Ethylene catalytic hydrogenation

The catalytic hydrogenation of ethylene occurs on various metal catalysts, such as nickel, including active or skeletal forms produced by dissolving out... 

Hydrogenation. Acetylene can be hydrogenated to ethylene and ethane. The reduction of acetylene occurs in an ammoniacal solution of chromous chloride (20) or in a solution of chromous salts in H2SO4 (20). The selective catalytic hydrogenation of acetylene to ethylene, which proceeds... 

Most refinery/petrochemical processes produce ethylene that contains trace amounts of acetylene, which is difficult to remove even with cryogenic distillation. Frequently it is necessary to lower the acetylene concentration from several hundreds ppm to < 10 ppm in order to avoid poisoning catalysts used in subsequent ethylene consuming processes, such as polymeri2ation to polyethylene. This can be accompHshed with catalytic hydrogenation according to the equation. 

Significant quantities of ethyl chloride are also produced as a by-product of the catalytic hydrochlorination over a copper chloride catalyst, of ethylene and hydrogen chloride to produce 1,2-dichloroethane, which is used as feedstock in the manufacture of vinyl choride (see Vinyl polymers). This ethyl chloride can be recovered for sale or it can be concentrated and catalyticaHy cracked back to ethylene and hydrogen chloride (25). As the market for ethyl chloride declines, recovery as an intermediate by-product of vinyl chloride manufacture may become a predominant method of manufacture of ethyl chloride. 

Significant quantities of Cj and C, acetylenes are produced in cracking. They can be converted to olefins and paraffins. For the production of high purity ethylene and propylene, the contained Cj and C3 acetylenes and dienes are catalytically hydrogenated leaving only parts per million of acetylenes in the products. Careful operation is required to selectively hydrogenate the small concentrations of acetylenes only, and not downgrade too much of the wanted olefin products to saturates. 

On catalytic hydrogenation a-methylmorphimethine yields first a dihydro-derivative oil, B. HCl, m.p. 133°, identical with Freund s de-iV-methyldihydrocodeine, in which the ethylenic linkage at C —C is saturated and finally the tetrahydro-a-methylmorphimethine (II), described above. 

The and -methylmorphimethines (formula, p. 251) are catalytically hydrogenated to hexahydro-derivatives by saturation of the two ethylenic linkages and opening of the oxide ring. The one from the e-form has m.p. 155° and that given by the -form, m.p. 174-5° (Speyer and Koulen ). 

Strychiyne, strychnidine and tetrahydrostrychnine are all converted into dihydro-derivatives on catalytic hydrogenation, indicating the presence of one ethylenic linkage in these substances, and dihydrostrychnine in turn yields on electrolytic reduction dihydrostrychnidine and hexa-hydrostrychnine. The formation of this group of reduction products from strychnine may be represented thus —... 

Ethyl l-cyano-2-methylcyclohexanecarboxylate has been prepared by catalytically hydrogenating the Diels-Alder adduct from butadiene and ethyl 2-cyano-2-butenoate3 and by the procedure described in this preparation.4 8 This procedure illustrates a general method for the preparation of alicyclic compounds by the cyclization of <5-ethylenic carbon radicals l.6 Whereas the primary 5-hexen-l-yl radical 1... 

Other products have been obtained from T8[CH = CH2]8 via additions to the double bonds (Table 16 and Figure 25). For example, TgEtg can be prepared by catalytic hydrogenation of T8[CH = CH2]8 giving a better yield than from the reaction of TgHs with ethylene (see Section V.B) (Table 16, entries 1-3) and... 

Second, catalytic reactions do not necessarily proceed via the most stable adsorbates. In the ethylene case, hydrogenation of the weakly bound Jt-C2H4 proceeds much faster than that of the more stable di-cr bonded C2H4. In fact, on many metals, ethylene dehydrogenates to the highly stable ethylidyne species, =C-CH3, bound to three metal atoms. This species dominates at low coverages, but is not reactive in hydrogenation. It is therefore sometimes referred to as a spectator species. Hence, weakly bound adsorbates may dominate in catalytic reactions, and to observe them experimentally in situ spectroscopy is necessary. 

Cunningham, Carberry, and Smith [AIChE J., 11 (636), 1965] have studied the catalytic hydrogenation of ethylene over a copper-magnesium oxide catalyst. 

Anionic and cationic species are particularly easy to study in the gas phase using mass spectrometric techniques. Studies of organometallic reactions involving neutral species are becoming more prevalent. The elegant study of the catalytic hydrogenation of ethylene by photochemical... 

The catalytic hydrogenation of the C=N bond of imines has attracted considerable attention, and a useful review covering the literature until 1996 has been reported by James.110 Chiral [Pg.91]

CO insertion reactions. The catalytic hydrogenation mechanism presented was based on detection of species 64 and HC1 during hydrogenation of ethylene, Eq. (92). Species 65 then catalyzes the reaction by pathways outlined in Eq. (5). 

Reaction of acetic acid solutions of Ru3(CO)i2 with mixtures of CO and R2 under pressure produces substantial amounts of methyl acetate and smaller quantities of ethylene glycol diacetate/ as shown in Table I. Other products observed in these reactions are traces of glycerine triacetate and small amounts of ethyl acetate. (The ethanol is apparently derived largely from acetic acid by catalytic hydrogenation, since reactions in propionic acid solvent yield similar quantities of propyl propionate and only traces of ethyl propionate.)... 

Unstable chemicals are subject to spontaneous reactions. Situations where unstable chemicals may be present include the catalytic effect of containers, materials stored in the same area with the chemical that could initiate a dangerous reaction, presence of inhibitors, and effects of sunlight or temperature change. Examples include acetaldehyde, ethylene oxide, hydrogen cyanide, nitromethane, organic peroxides, styrene, and vinyl chloride. 

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