Acetaldehyde

Abstract

Acetaldehyde [75-07-0] (ethanal), CH 3 CHO, was first prepared by Scheele in 1774, by the action of manganese dioxide and sulfuric acid on ethanol. The structure of acetaldehyde was established in 1835 by Liebig from a pure sample prepared by oxidizing ethyl alcohol with chromic acid. Liebig named the compound ''aldehyde'' from the Latin words translated as al(cohol) dehyd(rogenated). The formation of acetaldehyde by the addition of water to acetylene was observed by Kutscherow in 1881.Acetaldehyde, first used extensively during World War I as a starting material for making acetone [67-64-1] from acetic acid [64-19-7], is an important intermediate in the production of acetic acid, acetic anhydride [108-24-7], ethyl acetate [141-78-6], peracetic acid [79-21-0], pentaerythritol [115-77-5], chloral [302-17-0], glyoxal [107-22-2], alkylamines and pyridines. Commercial processes for acetaldehyde production include the oxidation or dehydrogenation of ethanol, the addition of water to acetylene, the partial oxidation of hydrocarbons, and the direct oxidation of ethylene [74-85-1].Acetaldehyde is a product of most hydrocarbon oxidations. It is an intermediate product in the respiration of higher plants and occurs in trace amounts in all ripe fruits that have a tart taste before ripening. The aldehyde content of volatiles has been suggested as a chemical index of ripening during cold storage of apples. Acetaldehyde is also an intermediate product of fermentation (qv), but it is reduced almost immediately to ethanol. It may form in wine (qv) and other alcoholic beverages after exposure to air imparting an unpleasant taste; the aldehyde reacts to form diethyl acetal [105-57-7] and ethyl acetate [141-78-6]. Acetaldehyde is an intermediate product in the decomposition of sugars in the it body and hence occurs in trace quantities in blood. Physical PropertiesAcetaldehyde is a colorless, mobile liquid having a pungent, suffocating odor that is somewhat fruity and quite pleasant in dilute concentrations. Its physical Vol. 1 ACETALDEHYDE 99Kirk-Othmer Encyclopedia of Chemical Technology.

Solvent-Free Synthesis of Acetal-Containing Polyols for Use in Recyclable Polyurethanes

“…To achieve depolymerization, the acetal-containing TPU with 30 wt % HPC was first treated with a 0.1 M HCl aqueous solution at 70 °C for 7 h under continuous stirring. After complete hydrolysis, the liberated acetaldehyde was released as a gas, which can be easily recovered using distillation when the reaction is performed on an industrial scale . The B14 dissolved in the aqueous phase, and the urethane-rich hard phase remained as an insoluble fine powder (Figure B).…”

“…After complete hydrolysis, the liberated acetaldehyde was released as a gas, which can be easily recovered using distillation when the reaction is performed on an industrial scale. 69 The B14 dissolved in the aqueous phase, and the urethane-rich hard phase remained as an insoluble fine powder (Figure 9B). After filtration, the acidic aqueous solution was treated with ionexchange resin (Amberlyst A26) to remove chloride, followed by the removal of water, yielding 90% of the total theoretical amount of the B14 monomer in high purity.…”

Review on Alternative Route to Acrolein through Oxidative Coupling of Alcohols

“…Formaldehyde can be produced through two processes: the oxidation of methanol with iron-molybdate catalysts, in multi-tubular reactors, or with silver catalysts through oxydehydrogenation, in shallow bed reactors operated at high temperature [17][18][19]. Acetaldehyde is produced by ethylene oxidation, with Pd-Cu catalysts [20,21], but it can be also produced through ethanol oxidation or oxydehydrogenation much like methanol [22]. Therefore, we proposed to combine all the reactions in a single step that we called an oxidative coupling of alcohols [23,24] (Reaction D, Scheme 1).…”