Benzene maleic anhydride

Maleic anhydride (2,5-furandione) is obtained as a by-product in the production of phthalic anhydride and by the vapor phase oxidation of butylene or crotonaldehyde. It is also obtained by the dehydration of maleic acid and by the oxidation of benzene. Maleic anhydride is used for the production of unsaturated polyester resin. This reactant, like most reactants, is fairly toxic and should be treated as such. 

Cycloaddition reactions proceed generally via the triplet state. However, the charge transfer interaction may be important for the initial photoexdtation. An example is the 1,2-cydoaddition of maleic anhydride with benzene. The benzene-maleic anhydride complex is the photoabsorbing species (76). 

Scheme 6 Preparation of the benzene-maleic anhydride exo-ortho adduct. (From Ref. 39.)...

In the presence of a second dienophile, the ortho adduct can be trapped. Koltzenburg et al. [43] have added duroquinone to a benzene solution of maleic anhydride and obtained a 1 1 1 adduct formed from benzene, maleic anhydride, and duroquinone. 

Figure 1. Infrared spectra (KBr) of (A) polyimide prepared by photolysis of benzene sobitions of ii,N -hexarnethylenebistnaleirnide (B) polyimi prepared from benzene-maleic anhydride photoadauct (2) and 1,6-hexanediamine and (C) the N,N -bis(n-...

Benzenediazomum-2-carboxylate, 46,1194 Benzenediazonium chloride, 394, 838 Benzenediazonium fluoroborate, 394 Benzenediazonium nitrate, 328 Benzenediazonium sulfonate, 713 Benzene-maleic anhydride 1 2 adduct, 557 Benzenesulfinyl fluoride, 849 Benzenesulfonamides, 46-47, 48... 

There have been notable shifts in raw materials for the manufacture of maleic anhydride and phenol. Made for many years by the oxidation of benzene, maleic anhydride now is made by a catalytic process from butane. The butane process was found to result in lower costs of operation as well as reduced environmental, safety, and health hazards. Another example is the manufacture of phenol, initially made from benzene or chlorobenzene. Subsequently, however, with large supplies of cumene from the catalytic reaction of benzene and propylene, production came to be dominated by cumene-derived phenol, which, requires a lower capital investment and offers reduced operating expenses as well as reduced environmental and safety problems. A novel... 

Vanadium pentoxide Asbestos 400 Benzene Maleic anhydride (32, 33)... 

Synonyms 2,5-Furandione, polymer with etheny I benzene Maleic anhydride/styrene copolymer Maleic anhydride/styrene polymer Poly (styrene-co-maleic anhydride) SMA Styrene/maleic anhydride copolymer Styrene/maleic anhydride polymer Styrene/maleic anhydride resin Classification Engineering thermoplastic styrene polymer... 

Syntheses have been reported of barrelene (505) and of Nenitzescu s hydrocarbon (503) on a reasonable scale and without some of the difficulties that attend the previously published routes." " The preparation of (503) is of central importance, it being obtained by the oxidative bisdecarboxylation of the cyclo-octatetraene-maleic anhydride Diels-Alder adduct (502) with dicarbonylbis(triphenylphosphine)-nickel in diglyme at reflux. Cycloaddition of (503) to 2,5-dimethyI-3,5-diphenyl-cyclopentadienone in hot benzene afforded (504) and its endo-isomer. Photolysis of (504) yielded (505) in 24% yield from cyclo-octatetraene. The thermally labile benzene-maleic anhydride [4 + 2] cycloadduct (506) was obtained in similar fashion from (502). A review of the mechanisms of pyrolysis of (503) and a number of isomers and benzo-fused (CH) derivatives (collectively termed Nenitzescu s hydrocarbons) has appeared." ... 

The reactor effluent, Stream 7—containing small amounts of unreacted benzene, maleic anhydride, quinone, and combustion products—is cooled in E-603 and then sent to an absorber column, T-601, which has both a reboiler and condenser. In T-601, the vapor feed is contacted with recycled heavy organic solvent (dibutyl phthalate). Stream 9. This solvent absorbs the maleic anhydride, quinone, and small amounts of water. Any water in the solvent leaving the bottom of the absorber, T-601, reacts with the maleic anhydride to form maleic acid, which must be removed and purified from the maleic anhydride. The bottoms product from the absorber is sent to a separation tower, T-602, where the dibutyl phthalate is recovered as the bottoms product. Stream 14, and recycled back to the absorber. A small amount of fresh solvent. Stream 10, is added to account for losses. The overhead product from T-602, Stream 13, is sent to the maleic acid column, T-603, where 95 mol% maleic acid is removed as the bottoms product. 

Styrene Copolymers, Copolymerization is another way to improve the mechanical properties and chemical resistance of polystyrene. Acrylonitrile, butadiene, alphamethylstyrene, methyl methacrylate, divinyl-benzene, maleic anhydride, and other monomers have been copolymerized with styrene to produce commercially important copolymers. Some of the most widely used of these are those prepared with acrylonitrile and butadiene. Styrene copolymerized with butadiene (SBR) is one of the more important elastomeric materials used today. (See Chapter 18.)... 

Commercially, maleic anhydride is prepared more cheaply by the catalytic vapour phase oxidation (in the presence of vanadium pentoxide at about 400°) of benzene with atmospheric oxygen ... 

Ma.leic Anhydride. The largest chemical use for / -butane is as feedstock for maleic anhydride. A dilute air—butane mixture is passed over a vanadium—phosphoms catalyst 400—500°C to produce maleic anhydride [108-31-6] in good yield. Formerly benzene was used as feedstock, but in the last few years nearly all maleic anhydride in the United States, and an increasing proportion worldwide, is made from butane. 

Maleic anhydride and the two diacid isomers were first prepared in the 1830s (1) but commercial manufacture did not begin until a century later. In 1933 the National Aniline and Chemical Co., Inc., installed a process for maleic anhydride based on benzene oxidation using a vanadium oxide catalyst (2). Maleic acid was available commercially ia 1928 and fumaric acid production began in 1932 by acid-catalyzed isomerization of maleic acid. 

Cyclobutane derivatives are formed after exposing a mixture of alkenes and maleic anhydride to light. Photoadducts are formed by reaction of maleic anhydride with ethylene [74-85-1] and benzene (50). 

Process Technology Evolution. Maleic anhydride was first commercially produced in the early 1930s by the vapor-phase oxidation of benzene [71-43-2]. The use of benzene as a feedstock for the production of maleic anhydride was dominant in the world market well into the 1980s. Several processes have been used for the production of maleic anhydride from benzene with the most common one from Scientific Design. Small amounts of maleic acid are produced as a by-product in production of phthaHc anhydride [85-44-9]. This can be converted to either maleic anhydride or fumaric acid. Benzene, although easily oxidized to maleic anhydride with high selectivity, is an inherently inefficient feedstock since two excess carbon atoms are present in the raw material. Various compounds have been evaluated as raw material substitutes for benzene in production of maleic anhydride. Fixed- and fluid-bed processes for production of maleic anhydride from the butenes present in mixed streams have been practiced commercially. None of these... 

Benzene-Based Catalyst Technology. The catalyst used for the conversion of ben2ene to maleic anhydride consists of supported vanadium oxide [11099-11-9]. The support is an inert oxide such as kieselguhr, alumina [1344-28-17, or sUica, and is of low surface area (142). Supports with higher surface area adversely affect conversion of benzene to maleic anhydride. The conversion of benzene to maleic anhydride is a less complex oxidation than the conversion of butane, so higher catalyst selectivities are obtained. The vanadium oxide on the surface of the support is often modified with molybdenum oxides. There is approximately 70% vanadium oxide and 30% molybdenum oxide [11098-99-0] in the active phase for these fixed-bed catalysts (143). The molybdenum oxide is thought to form either a soUd solution or compound oxide with the vanadium oxide and result in a more active catalyst (142). 

Capacities of maleic anhydride faciUties worldwide are presented in Table 7. The switch of feedstock from benzene to butane was completed in the United States in 1985, being driven by the lower unit cost and lower usage of butane in addition to the environmental pressures on the use of benzene. Worldwide, the switch to butane is continuing with 58% of the total world maleic anhydride capacity based on butane feedstock in 1992. This capacity percentage for butane has increased from only 6% in 1978. In 1992, 38% of the total world maleic anhydride capacity was based on benzene feedstock and 4% was derived from other sources, primarily phthaUc anhydride by-product streams. 

Oxidation. Benzene can be oxidized to a number of different products. Strong oxidizing agents such as permanganate or dichromate oxidize benzene to carbon dioxide and water under rigorous conditions. Benzene can be selectively oxidized in the vapor phase to maleic anhydride. The reaction occurs in the presence of air with a promoted vanadium pentoxide catalyst (11). Prior to 1986, this process provided most of the world s maleic anhydride [108-31 -6] C4H2O2. Currendy maleic anhydride is manufactured from the air oxidation of / -butane also employing a vanadium pentoxide catalyst. 

Prior to 1975, benzene was catalytically oxidized to produce maleic anhydride, an intermediate in synthesis of polyester resins, lubricant additives, and agricultural chemicals. By 1986 all commercial maleic anhydride was derived from oxidation of / -butane. It is expected that / -butane will remain the feedstock of choice for both economic and environmental reasons. 

Most maleic anhydride production in the United States is based on benzene as feedstock, even though substantial Hterature exists on the use of butenes (132—134). However, the rapidly increasing demand and price for benzene (as high as 620 /t in 1986 versus 310 /t for ethylene) have made benzene (qv) less attractive and butenes a better feedstock. Not only are theoretical yields better, 1.75 kg/kg of butenes compared to 1.26 kg/kg of ben2ene, but less oxygen is required and the oxidation produces less heat, which is critical in reactor design. 

Although benzene prices have escalated in recent years, a concurrent need for butenes for use in alkylates for motor fuel has also increased and butane prices have also escalated. As a result, a search for alternative feedstocks began and Amoco Chemical Co. commercialized a process in 1977 to produce maleic anhydride from butane. A plant in JoHet came on-stream in 1977 with a capacity of 27,000 t/yr (135,136). No new plants have been built in the United States based on butenes since the commercialization of butane to maleic anhydride technology. In Europe and particularly in Japan, however, where butane is in short supply and needs for butenes as alkylation feed are also much less, butenes may become the dominant feedstock (see Maleic anhydride). 

Maleic anhydride is made by oxidation of benzene with air above 350°C (662°F) with V-Mo catalyst in a mnltitiibiilar reactor with 2-cm tubes. The heat-transfer medium is a eutectic of molten salt at 375°C (707°F). Even with small tubes, the heat transfer is so hmited that a peak temperature 100°C (212°F) above the shell side is developed and moves along the tubes. 

Biphenyl [92-52-4] M 154.2, m 70-71 , b 255 , d 0.992. Crystd from EtOH, MeOH, aq MeOH, pet ether (b 40-60 ) or glacial acetic acid. Freed from polar impurities by passage through an alumina column in benzene, followed by evapn. A in CCI4 has been purified by vac distn and by zone refining. Treatment with maleic anhydride removed anthracene-like impurities. Recrystd from EtOH followed by repeated vacuum sublimation and passage through a zone refiner. [Taliani and Breed Phys Chem 88 2351 1984.]... 

Maleic anhydride [108-31-6] M 98.1, m 54 , b 94-96 /20mm, 199 /760mm. Crystd from benzene, CHCI3, CH2Cl2or CCI4. Sublimed under reduced pressure. [Skell et al. J Am Chem Soc 108 6300 7956.]... 

Maleic anhydride is commonly prepared by passing a mixture of benzene vapour and air over a catalyst (e.g. a vanadium derivative) at elevated temperatures (e.g. 450°C). It is a crystalline solid melting at 52.6°C (the acid melts at 130 C). 

Benzene CftHs Production of ethyl benzene, cumene, cyclohexane, maleic anhydride, nitrobenzene, chlorobenzene, detergents... 

The major aromatics (organics having at least one ring structure with six carbon atoms) manufactured include benzene, toluene, xylene, and naphthalene. Other aromatics manufactured include phenol, chlorobenzene, styrene, phthalic and maleic anhydride, nitrobenzene, and aniline. Benzene is generally recovered from cracker streams at petrochemical plants and is used for the manufacture of phenol, styrene, aniline, nitrobenzene, sulfonated detergents, pesticides such as hexachlorobenzene, cyclohexane (an important intermediate in synthetic fiber manufacture), and caprolactam, used in the manufacture of nylon. Benzene is also used as a general purpose solvent. 

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