Ethylene gas

The Mam2en process uses ethylene gas as a direct refrigerant in a two-stage process (77,78). The first stage slurry is centrifuged, partially remelted, and fed to the second centrifuge. 

An ethylene gas centrifugal compressor required the following operating conditions ... 

To change the temperature of a particular calorimeter and the water it contains by one degree requires 1550 calories. The complete combustion of 1.40 grams of ethylene gas, CJti,(g), in the calorimeter causes a temperature rise of 10.7 degrees. Find the heat of combustion per mole of ethylene. 

An important selection of materials to packaging, particularly food, is based on the permeability of the materials to oxygen, water vapor, and, in the case of packaging bananas, to ethylene gas that is used to artificially ripen the bananas. Selective permeability provides chemical separations, one of the most interesting of which is the use of PTFE materials to separate the hexafluorides of the different isotopes of uranium. 

An interesting example of regioselective CM with ethylene as a tool in natural product degradation was recently disclosed by Hawaiian authors [149]. Thus, CM using catalyst C and ethylene gas was used to degrade the plant polyacetylene oxylipin (+)-falcarindiol (342) with uncertain stereochemistry at C3. As the reaction provided a meso product (343) in 81% yield by regioselective attack at the aliphatic side chain, the natural compound 342, isolated from a Hawaiian endemic plant, had the 3R,8S configuration shown in Scheme 66. 

Clark and coworkers utilized enyne RCM for constructing the AB ring fragment of the manzamine alkaloids (Scheme 83) [177]. Exposing metathesis precursor 423 and ethylene gas to catalyst A provided bicycle 424 in near quantitative yield. Regioselective hydroboration of the vinyl group in 424, followed... 

The ethylene gas bag was purchased from the Aldrich Chemical Company, Inc., catalog number Z 18,674-0. 

Sf.I f-Tfst 4.4B In a petroleum refinery a 750.-L container containing ethylene gas at 1.00 bar was compressed isothermally to 5.00 bar. What was the final volume of the container ... 

Scheme 21 Diels-Alder reactions of the pyrazinone scaffold with ethylene gas...

When a blank reaction was run by purging the solution of pyrazinone (Scheme 22, pyrazinone b) in o-DCB with ethylene gas and irradiating it at 190 °C for 100 min, only a mere 53% conversion of the starting material was observed. Microwave-enhanced hydrolysis of the sensitive imidoyl chloride moiety of the cycloadduct using aqueous NaOH resulted in a yield of only 12%. However, the situation changed dramatically when the vial was pre-pressurized with ethylene gas at 5 bar. The reaction was completed after 30 min of microwave irradiation at 190 °C, and the hydrolyzed product was isolated in 87% yield. The reaction could be completed in a mere 10 min when carried out at 220 °C at an increased ethylene pressure of 10 bar, or in 20 min at 190 °C at 10 bar ethylene pressure. 

In the case of EC-DMC solutions, since the surface species are deposited quickly and form very compact passivating films, the passivation of the active mass is obtained before products such as ethylene gas have the chance to be accumulated in crevices and an internal pressure to grow. Indeed, in these solutions the irreversible capacity depends inversely on the size of the particles (as expected). 

Conditions 25 °C, atmospheric pressure, 5 min, ethylene gas feed 100 L h 1, catalyst 0.5 pmol akg polymer per mmol catalyst per h bDetermined by GPC... 

Intermolecular enyne metathesis has recently been developed using ethylene gas as the alkene [20]. The plan is shown in Scheme 10. In this reaction,benzyli-dene carbene complex 52b, which is commercially available [16b], reacts with ethylene to give ruthenacyclobutane 73. This then converts into methylene ruthenium complex 57, which is the real catalyst in this reaction. It reacts with the alkyne intermolecularly to produce ruthenacyclobutene 74, which is converted into vinyl ruthenium carbene complex 75. It must react with ethylene, not with the alkyne, to produce ruthenacyclobutane 76 via [2+2] cycloaddition. Then it gives diene 72, and methylene ruthenium complex 57 would be regenerated. If the methylene ruthenium complex 57 reacts with ethylene, ruthenacyclobutane 77 would be formed. However, this process is a so-called non-productive process, and it returns to ethylene and 57. The reaction was carried out in CH2Cl2 un-... 

All reactions were carried out in CH2C12 under ethylene gas using ruthenium catalyst 52b at room temperature for 45 h. 

To carry out this process ethylene gas is passed through a fluidised bed column that is filled with Zeigler-Natta catalyst... 

A 5A molecular sieve, not previously soaked in dilute ethylene, was used to dry compressed ethylene gas in a flow system. An exothermic reaction attained red heat and caused explosive failure of the dryer. The smaller-pored 3A sieve is not catalytically active towards ethylene. 

Fig. 3. (a) The inelastic scattering of electrons, (b) The energy loss spectrum for electron scattering by ethylene gas 8 near 90°. (Reproduced with permission from Kupperman and Ruff, 1962.)... 

High purity ethylene gas plus recycle ethylene are fed to a compression chamber, compressed and then fed along with catalyst previously dissolved in a suitable solvent into, parallel horizontal reactors, as many- as eight in parallel. Each reactor consists of a water-filled shell containing a single pipe, coiled to give maximum contact with the water. Reaction conditions are 350-425 F and 2000-3000 psi. 

As an application of this procedure, Snapper succeeded in the formal total synthesis of (+)-astericanolide. Treatment of iron complex 62, which is prepared from cyclopentenol derivative 60 and iron complex 61, with MeaNO gives fused cyclobutene derivative 63. ROM of cyclobutene of 63 using Ig under ethylene gas smoothly proceeds to produce an eight-membered ring of 64 via Cope rearrangement. The resulting product 64 is converted into Wender s intermediate for the synthesis of (+)-astericanolide ... 

Hoveyda et al. reported a novel method for synthesizing of chromene 71 by ROM-RCM of cycloalkene 70 bearing the phenyl ether at the 3-position [Eq. (6.48)]." ° The yield is improved when the reaction is carried out under ethylene gas. In the case of cyclopentene 70a (n = 0) or cyclohexene 70b (n = 1), the yield is poor because the starting cycloalkene is in a state of equihbrium with the product and a thermodynamic product should be formed under these reaction conditions. They obtained enantiomeric ally pure cycloheptene derivative (5)-70e using zirconium-catalyzed kinetic resolution of 70e developed by their group, and chromene 71c was synthesized as a chiral form via ROM-RCM using lb [Eq. (6.49)] ... 

---