Alkanes and cycloalkanes

From the alkene and 2,4-dinitrobenzenesulfenyl chloride in glacial acetic acid. 

From the alkene, mercaptosuccinic acid and benzoyl peroxide in methanol. 

For general references see M. C. Kloetzel in Organic Reactions, Vol. 4 (Ed. R. Adams), John Wiley and Sons, New York, 1948, p. 1 H. L. Holmes in Organic Reactions, Vol. 4, (Ed. R. Adams), John Wiley and Sons, New York, 1948, p. 60 O. Diels and K. Alder, Chem. Ber., 62,2081 (1929). 

WARNING This is not an instruction manual. References should be consulted for the preparation of derivatives. 

Hydrocarbon A compound that contains only carbon atoms and hydrogen atoms. 

Alkane A saturated hydrocarbon whose carbon atoms are arranged in an open chain. 

A hydrocarbon containing only carbon-carbon single bonds. 

Class Alkanes (Chapter 3) 1 Alkenes (Chapters 4-5) 1 Alkynes (Chapters 4-5) 1 

Carbon-carbon 1 Only carbon- 1 One or more 1 One or more 

Oxidations of alkanes and cycloalkanes are rare and not easy. The rates of oxidation with chromic acid of methyl, methylene, and methine 

A similar increase in reactivities in the methyl-methylene-methine series is found in the free-radical oxidations of lower alkanes with oxygen in the presence of hydrogen bromide as an initiator of the reaction. Ethane gives a 64% yield of acetic acid at 220 °C, propane gives a 72% yield of acetone at 189 °C, and isobutane gives a 69.5% yield of terf-butyl hydroperoxide, a 10% yield of fm-butyl alcohol, and a 6% yield of di-rm-butyl peroxide at 163 °C [54], 

Terminal methyl groups, as well as the halomethyl groups in aliphatic halides with 15-18 carbon atoms, are oxidized biochemically to carboxyls (equation 49) [1086, 1087], 

Similar microbial oxidations of terminal methyl groups accompanied by degradation and dehydrogenations of the carbon chains take place in alkyl benzenes [1053, 1071]. 

Methylene groups are hydroxylated to give alcoholic groups. Such hydroxylations are rarely achieved chemically but occur frequently in biochemical processes. The vast majority of such hydroxylations takes place in steroidal ketones and will be discussed in the section on ketones. 

The average C-C bond is 1.536 (4) whether or not the two cycloalkanes are included. This is so because the r of cyclopentane enters with a low weight it is significantly larger. For the three alkane 

Completely analogous analyses were made for C-H bonds, and C-C-C, C-C-H and H-C-H angles. 

The two C-C-C-C torsions, in n-butane g and cyclohexane, cannot be compared in this way. They are very important in optimisation especially for the determination of non-bonded potential energy function parameters. 

The INS spectra of the normal (unbranched) n-alkanes (n = 5—25)) are discussed in 10.1.2 and [6,7]. The light alkanes, ethane, propane and butane have also been investigated [8,9]. Methane has been extensively studied by tunnelling spectroscopy both in the solid [10] and as an adsorbate e.g. [11-13]. 

The INS spectra of methane, ethane, propane and butane are shown in Fig. 8.3 and the reason for the lack of INS spectra of methane is evident. The spectrum is dominated by its molecular recoil ( 2.6.5) and all spectroscopic information is washed out. This is a consequence of its light mass and the very weak intermolecular interactions methane boils at 112K. As the molecular weight of the alkane increases, it becomes possible to distinguish features at increasing wavenumber. Also modes measured at low wavenumber on a low-bandpass spectrometer, are measured at low Q and since recoil is proportional to spectral quality improves ( 5.2.2). 

A branched alkane which has been studied by INS is neopentane (2,2-dimethylpropane, C(CH3)4) [14]. Fig. 8.4 shows a comparison of the INS spectrum and that calculated using a classic Wilson GF force field 

As Figs. 8.3 and 8.4 show, the methyl torsion is a rare example of a reliable group frequency mode in ESTS spectroscopy. Most organic compounds that contain a methyl group bonded to an sp hybridized carbon atom have a strong band at 250 10 cm. This is often the most 

Of the monocyclic alkanes, cyclopropane has been studied by INS [16]. The work was able to resolve an uncertainty in the assignment by showing that two modes were accidentally degenerate. 

The saturated hydrocarbons, or alkanes, are compounds in which each carbon atom is bonded to four other atoms. Cycloalkanes are saturated hydrocarbons that contain carbon atoms joined to form a ring. 

Each H atom in a hydrocarbon is bonded to only one C atom. Saturated hydrocarbons contain only single bonds. Petroleum and natural gas are composed mostly of saturated hydrocarbons. 

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O The overlap of the four sp3 carbon orbitals with the sorbitals of four hydrogen atoms forms a tetrahedral 

Fill in the blanks below. To verify that your answers are conect, look in your textbook at the end of Chapter 4. Each of the sentences below appears verbatim in the section entitled f ev/evr of Concepts and 

Rotation about C-C single bonds allows a componnd to adopt a variety of 

The difference in energy between staggered and eclipsed conformations of ethane is referred to as strain. 

The conformation of cyclohexane has no torsional strain and very little angle strain. 

The term ring flip is used to describe the conversion of one conformation into the 

A flexible molecule is one that can adopt many different shapes, or conformations. The study of the three-dimensional shapes of molecules is called conformational analysis. This chapter will introduce only the most basic principles of conformational analysis, which we will use to analyze the flexibility of molecules. To simplify our discussion, we will explore compounds that lack a functional group, called alkanes and cycloalkanes. Analysis of these compounds will enable us to understand how molecules achieve flexibility. Specifically, we will explore how alkanes and cycloalkanes change their three-dimensional shape as a result of the rotation of C—C single bonds. 

Our discussion of conformational analysis will involve the comparison of many different compounds and will be more efficient if we can refer to compounds by name. A system of rules for naming alkanes and cycloalkanes will be developed prior to our discussion of molecular flexibility. 

If necessary, review the suggested sections to prepare for this chapter. 

PLUS Visit www.wileyplus.com to check your understanding and for valuable practice. 

Recall that hydrocarbons are compounds comprised of just C and H for example  

Steric repulsion occurs when two atoms with filled valence shells are forced so close together that their electron clouds must occupy, in part, the same region of space. 

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A single alkane may have several different names a name may be a common name or it may be a systematic name developed by a well defined set of rules The most widely used system is lUPAC nomencla ture Table 2 6 summarizes the rules for alkanes and cycloalkanes Table 2 7 gives the rules for naming alkyl groups... 

Summary of lUPAC Nomenclature of Alkanes and Cycloalkanes (Continued)... 

Alkanes and cycloalkanes are nonpolar and insoluble m water The forces of attraction between alkane molecules are induced dipole/induced dipole attractive forces The boiling points of alkanes increase as the number of carbon atoms increases Branched alkanes have lower boiling points than their unbranched isomers There is a limit to how closely two molecules can approach each other which is given by the sum of their van der Waals radii... 

Alkanes and cycloalkanes burn m air to give carbon dioxide water and heat This process is called combustion... 

In this chapter we explored the three dimensional shapes of alkanes and cycloalkanes The most important point to be taken from the chapter is that a molecule adopts the shape that minimizes its total strain The sources of strain m alkanes and cycloalkanes are... 

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