Dienes ethylene derivatives

EPDM-Derived Ionomers. Another type of ionomer containing sulfonate, as opposed to carboxyl anions, has been obtained by sulfonating ethylene—propjlene—diene (EPDM) mbbers (59,60). Due to the strength of the cross-link, these polymers are not inherently melt-processible, but the addition of other metal salts such as zinc stearate introduces thermoplastic behavior (61,62). These interesting polymers are classified as thermoplastic elastomers (see ELASTOLffiRS,SYNTHETIC-THERMOPLASTICELASTOLffiRS). 

FIGURE 30.17 Ethylene-propylene-diene monomer (EPDM) compounding corrected total torque harmonic content (TTHC) versus strain, at 1.0 Hz slope at 200%, as calculated with Hrst derivative of Equation 30.4 and fit parameters in Table 30.2. 

Due to its high ionic character, the carbon-lithium bond is very reactive and adds under mild conditions to ethylene or dienes and under more severe conditions to other alkenes. Some functionalized alkenes can be used, and high regio- and stereo-selectivity is usually observed in these carbolithiation reactions, especially if a precoordination of the lithium organometallic with the alkene is possible. Intramolecular carbolithiations of alkenes proceed under mild conditions and allow the preparation of several stereochemically well defined mono- and bi-cyclic compounds. Alkynes are too reactive, and can lead, with organolithium derivatives, to several side reactions, and seldom afford the desired carbolithiated product in good yield. 

Diels-Alder reactions.2 This ethylene derivative undergoes (4 + 2] cycloaddition even with relatively unreactive cyclic dienes. The adducts undergo reductive elimination of the sulfonyl groups on treatment with 2% sodium amalgam to provide bicyclodienes. The ethene therefore can function as an equivalent of acetylene in Diels-Alder reactions. 

A number of reactions are known, however, in which more extensive rearrangements of bonds occur and which involve cyclic intermediates or products. The Diels-Alder reaction is a classical example of this. In the normal Diels-Alder reaction a Ci s-1,3-diene reacts with an ethylene derivative (dienophile) to form a cyclohexene ... 

Beside the homopolymerization of BD Nd-based Ziegler/Natta catalyst systems are also applied for the homopolymerization of IP, the copolymerization of the dienes BD and IP, the homopolymerization and copolymerization of substituted dienes as well as for the copolymerization of BD with alkenes such as styrene, ethylene and other ethylene derivatives. 

Homogeneous vanadium-based catalysts formed by the reaction of vanadium compounds and reducing agents such as organoaluminum compounds [10-12] are used industrially for the production of elastomers by ethylene/propene copolymerization (EP rubber) and ethylene/propene/diene terpolymerization (EPDM rubber). The dienes are usually derivatives of cyclopentadiene such as ethylidene norbomene or dicyclopentadiene. Examples of catalysts are Structures 1-4. Third components such as anisole or halocarbons are used to prevent a decrease in catalyst activity with time which is observed in the simple systems. 

DA reactions are the largest family of cycloaddition processes. In a DA reaction, an ethylene derivative, named the dienophile, adds to a 1,3-diene to afford a six-membered carbocyclic product. By varying the nature of the diene and dienophile, many different types of carbocyclic structures can be built up. However, not all possibilities take place easily. For instance, the simplest cycloaddition reaction is the DA reaction between butadiene and ethylene. However, this reaction must be forced to take place after 17 hours at 165° C and 900 atmospheres, it does give a yield of 78%.28 29 An interesting alternative is that the presence of electron-releasing substituents in the diene and electron-withdrawing (EW) substituents in the dienophile or vice versa can drastically accelerate the process. 

Anthracene homologs can also be prepared in this way, by using derivatives of cyclohexadiene. Further, 1,4-naphthoquinone can be used as starting material (for a single diene synthesis) and the ethylene bridge may be substituted without destroying the ability of the product to split off the ethylene derivative. 

Arene chromium tricarbonyl complex Ethylene derivatives from 1,3-dienes Preferential hydrogenation... 

Zinc pyridine acetic acid Partial reduction of dienes to ethylene derivatives... 

A short synthesis of ( )-isostegane, a tetracyclic dibenzocycloota-diene lactone, has been achieved by a sequential double a, -substitution of an electron-deficient ethylene derivative, in this case zl P-butenolide, followed by non-phenolic oxidative coupling with VOFg . An equally short synthesis of methyl jasmonate has been achieved through 1,4-addition-alkylation of cyclopentenone . 

Competition between NR and bio-based SR (SR made from biosourced feedstock) should not be underestimated. For example in 2012, LANXESS is planning to produce the world s first SR, i.e. ethylene propylene diene monomer (EPDM) rubber (under the brand name of Keltan Eco) from ethylene derived from sugar cane at its Triunfo plant in Brazil. The ethanol is dehydrated into ethylene and polymerized to produce EPDM rubber." Besides, bio-based SR is suggested to be the bio-based feedstock of poly(butadiene) rubber for tyre industries. 

CM-l,2-Ethylene-l,2-disilanes from acetylene derivs. A soln. of tolan in benzene-d added to 2 eqs. r/5-bis(dimethylphenylsilyl)bis(methyldiphenylphosphine)platinum, and allowed to react at room temp, for 15 min - Z-l,2-bis(dimethylphenylsilyl)-l,2-diphenylethene. Y 79%. F.e. and 1,2-disilylation of unactivated ethylene derivs., also 1,4-disilylation of 1,3-dienes, s. T. Kobayashi et al., Chem. Letters 1989, 467-70. 

Synthesis of ethylene derivatives from 1,3-dienes with migration of a carbon-carbon double bond... 

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