N -butane

N-BUTANE 212-330 1.6427E402 -6.5056E+03 6 9340E-02 -2.7986E4-0I -3.2221E-05... 

One further problem remains. Most of the n-butane impurity which enters with the feed enters the vapor phase in the first separator. Thus the n-butane builds up in the recycle unless a purge is provided (see Fig. 4.13a). Finally, the possibility of a nitrogen recycle should be considered to minimize the use of fresh nitrogen (see Fig. 4.136). 

Insoluble in water, soluble in organic solvents b.p. — 15°C. Prepared by treating 1,4-dibromo-butane with metallic sodium. Reduced to n-butane by hydrogen at 200" C in presence of nickel catalysts. 

New processes such as isomerization and the dehydrogenation of n-butane will make their appearance. 

Figure A3.10.22 Relationship between seleetivity and surfaee stnieture forn-butane hydrogenolysis on iridium, (a) Illustrations of the Ir(l 10)-(1 x 2) and Ir(l 11) surfaees. The z-axis is perpendieular to the plane of the surfaee. (b) Seleetivity for C2Hg produetion (inol% total produets) for n-butane hydrogenolysis on both Ni single erystals and supported eatalysts at 475 K. The eflfeetive partiele size for the single erystal surfaees is based on the speeified geometrie shapes [43]. A Ir/Al203 nir/Si02.

Engstrom J R, Goodman D Wand Weinberg W H 1986 Hydrogenolysis of n-butane over the (111) and (110)-(1 2) surfaces of iridium a direct correlation between catalytic selectivity and surface structure J. Am. Chem. Soc. 108 4653... 

Engstrom J R, Goodman D W and Weinberg W H 1988 Hydrogenolysis of ethane, propane, n-butane and neopentane... 

Conformational free energy simulations are being widely used in modeling of complex molecular systems [1]. Recent examples of applications include study of torsions in n-butane [2] and peptide sidechains [3, 4], as well as aggregation of methane [5] and a helix bundle protein in water [6]. Calculating free energy differences between molecular states is valuable because they are observable thermodynamic quantities, related to equilibrium constants and... 

Figure 2-102. Dependence of the potential energy ctirve of n-butane on the torsion angle r between carbon atoins C2 and C3.

C Binning Jr and B Bigot 1931. Structures and Properties of Organic Liquids n-Butane and 1,2-... 

This reaction is precisely parallel to the Wurtz Reaction in the aliphatic series, by which, for instance, n-butane can be obtained by the action of sodium on ethyl bromide. 

The bond matrix expresses 2 C—C bonds plus 8 C—H bonds for propane and 3 C—C bonds plus 10 C—H bonds for n-butane. Eaeh enthalpy of atomization is obtained by subtraeting the enthalpy of formation of the alkane from the sum of atomie atomization enthalpies (C 716 H 218 kJ mol ) for that moleeule. For example, the moleeular atomization enthalpy of propane is 3(716) +8(218) — (—104) = 3996 kJ mol . Enthalpies of formation are available from Pedley et al. (1986) or on-line at www.webbook.nist.gov. 

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... 

Determine the molecular mechanics heat parameters for C—C and C—H using the enthalpies of formation of n-butane and n-pentane, which are —30.02 and —35.11 kcal mol respectively. 

Figure 4-18 The Potential Energy for Rotation of n-Butane About its Central Bond Axis. The anti conformer in the center is slightly lower in energy than the two gauche conformers.

In a 200 ml. distilling flask place 64 g. (50 ml.) of dry n-butyl bromide and 80 g. of dry silver nitrite (1). Insert a reflux condenser, carrying a cotton wool (or calcium chloride) guard tube, into the mouth of the flask and close the side arm with a small stopper. Allow the mixture to stand for 2 hours heat on a steam bath for 4 hours (some brown fumes are evolved), followed by 8 hours in an oil bath at 110°. Distil the mixture and collect the fraction of b.p. 149-151° as pure 1-nitro-n-butane (18 g.). A further small quantity may be obtained by distilling the fractions of low boihng point from a Widmer flask. 

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