Aldehyde acetaldehyde

The noncatalytic oxidation of propane in the vapor phase is nonselec-tive and produces a mixture of oxygenated products. Oxidation at temperatures below 400°C produces a mixture of aldehydes (acetaldehyde and formaldehyde) and alcohols (methyl and ethyl alcohols). At higher temperatures, propylene and ethylene are obtained in addition to hydrogen peroxide. Due to the nonselectivity of this reaction, separation of the products is complex, and the process is not industrially attractive. 

In the haloform reaction, methyl ketones (and the only methyl aldehyde, acetaldehyde) are cleaved with halogen and a base. The halogen can be bromine, chlorine, or iodine. What takes place is actually a combination of two reactions. The first is an example of 12-4, in which, under the basic conditions employed, the methyl group is trihalogenated. Then the resulting trihalo ketone is attacked by hydroxide ion ... 

Aldehydes acetaldehyde, benzaldehyde, formaldehyde, glyoxal, isobutyraldehyde, trichloroaldehyde... 

In contrast to transketolase and the DHAP-dependent aldolases, deoxyribose aldolase (DERA) catalyzes the aldol reaction with the simple aldehyde, acetaldehyde. In vivo it catalyzes the formation of 2-deoxyribose-5-phosphate, the building block of DNA, from acetaldehyde and D-glyceraldehyde-3-phosphate, but in vitro it can catalyze the aldol reaction of acetaldehyde with other non-phosphorylated aldehydes. The example shown in Scheme 6.28 involves a tandem aldol reaction... 

The a-oxidation pathway ofTV-nitrosodiethanolamine metabolism (Figure 2) leads to the formation of an a-hydroxynitrosamine that rapidly decomposes, producing glycol aldehyde, acetaldehyde, ethylene glycol and molecular nitrogen. The latter is assumed to arise from a reactive (2-hydroxyethyl)diazonium ion, which probably is responsible for the formation of 2-hydroxyethylated adducts in DNA (Scherer et al., 1991 Loeppky etal., 1998 Loeppky, 1999). 

Aldehydes Acetaldehyde Acrolein (inhibited) Butyraldehyde Dec aldehyde Ethylhexald ehyde Formaldehyde Glutaraldehyde Solution Glyoxal Solution Methylbutyraldehyde Octyl Aldehyde Pentyl Aldehyde Propionaldehyde Valeraldehyde... 

The necessary aldehyde (acetaldehyde) is prepared from acetic acid by reduction followed by oxidation in an anhydrous medium. 

As you can see from Figures 9.10 and 9.11, all steps of the oligomerization or polymerization of aldehydes in the presence of protons are reversible. The trimerizations of the mentioned aldehydes acetaldehyde and isobutyraldehyde are therefore thermodynamically controlled. This is the reason why they take place stereoselectively and the trimers C (R = Me... 

Furthermore, the presence of a tetrahydrometoxazine ring as in XV receives confirmation from a study of the condensation of a simple aldehyde (acetaldehyde) with geissoschizoline (11). The latter in 10%... 

Methyl glyoxal has never been reported in soy sauce or soy bean paste prior to this study. Certain aldehydes (acetaldehyde, n-propanal, 2-methylpropanal, and 3-methylbutanal) were found in soy sauce previously (32). A gas chromatogram of the extract from cysteamine-treated soy sauce and untreated soy sauce are shown in Figures 7 and 8. 

As is tile case for other aldehydes, acetaldehyde can condense with amino groups to form a Schiff base. Schiff base formation occurs in a number of pathological conditions. For example, breakdown of polyunsaturated fatty adds may generate malondialdehyde, which reacts with proteins to produce damage. To review another example, the elevated plasma glucose levels in diabetes results in an increased condensation of glucose, via a Schiff base, with various proteins in the bloodstream. Aldehyde damage to proteins has been reviewed by Stadtman (1990). 

Other Aldehydes. Acetaldehyde (85) and benzaldehyde (85, 94) react with wood by using either HNO3 or zinc chloride catalysts. Acetaldehyde modification produces a high ASE, but benzaldehyde... 

Ethylamine is not as readily metabolized as methyla-mine, and portions are excreted unchanged from the lung and in the urine. The metabolism of ethylamine is believed to occur in two stages. The amino group is initially dehydrogenated to an intermediate imine (ethyl imine), which reacts spontaneously with water, forming the corresponding aldehyde (acetaldehyde) and ammonia. The final metabolic products of acetic acid and urea are excreted in the urine. Ethylamine is a normal constituent of mammalian and human urine. 

Parameters Involved in MLF of Wine Aliphatic Aldehydes, Acetaldehyde, Diacetyl and Acetoin... 

Aldehydes. acetaldehyde. phenylacetaldehyde Amines Amino Acids... 

In addition to formaldehyde, fog- and cloudwater contain a variety of higher aldehydes. Acetaldehyde and proponal (or acrolein) often have concentrations comparable to formaldehyde. 

The synthesis of Mc-porphyrins (McPOR) in situ in zeolites has been reported out of a mixture of pyrrole and an aldehyde (acetaldehyde) (see scheme) [13]. As this synthesis is a much less clean process than the corresponding one with DCB, the abundant debris filling the... 

Conpared with 2-methylpropanal, 3-methylbutanal, and 2-methylbutanal, two other aldehydes, acetaldehyde and formaldehyde, were not detected in the model systems, but their corresponding substituted flavor conpounds were identified. Acetaldehyde, having a low boiling point of 21°C, might either be too volatile to be detected or be very active and completely react with other corrponents. Several heterocyclic conpounds with ethyl-substituents were identified in the model systems. 

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