Ethene decomposition

Kinetic Data for Ethene Desorption, Ethene Decomposition to give Ethylidyne, and Ethylidyne Formation from Ethene on Pt(Ill) Surfaces... 

As mentioned previously, the adsorbed ethene decomposition gives ethylidyne. Then the rate of intermediate formation is given by... 

Fig. 15. Adsorbed ethene decomposition data (laser-induced thermal desorption mass 27 against time) and ethylidyne formation data (IR signal against time) for selected coverages and reaction temperatures. [Reprinted from Ref. 386, Surf. Sci. 301, W. Erley, Y. Li, D. P. Lang, and J. C. Hemminger, p. 177. Copyright 1994 with kind permission of Elsevier Science-NL, Sara Burgerhartstraat 25, 1055 KV Amsterdam, The Netherlands.]...

Tris(ethene)platinum(0) is stable for several hours at 20°C under 1 atm of ethene and keeps for many weeks at — 20°C. In the absence of ethene, decomposition to metallic platinum occurs in minutes at room temperature. The complex is quite volatile, with a vile smeU, and sublimes slowly at 20°C in an atmosphere of ethene onto a cold finger at 0°C. 

BrCHi CHjBr. A colourless liquid with a sweet odour, m.p. 10°C, b.p. 132°C. Manufactured by passing ethene through bromine or bromine and water at about 20 C. Chemical properties similar to those of 1,2-dichloroethane when heated with alkali hydroxides, vinyl bromide is formed. Used extensively in petrols to combine with the lead formed by the decomposition of lead tetraethyl, as a fumigant for stored products and as a nematocide. 

Norbornene-ethene copolymer, 16 113 Norbornene-ethylene copolymers, 20 433 physical properties of, 20 420-422 Norbornenodiazetine derivatives, 13 306 Nordel IP (metallocene), 7 637 Nordihydroguaiaretic acid, antioxidant useful in cosmetics, 7 830t Nordstrandite, 2 421, 425 activation, 2 394 classification, 2 422 decomposition sequence, 2 392 from gelatinous boehmite, 2 427 structural properties of, 2 423t NO-reduction reactions, TWC catalyst, 10 49... 

The most exciting application of bond order indices concerns the description of chemical reactions involving the simultaneous change of several bonds. An example is the unimolecular decomposition of ethanol, which can happen at high temperature or IR multiphoton excitation of the molecule. Out of the possible dissociation channels, the lowest barrier characterizes the concerted water loss of the molecule, yielding ethene and H20 [30]. 

The alkoxyalkynylstannanes show the familiar instability associated with alkoxyalkynes. The decomposition of a trialkyl(ethoxyalkynyl)stannane, 17, can be rationalized as follows. Elimination of ethene and rearrangement gives the stannylketene, which reacts with the alkoxyalkyne to give the ester 18 and the distannylketene 19 as the observed products (Equation (87)).241,250... 

Extended Hiickel theory (EHT) was applied to study the decomposition of the five-membered metallacycle intermediate proposed by Mimoun for the epoxidation by Mo bisperoxo complexes [44, 45]. Another EHT study [40] proposed the coordination of ethene to the metal center of an MoO(02)2 complex as the first step, followed by a slipping motion of ethene toward... 

The hydride reacts immediately with ethene to give the expected ethyl complex selectively and quantitatively, which again is ideal for the catalytic activity. The hydride is very unstable when CO is bubbled into MeOH solution, even at low temperature [115] at room temperature it reacts immediately with ethene giving a cationic ethyl complex. In the presence of both CO and ethene, like under catalytic conditions, decomposition does not occur because the hydride reacts much faster with ethene than with CO. Once the ethyl intermediate is formed, fast insertion of CO occurs with formation of an acyl intermediate, which in turn reacts with MeOH yielding MP with quantitative regeneration of the starting hydride to continue the catalytic cycle [114,115]. The formation of the ethyl and of the acyl intermediates involves facile equi-... 

C. The high melting point of pure ethene/CO (265 °C) gives decomposition and formation of brown, fiiranised polymers in the melt, which makes processing in extruders impossible. 

Studies in deuterated water have shown that the hydroxyl proton does not end up in the ethanal formed. The decomposition of the 2-hydroxyethyl is not a simple P-elimination to palladium hydride and vinyl alcohol, which then isomerises to ethanal. Instead, the four protons stemming from ethene are all present in the initial ethanal product [6] (measured at 5 °C in order to suppress deuterium/hydrogen exchange in the product) and most authors have therefore accepted an intramolecular hydride shift as the key-step of the mechanism (see Figure 15.2). There remains some doubt as to how the hydride shift takes place. 

Metathesis of 1-octene leads cleanly to ethene and 7-tetradecene, but as the reaction proceeds also 2-octene is formed and metathesis products derived from the isomerisation reaction. It was found that after prolonged reaction times decomposition of the ruthenium alkylidene catalyst occurs. At least eight different products were formed and several of them have been identified [37], Figure 16.22 shows the identified compounds derived from Grubbs 1st generation catalyst (the 2nd generation gives basically the same result [38]). 

Heck arylation of ethene with, 42 494 lodomethane, catalytic decomposition, 35 144 2,3-IOI-isopropylidene-2,3-dihydroxy-l,4-bis-(dishenylphosphino) butane (DIOP) as catalyst, 25 90, 91... 

The mechanism for the decomposition of ethenal, CH3CHO, in the presence of iodine vapour is written as follows ... 

Further theoretical study of the mechanism of decomposition of /3-propiolactone and jS-butyrolactone, to form CO2 and ethene or propene, respectively, has concluded that the process can best be described as asynchronous and concerted. Calculations also suggest that concerted processes are preferred for both decarbonylation and decarboxylation of jj-thiobutyrolactone. ... 

Slow decomposition sets in at about 500 K and the decomposition lifetime (Table 4.2) decreases with increasing temperature. The available residence time (Table 4.1) decreases and the decomposition fraction increases rapidly for temperatures greater than 800 K, and all the AEBCB is converted to propionitrile - - ethene by about 950 K. 

A technique that allows rapid evaluation of molecular stability using small (20-30 mg) samples has been demonstrated and applied to three different families of strained molecules. All of the molecules studied are stable at room temperature, though most must be stored in nonmetallic containers to avoid catalytic decomposition. Of the four molecules shown in Fig. 4.1, the least thermally stable was quadricyclane, for which decomposition lifetimes drop below 10 ms at about 500 K. The other three molecules had similar stabilities, with lifetimes dropping below 10 ms above 700 K. For all systems studied, decomposition by loss of small hydrocarbon fragments (acetylene or ethene) was an important decomposition mechanism in the gas phase. For all but AEBCB, isomerization was also a significant decomposition mechanism. At high pressures, one would expect more isomerization because the very rapid collision rate should allow collisional stabilization of the isomerization products. 

A homoleptic thioether complex can be prepared by the reaction of perrhenate with 9S3 (15b) in glacial add in the presence of SnCl2. Red-brown crystals of [Re(9S3)2][PF6]2 have been isolated and studied structurally showing a mean Re—S distance of 2.37 A. Treatment of [Re(9S3)2] PF6]2 (268) with ascorbic acid does not result in reduction of the rhenium atom but in its oxidation and the release of ethene by decomposition of the cyclic thioether. The resulting rhenium(III) complex [Re(9S3)(SCH2CH2SCH2CH2S)][PF6] has been isolated and studied by X-ray crystallography. ... 

As related to Diels-Alder reaction this also represents a 6p electron electrocyclic reaction. Like Diels-Alder reaction the ene reaction is reversible. For example, the produce) 1-pentene of the ene reaction between ethene and propene, gives back ethene and propene on decomposition at 400° C. 

Dithienoheteroepines are readily synthesized from bis(2-bromo-3-thienyl)ethene on treatment with ferZ-butyllithium followed by the corresponding metal reagent, and readily undergo thermal decomposition to furnish benzodithio-phenes <1997H(45)1899>. Interestingly, the isomeric thienoheteroepines proved remarkably stable to thermal decomposition, presumably due to the inability to produce the required intermediate (Equation 74). 

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