Secondary reactions ethylene

The secondary reactions are parallel with respect to ethylene oxide but series with respect to monoethanolamine. Monoethanolamine is more valuable than both the di- and triethanolamine. As a first step in the flowsheet synthesis, make an initial choice of reactor which will maximize the production of monoethanolamine relative to di- and triethanolamine. 

An excess of ammonia in the reactor decreases the concentrations of monoetha-nolamine, diethanolamine, and ethylene oxide and decreases the rates of reaction for both secondary reactions. 

On the contrary, on oxygen-modified metal surfaces where secondary reactions between the adsorbed oxygen and ethylene decomposition products can easily occur, the effect of oxygen on the adsorptive capacity of the... 

Chronic injury results primarily from secondary reactions involving membrane injury. The oxidants could cause the formation of free radicals or other, more stable oxidants (such as hydrogen peroxide), which in turn could cause secondary reactions. These secondary reactions could stimulate the production of cellular ethylene, with tissue senescence re suiting. These secondary reactions may predispose plants to increased injury from later acute exposures by limiting their repair capability. This predisposition concept has been noted in several reports. 

The distribution of products in these reactions can change very substantially with reaction time, as illustrated in Fig. 1. The rate of ethylene glycol formation remains quite constant, but rates to other products change markedly as the reaction proceeds, indicating that secondary reactions are taking place. Some of the plausible secondary reactions in this system have been listed by Feder et al. (37) ... 

These results are presented here to emphasize the fact that selectivity and rates to various products can be subject to great variation as a result of secondary reactions. Any attempt to determine the fundamental responses of a catalytic system to changes in reaction variables must recognize the potential complications of such secondary reactions. Rathke and Feder have carried out calculations to determine the amounts of primary products actually produced by the cobalt system, assuming that these products are methanol, methyl formate, and ethylene glycol (38). The amounts of these primary products were estimated by the following relationships ... 

The concept of a (bound) formaldehyde intermediate in CO hydrogenation is supported by the work of Feder and Rathke (36) and Fahey (43). Experiments under H2/CO pressure at 182-220°C showed that paraformaldehyde and trioxane (which depolymerize to formaldehyde at reaction temperatures) are converted by the cobalt catalyst to the same products as those formed from H2/CO alone. The rate of product formation is faster than in comparable H2/CO-only experiments, and product distributions are different, apparently because secondary reactions are now less competitive. However, Rathke and Feder note that the formate/alcohol ratio is similar to that found in H2/CO-only reactions (36). Roth and Orchin have reported that monomeric formaldehyde reacts with HCo(CO)4 under 1 atm of CO at 0°C to form glycolaldehyde, an ethylene glycol precursor (75). The postulated steps in this process are shown in (19)—(21), in which complexes not observed but... 

Rabinovitch et al. (85) studied the reaction of H atoms with trans-ethylene-d2 as a function of ethylene pressure in the temperature range — 78 to 160°C. They were able to account for all secondary reactions of the hot ethyl radicals and to determine the rates of their decomposition (relative to stablization). Simultaneously they calculated the theoretical rates on the basis of the Rice-Ramsperger-Kassel theory of uni-molecular reactions, using expressions derived by Marcus (71), and found a reasonable agreement with the experimental values. Similar satisfactory agreements had been found previously by Rabinovitch and Die-sen (84) for hot sec-butyl radicals. Extensive studies of hot radicals produced by H or D atom additions to various olefins have been carried... 

Apart from the products mentioned, secondary reactions also form various amounts of trichlorosilane, silicon tetrachloride, as well as gases (hydrogen, ethylene, ethane, etc.) and carbon. They also form compounds with fragments containing... 

Here we also observe the secondary reaction of reduction, which forms methyltrichlorosilane and ethylene ... 

This overall reaction, however, does not show all the stages of the process, since apart from the substances mentioned it forms hexaethyldilead, ethylene, ethane and butane, which demonstrates some secondary reactions. In particular, at the first stage of the reaction ethylchloride seems to interact with metallic sodium forming free ethyl radicals, i.e. the reaction uses the radical mechanism and ethyl radicals are responsible for further synthesis. 

Two hundred twenty-six milliliters of silicon tetrachloride (2.0 mols) is allowed to react with 68 ml. of ethylene chlorohydrin (1.0 mol). This excess of silicon tetrachloride is used to reduce the probability of secondary reactions which might produce di-, tri-, and/or tetraalkoxy derivatives. 

Secondary reactions manifest, as explained next An amount of ethylene is lost by combustion at higher temperature ... 

Allylindium reagents bearing substituents at the 7-position react with carbonyl compounds in organic and aqueous media regioselectively at the 7-position, via a six-membered transition state, to afford the corresponding branched homoallylic alcohols, if no sterically bulky carbonyl or allyl substituent is involved.102 For example, the indium-mediated reaction of aldehydes with 3-bromo-l-cyano-l-propene proceeds readily in water to give cr-cyano-f3-ethylenic secondary alcohols (Scheme 4).103... 

Ethylene oxide (C2H40) and acetaldehyde (CH3CHO) were found as main products. CO was also detected. Figure 2 shows the time dependence of these three products. The yield of C2H40 increases linearly with time, which indicates that C2H40 does not react to any appreciable extent through secondary reactions or subsequent photolysis. The yield of... 

Tb avoid secondary reactions, the flow is cooled by cold ethylene injected by a proprietary device (8). Such quenching controls acetic acid at negligible values and corrosions are undetectable. 

The liquid phase processes resembled Wacker-Hoechst s acetaldehyde process, i.e., acetic acid solutions of PdCl2 and CuCl2 are used as catalysts. The water produced from the oxidation of Cu(I) to Cu(II) (Figure 27) forms acetaldehyde in a secondary reaction with ethylene. The ratio of acetaldehyde to vinyl acetate can be regulated by changing the operating conditions. The reaction takes place at 110-130°C and 30-40 bar. The vinyl acetate selectivity reaches 93% (based on acetic acid). The net selectivity to acetaldehyde and vinyl acetate is about 83% (based on ethylene), the by-products being CO2, formic acid, oxalic acid, butene and chlorinated compounds. The reaction solution is very corrosive, so that titanium must be used for many plant components. After a few years of operation, in 1969-1970 both ICI and Celanese shut down their plants due to corrosion and economic problems. 

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