Ethylene generating compounds

Of the analogous compounds related to a particular hormone, attention must be drawn to the large group of synthetic auxins, to the synthetic cytokinins (- recently not only adenine, but also urea derivatives -) and to the ethylene generators ( 1, 2). An extension of the range of analogous compounds is indicated in the case of abscisic acid, as well (3j. 

The ether group is common in some other a/f-copolymers. Many of these compounds have practical applications. For example, poly(ethylene oxybenzoate) is used as a filament yarn in the silk clothing industry. Other polymers are used as epoxy resins. Several examples of such ether-a/f-different groups are given in Table 9.3.3. Pyrolysis of these macromolecules generates compounds indicative of their composition. 

Pyrolysis of poly(1,4-butylene terephthalate) is in some respects similar to that of poly(ethylene terephthalate) and generates compounds such as benzoic acid, terephthalic acid dibutylene ester, probably terephthalic acid, etc. Also the formation of CO, CO2, benzene, biphenyl, etc. is similar. On the other hand, the percentage distribution of different compounds is rather different for poly(1,4-butylene terephthalate). A relatively high level of butadiene is generated from this polymer, white in the case of PET, formation of acetylene would not be thermodynamically possible and acetaldehyde is formed. Also, the esters of terephthalic acid with C4 alcohols are at considerably higher levels in the pyrolysate of PBT, which seems to indicate that they are more stable than the corresponding esters with C2 alcohols in PET pyrolysate. 

From the bis(ethylene) precursor complex the highly reactive unsaturated 14-electron intermediate Ir(PEt3)2Cl is generated as the actual catalyst by stepwise dissociation of ethylene. Related compounds M(Pr 3P)2Cl (M = Rh,... 

Post-column derivatlzation of reducing sugars with ethylene-diamine in a weakly alkaline medium at 150°C generates compounds detectable down to 1 pmol by electrochemical oxidation. This procedure was recommended over an earlier reaction involving 2-... 

Polymerization using oxygen is not well understood it is known that oxygen copolymerizes with ethylene to form peroxidic copolymers (10). Other free-radical generators such as azo compounds and carbon—carbon compounds have found only limited use in the synthesis of LDPE. 

Dithiophosphates. These compounds (13) are made by reaction of an alcohol with phosphoms pentasulfide, then neutralization of the dithiophosphoric acid with a metal oxide. Like xanthates, dithiophosphates contain no nitrogen and do not generate nitrosamines during vulcanization. Dithiophosphates find use as high temperature accelerators for the sulfur vulcanization of ethylene—propylene—diene (EPDM) terpolymers. 

The generation of caibocations from these sources is well documented (see Section 5.4). The reaction of aromatics with alkenes in the presence of Lewis acid catalysts is the basis for the industrial production of many alkylated aromatic compounds. Styrene, for example, is prepared by dehydrogenation of ethylbenzene made from benzene and ethylene. 

Fluorinated organosilicon compounds may be prepared from readUy available fluorohalocarbons by using phosphorous amides [84, 85, 86] or tetrakis(dimeth-ylamino)ethylene [57] for the generation of the fluoroorganic nucleophiles (equations 61-69). 

In the following procedure, use is made of the basic character of epoxides. In the presence of phosphonium salts, ethylene oxide removes hydrogen halide and the alkylidenetriphenylphosphorane is produced. If a suitable carbonyl compound is present in the reaction mixture, its reaction with the in situ generated phosphorane proceeds readily to give the Wittig product. 

Less by-products generated from ethylene reactions with other compounds than from other olefins. 

Whereas ethylene oxide gives with 17 at ambient temperature a quantitative yield of l-trimethylsilyloxy-2-iodoethane [5, 31], substituted epoxides such as 846b react with 17 to give 848 as the main product [32]. Excess 17, however, leads to the bis-iodo compounds 849 and HMDSO 7 [4, 5]. In the presence of DBU the epoxides 850 are converted by 17, which is generated in situ from hexamethyl-disilane 857 and I2, into the allyl alcohols 851 [4, 32] (Scheme 6.14). Cycloctene epoxide 852 is opened by SiCl4 at -78 °C in the presence of catalytic amounts of the asymmetric catalyst 853 to give 61% of the chlorohydrin 854 in 98% ee [33]. 

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