Isobutane , isomers

Iso (lao) level, equality same Isomer e.g. isobutane, isomer... 

Methane is the only alkane of molecular formula CH4 ethane the only one that is C2H6 and propane the only one that is C3Hj Beginning with C4H10 however constitutional isomers (Section 1 8) are possible two alkanes have this particular molecular formula In one called n butane, four carbons are joined m a continuous chain The nmn butane stands for normal and means that the carbon chain is unbranched The second isomer has a branched carbon chain and is called isobutane... 

Constitutional isomers (Section 1 8) Isomers that differ in re spect to the order in which the atoms are connected Butane (CH3CH2CH2CH3) and isobutane [(CH3)3CH] are constitu tional isomers... 

Butanes are naturally occurring alkane hydrocarbons that are produced primarily in association with natural gas processing and certain refinery operations such as catalytic cracking and catalytic reforming. The term butanes includes the two stmctural isomers, / -butane [106-97-8] CH2CH2CH2CH2, and isobutane [79-28-9], (CH2)2CHCH2 (2-methylpropane). 

Isomerization. Isomerization of any of the butylene isomers to increase supply of another isomer is not practiced commercially. However, their isomerization has been studied extensively because formation and isomerization accompany many refinery processes maximization of 2-butene content maximizes octane number when isobutane is alkylated with butene streams using HF as catalyst and isomerization of high concentrations of 1-butene to 2-butene in mixtures with isobutylene could simplify subsequent separations (22). One plant (Phillips) is now being operated for this latter purpose (23,24). The general topic of isomerization has been covered in detail (25—27). Isomer distribution at thermodynamic equiUbrium in the range 300—1000 Kis summarized in Table 4 (25). 

Like propane, butanes are obtained from natural gas liquids and from refinery gas streams. The C4 acyclic paraffin consists of two isomers n-butane and isobutane (2-methylpropane). The physical as well as the chemical properties of the two isomers are quite different due to structural differences, for example, the vapor pressure (Reid method) for n-butane is 52 Ib/in., while it is 71 Ib/in. for isobutane. This makes the former a more favorable gasoline additive to adjust its vapor pressure. However, this use is declining in the United States due to new regulations that reduce the volatility of gasolines to 9 psi, primarily by removing butane. ... 

Compounds like the two C4M [() molecules and the three C3I I 12 molecules, which have the same formula but different structures, are called isomers, from the Greek isos + meros, meaning "made of the same parts." Isomers are compounds that have the same numbers and kinds of atoms but differ in the way the atoms are arranged. Compounds like butane and isobutane, whose atoms are connected differently, are called constitutional isomers. We ll see shortly that other kinds of isomers are also possible, even among compounds whose atoms are connected in the same order. As Table 3.2 shows, the number of possible alkane isomers increases dramatically as the number of carbon atoms increases. 

Constitutional isomerism is not limited to alkanes—it occurs widely throughout organic chemistry. Constitutional isomers may have different carbon skeletons (as in isobutane and butane), different functional groups (as in ethanol and dimethyl ether), or different locations of a functional group along the chain (as in isopropylamine and propylamine). Regardless of the reason for the isomerism, constitutional isomers are always different compounds with different properties, but with the same formula. 

Alkanes are a class of saturated hydrocarbons with the general formula C H2n. -2- They contain no functional groups, are relatively inert, and can be either straight-chain (normal) or branched. Alkanes are named by a series of IUPAC rules of nomenclature. Compounds that have the same chemical formula but different structures are called isomers. More specifically, compounds such as butane and isobutane, which differ in their connections between atoms, are called constitutional isomers. 

Unlike the constitutional isomers butane and isobutane (Section 3.2), which have their atoms connected in a different order, the two 1,2-dimethyl-cyclopropanes have the same order of connections but differ in the spatial orientation of the atoms. Such compounds, which have their atoms connected in the same order but differ in three-dimensional orientation, are called stereochemical isomers, or stereoisomers. 

An alkane with all the carbons in a row is called butane, and the form with one carbon in the middle is known as isobutane. The iso is short for isomer, which means a molecule that has the same atoms arranged in a different way. 

Rule 1. Branching stabilizes alkanes neopentane-type branching stabilizes alkanes more than isobutane-type branching normal isomers are the least stable. 

The paraffin hydrocarbon containing four carbon atoms is called butane, but two 4-carbon (C4) paraffins are possible. The butane with its carbons in a line is known as normal butane or n-butane. The branched chain butane is isobutane or i-butane. Although each compound has the formula C4H10, they have different properties for example, n-butane boils at -0.5°C while isobutane boils at -11.7°C. n-Butane and i-butane are isomers of each other. The straight-chain paraffin is always called the normal form. 

Additional adsorption sites are provided on open metal sites, when available. [Cu3(BTC)2] is performant in the selective adsorption and separation of olefinic compounds. The highly relevant separations of propene from propane and of isobutene from isobutane have been accomplished with separation factors of 2.0 and 2.1, respectively [101, 102]. [Cu3(BTC)2] also selectively takes up pentene isomers from aliphatic solvent in liquid phase, and even discriminates between a series of cis- and trans-olefin isomer mixtures with varying chain length, always preferring a double bond in cis-position. This behavior is ascribed to tt -complexation with the open Cu sites [100]. 

DMBCOl), dimethylbicyclo[3.2.1]octanes (DMBC02), ethylsubstituted bicyclooctanes (EBCO) and trimethylbicycloheptanes (TMBCH). The last group consists of trimethylbicyclo[2.2.1]heptanes, trimethylbicyclo[3.1.1]heptanes and dimethylbicyclo[2.2.2]octanes. Some representative structures of the Iso groups are shown in Figure 2. Major cracking products (CP) were identified as cyclic hydrocarbons C5-C9 and isobutane. The main heavy products (HP) were methyl-and dimethyldecalins, or their isomers. No olefins and only traces of aromatics were found in the products. Detailed information about the product analysis is reported elsewhere (22). 

Isomer. Molecules having the same number and kind of atorns but differing in the spatial arrangement as in normal butane and isobutane. 

For a given molecular formula there is often more than one way of joining the atoms together, whilst still satisfying the rules of valency. Such variants are called structural isomers or constitutional isomers - compounds with the same molecular formula but with a different arrangement of atoms. A simple example is provided by C4H10, which can be accommodated either by the straight-chained butane, or by the branched-chain isobutane (2-methylpropane). 

This second branched molecule is called isobutane. Compounds sharing the same molecular formula but having different structures are called structural isomers. Normal butane and isobutane have different physical properties. The number of structural isomers for the alkanes is included in Table 15.1. It can be seen in this table that as the number of carbon atoms increases that the number of possible isomers also increases. The fact that numerous isomers exist for most organic compounds is another reason why there are so many organic compounds. 

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