Ethylene oxide addition rate

Using the modified rate equation above, rate constants for addition of ethylene oxide and propylene oxide to a number of alcohols are given in Table 2 (1, 35, 36). From Table 2, several important conclusions can be drawn. As expected, primary hydroxyl groups have a higher reactivity toward oxirane addition than do secondary hydroxyl groups. Second, ethylene oxide addition is considerably faster than that of propylene oxide third, the rate of addition of the beta-alkoxyethanols is about the same and is not affected by the particular alkoxy substituent. 

The ethylene oxide must be added quite rapidly in order to complete the addition in the time specified. It should be added at a maximum possible rate consistent with practically no loss of ethylene oxide through tube C. The best absorption of ethylene oxide appears to take place when the temperature is kept between... 

The RR developed by the author at UCC was the only one that had a high recycle rate with a reasonably known internal flow (Berty, 1969). This original reactor was named later after the author as the Berty Reactor . Over five hundred of these have been in use around the world over the last 30 years. The use of Berty reactors for ethylene oxide process improvement alone has resulted in 300 million pounds per year increase in production, without addition of new facilities (Mason, 1966). Similar improvements are possible with many other catalytic processes. In recent years a new blower design, a labyrinth seal between the blower and catalyst basket, and a better drive resulted in an even better reactor that has the registered trade name of ROTOBERTY . ... 

The addition of various alkali and alkaline earth cations to the cyclooligomerization of ethylene oxide by Dale and Daasvatn also provides strong presumptive evidence for the template effect. Recently, Reinhoudt, de Jong and Tomassen utilized several metal fluorides to effect crown formations . The reaction rates were found to be in the order Cs > Rb > > Na LE. Such an order would be expected on the basis of binding... 

Promoters may influence selectivity by poisoning undesired reactions or by increasing the rates of desired intermediate reactions so as to increase the yield of the desired product. If they act in the first sense, they are sometimes referred to as inhibitors. An example of this type of action involves the addition of halogen compounds to the catalyst used for oxidizing ethylene to ethylene oxide (silver supported on alumina). The halogens prevent complete oxidation of the ethylene to carbon dioxide and water, thus permitting the use of this catalyst for industrial purposes. 

Alkylation reactions reveal a mechanistic aspect of the cuprate reactions different from that of addition reactions. Theoretical analyses of reactions of alkyl halides (Mel and MeBr) [123, 124] and epoxides (ethylene oxide and cyclohexene oxide) [124] with lithium cuprate clusters (Me2CuLi dimer or Me2CuLi-LiCl, Scheme 10.11) resolved long-standing questions on the mechanism of the alkylation reaction. Density functional calculations showed that the rate-determining step of the... 

The kinetics and mechanism for oxygen transfer between 4-cyano-V,V,-dimethylaniline V-oxide and a C2-capped mexo-tetraphenylporphyrinatoiron(III) and mc5 o-tetrakis(pentafiuorophenyl)-porphyrinatoiron(III) have been established. Addition of a copper(II) porphyrin cap to an iron(II)-porphyrin complex has the expected effect of reducing both the affinities and rate constants for addition of dioxygen or carbon monoxide. These systems were studied for tetradecyl-substituted derivatives solubilized by surfactants such as poly(ethylene oxide) octaphenyl ether. ... 

In new studies heteropoly acids as cocatalysts were found to be very effective in combination with oxygen in the oxidation of ethylene.1311 Addition of phosphomo-lybdic acid to a chloride ion-free Pd(II)-Cu(II) catalyst system results in a great increase in catalytic activity and selectivity.1312 Aerobic oxidation of terminal alkenes to methy ketones can be performed with Pd(OAc)21313 or soluble palladium complexes. Modified cyclodextrins accelerates reaction rates and enhance selectivities in two-phase systems under mild conditions.1315 1316... 

In a separate investigation MargeHs and Roginekii1107 carried nut catalytic oxidation of ethylene at 350° over vanadium pentoxidc. reportedly similar to metallic silver in catalytic properties. TVv asoertainod that carbon dioxide was formed faster from, ethylene oxide, or from acetaldehyde under comparable conditions, than from ethylene itself. Further, they noted the formation of carbon monoxide, and determined that its rate of formation was considerably greater than that of carbon dioxide, increasing still more in the presence of adtk-d ethylene oxide. The addition of ethylene oxide also appeared to depro both ethylene oxide and acetaldehyde formation. They concluded that reactions leading to carbon dioxide and water did not proceed by wav of ethylene oxide, but by way of some other intermediates, and tlmt-this process could occur either on the catalyst surface or in the gas phase. 

Eastham and Derwent474 have also studied the kinetics of the perchloric acid-catalyzed reaction of ethylene oxide with pyridine. In excess of pyridine the rate was found to be dependent on the Conor Titrations of ethylene oxide and perchloric add. Addition of stronger bases,. g. ammonia, triethylamine, or benzylamiae, depressed the vum of cleavage, presumably by competing with ethylene oxide for thr-available proton source, believed to be pyridinium perchlorate in this case. Other acids examined included nitric acid and hydroiodie irireaction rate depended to a certain extent... 

Addition of an acid catalyst allows hydration of ethylene oxide to be accomplished under much milder conditions and at a markedly faster rate.21 f ° Numerous kinetic studies have been conducted for the reactions of ethylene oxide and several simple homologs with water, in the presence as well as the absence of acid catalysts. 4 - -1W7-13C1-Ml , U17. HU. UTS, son. ZOltt... 

Incompatible Mixtures. Even at very low levels, many of the poly-ether additives led to incompatible mixtures. These blends were not successfully milled to a smooth sheet under any conditions tried. Instead, a mass of crumbs was obtained. These crumbs could be molded into a coherent mass, but the physical properties were poor. For example, addition of 8.75 parts of polybutene-1 oxide to Masterbatch B for CPVC alone gave a brittle, free-flowing material with these properties notched Izod impact strength, 0.7 lb/in notch, flow rate 452 g/10 min. This is a particularly interesting result, since PBO has the same chemical formula as PTHF but structurally is a substituted ethylene oxide polymer rather than a linear homopolymer. No further studies were made of such blends. 

Ab initio molecular orbital studies on the whole catalytic cycle of hydroformylation of ethylene catalyzed by HRh(CO)2(PH3)2 has been performed [59,60], which points out the significance of the coordinating solvent—ethylene in this case—and identifies the oxidative addition of molecular hydrogen to the pentacoordinate acyl-Rh complex as the rate-determining step. In fact, this step is the only endothermic process in the catalytic cycle. 

The K-region oxides undergo nucleophilic addition with OH", C032", water, amines, and mercaptides.88,140 The second-order rate constants for the reactions of OH", water, and primary and secondary amines with 1 at 30°C and with ethylene oxide at 25°C141 can be simply related by Eq. (6),2 which shows that the sensitivity of the two oxides to the nature of the nucleophile is similar and that the arene oxide is more reactive. 

Equation 7 applies for thiolate anion addition. Ethylene oxide is nearly three times more sensitive than 1 to the nucleophilicity of the thiol. The second-order rate constants for the reactions of 2-mercaptoethanol with 1,47, and 48 are 3.32, 1.58, and 2.04M"1 sec-1, respectively. This shows that 1 is only slightly more reactive and that the K-region does not necessarily make the... 

If the depolymerization stops short of complete disappearance of polymer because of insufficient catalyst, the reaction can be revived by addition of ethylene oxide but the yield of dioxane is then only about five moles per mole of reacting monomer, a value far below that obtained by direct addition of oxonium ions. This difference is important because conditions after regeneration must resemble those in a polymerizing mixture, but unfortunately the reason for the difference is still far from clear. It is found that the rate of disappearance of monomer under these conditions is essentially independent of monomer concentration so Eastham and co-workers (74) concluded that monomer is involved only in the regeneration of oxonium ions,... 

It can be seen that it is possible to vary the alcohol chain greatly and the alkoxylate chain can be varied in the same way as with nonylphenol to produce both water and oil soluble products. The major difference between nonylphenol and alcohol ethoxylates is the distribution of ethoxylate chains. The rate constants for the addition of ethylene oxide to primary alcohols are comparable and are essentially the same as for the 1-mol or the 2-mol adduct. These addition products, of course, are still primary alcohols. Thus, if one were making a 2-mol adduct of the alcohol, there would be a fair proportion of free alcohol still present - of the order of 10-20%. Chain growth starts well before all the starting alcohol has reacted and alcohol ethoxylates have therefore a much broader ethoxylate chain distribution than the comparable nonylphenol ethoxylate. It has been shown that ethylene oxide consumption becomes constant after 8 or 9 mol of ethylene oxide per mole of alcohol has been added [10,11]. 

---