Isopentane

The direct photolysis of isopentane has been studied by Scala and Ausloos in both the solid phase and the gas phase . In both studies the photolysis was examined at 1470, 1236 and 1048-1067 A. 

The photolysis mechanism is complicated by the fact that so many free-radical and molecular processes may occur. With the aid of free-radical inhibitors and the low-temperature study, the role of the molecular processes has been quite well established, but the role of many individual free-radical reactions remains uncertain. 

The main products of the gas-phase photolysis at 300 °K, with nitric oxide added, are hydrogen, propene, ethylene and pentenes. Other important products are ethane, butenes, methane, propane, butane and acetylene. A reaction scheme that accounts for most of the products of the nitric oxide-inhibited photolysis is as follows 

The relative importance of various free radicals in the photolysis has been determined by the photolysis of i-CsD j in the presence of H2S. The relative yields of the monoprotonated products indicates the relative importance of free radicals. Thus it was found that H CH3 C2HJ C3H7 are present in the proportion 1 1.1 0.42 0.10. These experiments also point to the importance of free-radical processes in the photolysis of isopentane, relative to the molecular eliminations. 

PROPERTIES RESEARCH GRADE PURE GRADE TECHNICAL GRADE 

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ISOPENTANE 217-383 -7 1803E 0I -2.2593E 03 -6.7898E-02 1. 6942E>01 3. 33B9E-05... 

Ultimate products are the iso-paraffins isopentane and the Ce isomers, mainly 22 and 23 dimethylbutane. 

Nearly all experimental eoexistenee eurves, whether from liquid-gas equilibrium, liquid mixtures, order-disorder in alloys, or in ferromagnetie materials, are far from parabolie, and more nearly eubie, even far below the eritieal temperature. This was known for fluid systems, at least to some experimentalists, more than one hundred years ago. Versehaflfelt (1900), from a eareflil analysis of data (pressure-volume and densities) on isopentane, eoneluded that the best fit was with p = 0.34 and 8 = 4.26, far from the elassieal values. Van Laar apparently rejeeted this eonelusion, believing that, at least very elose to the eritieal temperature, the eoexistenee eurve must beeome parabolie. Even earlier, van der Waals, who had derived a elassieal theory of eapillarity with a surfaee-tension exponent of 3/2, found (1893)... 

Other pairs of liquids which exhibit an upper consolute temperature are methyl alcohol - cyclohexane (C.S.T. 49 -1° critical composition 29 per cent, by weight of methyl alcohol) isopentane - phenol (63 5° 51 per cent, of isopentane) and carbon disulphide - methyl alcohol (40-5° 80 per cent, of carbon disulphide). 

These are effective high-octane gasoline additive oxygenates. The conversion of isobutane into isopropyl, methyl ketone, or isopentane into isobutyl, methyl ketone is illustrative. In this reaction, no branched carboxylic acids (Koch products) are formed. 

There are three constitutional isomers of C5H12 n pentane (CH3CH2CH2CH2CH3) isopentane [(CH3)2CHCH2CH3] and neopen tane [(CH3)4C]... 

Isopentane (Section 2 10) The common name for 2 methyl butane (CH3)2CHCH2CH3... 

There are three isomeric pentanes, ie, saturated aHphatic hydrocarbons of molecular formula C H 2- They are commonly called / -pentane [109-66-0] isopentane [78-78-4] (2-methylbutane), and neopentane [463-82-1] (2,2-dimethylpropane). 

The ICC classifies all three pentanes as flammable Hquids and requires that they be affixed with a red label for shipping. Because of their high vapor pressures, n- and isopentane are transported in heavy-walled dmms and neo-pentanes are transported in cylinders (see Packaging containers and INDUSTRIAL MATERIALS). 

Some isopentane is dehydrogenated to isoamylene and converted, by processes analogous to those which produce methyl /-butyl ether [1634-04-4] (MTBE) to /-amyl methyl ether [994-05-8] (TAME), which is used as a fuel octane enhancer like MTBE. The amount of TAME which the market can absorb depends mostly on its price relative to MTBE, ethyl /-butyl ether [637-92-3] (ETBE), and ethanol, the other important oxygenated fuel additives. 

Isopentane Dehydrogenation. In isopentane dehydrogenation, which is used in the CIS, isopentane or a C fraction from a catalytic cracker is dehydrogenated to isoprene (6) ... 

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