Butenes Production

Predict the effect on the 1-butene Z-2-butene E-2-butene product ratio when the E2 elimination of erythro- i-deuteno-lAxomobutaae is compared with that of 2-bromo-butane. Which alkene(s) will increase in relative amount and which will decrease in relative amount Explain the basis of your prediction. 

The G values for S02 and butene production from the irradiation of poly (1-butene sulfone) are shown in Figure 3 as a function of temperature from... 

The change from a predominantly trans-2-butene product to one consisting mainly of 1-butene at ratios of 6 or higher is striking, and has also been observed by others (16). These reductions may be described as selective, since only monoolefin is formed and the product composition may be controlled. 

Woody, Lewis, and Wills 72> studied the disproportionation of [1-14C] propylene over cobalt oxide-molybdate-alumina at 149 and 177 °C. Approximately equal amounts of radioactivity were found in the approximately equal molar quantities of ethylene and butene. These results are in agreement with those of Clark and Cook showing that double-bond isomerization was a factor in this temperature region. Woody and coworkers suggest that since the isomerization of the 2-butene product was negligible, an explanation of double-bond mobility as simple isomerization is probably an oversimplification. 

However, it is believed that CH3CCD2CH3t does not maintain its integrity for more than a few vibrations and that it is indistinguishable from CH3CDCDCH,t and CH2CHCD2CH,t. As in the case of CH3 CD2CH3 photolysis, it is not immediately obvious whether the H2 and HD are products of elimination from the excited parent or from the excited butene product. 

The hydroisomerization step features complete C4 acetylenes and butadiene conversion to butenes, maximum 2-butenes production, flexibility to process different feeds, polymer-free product and no residual hydrogen. The second step separates isobutylene either by conventional distillation, or by reacting the isobutylene with methanol to produce MTBE. 

Application Increase the value of steam cracker C4 cuts via low-temperature selective hydrogenation and hydroisomerization catalysis. Several options exist removal of ethyl and vinyl acetylenes to facilitate butadiene extraction processing downstream conversion of 1, 3 butadiene to maximize 1-butene or 2-butene production production of high-purity isobutylene from crude C4 cuts total C4 cut hydrogenation and total hydrogenation of combined C3/C4 and C4C5 cuts for recycle to cracking furnaces or LPG production. 

Ethylene dimerization forming 1-butene can also be carried out selectively with a titanium(IV) derivative which is reduced in situ to titanium(II) (Alpha-butol process, Institut Frangais du Petrole). The result has been attributed to the formation of a titanacyclopentane, which decomposes to 1-butene. The absence of a hydride species active in oligomerization would account for the high selectivity (Figure 15). No additional solvent is required, as 1-butene also acts as solvent. The total world butene production capacity by this process is estimated to be >300 kt/a. 

Initial value for ci8-2-butene/[Pg.391]

Ward (24) has suggested that with ZnX the active centers are essentially Bronsted acid sites associated with residual hydroxyl groups. -Partial hydration could promote movement of cations and result in the formation of additional such sites. The activity of the ZnX-IV zeolite can be explained satisfactorily in this manner, but with ZnX-I other factors must be involved. It is possible that with the higher exchanged zeolite, the increase in surface cations provides stronger adsorption sites for the butenes. If this were the case, then a slow rate of desorption of the products (relative to the surface reaction) could allow the 2-butene product ratio to approach that of thermodynamic equilibrium (13). 

Table II indicates the isomer distribution of the butene product obtained at a cyanide to cobalt ratio of 5.1 under two reaction conditions. The upper set of figures for each substrate refers to the product distribution obtained in the presence of excess hydrido complex. The lower set of figures refers to results obtained with pentacyanocobaltate(II) in an inert atmosphere. Under such conditions, hydrido complex is formed via cleavage of water (Reaction 2).

Selective dimerization has been achieved with some success over boron trifloride, pure nickel, cobalt over charcoal, nickel oxide, silica, and alumina, trialkylaluminum titanates, and zirconates to name a few. However, in most cases, the catalysts are complex mixtures of several components since the selectivity for butene production is not prominent. 

The liquid product from the reaction section containing unreacted ethylene, product butenes and catalyst is sent to the catalyst quench section. The catalyst is deactivated by contacting with 2 wt. percent acetic acid and separated from the butene product in an extractor. The catalyst-free butene stream of the extractor effluent proceeds to a neutralization vessel where it is contacted with dilute caustic soda solution. The butene stream leaving the neutralization vessel is filtered, distilled and recovered as product. 

Finally, experiments using TPD of NH3 show that increases the acidity of M0O3, consistent with an increase of butene production from 2-butanol when mixtures of Sn02 and M0O3 are used as the catalyst. 

This method provides a straightforward access to chiral alkyl-substituted 1-alkenes via asymmetric oligomerization of propene or 1-butene. Products of this type are of interest for the synthesis of pheromones and other modestly functionalized chiral compounds. 

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