Butadiene, from butene with ethylene

Manufacture Some of the butadiene produced is recovered from steam crackers along with ethylene and propylene. However, most of it is now produced by the dehydrogenation of butene. CH3 CH-CH-CH3 CH2-CH-CH-CH2 + H2... 

The results of an experimental Investigation are presented for the separation of mixtures of 1,3-butadiene and 1-butene at near critical conditions with mixed and single solvent gases. Ammonia was used as an entrainer to enhance the separation. Several non-polar solvents were used which included ethylene, ethane and carbon dioxide, as well as mixtures of each of these gases with ammonia in concentrations of 2, 5, 8 and 10% by volume. Each solvent and solvent mixture was studied with respect to its ability to remove 1-butene from an equimolar mixture of 1,3-butadiene/ 1-butene. Maximum selectivities of 1.4 to 1.8 were measured at a pressure of 600 psia and a temperature of 20 C in mixtures containing 5%-8% by volume of ammonia in ethylene. All other solvents showed little or no success in promoting separation of the mixture. The experimental results are reported for ethylene/ ammonia mixtures and are shown to be in fair agreement with VLE flash calculations predicted independently by a modified two parameter R-K type of equation of state. 

We have applied some of these principles to the extraction of 1-butene from a binary mixture of 1,3-butadiene/1-butene. Various mixtures of sc solvents (e.g., ethane, carbon dioxide, ethylene) are used in combination with a strongly polar solvent gas like ammonia. The physical properties of these components are shown in Table I. The experimental results were then compared with VLE predictions using a newly developed equation of state (18). The key feature of this equation is a new set of mixing rules based on statistical mechanical arguments. We have been able to demonstrate its agreement with a number of binary and ternary systems described in the literature, containing various hydrocarbon compounds, a number of selected polar compounds and a supercritical component. 

Note Ethylene may be copolymerized with varying percentages of other materials, e.g., 2-butene or acrylic acid a crystalline product results from copolymerization of ethylene and propylene. When butadiene is added to the copolymer blend, a vulcan-izable elastomer is obtained. 

Marked decreases of the primarily formed butenes and butadiene with ethylene conversion suggest that these olefins play an important role forming secondary products. In fact, subsequent experiments showed that the addition of butadiene, 3-5 mole %, to ethylene accelerates the formation of cyclopentene, cyclohexene, cyclohexadiene, and benzene (Table I). It seems reasonable, therefore, to propose the following reaction scheme for the formation of cyclic compounds from olefins. 

The next discussion concerns the formation of propylene, 1-butene and butadiene which are the other main primary products of the reaction. The hot allyl (or 4-pentenyl) radical generated in reaction 29 (or 30) may abstract hydrogen from ethylene to form propylene (or 1-pentene) and a vinyl radical. From the highly endothermic nature of the vinyl radical formation, the postulation of a hot radical is again reasonable in this step. A similar reaction of a cyclopentyl radical with ethylene, i.e., + C=C... 

Fig. 4.11. A plot of observed melting temperature, Tm, against the mole percentage of structural irregularities in the polyethylene chain, o, HPBD , ethylene-butene V, ethylene-octene A, ethylene-hexene , ethylene-norbomene. M 90000. HPBD stands for hydrogenated poly (butadiene). Reproduced from [30], copyright 2000 with permission from Elsevier.

Butadiene is obtained mainly as a coproduct with other light olefins from steam cracking units for ethylene production. Other sources of butadiene are the catalytic dehydrogenation of butanes and butenes, and dehydration of 1,4-butanediol. Butadiene is a colorless gas with a mild aromatic odor. Its specific gravity is 0.6211 at 20°C and its boiling temperature is -4.4°C. The U.S. production of butadiene reached 4.1 billion pounds in 1997 and it was the 36th highest-volume chemical. ... 

Pd2+ salts are useful reagents for oxidation reactions of olefins. Formation of acetaldehyde from ethylene is the typical example. Another reaction is the formation of vinyl acetate by the reaction of ethylene with acetic acid (16, 17). The reaction of acetic acid with butadiene in the presence of PdCl2 and disodium hydrogen phosphate to give butadienyl acetate was briefly reported by Stem and Spector (110). However, 1-acetoxy-2-butene (49) and 3-acetoxy-l-butene (50) were obtained by Ishii and co-workers (111) by simple 1,2- and 1,4-additions using PdCl2/CuCl2 in acetic acid-water (9 1). 

The in situ regeneration of Pd(II) from Pd(0) should not be counted as being an easy process, and the appropriate solvents, reaction conditions, and oxidants should be selected to carry out smooth catalytic reactions. In many cases, an efficient catalytic cycle is not easy to achieve, and stoichiometric reactions are tolerable only for the synthesis of rather expensive organic compounds in limited quantities. This is a serious limitation of synthetic applications of oxidation reactions involving Pd(II). However it should be pointed out that some Pd(II)-promoted reactions have been developed as commercial processes, in which supported Pd catalysts are used. For example, vinyl acetate, allyl acetate and 1,4-diacetoxy-2-butene are commercially produced by oxidative acetoxylation of ethylene, propylene and butadiene in gas or liquid phases using Pd supported on silica. It is likely that Pd(OAc)2 is generated on the surface of the catalyst by the oxidation of Pd with AcOH and 02, and reacts with alkenes. 

Extracting the isobutylene with sulfuric acid and distilling the 1-butene away from butane and butadiene is used for separation of the 1-butene. It is also made by Ziegler (or non-Ziegler) oligomerization of ethylene (Fig. 1). 

All extraction runs were made with equimolar mixtures of butene/butadiene using ethylene, ethane or carbon dioxide as the solvent with various concentrations of ammonia from 0-10 vol%. 

Thermal decomposition of 1-butene provides a more complex product spectrum than is obtained from either cis- or trans-2-butenes. Between 550° and 760°C in a flow system with nitrogen dilution (3), methane, propylene, butadiene, and ethylene were major products as well as hydrogen, ethane, 1-pentene, 2-pentene, 3-methyl-1-butene, and 1,5-hexa-diene. In studies in a static system (4), cyclohexadienes, benzene, cyclopentene, cyclopentadiene, toluene, orthoxylene, and cyclohexene were observed among the liquid products of the reaction over the temperature range 490°-560°C. 

Formation of the relatively unstable complexes (olefin)M(C0)5 and (olefin)2M(C0)4 (M = Mo or W) with propylene and butadiene has been accomplished (559) by UV irradiation of M(CO)o with olefin in w-hexane. From W(CO)e, the complexes (cis-2-butene)W(CO)6, (fmws-2-butene)-W(CO)5, and (cis-2-butene)2W(CO)4 have been produced similarly. As with the corresponding ethylene complexes, the olefin ligands in the bis-olefin complexes are in trans positions. Although, in these complexes, the butadiene molecule is coordinated at only one double bond, upon lengthy irradiation of (butadiene)2Mo(CO)4 (559), the previously reported (268) complex (butadiene)2Mo(CO)2 involving chelated butadiene molecules is produced. 

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