Butene fraction

Secondary butyl alcohol, methylethyl car-binol, 2-butanol, CH3CH2CH(Me)OH. B.p. I00°C. Manufactured from the butane-butene fraction of the gas from the cracking of petroleum. Used to prepare butanone. 

Reduction with Deuterium. Cyanocobaltate(II) (42.6 ml. of solution, 0.15M cobalt, CN/Co = 5.1) was formed in an atmosphere containing equimolar quantities of deuterium and butadiene and stirred for 15 minutes, at which time a sample of the atmosphere was taken for analysis, trans-2-Butene (26%), cis-2-butene (0.51%), ana 1-butene (4.1%) as well as unreacted butadiene (53%) were separated by vapor phase chromatography and each fraction was submitted for mass spectrographic analysis. The presence of di-, mono-, and nondeuterated species was detected in each butene fraction, while the butadiene was shown to contain small quantities of mono- and dideutero species. 

Recently, Angelescu et a/.[92] have studied the activity and selectivity for dimerization of ethylene of various catalysts based on Ni(4,4-bipyridine)Cl2 complex coactivated with A1C1(C2H5)2 and supported on different molecular sieves such as zeolites (Y, L, Mordenite), mesoporous MCM-41 and on amorphous silica alumina. They found that this type of catalyst is active and selective for ethylene dimerization to n-butenes under mild reaction conditions (298 K and 12 atm). The complex supported on zeolites and MCM-41 favours the formation of higher amounts of n-butenes than the complex supported on silica alumina, which is more favourable for the formation of oligomers. It was also found that the concentration in 1-butene and cw-2-butene in the n-butene fraction obtained with the complex supported on zeolites and MCM-41, is higher compared with the corresponding values at thermodynamic equilibrium. 

Applications of POMs to catalysis have been periodically reviewed [33 0]. Several industrial processes were developed and commercialized, mainly in Japan. Examples include liquid-phase hydration ofpropene to isopropanol in 1972, vapor-phase oxidation of methacrolein to methacrylic acid in 1982, liquid-phase hydration of isobutene for its separation from butane-butene fractions in 1984, biphasic polymerization of THE to polymeric diol in 1985 and hydration of -butene to 2-butanol in 1989. In 1997 direct oxidation of ethylene to acetic acid was industrialized by Showa Denko and in 2001 production of ethyl acetate by BP Amoco. 

Acetone and the butenes together amount to more than 95 % of the products. According to Ausloos , the butene fraction consists of 7 % butene-1, 70 % trans-butene-2, and 23 % c/j-butene-2. The distribution of the isomers is independent of the wavelength (between 2360 and 3130 A) and the temperature (between —140 and 4-73 °C), and is not influenced by solvents. 

The other major use for the -butene fraction (both 1-butene and the 2-butenes) of the butylenes is as a feedstock for 1,3-butadiene manufacture, ultimately destined for the production of synthetic rubber. Careful thermal catalytic dehydrogenation in the presence of steam gives a 75-86% yield of 1,3-butadiene from a 25-30% butene conversion per pass (Eq. 19.55). 

Fig. 9. Change in the composition of the butene fraction during the hydrogenation of 1-butene over palladium-alumina at Zl (31) -i- indicates thermodynamic equilibrium concentrations.

The product distribution determined at equal conversions in dependence of the hydrogen partial pressure demonstrates significant difference between the two catalysts (Fig.6). When partial pressure of hydrogen varied from 0 to 0.4 MPa, the C3/C3 ratio on Pt/Ga-silicate changes more than 30 times while this ratio on Ga-silicate decreases by only 2-2.5 times. The butene fraction also decreased more strongly over the Pt/Ga-silicate. 

Nevertheless, despite the strong hydrogenation platinum activity, the butene fraction remained higher over the Pt/Ga-silicate. 

A rectification zone in which the dissolved butenes fraction is displaced from the solvent in countercurrent flow with butadiene vapor, which is obtained by controlled reboiling of the extract. These butenes, which contain butadiene, are returned to the absorption zone. A sidestream is drawn off at a level where the olefin content is practically nil, the acetylene content low, and the 1,3-butadiene content a maximum. Separation takes place in a column with about 45 trays operating at the bottom around 75°C at 0.7. 10 Pa. 

As the data of Table 10-7 indicate, butadiene can be selectively reduced to butene in good yield with the proper choice of conditions. Further, the composition of the butene fraction varies with the conditions and catalyst as shown in Table 10-8. 

In the butene isomerization section (1), raffinate-2 feed from OSBL is mixed with butene recycle from the butene distillation section and is vaporized, preheated and fed to the butene isomerization reactor, where butene-2 is isomerized to butene-1 over a fixed bed of proprietary isomerization catalyst. Reactor effluent Is cooled and condensed and flows to the butene distillation section (2) where it is separated into butene-1 product and recycle butene-2 in a butene fractionator. Butene-1 is separated overhead and recycle butene-2 Is produced from the bottom. The column uses a heat-pump system to efficiently separate butene-1 from butene-2 and butane, with no external heat Input. A portion of the bottoms is purged to remove butane before it is recycled to the isomerization reactor. 

The alcohol part comes from variorrs synthetic sources. One source described in ht-erature is Cg alcohol mixture that is obtained by the hydroformylation and Itydrogenation of Cg olefin mixture obtained by dimerization of butene fraction. Two processes of purification are used by this technology. First corrsisterrt octene fraction obtained by the butene dimerization is purified by distillatiort. This is followed by rectification of reaction mixture obtained from alcohol productiorr. After the plasticizer is produced it is still purified by usual methods used in plastieizer syrrthesis. ... 

The chromium complexes are CrCl3L3 and CrCl2L2(NO)2, wherein the ligand L are pyridine and tri-n-butylphosphine in conjunction with ethylaluminum dichloride, effect simple dimerization of ethylene at 50°C [133-135]. A conversion of 4700 g butenes per g of chromium complex is achieved with the catalyst CxCX i -Etpy),. The butene fraction consists of 1-butene (50%), trans-2-butene (32%), ds-2-butene (18%), and isobutene (0.1%). Cr or Cr species may be involved in the reaction. Here chromium atoms are probably associated with the organoalu-minum halides to form bridged chromium-halogen-aluminum species. 

According to another process, ethene and butadiene are economically obtained through a propene metathesis reaction integrated into the cracking and fractionation units of the petroleum plant [15]. Thus, ethene resulting from the disproportionation step enriches the ethene content of the C2 fraction from the cracking unit, whereas butadiene is formed by subsequent dehydrogenation of the butene fraction. 

Analysis of the butene fraction obtained in reactions between 2-halogeno-butanes and the alkoxides CHa-CHj ONa and CFs-CHg-ONa at 25 C in dipolar aprotic solvents (DMF and DMSO, to minimize solvation effects) has revealed that in each case change from ethoxide to 2,2,2-trifluoroethoxide results in a decrease in the tendency for but-l-ene to be formed. This demonstrates that base strength and not size is of prime importance in determining orientation in elimination reactions between 2-halogenoalkanes and alkoxides of modest proportions. ... 

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