Butadiene BD

Bromine is used to haiogenate butyi rubber (HR) into bromobutyl rubber (BUR), which is iargeiy used in tire innerliners. 

Bromine is used to synthesize brominated flame retardants that are occasionally used in rubber. 

Bromine is used to manufacture ethylene dibromide as an antiknock agent for gaso-iine. Bromine is used as an intermediate to make fumigants such as methyl bromide. It is commonly used to produce flame retardants for plastics and in photochemistry and dye synthesis. 

more butadiene is produced from butene (another C4) through steam cracking of naphtha gas oii from ethyiene/propylene production. Through extractive dis-tiiiation of this C4 cracker stream, the butadiene is obtained. The yield achieved for BD is dependent on the quaiity of the feedstock used for ethylene production. The heavier the feedstock is, the greater the BD production usually is. Reportedly, the light feedstock only yields about one-fifth the yield of butadiene compared to the heavy feedstock. 

A major problem has been the availability of the butadiene monomer. Because of the gradual switchover from naphtha feedstocks from petroleum over to ethane feedstocks from natural gas in the production of ethylene for the plastics industry, there are fewer C4 streams available for butadiene production. (Ethylene plants are gaining significant economic savings by making this feedstock conversion from naphtha to ethane.) This has resulted in significant shortages of butadiene to the rubber industry in the first decade of the twenty-first century. However, there is optimism in this decade that butadiene will be more available than before because of the 

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A new class of organolanthanide complex has been reported from the metal-atom reaction of lanthanide atoms and butadiene (BD) or 2,-... 

Yu J.M., Dubios P., and Jerome R., Synthesis and properties of polypsobomylmethacrylate (IBMA)-b-butadiene (BD)-b-IBMA] copolymers New thermoplastic elastomers of a large service temperature range. Macromolecules, 29, 7316, 1996. 

Hydrogen cyanide smoothly adds to butadiene (BD) in the presence of zero-valent nickel catalysts to give (3PN) and (2M3BN) [1,4- and 1,2-addition products, respectively, Eq. (7)]. A variety of Ni[P(OR)3]4 (R = alkyl or aryl) complexes are suitable as catalysts. The reaction may be carried out neat or in a variety of aromatic or nitrile solvents at temperatures from 50-120°C. Whereas in many olefin hydrocyanations it is desirable to keep the HCN concentration very low to protect the nickel from degradation, with butadiene HCN may be added batchwise as long as the HCN concentration is kept near the butadiene concentration. In the case of batch reactions one must be cautious because of possible temperature rises of 50°C or more over a period of a few minutes. Under typical batch conditions, when Ni[P(OEt)3]4, butadiene, and HCN are allowed to react in a ratio of 0.03 1.0 1.0 at 100°C for 8 hr, a 65% conversion to 3PN and 2M3BN (1.5 1) is observed (7). 

The polymerization of butadiene (BD) on this site proceeds to yield a cis-1,4-polybutadiene through the addition of a cisoid monomer in the form of the cobalt complex. 

Fig. 3 IR Spectra of Butadiene (BD)-Acrylonitrile(AN)-Acrylamid-oxime (AX) Terpolymer Exposed to Methanesulfonyl Fluoride (MSF) and Dimethyl Methylphosphonate (DMMP) Simulants.

There has been a great amount of theoretical and experimental studies on the spectra of stereoisomers of butadiene (BD) and their photochemistry [141, 60, 142]. In spite of this interest in the electronic excited states of BD there exist no other theoretical considerations of the intensity of the lowest energy transition a3Bu — X1Ag, besides the short communication in Ref. [125] using a semi-empirical SOC method (CNDO/S Cl). 

Figure 7.8 Dimerization of butadiene. L is a phosphine or phosphite (see Problem 11). 7.26 and 7.27 can be formed from butadiene (BD) and L-Ni by 7.8-type formalism.

The C4 acetylenes, which have higher solubilities in NMP than 1,3-butadiene, are removed by the solvent in the bottoms and returned to the rectifier. A crude butadiene (BD) stream, from the overhead of the second extractive distillation column, is fed into the BD purification train. Both extractive distillation columns have a number of trays above the solvent addition point to allow for the removal of solvent traces from the overheads. 

The first figure illustrates that ethane and propane dehydrogenation becomes favourable at temperatures over about 900 K under ambient pressures. For the conversion of butane (C4) to butadiene (BD), higher temperatures are required. 

Figure 6.5 Structure-activity link between growth of surface carbon, formation of butadiene (BD) and formal oxidation state of vanadium (reaction conditions 0.4 mbar n-butane and 723 K).

Figure 46. Photocurrent transients for hole transport in TTA (40 wt.%)-doped polycarbonate containing as an added impurity l,l-bis(p-diethylaminophenyl)-4,4-diphenyl-l,3-butadiene (BD) at various concentrations. The current (vertical) scale is arbitrary. The samples were 16 pm thick, the temperature 298 K, and the field strength 3.75 x 10 V cm . (Reprinted with permission from Ref [74j].)...

The more complex selective 1,3-butadiene (BD) hydrogenation was also examined [56, 57]. Butadiene hydrogenation produces 1-butene, tranx-2-butene, cti-2-butene, and n-butane, with 1-butene as the desired product. Pd-Al Oj model catalysts with mean particle diameters of 2-8 nm were applied to examine size effects. The abihty to accurately determine the relative abundance of specific surface sites (such as terrace, edge, interface atoms, etc. cf. surface site statistics in Table 1, 2 of [51]) is a tremendous advantage of model catalysts. Knowledge of the exact number and type of available surface sites allows the calculation of more accurate turnover frequencies. 

Thermal cyclooligomerizations of olefins and alkynes require severe and often dangerous reaction conditions and the yields of cyclic products are usually very low. Acetylene ean be trimerized to benzene at 500 °C [1] and butadiene (BD) dimerizes at 270 °C and under high pressure to give small amounts of 1,5-cyclo-octadiene [2]. Reppe s discovery in 1940 that acetylene can be cyclotetramerized to cyclooctatetraene (COT) using a nickel catalyst [3] shows that transition metals can act as templates for the synthesis of cyclic hydrocarbons from acetylenic or olefinic building blocks (Scheme 1). 

The first catalytic cyclodimerization of 1,3-butadiene (BD) to 1,5-cycloocta-diene using modified Reppe catalysts was reported by Reed in 1954 [4], and only two years later Wilke reported on the titanium-catalyzed synthesis of cyclo-dodecatrienes from BD [5]. It remained for Wilke and his co-workers to show the tremendous versatility and scope of the nickel-catalyzed cyclooligomerizations of... 

As background for the preparation of this article, a Google search of polybutadiene (PB) was made and 24,700 hits were generated. The addition of other terms to the quoted search reduced the number of hits to 1668 for structural features, 660 for modifications, 525 for uses of blends, and 52 for polymerization variations. This still is an impressive and formidable number of potential references that show the significant activity and utilization of PB. This does not include styrene/butadiene (BD)/styrene triblock and random copolymers (SBR), that are separate subjects and will not be considered. The reason for the plethora of literature available on PB is derived from a combination of factors. Primarily the base monomer BD is abundant, inexpensive, and can be converted readily to a variety of different reactive polymeric structures. 

Application To produce high-purity butadiene (BD) from a mixed stream, typically a byproduct stream from an ethylene plant using liquid feeds (liquids cracker). The BASF process uses n-methylpyrrolidone (NMP) as the solvent. 

Description The cut enters the pre-distillation tower, in which methyl acetylene, propadiene and other light components are separated as gaseous overhead product. Its bottom product enters the bottom section of the main washer column while NMP solvent enters at the column top. Overhead product raffinate consisting of butanes and butenes is drawn off. The loaded solvent is sent to the rectifier, which comprises a vertical plate in its upper section. In its first compartment, the less soluble butenes are stripped and fed back into the main washer. In its second compartment, the acetylenes are separated from crude butadiene (BD) due to their higher solubility in NMP. 

The main limitation to the method is that the anion of one monomer must be able to initiate the polymerization of a second monomer, and this may not always be the case. Thus, polystyryl lithium can initiate the polymerization of methyl methacrylate to give an (A - B) diblock but, because of its relatively low nucleo-philicity, the methyl methacrylate anion cannot initiate styrene propagation. Best results are achieved when two monomers of high electrophilicity are used, e.g., styrene (St) with butadiene (Bd) or isoprene and (A - B - A) triblocks can be formed as shown in Equation 5.17a and Equation 5.17b. 

The anionic polymraization of butadiene (BD) with -butyl lithium to form Uving polybutadiene hthium can be taminated by reaction with a nitroxide, which can then be used to mediate a subsequent styrene polymerization, as shown. 

The nickel-catalyzed cyclooligomerization of butadiene (BD) is one of the most thoroughly studied homogeneous catalytic reactions. Extensive NMR studies of intermediates and model compounds have recently been reported. It provides one of the best examples of the ability of phosphorus ligands to control both rates and product distributions in homogeneous catalysis and shows just how complex catalytic systems can become. 

Butadiene (BD) is produced by the expensive extraction of BD from a crude C4 stream in an ethylene plant. The BD value is about 0.06/lb when it is contained in the crude C4 stream, but about 0.18/lb after it is extracted. Because of this price difference, processes are always being sought to use the BD in the crude C4 stream without extracting it, and returning the remaining C4 stream to the ethylene plant. A typical crude C4 stream has the following composition in weight percent ... 

In order to obtain well-defined AB diblock copolymers by anionic polymerization and sequential monomer addition, some crucial conditions must be fulfilled (1) the carbanion formed by the second monomer must be more, or at least equally, stable than the one derived from the first monomer, and (2) the initiation of polymerization of the second monomer by the anion of the first monomer must be higher than the rate of propagation of monomer B. To fulfill these requirements, the monomers used must be added sequentially in the order of increasing electron affinity (e.g., a-methyl styrene (aMeSt) < St butadiene (Bd)< vinyl pyridine < methyl methacrylate (MMA)) and the nucleophilicity of the intermediate macromolecular carbanion A formed should at least match (though... 

In nitrile rubber (NBR), the rubber polarity changes with the acrylonitrile (AN) content of the rubber. Since AN is polar and butadiene (BD) is nonpolar, the rubber polarity will increase with AN level. Therefore, the level of compatibility with other polymers will depend upon NBR composition. The glass transition temperature (Hy also increases with increasing AN level. 

The elimination of small amounts of 1,3-butadiene (BD) and acetylenic compounds (e.g. 1-butyne) in the purification of C4 cuts rich in olefins, 1-butene (IBE), cis2-butene (cBE) and trans 2-butene (tBE), is conveniently carried out by liquid-phase selective hydrogenation on Pd/Al203 catalysts [1]. 

Structural formula (32) shows poly-1,4-butadiene (BD), but 1,2-poly BD and the mixture of the two are also produced. 

Special polymerization approaches are necessary to prepare random solution SBRs with organolithium in hydrocarbon solvent. The main polymerization methods for producing random copolymers, or containing only short (non-blocky) styrene sequences, are given in Table 5. For convenience, the procedures are divided into those that control the polymerization process in order to maintain a high styrene/butadiene (Bd) ratio in the hydrocarbon media, and those that... 

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