkynes, and aromatics. The term saturated indicates the impossibihty of adding more hydrogens to the molecule. 

The theoretical and experimental principles of PE spectroscopy have been reviewed extensively7-10. In particular, the reader is referred to the chapter The Photoelectron Spectra of Saturated Hydrocarbons in the volume The Chemistry of Alkanes and Cycloalkanes of the present series11. Consequently we shall limit ourselves to the essentials needed for following the arguments presented in this chapter. 

E. Heilbronner, The Photoelectron Spectra of Saturated Hydrocarbons, in The Chemistry of Alkanes and Cycloalkanes (Eds. S. Patai and Z. Rappoport), Wiley, Chichester, 1992. 

One of the most ubiquitous multiple-component contaminants that reaches the soil and deeper subsurface layers is crude oil and its refined products. In the subsurface, these contaminants are transformed differently by various mechanisms (Cozzarelli and Baber 2003). Crude oil contains a multitude of chemical components, each with different physical and chemical properties. As discussed in Chapter 4, the main groups of compounds in crude oils are saturated hydrocarbons (such as normal and branched alkanes and cycloalkanes without double bonds), aromatic hydrocarbons, resins, and asphaltenes, which are high-molecular-weight polycyclic compounds containing nitrogen, sulfur, and oxygen. 

The main groups of compounds in crude oils are saturated hydrocarbons (such as normal and branched alkanes and cycloalkanes that contain no double bonds), aromatic hydrocarbons, resins and asphaltenes (higher molecular weight polycyclic compounds containing nitrogen, sulfur. 

The objective of the process is to convert saturated hydrocarbons (alkanes and cycloalkanes) in petroleum naphtha fractions to aromatic hydrocarbons as selectively as possible, since the latter have excellent antiknock ratings (1,2). Naphtha fractions are composed of hydrocarbons with boiling points in the approximate range of 50-200°C. Reaction temperatures of 425-525°C and pressures of 10-35 atm are employed in the process. Reforming catalysts commonly contain platinum (3-5) or a combination of platinum and a second metallic element such as rhenium (6) or iridium (2,7). 

Methane, CH4, is the simplest of the alkanes, a family of hydrocarbons with the general formula C H2 +2, Cyclopropane, C3Hg, is the simplest of the cycloalkanes, a family of alkanes whose carbon atoms are joined in a ring. Alkanes and cycloalkanes are saturated hydrocarbons. 

In this chapter, we examine radiolysis of neat organic liquids. The better studied and most common organic solvents are saturated hydrocarbons and alcohols. By virtue of having low dielectric constant and only C-C and C-H bonds, hydrocarbons represent an ideal medium to examine the fundamental mechanisms of radiolysis in non-polar media. For lack of space, the discussion wUl be limited to paraffins, branched alkanes, and cycloalkanes. 

Radiation chemistry of saturated hydrocarbons is far from being well understood, and is a province of numerous controversies and speculations. No closure is in sight. At the same time, no other medium with exception of liquid water has been studied as comprehensively as liquid alkanes and cycloalkanes. Below, we provide our list of the most important and challenging problems in the radiation chemistry of saturated hydrocarbons ... 

P450 are found in complex molecules as well as in saturated hydrocarbons (alkanes and cycloalkanes). For example, the steroid progesterone is hydroxylated in positions 11(3, 17a and 21 to yield hydrocortisone. In practice, a nonactivated aUcyl group undergoes mainly to- and co - 1 oxidation. On the other hand, n-hexadecane is co-hydroxylated in the liver to yield hexadecanol which is further oxidized to hexadecanoic acid. For shorter chains, both terminal and (0 — 1 oxidations are observed (Fig. 31.5). Cyclic aliphatic systems are usually hydroxylated on the least hindered or most activated carbon atoms. 

The terminology saturated hydrocarbons used to describe alkanes and cycloalkanes conveys that these compounds are generally unreactive. They are the least reactive of all organic compounds. Unlike other families, alkanes and cycloalkanes do not contain a bond or bonds which are relatively... 

Hummel, A. Radiation Chemistry of Alkanes and Cycloalkanes. In The Chemistry of Alkanes andCycloalkanes PaXai, S. Rappoport, Z., Eds. John WUey and Sons Chichster, 1992 743 pp. Shkrob, I.A., Sauer, M.C., Jr., Trifunac, A.D. Radiation chemistry of organic liquids saturated hydrocarbons. In Radiation Chemistry Present Status and Future Trends, Studies in Physical and Theoretical Chemistry 87 Jonah, C.D., Rao, B.S.M., Eds. Elsevier Amsterdam, 2001 175 pp. 

Among the spectroscopic methods, MS is perhaps the most useful for the identification of alkanes and cycloalkanes. A simple computer search of reference spectra of thousands of compounds greatly enhances the utility of the method. The NMR method for single compounds is very helpful in structure determination for small molecules. However, the larger the saturated hydrocarbon, the less absolute information can be obtained by this spectroscopical method. Both two-dimensional NMR and NMR can furnish decisive information as to the structure of cycloalkanes. 

The application of mass spectrometry, including electron impact (El) studies, to the analysis of hydrocarbon fractions obtained from petroleum is as old as the earliest exploitation of the technique. Almost all of the ionization methods known have been applied to saturated hydrocarbons. The number of papers dealing with one or another aspect of the MS of alkanes and cycloalkanes is enormous. However, the computerized compilation of the mass spectra in libraries such as NBS makes the search easier ... 

The major source of saturated hydrocarbons (alkanes and cycloalkanes) in the geosphere is petroleum. Other fossil fuels, i.e. coal and bitumens, may have small fractions of alkanes and cycloalkanes. 

Crude oil consists principally of a complex mixture of saturated hydrocarbons—mainly alkanes (paraffins) and cycloalkanes (naphthenes) with smaller amounts of alkenes and aromatics—plus small amounts (<5% in total) of compounds containing nitrogen, oxygen or sulphur. The presence of the latter is undesirable since many sulphur-containing compounds, e.g. mercaptans, have rather unpleasant odours and also, more importantly, are catalyst poisons and can therefore have disastrous effects on some refinery operations and downstream chemical processes. In addition, their combustion may cause formation of the air pollutant sulphur dioxide. They are therefore... 

Saturated hydrocarbons, including branched and unbranched chain alkanes as well as cycloalkanes, react with carbon monoxide in the presence of copper(I) oxide in HSOsF-SbFs to afford ter tiary and secondary carboxylic adds in high yield (eq 20). The reaction proceeds at 0 °C under 1 atm CO. In some cases the reaction involves cleavage of C C bonds and isomerization of the intermediate carbocatlons. 

Saturated hydrocarbons (alkanes and cycloalkanes) contain only C—C single Problems 2.16-2.18 bonds. Alkanes have the general formula C H2 +2. 

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