Diels-Alder reaction of maleic anhydride

Chlorendic Acid. Chlorendic acid [115-28-6] and its anhydride [115-27-5] are widely used flame retardants. Chlorendic acid is synthesized by a Diels-Alder reaction of maleic anhydride and hexachlorocyclopentadiene (see CyclopentadlENE and dicyclopentadiente) in toluene followed by hydrolysis of the anhydride using aqueous base (60). The anhydride can be isolated directly from the reaction mixture or can be prepared in a very pure form by dehydration of the acid. The principal use of chlorendic anhydride and chlorendic acid has been in the manufacture of unsaturated polyester resins. Because the esterification rate of chlorendic anhydride is similar to that of phthalic anhydride, it can be used in place of phthalic anhydride in commercial polyester... 

The Diels Alder reactions of maleic anhydride with 1,3-cyclohexadiene, as well the parallel reaction network in which maleic anhydride competes to react simultaneously with isoprene and 1,3-cyclohexadiene [84], were also investigated in subcritical propane under the above reaction conditions (80 °C and 90-152 bar). The reaction selectivities of the parallel Diels-Alder reaction network diverged from those of the independent reactions as the reaction pressure decreased. In contrast, the same selectivities were obtained in both parallel and independent reactions carried out in conventional solvents (hexane, ethyl acetate, chloroform) [84]. 

TABLE 7.1 Relative Rates for the Diels-Alder Reaction of Maleic Anhydride with Isoprene at 30.3° C ... 

Derivation By Diels-Alder reaction of maleic anhydride and hexachlorocyclopentadiene. 

When catalyst 333 was applied in the cycloaddition reaction of 2-methoxy-l,3-butadiene (334) with /-(o-tolyl)maleimide (335), the conesponding cycloadduct 337a was obtained with only 58% ee. However, an ee of 95% was observed when catalyst 338 and N-(o-t-butylphenyl)maleimide (336) were employed (equation 94). The meta methyl substituents on the phenyl groups of catalyst 338 proved crucial for producing 337 with high enantioselectivity. In contrast, the Diels-Alder reaction of maleic anhydride with 2-methoxy-1,3-butadiene using catalyst 338 afforded a racemic adduct. These results were considered to result from a different complexation behavior of the catalyst in the case of maleic anhydride in comparison with, V-arylmaleimides-, ... 

The studies reported last year on the stereoisomeric control of the photo-induced Diels Alder reaction of maleic anhydride with homo-chiral anthracene derivatives such as (46) have been extended using 320-400 nm radiation, and this gives the head-to-tail anthracene dimer as well as the previously reported adduct (47) with excellent diastereoselectivity. The thermal and photochemical retroaddition process has been examined and the results suggest that this facile process may promote the anthracene as a new chiral auxiliary. 

The Diels-Alder reaction of maleic anhydride with 3,4-dimethoxyfuran affords endo- and exo-adducts at about the same rate, in contrast to furan, where the endo-isomer is the product of kinetic control. In both cases the exo-adduct is thermodynamically more stable. 3,4-Dimethoxyfuran and p-benzoquinone give the eiufo-compound (37), whereas in the reaction with 2,3-dimethyl-1,4-benzoquinone only the exo-adduct (38) was detected. The Diels-Alder adduct (40) of methyl acrylate to 2-amino-3-cyano-4,5-dimethylfuran (39) is readily... 

PRACTICE PROBLEM 13.11 Draw transition states for the endo and exo Diels-Alder reaction of maleic anhydride... 

An improved procedure for the Diels-Alder reaction between cyclo-octatetraene and dimethyl acetylene dicarboxylate to give dimethyl unti-tricyclo[4,2,2,0 ]deca-3,7,10-triene-7,8-dicarboxylate (85 %) has been described. Diels-Alder reactions of maleic anhydride and mono-substituted (Mr, CHjOAc, Ph, CO2CH3. OMe, cyclopropyl substituents) and di-substituted (Me, Me CHjOAc, CHjOAc —(CH2)4— Me, CH2 O Ac substituents) cyclo-octatetraenes have been described cyclopropyl cyclo-octatetraene was obtained from bromocyclo-octatetraene and cyclopropyl lithium. The Diels-Alder reaction between cyclo-octatetraene and acryloyl chloride which gives a mixture of endo- and exo-adducts (80% total yield), was the first step in a reported synthesis of Nenitzescu s hydrocarbon. ... 

The effect of high pressure (up to 2500 bar) on the Diels-Alder reactions of maleic anhydride and isoprene with 9-phenanthracene and 9,10-dimethylanthracene in toluene has been investigated kinetically. ... 

Knutson et al. (280) measured the kinetics of the Diels-Alder reaction of maleic anhydride (MA) and 2,3-dimethyl-1,3-butadiene (DMB) in SCF propane solutions at 100-140°C and 46-141 bar. Reaction to the product 4,5-dimethyl-CM-l,2,3,6-tetrahydrophthalic anhydride (DMTA) was evaluated with excess DMB as a reactive cosolvent and 2,2,2-trifluoroethanol (TFE) as an unreac-tive cosolvent (Scheme 21). Near-critical effects and cosolvent effects on reaction rates were analyzed from transition state theory. Rate constants increased with increasing pressure at 140 C, but were not significantly affected at 100°C and 120 C at near-critical densities. A similar lack of pressure dependence has been reported by Reaves and Roberts (281) for the Diels-Alder reaction of MA with isoprene in subcritical propane at 80°C. This minimal pressure effect is in contrast to those noted above for Diels-Alder reactions in SCCO2 where the reactants were at approximately equal and dilute concentrations. The influence of the unreactive cosolvent, TFT, on reaction rates was found to be minimal. These results suggest that the local reactant composition, as well as pressure, temperature, and cosolvent, can be used to control the reaction rate of such reactions in the near-critical region. 

The balance between aromatic and aUphatic reactivity is affected by the type of substituents on the ring. Furan functions as a diene in the Diels-Alder reaction. With maleic anhydride, furan readily forms 7-oxabicyclo [2.2.1]hept-5-ene-2,3-dicarboxyhc anhydride in excellent yield [5426-09-5] (4). 

Chlorendic anhydride is the common name of the Diels-Alder adduct of maleic anhydride and hexachlorocyclopentadiene, 3,4,5,6,7,7-hexachloroendomethylene-l,2,3,6-tetrahydrophthahc anhydride (HET). The resultant resins from HET contribute to the flame retardancy of the alkyd coatings. HET gives a greater reaction rate than phthaUc anhydride, to the extent that at 204—210°C the reaction rate approximates that of phthaUc anhydride at a temperature of 238°C (8). However, the resins tend to develop darker color, particularly at high processing temperature. Tetrachlorophthahc anhydride [117-08-8] made by conventional chlorination of phthaUc anhydride, would also impart flame retardancy to its alkyds. However, it is appreciably less soluble in the usual processing solvents than is phthaUc anhydride, and is reported to be of appreciably lower chemical reactivity (8). 

Flame Retardants. Although the use of chlorinated derivatives of DCPD has been restricted in the pesticide area, some are widely used in flame and fire retardant chemicals (see Flame retardants). The starting material is the fliUy chlorinated DCPD cracked to monomeric hexachlorocyclopentadiene, which is then converted via a Diels-Alder reaction with maleic anhydride to a reactive bicycHc anhydride (9), known as chlorendic anhydride [115-27-5]. 

Dimethylquinoxaline (303) has been reported to undergo a Diels-Alder reaction with maleic anhydride to give 304, 305 having been postulated to be the reactive form. However, attempted confirmation of this unexpected result has shown that 304 is not the correct structure of the reaction product. " In 1931, other chemical evidence was advanced in support of structure 305,but it would no longer be considered valid. 

The use of lead tetraacetate to carry out oxidative bisdecarboxylation of diacids has been found to be a highly useful procedure when used in conjunction with the Diels-Alder addition of maleic anhydride to dienes, the latter process providing a ready source of 1,2-dicarboxylic acids. The general pattern is illustrated in the reaction... 

Cyclic 1,3-diacetoxy-l,3-dienes can be generated in situ from cyclic 1,3-diketones under the influence of isopropenyl acetate. The dienes then undergo Diels-Alder reactions with maleic anhydride giving as products 1-acetoxybicycloalkane dicarboxylic anhydride derivatives (10). The procedure is also successful with cyclic 1,2- and 1,4-diketones as well as cyclic a,j3-unsaturated ketones. The products, after hydrolysis to... 

Various o-quinodimethanes, generated in situ from o-alkenylbenzyltributyl-stannane precursors, have been used to synthesize functionalized polycycles by Diels Alder reaction with maleic anhydride, methylacrylate, dimethylfumarate and N-phenyl maleimide in the presence of electrophiles [37] (Scheme 2.16). 

The effect of pressure on the rate constant of the Diels-Alder reaction between maleic anhydride and isoprene was investigated in SC-CO2 at 35 °C and at pressures ranging from 90 to 193 bar. For comparison purposes, the reaction was also carried out in an apolar solvent such as propane under... 

For a review of Diels-Alder reactions with maleic anhydride see Kloetzel, M.C. Org. React., 1948, 4, 1. 

The salt is a colorless crystalline solid which is virtually insoluble in all common organic solvents. It reacts slowly with chloroform and carbon tetrachloride to give thallium(I) chloride 25), gives a characteristic red coloration with carbon disulfide, and undergoes the Diels-Alder reaction with maleic anhydride 110). It is rapidly decomposed by acids, but is stable to water this latter fact has been interpreted (55) in terms of the small free energy change for the reaction... 

Detonations sometimes occur during Diels-Alder reactions with maleic anhydride. They are explained by the decomposition of this anhydride. 

Figure 7.15 Improvement of the efficiency of rosin as a sizing agent by Diels-Alder reaction with maleic anhydride.

The effect of pressure on the measured bimolecular rate constant of the Diels-Alder reaction between maleic anhydride and isoprene was investigated in supercritical CO2 and subcritical propane. The reaction was carried out at 35°C in CO2 and 80°C in propane. The rate constants in supercritical CO2 agreed closely with the thermodynamic pressure effect predictions over the entire pressure range. The rate constants in the subcritical propane solvent significantly diverged from the thermodynamic pressure effect predictions and were found to deviate from this linear density dependence at the lower pressures studied. The results show solvent-solute and cosolvent-solute interaction (Reaves and Roberts, 1999). 

Several other heterohelicenes resist this reaction even when the Friedel-Crafts catalyst (A1C13) is exchanged for FSOjH, 90% HjSO, 40% HF and other strong acids. Some dehydroheterohelicenes have been used to prepare heterocirculenes by a Diels-Alder reaction with maleic anhydride and subsequent hydrolysis and removal of the carboxylic acid groups167). 

A new stereoselective synthesis of 1,2,3-trisubstituted cyclopentanes based on the Wag-ner-Meerwein rearrangement of a 7-oxabicyclo[2.2.1]heptyl 2-cation starts with the Diels-Alder product of maleic anhydride and a furan (78TL2165, 79TL1691). The cycloadduct was hydrogenated and subjected to methanolysis. The half acid ester (47) was then electrolyzed at 0 °C to generate a cationic intermediate via the abnormal Kolbe reaction (Hofer-Moest reaction). Work-up under the usual conditions provided the 2-oxabicyclo[2.2.1]heptane (48) in 83% yield. Treatment of this compound in turn with perchloric acid effected hydrolysis of the ketal with formation of the trisubstituted cyclopentane (49) in nearly quantitative yield (Scheme 11). Cyclopentanes available from this route constitute useful... 

The dibenzarsenins (125) are prepared by the pyrolysis of a 10-benzyl-5,10-dihy-drodibenz[6,e]arsenin (equation 27). This reaction proceeds via a radical abstraction process. The parent (125 R = H) is unstable and could not be isolated, but the phenyl (125 R = Ph), tolyl (125 R = 4-MeCeH4) and p-methoxyphenyl (125 R = 4-MeOCeH4) derivatives were isolated. Like arsenin itself, (125) can act as a diene in the Diels-Alder reaction and maleic anhydride adducts were prepared for each of the above (77RTC265). 

Compound 83 is a diene that comprises four carbon atoms of a hexose chain, and it takes part in the Diels-Alder reaction with maleic anhydride to give 86% of the product 84, the stereochemistry of the addition being directed by the acetal ring [42]. 

The Diels-Alder reaction of benzenoid aromatic hydrocarbons with dienophiles was discovered more than fifty years ago [61, 62]. A classical example is the reaction of anthracene with maleic anhydride (Scheme 5). Although this type of reaction, termed endogenic or endocyclie Diels-Alder reaction, could be expected to be particularly well suited for correlating structure (topology) of benzenoid hydrocarbons with kinetic data, the problem has been systematically studied only very recently. Biermann and Schmidt in a series of publications [12, 29, 45, 63, 64] reported second-order rate constants (k2), measured under standard conditions (1,2,4-trichlorobenzene, 91.5 + 0.2 °C), for the endocyclie Diels-Alder reaction between maleic anhydride and 102 benzenoid hydrocarbons. Each rate constant was measured twice, the values usually... 

The Diels-Alder reaction with maleic anhydride is illustrative of the high reactivity and potential utility of this diene. 

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