Oxidation of propionaldehyde

With the exception of acetic, acryUc, and benzoic all other acids in Table 1 are primarily produced using oxo chemistry (see Oxo process). Propionic acid is made by the Hquid-phase oxidation of propionaldehyde, which in turn is made by appHcation of the oxo synthesis to ethylene. Propionic acid can also be made by oxidation of propane or by hydrocarboxylation of ethylene with CO and presence of a rhodium (2) or iridium (3) catalyst. 

Propionaldehyde is produced by the oxo reaction of ethylene with carbon monoxide and hydrogen. n-Propyl alcohol is produced by hydrogenation of propionaldehyde, and propionic acid is made by oxidation of propionaldehyde. 

In the oxidation of propionaldehyde detectable amounts of ethane are formed by reaction (70)... 

Recent work by Baldwin and co-workers on the oxidation of propionaldehyde using KCl coated vessels is considered in Sect. 4.6.2. 

In other respects, and particularly at lower temperatures, the oxidation of propionaldehyde closely resembles that of acetaldehyde. In particular, Fig. 3 shows that, in the early stages, the course of the reaction is in agreement with eqn. (VI) (p. 383), feia/ sc being 1/31 at 62.5 [43]. 

Although HO2 radicals are produced by (la), and possibly also at other stages of the reaction, it seems that, in contrast to the corresponding high temperature oxidation of propionaldehyde (see below), the reaction... 

Product formation during the high temperature oxidation of propionaldehyde [22]... 

Larson, U.S. pal. 2,448,375 (1948 to du Pont) from ethanol and carbon monoxide using a boron trifluoride catalyst Loder, U.S. pats. 2,135,448 2,135,451 2,135,453 (1939 to du Pont) by oxidation of propionaldehyde Hasche, U.S, pat. 2,294,984 (1942 to Kodak) from natural gas by the Fischer-Tropsch process as a byproduct in the pyrolysis of wood by the action o( microorganisms on a variety of materials in small yields. Very pure propionic acid can be obtained from propionitrile. 

Propionic acid was prepared selectively from propionaldehyde using manganese diacetate [240]. The catalytic acitivity of nitrates of Cu(II), Fe(II), Zn(II) and Mn(II) toward the oxidation of propionaldehyde was improved by the addition of 2,2 -bipy-ridyl (bipy) in quantities from 1-4 moles per mole of metal ion [241,242]. The catalytic activity of copper complexes was in the order [Cu(bipy)3] [Cu(bipy)2] >... 

Furthermore, the presence of bipyridyl increased the selectivity of the copper catalyzed oxidation to peracetic acid. For example, oxidation of propionaldehyde in acetic acid at 30 °C in the presence of [Cu(bipy)2(N03)2] gave the peracid in 58% yield and the acid in yields of 32-40%. When reaction was run using Cu(N03)2 in the absence of bipyridyl, the peracid was formed in 9% yield while the yield of carboxylic acid was 80%. The nature of the amine was varied and the catalytic activity of the copper complex toward oxidation of propionaldehyde varied with the amine as follows bipyridyl, phenanthroline > none, pyridine > 2,9-dimethyl-l, 10-phenan-throline > quinoline > ethylenediamine. The rate equations for oxidation in the presence of Cu(N03)2 and [Cu(bipy)2(N03)2] differed substantially and the apparent activation energies were 8.2 and lO.lkcal/mole, respectively [241]. 

Kinetics of the Rh(III)-catalysed oxidation of D-xylose and L-sorbose with N-bromo-acetamide, " ofpalladium(II)-catalysed oxidation of methylamine and ethylamine by IV-bromosuccinimide (NBS), and of alcohols by A -bromoisonicotinamide have been determined and suitable mechanisms have been suggested. Catalytic role of cetyltrimethylammonium bromide in the oxidation of galactose and acetaldehyde by IV-bromophthalimide (NBP) has been examined. Various activation and kinetic parameters have been evaluated and a mechanism has been proposed. Kinetic and activation parameters of the oxidation of glutamic acid by NBP have been determined and a mechanism has been suggested. The kinetics of oxidation of meta- and para-substituted piperidin-4-ones with and of oxidation of propionaldehyde... 

The attack of OH obeys the Markovnikov rule. Higher alkenes are oxidized to ketones and this unique oxidation of alkenes has extensive synthetic appli-cations[23]. The oxidation of propylene affords acetone. Propionaldehyde is... 

Propanol has been manufactured by hydroformylation of ethylene (qv) (see Oxo process) followed by hydrogenation of propionaldehyde or propanal and as a by-product of vapor-phase oxidation of propane (see Hydrocarbon oxidation). Celanese operated the only commercial vapor-phase oxidation faciUty at Bishop, Texas. Since this faciUty was shut down ia 1973 (5,6), hydroformylation or 0x0 technology has been the principal process for commercial manufacture of 1-propanol ia the United States and Europe. Sasol ia South Africa makes 1-propanol by Fischer-Tropsch chemistry (7). Some attempts have been made to hydrate propylene ia an anti-Markovnikoff fashion to produce 1-propanol (8—10). However, these attempts have not been commercially successful. 

Isomerization and Hydrogenolysis. lsomeri2ation of propylene oxide to propionaldehyde and acetone occurs over a variety of catalysts, eg, pumice, siUca gel, sodium or potassium alum, and 2eohtes (80,81). Stronger acid catalysts favor acetone over propionaldehyde (81). AHyl alcohol yields of 90% are obtained from use of a supported lithium phosphate catalyst (82). 

The most common procedure previously employed to effect the elimination of thiols from thioacetals has been heating in the presence of a protic acid. For example, propionaldehyde diethyl thioacetal is converted to 1-ethylthio-l-propene on heating at 175° in the presence of phosphoric acid. The relatively high temperature and acidic conditions of such procedures are, however, distinct disadvantages of this method. Another approach consists of oxidation of a thioacetal to the mono S-oxide and thermal elimination of a sulfenic acid at 140-150°. ... 

These materials are very easily autoxidised and often have a low autoignition temperature. It is reported that many of the less volatile liquid aldehydes will eventually inflame if left exposed to air on an absorbent surface. The mechanism is undoubtedly similar to that giving rise to easy ignition in the air-oxidation of acetaldehyde and propionaldehyde initial formation of a peroxy-acid which catalyses the further oxidation[l]. Autoignition temperatures of lower aldehydes are much reduced by pressure, but appear to depend little on oxygen content. The effect is worst in the presence of free liquid, in which initial oxidation appears to occur, possibly catalysed by iron, followed by ignition of the vapour phase [2], An acetaldehyde/rust mix exploded at room temperature on increasing the air pressure to 7 bar. 

At high pressures the presence of the H02 radical also contributes via HCO + H02 — H202 + CO, but H02 is the least effective of OH, O, and H, as the rate constants in Appendix C will confirm. The formyl radical reacts very rapidly with the OH, O, and H radicals. However, radical concentrations are much lower than those of stable reactants and intermediates, and thus formyl reactions with these radicals are considered insignificant relative to the other formyl reactions. As will be seen when the oxidation of large hydrocarbon molecules is discussed (Section H), R is most likely a methyl radical, and the highest-order aldehydes to arise in high-temperature combustion are acetaldehyde and propionaldehyde. The acetaldehyde is the dominant form. Essentially, then, the sequence above was developed with the consideration that R was a methyl group. 

BASF led the development of a route based on ethylene and synthesis gas. Its four step process begins with the production of propionaldehyde from ethylene, CO, and H2 using a proprietary catalyst mixture that they aren t telling anything about. Reaction with formaldehyde gives methacrolein. The last two steps are the same as above—oxidation with air yields the MAA subsequent reaction with methanol yields MMA. 

The oxidation of 2-ethylhexan-l-ol to 2-ethyl-hexanal by the Oppenauer oxidation with aliphatic aldehydes such as acetaldehyde, propionaldehyde, and isobutyr-aldehyde has been investigated with gas-phase reactants and MgO as the catalyst (196). Reaction with propionaldehyde was found to be an effective synthetic route for 2-ethylhexanal preparation, whereas with acetaldehyde and isobutyraldehyde a gradual catalyst deactivation in a flow reactor was observed. 

In comparable reaction conditions as Pd +Cu +Y, Pd + and Cu2+ exchanged pentasil and ferrierite zeolites show a different type of activity [31]. The main products formed by propylene oxidation on these catalysts are acrolein and propionaldehyde below 120°C and 2-propanol above 120 C. Above 150°C consecutive oxidation of 2-propano1 to acetone is observed. The catalytic role of Pd and Cu in the 2-propanol synthesis is proposed to follow the Wacker concept. It is striking that when Pd + and Cu2+ are exchanged in 10-membered ring zeolites, oxidation of a primary carbon atoms seems possible, as acrolein and propionaldehyde are obtained from propylene. 

Commercial acrolein (Shell Chemical Corp.) was distilled and shaken with an equal volume of anhydrous calcium sulfate for 30 minutes. The acrolein (containing an impurity of 3.5% of propionaldehyde) was distilled again just before use (b.p., 52.5—52.9° C.). Oxidation products identified using acrolein (99.9% purity) without propionaldehyde, which was removed by the Tischenko reaction (31). Solvents were used after purification (especially dehydration) by conventional methods. 

S)-Proline also catalyzed the Mannich-type reactions of unmodified aldehydes and N-PMP-protected imines to afford the corresponding enantiomerically enriched / -aminoaldehydes at 4 °C (Table 2.13) [71b]. The products were isolated after reduction with NaBH4, though oxidation to the / -amino acid is also possible. These reactions also provided the syn-isomer as the major diastereomer with high enantioselectivities, and proceeded well in other solvents (e.g., dioxane, THF, Et20). In the reaction of propionaldehyde and the N-PMP-imine of 4-nitrobenzaldehyde in DMF, the addition of water (up to 20%, v/v) did not affect the enantioselectivity. Similar results were obtained for the (S)-proline-catalyzed Mannich-type reactions with the glyoxylate imine where water did not reduce enantioselectivity [71b]. However, the enantioselectivity of the reaction of propionaldehyde and the N-PMP-imine of benzaldehyde in DMF was decreased by the addition of water or MeOH [71b]. 

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