Butadiene acetylene-based

The 1,3-butadiene-based 1,4-butanediol process was reviewed in this chapter. This method ended the half-century monopoly of the acetylene-based Reppe method. This development was in line with the switch from coal to petroleum feedstock. Because the acetoxylation of 1,3-butadiene was the first successful commercial... 

Although a feedstock, or a particular feedstock source, is initially taken up because it is produced in excess or is even a waste product, its success can result in the need to manufacture it specially for that process, thereby losing the rationale for its original adoption. One can see this progression at work with coal-tar (in particular phenol ) and synthetic dyes, with coke-based ammonia and the Solvay process, with calcium carbide and acetylene-based chemicals, and, more recently, with refinery gases and petrochemicals. Conversely, butanol became such a major by-product of butadiene production that I.G. could only sell a quarter of it by 1943. ... 

At one time, the only commercial route to 2-chloro-1,3-butadiene (chloroprene), the monomer for neoprene, was from acetylene (see Elastomers, synthetic). In the United States, Du Pont operated two plants in which acetylene was dimeri2ed to vinylacetylene with a cuprous chloride catalyst and the vinyl-acetylene reacted with hydrogen chloride to give 2-chloro-1,3-butadiene. This process was replaced in 1970 with a butadiene-based process in which butadiene is chlorinated and dehydrochlorinated to yield the desired product (see Chlorocarbonsandchlorohydrocarbons). 

KLP [Dow K Catalyst liquid phase] A selective hydrogenation process for removing acetylenes from cmde C4 hydrocarbons from ethylene cracking, with no loss of butadiene. The catalyst is based on either copper metal or alumina. Developed by Dow Chemical Company and first commercialized at its plant in Temeuzen, The Netherlands. The KLP licensing business was sold to UOP in 1991. 

Diels-Alder reactions of bis(trimethylsilyl)acetylene.1 A catalyst obtained from TiCl4 and (C2H5)2A1C1 (1 20) effects Diels-Alder reactions of this acetylene with butadiene and methyl-substituted derivatives to form l,2-bis(trimethylsilyl)-cyclohexa- 1,4-dienes in 70-78% yield (equation I). The yield is low (15%) only when R, R4 = CH3,R2,R3 = H because of polymerization of the diene. The products undergo thermal dehydrogenation at 240° to form l,2-bis(trimethylsilyl)ben-zenes in almost quantitative yield. This cycloaddition has been effected in low yield with an iron-based catalyst. 

Palladium-catalyzed 1,4-diacetoxylation of butadiene is a useful reaction of commercial interest which provides an interesting alternative for the synthesis of butanediol and tetrahydrofuran, previously based on acetylene feedstocks (equation 165). 

Chloroprene is of high industrial importance for manufacture of synthetic rubbers. For a long time the synthesis was based on acetylene. More recent processes are based on butadiene as a feedstock, which is substantially cheaper [29]. The initial step is a gas-phase free-radical chlorination at 250 °C and temperature control is ensured by use of excess butadiene (molar ratio of Cl2 to butadiene 1 5 to 1 50) [44]. To limit side reactions, short contact time reactors operating at higher temperatures and residence times below one second are also known [45], Good mix-... 

Figure 10. Coke at interface between alonized surface and Incoloy 800 base. (Top left) Butadiene—560°C (2nd position) (top right) butadiene—600° C (3rd position) (middle left) acetylene—380°C (1st position) (middle right) acetylene—440°C (2nd position) (bottom left) acetylene—450°C (3rd position) (bottom right) acetylene—440°C (4th...

Ethanol is the key reactant in Eq. (1), and also in Eq. (2) because it is readily converted to acetaldehyde. The process based on Eq. 1 was developed in Russia and the process based on Eq. 2 was developed in the United States. The yield of butadiene for the Russian process is about 30-35%. It is about 70% if mixtures of ethanol and acetaldehyde are employed as in the U.S. process. Equation (3) represents a process that involves 2,3-butylene glycol, a product from the microbial conversion of biomass. The process is carried out in two sequential steps via the glycol diacetate in overall yields to butadiene of about 80%. The process of Eq. (4) starts with a biomass derivative, the cyclic ether tetrahydrofuran, and can be carried out at high yields. When this process was first operated on a large scale in Germany, acetylene and formaldehyde were the raw materials for the synthesis of intermediate tetrahydrofuran. It is manufactured today from biomass feedstocks by thermochemical conversion, as will be discussed later. 

Dialkylamino-l-butynes (1), readily available from reaction of acetylene with secondary amines, are isomerized by this base to 2-dialkylamino-1,3-butadienes (2) no allenic products are observed.611... 

The Reppe process is based on acetylene and formaldehyde feed originally, it was developed in Germany during World War II to form butadiene. The last step of the Reppe process was eliminated and the intermediate product was used to produce THF. The process is ... 

The Reppe process is based on acetylene as a raw material. These reactions were developed by Reppe et al. [2]. In accordance with the rise of the petrochemical industry, most processes switched from acetylene to olefins as raw material. However, only the 1,4-butanediol production process continued to rely on the Reppe process. Mitsubishi Chemical Corporation developed a totally different production method that uses 1,3-butadiene to produce 1,4-butanediol and THF. Commercial production was launched in 1982 and has been continued ever since. This process ended the over-half-century monopoly of the Reppe method. The Mitsubishi Chemical method has an advantage over the Reppe method with respect to the handling of raw materials and production costs, but in recent years, Chinese companies that can take advantage of inexpensive natural gas and coal have built a new production plant by using the Reppe method and international competition is getting more intense. 

Thermoplastic polymers were also earlier reported to have been prepared by heating tricyclodecane dithiol with terephthaloyl chloride in a chlorinated solvent [16b]. Additional examples are cited for polythioesters based on bis-phenol A and random other polythioesters derived from bicyclic thiols. The starting diolefins for the dithols are prepared by the Diels-Alder synthesis using cyclopentadiene, acetylene, butadiene, etc. 

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