Acetaldehyde from oxidation

Production of acetaldehyde from oxidation of C2H4 in a solution of... 

Production of acetaldehyde from oxidation of C H. In a solution of CuCU containing PdCU as a catalyst Liquid-phase esterification of terephthallc acTd lth methanol Hydrogenation of methyl llnoleate In the presence of a palladium catalyst Oxidation of sodium sulfite with cobaltous sulfate catalyst... 

Since 1960, the Hquid-phase oxidation of ethylene has been the process of choice for the manufacture of acetaldehyde. There is, however, stiU some commercial production by the partial oxidation of ethyl alcohol and hydration of acetylene. The economics of the various processes are strongly dependent on the prices of the feedstocks. Acetaldehyde is also formed as a coproduct in the high temperature oxidation of butane. A more recently developed rhodium catalyzed process produces acetaldehyde from synthesis gas as a coproduct with ethyl alcohol and acetic acid (83—94). 

There are two ways to produce acetaldehyde from ethanol oxidation and dehydrogenation. Oxidation of ethanol to acetaldehyde is carried out ia the vapor phase over a silver or copper catalyst (305). Conversion is slightly over 80% per pass at reaction temperatures of 450—500°C with air as an oxidant. Chloroplatinic acid selectively cataly2es the Uquid-phase oxidation of ethanol to acetaldehyde giving yields exceeding 95%. The reaction takes place ia the absence of free oxygen at 80°C and at atmospheric pressure (306). The kinetics of the vapor and Uquid-phase oxidation of ethanol have been described ia the Uterature (307,308). 

In a similar manner, ethanol can be oxidized by the dichromate ion to form a compound called acetaldehyde, CHaCHO. The molecular structure of acetaldehyde, which is similar to that of formaldehyde, is shown at the bottom in Figure 18-6. We see that the molecule is structurally similar to formaldehyde. The methyl group, —CH3, replaces one of the hydrogens of formaldehyde. The balanced equation for the formation of acetaldehyde from ethanol is... 

Evidence concerning the relative extents of C-C and C-H fission is less well defined for Ce(IV) and Mn(III) as compared with V(V). Pinacol is cleaved to acetone in all cases, but while Mn(IlI) pyrophosphate [like V(V)] oxidises pinacol much faster than butane-2 3-diol, the rate ratio with Ce(IV) is only approximately 3 and the production of acetaldehyde from butane-2 3-diol by Ce(IV) oxidation demonstrates C-C cleavage . It is probable, therefore, that Mn(III) oxidises the disecondary glycol by C-H fission. 

Infrared spectroscopy has also been employed to follow the formation of acetaldehyde and acetic acid on Pt during ethanol electro-oxidation. On the basal planes, acetaldehyde could be observed starting at about 0.4 V (vs. RHE), well before the onset of CO oxidation, while the onset of acetic acid formation closely follows CO2 formation [Chang et al., 1990 Xia et al., 1997]. This is readily explained by the fact that both CO oxidation and acetic acid formation require a common adsorbed co-reactant, OHads, whereas the formation of acetaldehyde from ethanol merely involves a relatively simple proton-electron transfer. 

The addition of propylene also led to the increase of NO removal efficiency in a pulsed DBD in a mixture containing N2, 02, NO and 500 ppm C3H6 [30,35], Consequently, the energy cost for NO oxidation decreased from 42 to 25 eV/NO molecule [30], The authors also observed an increase in NO removal up to 30%. The major reaction products detected were carbon oxides, formaldehyde, acetaldehyde, propylene oxide, formic acid, ethyl acetate, methyl nitrate and nitromethane. 

It is well known that the catalytic effect of Ti02 is attributed to the generation of a strong oxidant, hydroxyl radicals [44]. Following this theory, the quantum efficiency of the felt material prepared with the titania/silica fiber was calculated from the aforementioned result. In this case, if the number of molecules is significantly larger than the number of photon, acetaldehyde is oxidized to CH3COOH as follows ... 

Pd2+ salts are useful reagents for oxidation reactions of olefins. Formation of acetaldehyde from ethylene is the typical example. Another reaction is the formation of vinyl acetate by the reaction of ethylene with acetic acid (16, 17). The reaction of acetic acid with butadiene in the presence of PdCl2 and disodium hydrogen phosphate to give butadienyl acetate was briefly reported by Stem and Spector (110). However, 1-acetoxy-2-butene (49) and 3-acetoxy-l-butene (50) were obtained by Ishii and co-workers (111) by simple 1,2- and 1,4-additions using PdCl2/CuCl2 in acetic acid-water (9 1). 

Small amounts of acetaldehyde (from acetylene) are converted industrially into alcohol by catalytic hydrogenation, and large amounts are transformed into acetic acid by catalysed autoxidation (with oxides of manganese). 

S)-(-)-CITRONELLOL from geraniol. An asymmetrically catalyzed Diels-Alder reaction is used to prepare (1 R)-1,3,4-TRIMETHYL-3-C YCLOHEXENE-1 -CARBOXALDEHYDE with an (acyloxy)borane complex derived from L-(+)-tartaric acid as the catalyst. A high-yield procedure for the rearrangement of epoxides to carbonyl compounds catalyzed by METHYLALUMINUM BIS(4-BROMO-2,6-DI-tert-BUTYLPHENOXIDE) is demonstrated with a preparation of DIPHENYL-ACETALDEHYDE from stilbene oxide. A palladium/copper catalyst system is used to prepare (Z)-2-BROMO-5-(TRIMETHYLSILYL)-2-PENTEN-4-YNOIC ACID ETHYL ESTER. The coupling of vinyl and aryl halides with acetylenes is a powerful carbon-carbon bond-forming reaction, particularly valuable for the construction of such enyne systems. 

Alkenes are directly oxidized to aldehydes and/or ketones by ozone (O3) at low temperatures (—78 °C) in methylene chloride, followed by the reductive work-up. For example, 2-methyl-2-butene reacts with O3, followed by a reductive work-up to yield acetone and acetaldehyde. This reducing agent prevents aldehyde from oxidation to carboxylic acid. 

Monosubstituted and 1,2-disubstituted olefins can be oxidized to aldehydes and ketones by palladium chloride and similar salts of noble metals.367 1,1-Disubstituted olefins generally give poor results. The reaction is used industrially to prepare acetaldehyde from ethylene... 

Catalysts used to convert ethylene to vinyl acetate are closely related to those used to produce acetaldehyde from ethylene. Acetaldehyde was first produced industrially by the hydration of acetylene, but novel catalytic systems developed cooperatively by Farbwerke Hoechst and Wacker-Chemie have been used successfully to oxidize ethylene to acetaldehyde, and this process is now well established (7). However, since the largest use for acetaldehyde is as an intermediate in the production of acetic acid, the recent announcement of new processes for producing acetic acid from methanol and carbon monoxide leads one to speculate as to whether ethylene will continue to be the preferred raw material for acetaldehyde (and acetic acid). 

Fig. 59. Catalytic oxidative dehydrogenation of cyclohexene (O, surface catalysis) and oxidation of acetaldehyde ( , bulk-type II) the catalyst was HjPMonO supported on Si02. Masses catalyst 0.2 g for cyclohexene and 0.1 g for acetaldehyde. (From Ref. 327.)...

Fig. 60. Correlations between catalytic activity and oxidizing ability for (a) oxidation of acetaldehyde (surface reaction) and (b) oxidative dehydrogenation of cyclohexene (bulk-type 11 reaction). (From Ref. 327.) r(aldehyde) and r(hexene) show the rates of catalytic oxidation of acetaldehyde and oxidative dehydrogenation of cyclohexene, respectively. (From Ref. 337.) r( CO) is the rate of reduction of catalysts by CO r(H2) is the rate of reduction of catalysts by H2. M, denotes M,H3-,PMO 2O40. Na2-1, 2, 3, and 4 are Na2HPMoi2O40 of different lots, of which the surface areas are 2.8, 2.2, 1.7, and 1.2 m2 g, respectively.

Fig. 64. Redox cycle for the oxidation of ethylene to acetaldehyde. V5+ (oxidized heteropolyanion) represents vanadium in the oxidized heteropolyanion. (From Ref. 368.)...

Wacker Process The Wacker process is primarily used to produce acetaldehyde from the oxidation of ethylene by palladium(II)Copper(II) chloride solution. 

Miyake, T., and Shibamoto, S. 1995. Formation of acetaldehyde from L-ascorbic acid and related compounds in various oxidation systems. J. Agric. Food Chem., 43, 1669-1672. 

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