Anhydride, maleic

Maleic anhydride (MA) is an important raw material in the production of alkyd and polyester resins. It was first obtained by Nikolas Louis Vauquelin in 1817, by heating maleic acid to over 140 °C. In 1905, Richard Kempf obtained maleic acid by the oxidation of benzoquinone. The first patents covering the production of maleic anhydride from benzene originate from John M. Weiss and Charles R. Downs in 1918. The oxidation of benzene remains a feasible route to maleic anhydride even today, although since around 1975, n-butane and n-butylene have increasingly replaced benzene as raw materials. n-Butane and n-butylene are available as co-products in steam cracking of naphtha and from natural gas condensates. 

1 Benzene vaporizer 2 Multitubular reactor 3 Salt bath cooler 4 Gas scrubber 5 Dehydration column 6 Storage tank 7 Distillation boiler 8 Distillation column 

Benzene vapor is mixed with air (benzene concentration 1 to 1.4 mol%) and fed over a fixed-bed catalyst contained in a multitubular reactor. The tubes, which are arranged vertically, have a diameter of 20 to 50 mm one reactor contains up to 20,000 tubes. The reaction temperature is kept at 350 to 400 °C by cooling with a salt bath the pressure is 1 to 2 bar. 

The reaction products leaving the reactor are first quenched to below 200 C, then cooled further in a condenser to around the dew point (55 to 65 C). The uncondensed maleic anhydride is recovered in an attached absorber. The off gas, carrying unconverted benzene, can be processed in a benzene-adsorption plant. The crude maleic anhydride is refined by distillation with o-xylene as an entrainer. Care should be taken in operating the dehydrating column that the temperature does not exceed 130 °C, in order to restrict the undesirable isomerization of maleic acid to fumaric add. 

In addition to condensation, the oxidation product may also be collected in solid form, by cooling to around 40 °C. In this process, the crude maleic anhydride solidifies on the surface of the cooler in the form of needle-shaped crystals. At least two such collectors (switch condensers) are needed. The full collector is heated to 60 to 80 and the molten MA drawn off into a collecting vessel for further refining by distillation. 

Maleic anhydride 495 reacted with chlorosulfonic acid in phosphorus oxychloride to give the sulfonyl chloride 496. On the other hand, prolonged treatment of the anhydride 495 with boiling chlorosulfonic acid (150-160 °C) afforded a mixture of the a-chloro derivative 497 and the sulfonyl chloride 496 (Equation 158). This result shows that at 150-160 °C, chlorosulfonic acid is acting both as a sulfonating and a chlorinating agent. 

11 Maleic Anhydride and Phthalic Anhydride for THF, Spandex, Swim-suits and Ladies Tights 

Maleic anhydride (1.17 Mt/a world installed capacity) finds its major use in the synthesis of unsaturated polyester resins ca. 41%), with the remainder going to produce butanediol (14%), maleic copolymers (8%), tetrahydrofuran (7%), 

In the first commercial process, introduced in 1933, maleic anhydride was produced by the catalytic oxidation of benzene with air. Although its appeal declined after the 1970s the benzene process is still operated, particularly where -butane is not available. The catalyst is a mixed oxide (70% V2O5 30% M0O3) deposited on a low surface area carrier to limit side reactions. Atom efficiency is inherently low, as implied by the stoichiometry of the oxidation in which two carbon atoms out of six are lost as CO2 (Equation B4). Molar yields however can be relatively high ca. 73%) and are generally higher than those in the -butane processes. 

Both the partial oxidation to the product and the combustion to carbon oxides are strongly exothermic. The technical solution devised to prevent hot spots and dissipate the heat consists of a multitubular fixed bed reactor cooled by a circulating molten salts fluid. The production of steam is well above the needs of the plant and the site location is often dictated by the possibilities for heat utilization. 

A complex network of reactions is hidden behind the simple stoichiometry of -butane oxidation (Equation 35). Butene, butadiene and furan have been suggested to be intermediates in a cascade of reactions eventually producing the anhydride. Carboxylic acids and carbon oxides are formed in parallel and consecutive oxidations. 

There are a few alternative approaches to imide copolymers that allow the resin producer to make imide-modified high heat ABS without incurring the cost of the synthesized imide monomer. One is by reacting styrene-maleic anhydrides with a primary amine, either during the polymerization reaction with styrene or in a separate step. Mitsubishi Monsanto has practiced imidiza-tion on a commercial scale and described a process which follows the formation of S-MA with addition of amine and AN [60]. They described the manufacture of maleimide copolymers by heating the SMA copolymers with aniline in an extruder [61]. The maleimidation of the anhydride function is not complete, as there is unreacted amine or maleic anhydride in the product. The polymer stability and physical properties depend on the mole percent of maleimidation. 

Another approach is free radical copolymerization of a maleimic acid with styrene. Quantitative ring closure to the imide form was described by Newman of Dow Chemical Company [62,63]. 

The predominant commercial synthesis of MA is by vapor-phase oxidation of hydrocarbons, e.g. benzene, n-butane, or a C-4 hydrocarbon mixture, over a solid catalyst [67]. The oxidation of benzene over a supported vanadium oxide catalyst is the preferred procedure. In a typical process, the reactor gas containing low concentrations of MA is passed through a heat exchanger and 

Monsanto claimed that a maximum of 11 wt% AN can be added before severe crosslinking occurs. Melt processing of materials with this tendency to crosslink is challenging. 

Product Technology MFR (g/lOmin) Notched Izod° (J/m) Vicat6 ( C) 

Butane and butenes from refinery crackers and natural gas. Since 1985 butane was introduced to replace benzene as the feedstock. The first commercial production, based on benzene, started in 1930. 

Maleic anhydride is an important intermediate in the chemical industry [8-9]. It is used in polycondensation and addition reactions. The end products of these reactions are polyesters, alkyd resins, lacquers, plasticizers, copolymers and lubricants. For example, the copolymer of styrene and maleic anhydride is an engineering plastic. 

The typical size of the plant of the process described here is 20,000-30,000 tons per year. World production is 0.5 million tons per year. 

The elucidation of the kinetic network has received a lot of attention. The following simplified scheme has been proposed  

From the extensive literature it can be concluded that a Mars-van Krevelen mechanism applies the oxidation of the hydrocarbons is achieved using the surface oxygens and the reoxidation of the catalysts is accomplished by reduction of oxygen at separate sites. 

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The crude phthalic anhydride is heated and held at 260 C to allow some byproduct reactions to go to completion. Purification is by continuous distillation in two columns. In the first column, maleic anhydride and benzoic and toluic acids are removed overhead. In the second column, pure phthalic anhydride is removed overhead. High boiling residues are removed from the bottom of the second column. 

M.p. 234-235 C. Hydrolyses to aspartic acid. L-asparagine can be prepared from lupin seedlings, and DL-asparagine is synthesised from ammonia and maleic anhydride. L-asparagine is very widely distributed in plants, being found in all the Leguminosae and Gramineae, and in many other seeds, roots and buds. 

CHa CHlCH CHO. Colourless lachrymatory liquid with a pungent odour. B.p. 104 "C. Manufactured by the thermal dehydration of aldol. May be oxidized to crotonic acid and reduced to crolonyl alcohol and 1-butanol oxidized by oxygen in the presence of VjOj to maleic anhydride. It is an intermediate in the production of l-butanol from ethanol. 

COT is prepared by the polymerization of ethyne at moderate temperature and pressure in the presence of nickel salts. The molecule is non-planar and behaves as a typical cyclic olefin, having no aromatic properties. It may be catalytically hydrogenated to cyclo-octene, but with Zn and dil. sulphuric acid gives 1,3,6-cyclooclairiene. It reacts with maleic anhydride to give an adduct, m.p. 166 C, derived from the isomeric structure bicyclo-4,2,0-octa-2,4,7-triene(I) ... 

Colourless prisms m.p. 130 C. Manufactured by treating maleic anhydride with water. It is converted to the anhydride by heating at By prolonged heating at 150 "C or by heating with water under pressure at 200 C, it is converted to the isomeric (trans) fumaric acid. Reduced by hydrogen to succinic acid. Oxidized by alkaline solutions of potassium permanganate to mesotartaric acid. When heated with solutions of sodium hydroxide at 100 C, sodium( )-malate is formed. Used in the preparation of ( )-malic acid and in some polymer formulations. 

Used as fibres, particularly in textiles and film. Many other polyester polymers are of importance, e.g. unsaturated polyester resins from phthalic anhydride, propylene glycol and maleic anhydride used with reinforcement in boats, cars, etc. (alkyd resins). U.S. production 1983 1-7 megatonnes. 

For chemical processes, some examples are the elimination of aromatics by sulfonation, the elimination of olefins by bromine addition on the double bond (bromine number), the elimination of conjugated diolefins as in the case of the maleic anhydride value (MAV), and the extraction of bases or acids by contact with aqueous acidic or basic solutions. 

Represented by its abbreviation, MAV, the Maleic Anhydride Value Is based on the fact that olefinic conjugated double bonds can be added to maleic anhydride by the reaction below m]... 

A second family is based on isobutene polymers (PIB) having molecular weights from 600 to 2000 that are equally important raw materials for detergent additives. So as to render them reactive with the hydrophilic part, they can be chlorinated or condensed with the maleic anhydride. A third way is based on the utilization of polypropylphenols of molecular weights between 600 and 3000. 

Derivatives of polyisobutylene (6. in Figure 9.1) offer the advantage of control over the molecular weight of the polyisobutylene obtained by cationic polymerization of isobutylene. Condensation on maleic anhydride can be done directly either by thermal activation ( ene-synthesis reaction) (2.1), or by chlorinated polyisobutylene intermediates (2.2). The condensation of the PIBSA on polyethylene polyamines leads to succinimides. Note that one can obtain mono- or disuccinimides. The mono-succinimides are used as... 

The polyispbptylenes (PIB) having molecular weights ranging from 1000 to 2000 are substituted by maleic anhydride, and the polyisobutylene succinic anhydride (PIBSA) formed is neutralized by a polyethylene-polyamine as indicated in Figure 9.10. 

Since the octatetrene contains two CH CH-CH CH units, it will readily combine with two molecules of maleic anhydride and other adducts by the Diels-Alder reaction (p. 292). 

The Diels-Alder Reaction consists in the direct combination of a compound containing a conjugated diene system u ith a reagent which possesses a double or triple bond activated bj suitable adjacent groups. Examples of such reagents are maleic anhydride, p-benzoquinone, acraldehyde and acetylene dicarboxylic esters. Combination always occurs at the 1,4 positions of the diene system ... 

In the following preparation, this reaction is exemplified by the union of anthracene with maleic anhydride, to form 9,io-dihydroanthracene-9,io-e do-a -succinic anhydride note that as a result of this reaction both the outer rings of the anthracene system become truly aromatic in character. 

Mix 100 g. of maleic acid (Section 111,143) and 100 ml. of tetra chloroethane in a 250 ml. Claisen or distilling flask provided with a thermometer, and attach a Pyrex Liebig condenser. Heat the flask in an air bath (Fig. 11, 5, 3) and collect the distillate in a measuring cylinder. When the temperature reaches 160°, 76 ml. of tetrachloroethane and 15-15-5 ml. of water are present in the receiver. Empty the water in the condenser and continue the distillation change the receiver when the temperature reaches 190°. Collect the maleic anhydride at 195-197°. Recrystallise the crude anhydride from chloroform. The yield of pure maleic anhydride, m.p. 54°, is 70 g. 

Maleic acid may be prepared by warming malic acid with acetyl chloride, distilling the mixture under atmospheric pressure to isolate maleic anhydride, and hydrolysing the latter by boding with water. 

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 ... 

Both acids 3deld succinic acid, m.p. 185°, upon catalytic reduction (see Section 111,150), thus establishing their structures. Maleic and fumaric acids are examples of compounds exhibiting cis-trans isomerism (or geometric isomerism). Maleic acid has the cm structure since inter alia it readily 3delds the anhydride (compare Section 111,93). Fumaric acid possesses the trans structure it does not form an anhydride, but when heated to a high temperature gives maleic anhydride. 

A. Maleic acid. Assemble the apparatus shown in Fig. Ill, 28, 1. Place 45 g. of dry mahc acid in the 200-250 ml. distilling flask and cautiously add 63 g. (57 ml.) of pure acetyl chloride. Warm the flask gently on a water bath to start the reaction, which then proceeds exothermically. Hydrogen chloride is evolved and the malic acid passes into solution. When the evolution of gas subsides, heat the flask on a water bath for 1-2 hours. Rearrange the apparatus and distil. A fraction of low boiling point passes over first and the temperature rises rapidly to 190° at this point run out the water from the condenser. Continue the distillation and collect the maleic anhydride at 195-200°. Recrystallise the crude maleic anhydride from chloroform (compare Section 111,93) 22 g. of pure maleic anhydride, m.p. 54°, are obtained. 

To obtain maleic acid, evaporate the maleic anhydride with one half of its weight of water on a water bath remove the last traces of water by leaving in a desiccator over concentrated sulphuric acid. The resulting maleic acid has m.p. 143° and is quite pure (1). It may be recrystaUised, if desired, from acetone- light petroleum (b.p. 60-80°) and then melts at 144° (1). 

The mechanism of the diene synthesis appears to involve an electron transfer from the diene to the dienophile, .e., it is initiated by an ionic reaction. The following scheme may represent the addition of 2 3-dimethylbutadiene to maleic anhydride ... 

The Dieb-Alder reaction is a purely cia addition the relative positions of the substituents are retained in the adduct (compare anthracene and maleic anhydride above). ... 

Anthracene and maleic anhydride. In a 50 ml. round-bottomed flask fitted with a reflux condenser, place 2 0 g. of pure anthracene, I 1 g. of maleic anhydride (Section 111,93) and 25 ml. of dry xylene. Boil the mixture under reflux for 20 minutes with frequent shaking during the first 10 minutes. Allow to cool somewhat, add 0 5 g. of decolourising carbon and boil for a further 5 minutes. Filter the hot solution through a small, preheated Buchner funnel. Collect the solid which separates upon coohng by suction filtration, and dry it in a vacuum desiccator containing paraffin wax shavings (to absorb traces of xylene). The yield of adduct (colourless crystals), m.p. 262-263° (decomp.), is 2-2 g. Place the product (9 10-dihydroanthracene-9 10-cndo-ap-succinic anhydride) in a weU-stoppered tube, since exposure to air tends to cause hydration of the anhydride portion of the molecule. 

Vinylidene chloride and vinyl chloride lead to the copolymer known as Saran. Other commercial copolymers are produced from vinyl chloride and acrylonitrile (Dynel), and from maleic anhydride and styrene. 

Another class of reaction where you can see at once that the disconnection is the reverse of the reaction is Pericychc Reactions. An example would be the Diels-Alder reaction between butadiene and maleic anhydride. Draw the mechanism and the product. 

Synthesis A successful synthesis (J. Amer. Chem. Soc., 1958, 90, 3937) by this route actually uses maleic anhydride ... 

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