Epoxidized butadiene

Adler, I.-D., Kliesch, U., Nylund, L. Peltonen, K. (1997) In vitro and in vivo mutagenicity of the butadiene metabolites butadiene diol epoxide, butadiene monoepoxide and diepoxybutane. Mutagenesis, 12, 339-345... 

Notably, the Dimroth rearrangement has been shown to occur in nature with the purine and pyrimidine bases of nucleosides and nucleotides upon exposure to certain chemical entities. For example, 3,4-epoxybutene, styrene oxide and other aromatic hydrocarbon based epoxides, butadiene and butadiene monoxide, chloroethylene oxirane, chlorambucil, and acrolein, " among others, have been shown to facilitate Dimroth rearrangement, and in some cases subsequent cross-linking of DNA. While interesting from a mechanistic and biological perspective, these reactions will not be reviewed here. 

B.i.a. Reactivity and Regioselectivity. As a model for studies on the Pd-catalyzed addition of carbon nucleophiles on acyclic vinyl epoxides, butadiene monoxide has been studied extensively. Nucleophiles attack predominantly at the less hindered position of the cationic Tr-allylpalladium complex. Due to steric effects and in some part for electronic reasons, it appeared that with vinyl epoxides, highly regioseleclive reactions took place and 1,4-addition of the nucleophile is generally the major process. 

Table I gives the results of the polymerization of the unsaturated epoxides butadiene monoepoxide (BDME) and SO (entries 4 and 5, respectively). Surprisingly, BDME does not form any polymer but instead slowly converts exclusively to the cycloaddition by-product. SO, however, undergoes copolymerization but with low selectivity only 35% of the epoxide is converted to polycarbonate. Increasing the CO2 pressure in both systems does not improve the selectivity to polymer.

The first example in Table 2.5 was made from a partly epoxidized butadiene resin by reaction with dimethylamine followed by acrylic acid. The second example was again a reaction product of polybutadiene with maleic acid, followed by treatment with N,N-dimethylaminopropyl-amine. This polyamine was mixed with a novolac resin containing sites of unsaturation, an example of which is shown in Fig. 2.10. 

Such copolymers of oxygen have been prepared from styrene, a-methylstyrene, indene, ketenes, butadiene, isoprene, l,l-diphen5iethylene, methyl methacrjiate, methyl acrylate, acrylonitrile, and vinyl chloride (44,66,109). 1,3-Dienes, such as butadiene, yield randomly distributed 1,2- and 1,4-copolymers. Oxygen pressure and olefin stmcture are important factors in these reactions for example, other products, eg, carbonyl compounds, epoxides, etc, can form at low oxygen pressures. Polymers possessing dialkyl peroxide moieties in the polymer backbone have also been prepared by base-catalyzed condensations of di(hydroxy-/ f2 -alkyl) peroxides with dibasic acid chlorides or bis(chloroformates) (110). 

Butadiene can also be readily epoxidized with peracids to the monoepoxide or the diepoxide (109,110). These have been proposed as important intermediates in the metaboHc cycle of butadiene in the human body (111). 

Telomerization Reactions. Butadiene can react readily with a number of chain-transfer agents to undergo telomerization reactions. The more often studied reagents are carbon dioxide (167—178), water (179—181), ammonia (182), alcohols (183—185), amines (186), acetic acid (187), water and CO2 (188), ammonia and CO2 (189), epoxide and CO2 (190), mercaptans (191), and other systems (171). These reactions have been widely studied and used in making unsaturated lactones, alcohols, amines, ethers, esters, and many other compounds. 

Low molecular weight liquid nitrile rubbers with vinyl, carboxyl or mercaptan reactive end groups have been used with acrylic adhesives, epoxide resins and polyesters. Japanese workers have produced interesting butadiene-acrylonitrile alternating copolymers using Ziegler-Natta-type catalysts that are capable of some degree of ciystallisation. 

The commonly held view of the uniqueness of Ag for ethylene epoxidation may soon change in view both of the propene epoxidation work of Haruta and coworkers on Au/Ti02 catalysts upon cofeeding H2 123 and also in view of the recent demonstration by Lambert and coworkers124 126 that Cu(lll) and Cu(110) surfaces are both extremely efficient in the epoxidation of styrene and butadiene to the corresponding epoxides. In fact Cu was found to be more selective than Ag under UHV conditions with selectivities approaching 100%.124-126 The epoxidation mechanism appears to be rather similar with that on Ag as both systems involve O-assisted alkene adsorption and it remains to be seen if appropriately promoted Cu124 126 can maintain its spectacular selectivity under process conditions. 

Isomerization has been observed with many a,j3-unsaturated carboxylic acids such as w-cinnamic 10), angelic, maleic, and itaconic acids (94). The possibility of catalyzing the interconversion of, for example, 2-ethyl-butadiene and 3-methylpenta-l,3-diene has not apparently been explored. The cobalt cyanide hydride will also catalyze the isomerization of epoxides to ketones (even terminal epoxides give ketones, not aldehydes) as well as their reduction to alcohols. Since the yield of ketone increases with pH, it was suggested that reduction involved reaction with the hydride [Co" (CN)jH] and isomerization reaction with [Co (CN)j] 103). A related reaction is the decomposition of 2-bromoethanol to acetaldehyde... 

Epoxides will also participate in radical reactions and this usually results in ring opening of the epoxide. The addition of a radical derived from xanthate 38 to butadiene monoepoxide provides the addition product 39 in good yields as an E/Z mixture of olefins <06AG(I)6520>. This reaction presumably proceeds through the addition of the xanthate-derived radical to the olefin, which then opens the epoxide. 

In the following, the screening power and the scientific potential applying HIE Stage n technologies in gas-phase oxidation are demonstrated for two illustrative case studies (1) the epoxidation of 1,3-butadiene with Ag-based catalysts and (2) dynamic experiments for automotive applications (DcNOJ. 

The showcase is also attractive, as the epoxidation of 1,3-butadiene to vinyloxirane in air is as challenging as the sophisticated synthesis of the Ag/ -Al203 catalysts. 

Table 11.4 Comparison of Influence of the Synthesis Procedure on the Catalytic Performance of Ag-Containing Catalysts in the Epoxidation of 1,3-Butadiene...

Both the mono- and diepoxides of butadiene are substrates for epoxide hydrolase [163], In rat liver microsomes, (R)- and (S)-butadiene monoepoxides were hydrolyzed to but-3-ene-l,2-diol (10.104, Fig. 10.24) with complete retention of configuration at C(2), indicating attack at C(l) [164], In mouse liver microsomes, in contrast, 15 - 25% inversion of configuration was observed, suggesting partial attack at C(2). Preliminary results indicate that human liver microsomes are more efficient than mouse or rat liver microsomes in hydrolyzing butadiene monoepoxide [165]. The hydrolysis of diepoxybutane (10.103) yields 3,4-epoxybutan-l,2-diol (10.105), which can be further hydrated to erytritol (10.106) [163]. 

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