Maleic anhydride, Diels-Alder reaction with 1,3-butadiene

Derivatives of maleic anhydride such as captan Chevron), are also used as plant protection agents. Captan is obtained from maleic anhydride by Diels-Alder reaction with butadiene to give cis-l,2,3,6-tetrahydrophthalic anhydride, followed by ammonolysis and treatment of the cis-l,2,3,6-tetrahydrophthalimide with tri-chloromethanesulfenyl chloride. 

The Lewis acid-catalyzed 1,3-migration of divinyl esters allows the formation of 1,3-butadienes, which can undergo cycloaddition. In this respect, Dai and coworkers described a rearrangement of the divinyl alkoxyacetate 1-203 followed by a Diels-Alder reaction with a dienophile such as maleic anhydride 1-204 in the presence of catalytic amounts of Ln(fod)3 to produce 1-205 in up to 61 % yield (Scheme 1.47) [53],... 

Dichlorodibutyl ether, 27 Diels-Alder reaction of butadiene with maleic anhydride, 93 Diene synthesis of cis-A -tetrahydro-phthalic anhydride, 93 Diethyl benzalmalonate, 84 Diethyl carbonate, 44 Diethyl fumarate, 46 Diethyl cis-HEXAiiYDROPiiTHALATE, 29 Diethyl malonate, 70 Diethyl o-nitrobenzoylmalonatc, 71 Diethyl sodium phthalimidomalonate, 7... 

Diels-Alder reactions of the type shown in Table 12.1, that is, Diels-Alder reactions between electron-poor dienophiles and electron-rich dienes, are referred to as Diels-Alder reactions with normal electron demand. The overwhelming majority of known Diels-Alder reactions exhibit such a normal electron demand. Typical dienophiles include acrolein, methyl vinyl ketone, acrylic acid esters, acrylonitrile, fumaric acid esters (fnms-butenedioic acid esters), maleic anhydride, and tetra-cyanoethene—all of which are acceptor-substituted alkenes. Typical dienes are cy-clopentadiene and acyclic 1,3-butadienes with alkyl-, aryl-, alkoxy-, and/or trimethyl-silyloxy substituents—all of which are dienes with a donor substituent. 

Cycloadditions. A cyclic movement of electrons can be drawn for any number of cycloadditions, but not all of them take place. Thus butadiene undergoes a Diels-Alder reaction with maleic anhydride, but ethylene and maleic anhydride do not give a cyclobutane when they are heated together. 

Maleic anhydride can also be made by the air oxidation of butenes. Maleic anhydride is used in the preparation of unsaturated polyester resins. It can also be reduced to buty-rolactone and to 1,4-butanediol. It also offers a possible synthesis of phthalic anhydride by a Diels-Alder reaction with 1,3-butadiene (12.9). 

Diels-Alder reactions. This butadiene dimer reacts with tetracyanoethyl-ene and maleic anhydride to give only 1 1 adducts, (2) and (3), even under forcing conditions. However, it does give the diadduct (4) with the highly reactive 4-phenyl-l, 2,4-triazoline-3,5-dione. 

The analogy of the reactivity of furan with that of butadiene is further underlined by the fact that furan undergoes a Diels-Alder reaction with dienophiles such as maleic anhydride ... 

As with butadiene, a Diels-Alder reaction with normal electron demand occurs, that is, the HOMO of furan (see Figure 5.2c) interacts with the LUMO of maleic anhydride. The reaction is diastereoselective. Alder s endo-rule applies to the stereochemistry of the cycloadducts 21/22 thus, in acetonitrile at 40°C, the mdo-adduct 21 is formed 500 times faster than the evo-adduct 22 owing to kinetic control. However, with a sufficiently long reaction time, product formation becomes subject to thermodynamic control the initially formed mdo-compound is completely converted via the educts to the exo-compound, which is more stable by 8 kj mol. ... 

Soon after the discovery of the addition reaction between diene-ophiles and dienes which now bears their names, Diels and Alder extended their investigations to include potential heterocyclic dienes. In 1929 the first compound investigated, furan, was observed to combine with maleic anhydride, like butadiene in a typical Diels-Alder reaction, across the 2,5-positions yielding a 1 1 molar adduct... 

The Diels-Alder reaction,is a cycloaddition reaction of a conjugated diene with a double or triple bond (the dienophile) it is one of the most important reactions in organic chemistry. For instance an electron-rich diene 1 reacts with an electron-poor dienophile 2 (e.g. an alkene bearing an electron-withdrawing substituent Z) to yield the unsaturated six-membered ring product 3. An illustrative example is the reaction of butadiene 1 with maleic anhydride 4 ... 

The cycloaddition between furan and maleic anhydride was the first uncatalyzed aqueous Diels-Alder reaction reported in the literature and was studied by Diels and Alder themselves [11]. This cycloaddition was successfully revised by Woodward and Baer [12] and some years later by De Koning and coworkers [13]. The aqueous medium was also used in the cycloaddition of aromatic diazonium salts with methylsubstituted 1,3-butadienes [14]. 

Diels-Alder reactions provide one of the few general methods of forming two carbon-carbon bonds simultaneously. The main features of these reactions are described in Box 1.3. The reaction finds widespread industrial use for example hardeners for epoxy resins are made by reaction of maleic anhydride with dienes such as 2-methyl-1,4-butadiene. 

The Diels-Alder reaction is in fact a [4 -i- 2] cycloaddition reaction, where C-1 and C-4 of the conjugated diene system become attached to the double-bonded carbons of the dienophile to form a six-membered ring. For example, 1,3-butadiene reacts with maleic anhydride to produce tetrahy-drophthalic anhydride on heating. 

Diels-Alder reaction, of acrolein with -butyl cyclohexenyl ether, n-butyl vinyl ether, and ethyl iso-propenyl ether, 34,30 of butadiene with maleic anhydride, 30,93... 

The sulfenyl phthalimides are one of the oldest groups of fungicides and are effective, safe and persistent (B-77MI10706). Captan (59) is cheaply made from the Diels-Alder adduct of butadiene and maleic anhydride, followed by conversion to the imide and reaction with trichloromethanesulfenyl chloride. Folpet (60) and captafol (61) are similar in structure. 

Although the Diels-Alder reaction of a conjugated diene, such as butadiene or isoprene, with maleic anhydride, has been known to yield tetrahydrophthalic anhydride, it has recently been shown (81, 85) that alternating copolymers are prepared under the influence of ionizing radiation (81) or free radical initiators (81, 85). The participation of the charge transfer complex as a common intermediate in both adduct... 

With its concerted mechanism implying little charge distribution change along the pathway, the Diels-Alder reaction has been understood to have little rate dependence on solvent choice. For example, the relative rate of cyclopentadiene dimerization increases only by a factor of 3 when carried out in ethanol. The relative rate for the Diels-Alder reaction of isoprene with maleic anhydride (Table 7.1) varies by only a factor of 13 with solvents whose dielectric constants vary by almost a factor of 10, but the rate acceleration is not a simple function of the solvent polarity. Furthermore, the dimerizations of cyclopentadiene and 1,3-butadiene proceed at essentially identical rates in the gas and solution phases. ... 

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