Propane carbon atoms

The noncondensable hydrocarbons comprise the hydrocarbons having less than five carbon atoms methane, ethane, propane and butanes encountered in production refining will add the olefins and diolefins ... 

Beyond propane, it is possible to arrange the carbon atoms in branched chains while maintaining the same number of hydrogen atoms. These alternative arrangements are called isomers, and display slightly different physical properties (e.g. boiling point, density, critical temperature and pressure). Some examples are shown below ... 

The structural features of methane ethane and propane are summarrzed rn Ergure 2 7 All of the carbon atoms have four bonds all of the bonds are srngle bonds and the bond angles are close to tetrahedral In the next sectron we 11 see how to adapt the valence bond model to accommodate the observed structures... 

Bonding m n butane and isobutane continues the theme begun with methane ethane and propane All of the carbon atoms are sp hybridized all of the bonds are ct bonds and the bond angles at carbon are close to tetrahedral This generalization holds for all alkanes regardless of the number of carbons they have... 

The lUPAC rules assign names to unbranched alkanes as shown m Table 2 2 Methane ethane propane and butane are retained for CH4 CH3CH3 CH3CH2CH3 and CH3CH2CH2CH3 respectively Thereafter the number of carbon atoms m the chain is specified by a Latin or Greek prefix preceding the suffix ane which identifies the com pound as a member of the alkane family Notice that the prefix n is not part of the lUPAC system The lUPAC name for CH3CH2CH2CH3 is butane not n butane... 

Athene formation requires that X and Y be substituents on adjacent carbon atoms By mak mg X the reference atom and identifying the carbon attached to it as the a carbon we see that atom Y is a substituent on the p carbon Carbons succeedmgly more remote from the reference atom are designated 7 8 and so on Only p elimination reactions will be dis cussed m this chapter [Beta (p) elimination reactions are also known as i 2 eliminations ] You are already familiar with one type of p elimination having seen m Section 5 1 that ethylene and propene are prepared on an industrial scale by the high temperature dehydrogenation of ethane and propane Both reactions involve (3 elimination of H2... 

With this type of burner, a wide variety of raw materials, ranging from propane to naphtha, and heavier hydrocarbons containing 10—15 carbon atoms, can be used. In addition, the pecuhar characteristics of the different raw materials that can be used enable the simultaneous production of acetylene and ethylene (and heavier olefins) ia proportioas which can be varied within wide limits without requiring basic modifications of the burner. 

Compounds containing only carbon and hydrogen are termed paraffins or alkanes. The general formula for these compounds is C H2n+2 where n is an integer. When only single bonds are present between carbon atoms they are classified as saturated . Examples include, etliane, propane, and butane the last two are common fuel gases ... 

For paraffins the stoichiometric ratio decreases as the nnmber of carbon atoms increases. Using a more precise calcnlation (which inclndes other species snch as CO, OH, etc.) than that shown in Eq. (4-lb), methane s stoichiometric ratio in air is 9.48 mole percent, propane s is 4.01 mole percent, and hexane s is 2.16 mole percent. Hydrogen, which combines with oxygen to form only water, has a stoichiometric ratio of 29.6 mole percent in air. 

This will generally be tr-ue as we proceed to look at other alkanes as the number of carbon atoms increases, so does the boiling point. All the alkanes with four car bons or less are gases at room temperature and atmospheric pressure. With the highest boiling point of the three, propane is the easiest one to liquefy. We are all faniliar- with propane tanks. These are steel containers in which a propane-rich mixture of hydrocar bons called liquefied petroleum gas (LEG) is maintained in a liquid state under high pressure as a convenient clean-burning fuel. 

Straight-chain alkanes are named according to the number of carbon atoms they contain, as shown in Table 3.3. With the exception of the first four compounds—methane, ethane, propane, and butane—whose names have historical roots, the alkanes are named based on Greek numbers. The suffix -one is added to the end of each name to indicate that the molecule identified is an alkane. Thus, pentane is the five-carbon alkane, hexeme is the six-carbon alkane, and so on. We ll soon see that these alkane names form the basis for naming all other organic compounds, so at least the first ten should be memorized. 

Geminal (Section 19.5) Referring to two groups attached to the same carbon atom. For example, 1,1-dibromo-propane is a geminal dibromide. 

In recent years a lot of investigations have been made on this subject. E.g. Maciel and co-workers 41,42) found that several of the most prominent signals in the CP/M AS NMR spectra can be tentatively assigned for Norway spruce lignin to specific carbon atoms in the phenyl propane unit. Further also in the solid state the signals at about 105 ppm are indicative of hardwood. 

The other way five carbon atoms can be arranged in an alkane is to attach two of them to the middle carbon atom in propane. The molecule above has two methanes and a propane, and both methanes are attached to the second carbon in the propane. Thus it is called 2,2-dimethylpropane. 

To name an alkane in which the carbon atoms form a single chain, we combine a prefix denoting the number of carbon atoms with the suffix -ane (Table 18.1). For example, CH,—CH, (more simply, CH,CH,) is ethane and CH,—CH2—CH, (that is, CH,CH2CH,) is propane. Cyclopropane, C,H6 (15), and cyclohexane, C6H12 (16), are cycloalkanes, alkanes that contain rings of carbon atoms. 

The convenience and usefulness of the concept of resonance in the discussion of chemical problems are so great as to make the disadvantage of the element of arbitrariness of little significance. Also, it must not be forgotten that the element of arbitrariness occurs in essentially the same way in the simple structure theory of organic chemistry as in the theory of resonance — there is the same use of idealized, hypothetical structural elements. In the resonance discussion of the benzene molecule the two Kekule structures have to be described as hypothetical it is not possible to synthesize molecules with one or the other of the two Kekule structures. In the same way, however, the concept of the carbon-carbon single bond is an idealization. The benzene molecule has its own structure, which cannot be exactly composed of structural elements from other molecules. The propane molecule also has its own structure, which cannot be composed of structural elements from other molecules — it is not possible to isolate a portion of the propane molecule, involving parts of two carbon atoms... 

In the case of malonic acid, CH2(COOH)2 propane, CH2Me2 or any other molecule of the form CH2Y2, if we replace either of the CH2 hydrogens by a group Z, the identical compound results. The two hydrogens are thus equivalent. Equivalent atoms and groups need not, of course, be located on the same carbon atom. For example, all the chlorine atoms of hexachlorobenzene are equivalent as are the two bromine atoms of 1,3-dibromopropane. 

The valence bonds of carbon have bxed directions and are equidistant in space, pointing from the center to the corners of a tetrahedron forming an angle of 109°. Thus, in propane, which we usually write as CH3-CH2 CH3, the carbon atoms are not connected in a straight line, but are actually as shown in the above three-dimensional diagram. 

Carbon forms a huge number of binary compounds with hydrogen. Three major categories of these compounds are alkanes, alkenes, and alkynes. An alkane has only single bonds between carbon atoms. The four simplest alkanes, which are shown in Figure 3-7. are methane, ethane, propane, and butane. An alkene, on the other hand, contains one or more double bonds between carbons, and an alkyne has one or more triple bonds between carbon atoms. Figure shows the structures of ethylene, the simplest alkene, and acetylene, the simplest alkyne. 

It is easiest to balance a chemical equation one element at a time, starting with the elements that appear in only one substance on each side. Notice that all of the carbon atoms in propane end up in carbon dioxide molecules, and all of propane s hydrogen atoms appear in water molecules. This feature allows us to balance carbon and hydrogen easily. 

To take care of the three carbon atoms per propane molecule, we need three molecules of CO2. Thus, the carbon atoms are balanced by changing the stoichiometric coefficient of CO2 from 1 to 3. In this reaction the ratio of CO2 to propane is 3 1. Similarly, we need four molecules of water for the eight hydrogen atoms in one molecule of propane. Using this information, we modify the equation as follows ... 

Lewis structure and ball-and-stick models of ethane (a) and propane (b). All the carbon atoms have tetrahedral shapes, because each has four pairs of electrons to separate in three-dimensional space. 

Building on propane, we can replace a hydrogen atom on a terminal carbon with a methyl group to form butane, an alkane with four carbon atoms in a row. Alternatively, we can replace either hydrogen atom on the inner carbon of propane to give a different compound, 2-methylpropane. In this molecule, three carbon atoms are in a row, but the fourth carbon atom is off to one side. 

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