Isobutane 2-Methylpropane

Solve the same problem for propane and isobutane (2-methylpropane). The bond matrix is the same as it is for n-butane, but the enthalpy of formation is somewhat different (n-butane) = —127.1 kJ mol vs. (isobutane) = —134.2... 

Fluorination of aliphatic hydrocarbons with cobalt trifluoride gives complex mixtures Isobutane (2-methylpropane) fluorinated at 140-200 °C affords a mixture of 30 products of different degrees of fluorination and of isobutane as well as butane skeletons. The tertiary hydrogen is replaced preferentially Products containing 5-10 atoms of fluorine including a small amount of perfluoroisobutane were isolated [10]. 

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. ... 

Reported vapor pressures of isobutane (2-methylpropane) at various temperatures and the coefficients for the vapor pressure equations... 

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). 

Butane (C4H10) can exist in two different isomeric forms, e.g. n-butane and isobutane (2-methylpropane). Open chain alkanes have free rotation about their C—C bonds, hut cycloalkanes cannot undergo free rotation, so substituted cycloalkanes can give rise to cis and trans isomers (see Section 3.2.2). 

Butanes produced are predominantly isobutane (2-methylpropane), the proportion ranging from 80 to 90 % of the total C4 saturates. 

Carlier fundamental studies of autoxidations of hydrocarbons have concentrated on liquid-phase oxidations below 100 °C., gas-phase oxidations above 200°C., and reactions of alkyl radicals with oxygen in the gas phase at 25°C. To investigate the transitions between these three regions, we have studied the oxidation of isobutane (2-methylpropane) between 50° and 155°C., emphasizing the kinetics and products. Isobutane was chosen because its oxidation has been studied in both the gas and liquid phases (9, 34, 36), and both the products and intermediate radicals are simple and known. Its physical properties make both gas- and liquid -phase studies feasible at 100°C. where primary oxidation products are stable and initiation and oxidation rates are convenient. 

Only two alkanes have the molecular formula C4H10 butane and isobutane (2-methylpropane)— both of which give two monochlorides on free-radical chlorination. However, dehydrochlorination of one of the monochlorides derived from butane yields a mixture of alkenes. 

Propane has the formula C3H8 and butane C4H8. There are two isomers of butane, / -butane and isobutane (2-methylpropane). Propane and the butane isomers are gases at room temperature and atmospheric pressure like methane and ethane, all three are asphyxiants. A high concentration of propane affects the central nervous system. There are essentially no known systemic toxicological effects of the two butane isomers behavior similar to that of propane might be expected. 

A 31 (hydrocarbon) Caswell No. 503A 1,1-Dimethyl-ethane EINECS 200-857-2 ERA Pesticide Chemical Code 097101 HSDB 608 Isobutane 2-Methylpropane Propane, 2-methyl- R 600a Trimethylmethane, Hydro-carbon gas used as a fuel and an Aerosol propellant. Colorless gas mp = -138.3° bp = -11,7° d 0.5510 insoluble in H2O, soluble in organic solvents, Air Prods Chems Phillips 66. 

Ball-and-stick models of isobutane (2-methylpropane) and butane. 

FIGURE 3.14 Pourbaix diagram for species derived from isobutane (2-methylpropane), represented as (C H, in solution in HF. The neutral point in HF is at pH = 6.9, at which = -15. Addition of KF or SbF serves to adjust the pH to more basic or acidic values, within the practical limits, 1-13, approximately a range of // abont -21 to -9 (double arrow). Source Fabre et al. (1982) with permission of the American Chemical Society. 

Describe the effect of spin-spin coupling on the proton NMR absorptions of (a) butane, (b) cyclobutane, and (c) isobutane (2-methylpropane). How would you tell these compounds apart by their NMR spectra ... 

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