Cyclic alkane carbon-hydrogen

The normal (unbranched) hydrocarbons are often referred to as straight-chain hydrocarbons. What does this name refer to Does it mean that the carbon atoms in a straight-chain hydrocarbon really have a linear arrangement Explain. In the shorthand notation for cyclic alkanes, the hydrogens are usually omitted. Elow do you determine the number of hydrogens bonded to each carbon in a ring structure ... 

In the shorthand notation for cyclic alkanes, the hydrogens are usually omitted. How do you determine the number of hydrogens bonded to each carbon in a ring structure ... 

Cracking and isomerization reactions occur readily in acidic chloroaluminate(III) ionic liquids. A remarkable example of this is the reaction of poly(ethene), which is converted into a mixture of gaseous alkanes of formula (C Ff2n+2, where n = 3-5) and cyclic alkanes with a hydrogen to carbon ratio of less than two (Figure 5.1-4, Scheme 5.1-68) [99]. 

Cyclohexane, the six-carbon ring hydrocarbon with the molecular formula C6H12, is the most significant of the cyclic alkanes. Under ambient conditions it is a clear, volatile, highly flammable liquid. It is manufactured by the hydrogenation of benzene and is used primarily as a raw material for the synthesis of cyclohexanol and cyclohexanone through a liquid-phase oxidation with air in the presence of a dissolved cobalt catalyst. 

The names of all alkanes end with -ane. Whether or not the carbons are linked together end-to-end in a ring (called cyclic alkanes or cycloalkanes or whether tliey contain side chains and branches, the name of every carbon-hydrogen chain that lacks any double bonds or functional groups will end with the suffix -ane. 

Although non-cyclic alkanes are called straight-chain alkanes they are technically made of kinked chains. This is reflected in the line-drawing method. Each ending point and bend in the line represents one carbon atom and each short line represents one single carbon-carbon bond. Every carbon is assumed to be surrounded with a maximum number of hydrogen atoms unless shown otherwise. 

Substitution of the cyclic alkanes by a deshielding substituent leads to a characteristic chemical shift for the hydrogen attached to the alpha carbon depending upon the size of the ring and the deshielding effect of the substituting group as listed below. 

We have met the breaking of C—C bonds by hydrogen already in Chapter 11, but the molecules considered there (cyclopropane and cyclobutane) had some degree of alkene-like character and reacted easily (especially the former). In this chapter we shall be involved with linear and branched alkanes having two, three or four carbon atoms. C—C bond fission is the principal process, but with the butanes skeletal isomerisation is also possible, and dehydrogenation sometimes happens at the same time. Reactions of acyclic and cyclic alkanes having five or more carbon atoms feature in the following chapter, where isomerisation and dehydrocyclisation are the important reactions. Some limited overlap between this chapters and the next is unavoidable. 

Alkane al- kan [alkyl+-ane] (1899) n. The generic term for any saturated, aliphatic hydrocarbon, i.e., a compound consisting of carbon and hydrogen only and containing no double or triple bonds. Linear alkanes are representable as C H2 +2 while cyclic alkanes have the general formula C H2 . Examples are propane, C3H8, and cyclohexane, C6H12. 

In an acyclic alkane (acyclic means there is no ring), every carbon has the maximum number of hydrogen atoms attached to it (determined by the feet that each carbon must have four bonds). In a cyclic alkane, two carbon atoms must be joined to form a ring, and there are two fewer hydrogen atoms when compared to an acyclic alkane. Because of this, the general formula for cyclic alkanes is... 

Hydrocarbons are molecules composed only of hydrogen and carbon. Some of the chemistry associated with acyclic and cyclic alkanes, alkenes, and alkynes, as well as the aromatic compounds (arenes) has already been touched upon briefly, for example, combustion (in Chapter 1), electrocycUc processes (in Chapter 4), and acidity (in Chapter 5). These processes, as well as others to be encountered here, can be cast into the traditional groupings of oxidation and reduction, addition and elimination, and substitution and rearrangement. 

The initial step of the adsorption of cyclic sulfides on a Mo(100) surface is also the formation of adsorbed thiolate groups.395-397 Adsorbed alkyl thiolates decompose to adsorbed sulfur, carbon, and hydrogen on the clean Mo surface, but once the surface is deactivated by adsorbed sulfur, alkanes and alkenes evolve from the surface. Tetrahydrothiophene (34) and trimethylene sulfide decompose on Mo(110) to alkanes and alkenes by way of a common intermediate, which is proposed to be a surface thiolate (33). The thiolate undergoes hydrogenation or dehydrogenation, depending on the surface hydrogen concentration (Scheme 4.115).398 399... 

The chromatograms of the liquid phase show the presence of smaller and larger hydrocarbons than the parent one. Nevertheless, the main products are n-alkanes and 1-alkenes with a carbon number between 3 to 9 and an equimolar distribution is obtained. The product distribution can be explained by the F-S-S mechanism. Between the peaks of these hydrocarbons, it is possible to observe numerous smaller peaks. They have been identified by mass spectrometry as X-alkenes, dienes and also cyclic compounds (saturated, partially saturated and aromatic). These secondary products start to appear at 400 °C. Of course, their quantities increase at 425 °C. As these hydrocarbons are not seen for the lower temperature, it is possible to imagine that they are secondary reaction products. The analysis of the gaseous phase shows the presence of hydrogen, light alkanes and 1-alkenes. 

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