Peracetic acid with acetaldehyde, reaction

Peracetic Acm-AcErALDEHYDE Reaction. The cobalt- and manganese-catalyzed reactions of peracetic acid with acetaldehyde were studied by a continuous flow technique (9). Peracetic acid (0.15M in acetic acid) and acetaldehyde-catalyst solutions were metered through rotameters to a mixing T (standard 0.25-inch stainless steel Swagelok T) and... 

Acetic acid values are by difference = 100 — 2 other products. In the reaction of peracetic acid with acetaldehyde the acetic acid efficiency is based only on peracetic acid reacted and assuming 100% efficiency of acetaldehyde. 

Reaction of Peracetic Acid with Acetaldehyde. The reaction of peracetic acid with acetaldehyde was studied in the absence of metal ions... 

Figure 4. Effect of cohalt acetate on the reaction of peracetic acid with acetaldehyde at 30°C.

In the reaction of peracetic acid with acetaldehyde we do not know that manganese and cobalt ions in the 3+ oxidation state are the predominant species. Based on the color of the solutions during reaction... 

With manganese and cobalt acetate the reaction of peracetic acid with acetaldehyde is very fast, and AMP is not detected. By comparing our rates with literature values of k17, k.17, and k18 we cannot propose a mechanism in which the only role of the metal ion is to catalyze the decomposition of AMP. The experimental rates in the presence of either manganese or cobalt acetates are much faster than the noncatalytic rate of formation of AMP. Thus, AMP per se is probably not an intermediate in the presence of these catalysts. 

In the reaction of peracetic acid with acetaldehyde (in the absence of oxygen) the majority of the methyl radicals abstract hydrogen, preferentially from acetaldehyde, to form methane ... 

Oxidation of Acetaldehyde. When using cobalt or manganese acetate the main role of the metal ion (beside the initiation) is to catalyze the reaction of peracetic acid with acetaldehyde so effectively that it becomes the main route to acetic acid and can also account for the majority of by-products. Small discrepancies between acetic acid efficiencies in this reaction and those obtained in acetaldehyde oxidation can be attributed to the degradation of peracetoxy radicals—a peracetic acid precursor— by Reactions 14 and 16. The catalytic decomposition of peracetic acid is too slow (relative to the reaction of acetaldehyde with peracetic acid) to be significant. The oxidation of acetyl radical by the metal ion in the 3+ oxidation state as in Reaction 24 is a possible side reaction. Its importance will depend on the competition between the metal ion and oxygen for the acetyl radical. 

Oxidation. Acetaldehyde is readily oxidised with oxygen or air to acetic acid, acetic anhydride, and peracetic acid (see Acetic acid and derivatives). The principal product depends on the reaction conditions. Acetic acid [64-19-7] may be produced commercially by the Hquid-phase oxidation of acetaldehyde at 65°C using cobalt or manganese acetate dissolved in acetic acid as a catalyst (34). Liquid-phase oxidation in the presence of mixed acetates of copper and cobalt yields acetic anhydride [108-24-7] (35). Peroxyacetic acid or a perester is beheved to be the precursor in both syntheses. There are two commercial processes for the production of peracetic acid [79-21 -0]. Low temperature oxidation of acetaldehyde in the presence of metal salts, ultraviolet irradiation, or osone yields acetaldehyde monoperacetate, which can be decomposed to peracetic acid and acetaldehyde (36). Peracetic acid can also be formed directiy by Hquid-phase oxidation at 5—50°C with a cobalt salt catalyst (37) (see Peroxides and peroxy compounds). Nitric acid oxidation of acetaldehyde yields glyoxal [107-22-2] (38,39). Oxidations of /)-xylene to terephthaHc acid [100-21-0] and of ethanol to acetic acid are activated by acetaldehyde (40,41). 

Comparing the reaction rates of peracetic acid and acetaldehyde in the presence of each of the metal ion acetates clearly indicates why mixtures of either cobalt or copper acetate with managnese acetate behave in a fashion similar to manganese acetate when used alone. 

Very recently we have developed a new, easier, and selective metal-free NHPTcatalyzed aerobic epoxidation of primary olefins [19] based on the in situ generation of peracetic acid from acetaldehyde. In this chapter, we will discuss the reaction mechanism in order to explain the significant differences in selectivity with respect to the epoxidation by peracids and we will show preliminary successful results in the synthesis of propylene oxide. 

About half of the wodd production comes from methanol carbonylation and about one-third from acetaldehyde oxidation. Another tenth of the wodd capacity can be attributed to butane—naphtha Hquid-phase oxidation. Appreciable quantities of acetic acid are recovered from reactions involving peracetic acid. Precise statistics on acetic acid production are compHcated by recycling of acid from cellulose acetate and poly(vinyl alcohol) production. Acetic acid that is by-product from peracetic acid [79-21-0] is normally designated as virgin acid, yet acid from hydrolysis of cellulose acetate or poly(vinyl acetate) is designated recycle acid. Indeterrninate quantities of acetic acid are coproduced with acetic anhydride from coal-based carbon monoxide and unknown amounts are bartered or exchanged between corporations as a device to lessen transport costs. 

Most of the peracetic acid decomposes via a cyclic reaction with acetaldehyde to form two moles of acetic acid. 

Aliphatic amines have much less effect on the later reactions of the gas-phase oxidation of acetaldehyde and ethyl ether than if added at the start of reaction. There is no evidence that they catalyze decomposition of peroxides, but they appear to retard decomposition of peracetic acid. Amines have no marked effect on the rate of decomposition of tert-butyl peroxide and ethyl tert-butyl peroxide. The nature of products formed from the peroxides is not altered by the amine, but product distribution is changed. Rate constants at 153°C. for the reaction between methyl radicals and amines are calculated for a number of primary, secondary, and tertiary amines and are compared with the effectiveness of the amine as an inhibitor of gas-phase oxidation reactions. 

To understand the significant effect of catalyst nature, a better understanding of the main reactions, peracetic acid decomposition, and its reaction with acetaldehyde was needed. A literature -survey showed that the kinetics were not well studied, most of the work being done at very low catalyst concentration 1 p.p.m.), and there is disagreement with respect to the kinetic expressions reported by different authors. The emphasis has always been on the kinetics but not on the products obtained, which are frequently assumed to be only acetic acid and oxygen. Consequently, the effectiveness of a catalyst was measured only by the rates and not by the significant amount of by-products that can be produced. We have studied the kinetics of these reactions, supplemented by by-product studies and experiments with 14C-tagged acetaldehyde and acetic acid to arrive at a reaction scheme which allows us to explain the difference in behavior of the different metal ions. 

The reaction between acetaldehyde and peracetic acid in the presence of copper or with no metal acetate present was studied by the method of Bawn and Williamson (4) using Methods I and II (see below) for determining peracetic acid and total peroxide, respectively. 

In the presence of manganese and cobalt acetates the reaction becomes very fast, and the intermediate AMP cannot be detected. The kinetics of these reactions were studied in a flow reactor, and the results gave a good second-order fit (first order in peracetic acid and first order in acetaldehyde) at different catalyst concentrations. The plot of [acetaldehyde] vs. [peracetic acid] was linear with a slope of 1, indicating that equimolar quantities of the two substances are reacting. A plot of the experimental second-order rate constants (k Co) as a function of catalyst concentration gave a very good first-order fit for cobalt acetate... 

Some experiments were conducted with p-toluenesulfonic acid and acetyl borate as catalysts, using the same concentration range as for the metal acetates, to test their catalytic action in the reaction of acetaldehyde with peracetic acid. The results, although they did not rule out some catalytic activity, clearly indicated that these acids are much less active catalysts than manganese and cobalt acetates. 

Peracetic Acid Decomposition. Although, by comparing the rate of peracetic acid decomposition with the rate of its reaction with acetaldehyde, we can rule out the decomposition as a major path in acetaldehyde oxidation (see below), we will discuss the possible mechanisms for the catalytic decomposition of peracetic acid. 

Reaction 22a is important only with cobalt acetate catalyst and accounts for the fast rate of methane formation during the reaction of peracetic with acetaldehyde. It can also explain how methane is produced only from the methyl group of peracetic acid. This reaction path is more important with cobalt probably because of the higher oxidation potential of the cobalt (III)-cobalt (II) couple relative to that of the manganese (III) -manganese (II) couple. 

When acetaldehyde is oxidized in the presence of copper (II), the noncatalytic reaction between acetaldehyde and peracetic acid may be the main route to acetic acid. Since this reaction is slow, one would expect the presence of a significant concentration of peroxide in the reactor product, and we have confirmed this experimentally. Acetic acid can also be produced by oxidizing acetyl radicals by copper (II) the copper(I) formed could be easily reoxidized by oxygen. The by-products when using copper (II) acetates must be produced mainly by degradation of peracetoxy radicals by Reaction 14 and 16 since peracetic acid decomposition is negligible and the reaction of acetaldehyde with peracetic acid produces essentially only acetic acid. 

Depending on the conditions, metal-catalyzed autoxidation of acetaldehyde can be utilized for the manufacture of either acetic acid or peracetic acid.321 In addition, autoxidation of acetaldehyde in the presence of both copper and cobalt acetates as catalysts produpes acetic anhydride in high yield.322 b The key step in anhydride formation is the electron transfer oxidation of acetyl radicals by Cu(II), which competes with reaction of these radicals with oxygen ... 

The reaction is used commercially in the oxidation of acetaldehyde to peracetic acid [234], acetic anhydride [235] and acetic acid [236], respectively (Fig. 4.79). In the production of acetic anhydride, copper(II) salt competes with dioxygen for the intermediate acyl radical affording acetic anhydride via the acyl cation. 

Forms unstable explosive products in reaction with acetaldehyde + desiccants (forms polyethyUdine peroxide) acetic acid (forms peracetic acid) acetic + 3-thietanol acetic anhydride acetone (forms explosive peroxides) alcohols (products are shock-and heat-sensitive) carboxylic acids (e.g., formic acid, acetic acid, tartaric acid), diethyl ether, ethyl acetate, formic acid -f- metaboric acid, ketene (forms diacetyl peroxide) mercur f(II) oxide + nitric acid (forms mercur f(II) peroxide) thiourea -f- nitric acid polyacetoxyacryUc acid lactone + poly(2-hydroxyacrylic acid) + sodium hydroxide. 

The oxidation reaction of /3-lactams can be extended to the aerobic oxidation reaction [141], Typically, the RuCl3-catalyzed oxidation of /3-lactam 70 with molecular oxygen (1 atm) in the presence of acetaldehyde and sodium carboxylate gave the corresponding 4-acyloxy /3-lactam 71 in 91% yields (d.e. >99%) (Eq. 3.83). This aerobic oxidation gives peracetic acid in situ by ruthenium-catalyzed reaction of acetaldehyde with molecular oxygen, and hence similar results with those obtained by the oxidation with peracetic acid. 

Many additives, e.g. N2, CO2, H2O [45], have little or no effect on the low temperature oxidation rate. Others may promote reaction or give rise to retardation or, possibly, inhibition. Promotion or acceleration is usually associated with additives which are themselves directly or indirectly radical sources at the temperature of the system (e.g. ditertiary butyl peroxide [58], peracetic acid [19], HBr [59]), and the effect is understandable in terms of an increased (induced) rate of initiation. The most important additive in this category is peracetic acid. This is a product in the oxidation of acetaldehyde, and the effect of its addition on the oxidation kinetics has been used by Combe et al. [19] to obtain supporting evidence for the now accepted branching step. 

Reaction with acetaldehyde to produce peracetic acid and an acetyl radical ... 

Distillation of the crude acid normally takes places in two stages. The first column removes the low-boiling components such as hydrocarbons and alcohols overhead. Early removal of alcohols is especially important to prevent esterification reactions between them and the product acid. The bottoms from this column are then fed to the final column where pure acid is recovered as the overhead product and catalyst and any heavy ends are removed in the bottoms. In the technical process the reaction temperature lies between 50 and 60 °C and the catalyst concentration should be between 0.1 and 0.2 %. Under these conditions, no peracetic acid is detected at the reactor outlet, thus eliminating an additional peracid decomposition step. In commercial acetaldehyde oxidation, conversion rates above 98 % can be achieved along with selectivities between 93 and 98 %. 

The oxidation of acetaldehyde may also be carried out at temperatures of 80° to 100° C. by means of oxidation towers either in the presence or absence of a catalyst.127 Under these conditions peracetic acid is normally decomposed as rapidly as it is formed. Ill towers wetted with acetic acid and containing catalysts such as vanadium pentoxide, uranium oxide, roasted ferroso-ferric oxide, etc., the reaction between the aldehyde vapors and air tS"very rapid and complete, and temperatures as low as 30° to... 

It should also be emphasized that very little experimental kinetic research has been done on oxidations with high aldehyde conversion rates because such oxidations are made complex by the reaction of the peracid formed on the aldehyde present, by the complementary initiation caused by the peracid, and by the inhibition reactions. Likewise, very little kinetic data have been published on the oxidation of aldehydes on an industrial scale, particularly concerning the oxidation of acetaldehyde in acetic acid, the oxidation of aldehydes in peracetic acid, or the oxidation of acetaldehyde in acetic anhydride. 

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