Acetaldehyde, synthesis from

CHICHIBABIN Pyridine synthesis Pyridine synthesis from aromatic acetaldehydes and ammonia... 

The most important reaction based on Pdn-catalysis is the Wacker oxidation [171], which is used industrially for the synthesis of acetaldehyde, starting from ethane. This process can be combined with a Heck reaction and has been used by Tietze and coworkers [172] for an efficient enantioselective synthesis of vitamin E (6/1-... 

Scheme 9.3 DR5P synthesis from glucose and acetaldehyde by baker s yeast and deoxyriboaldolase-expressing E. coli.

An alternative synthesis from the Glaxo patents involves Fnedel-Crafts acylation of the 3-position of the indole intermediate 22 (Scheme 5) Reaction of hydrazine 10 with (phenylthio)acetaldehyde gave hydrazone 20, which was subjected to the Fischer indole reaction to give 3-thiophenylindole 21. It is noteworthy that this Fischer cyclization took place at room temperature because most require heat. Reductive desulfurization of 21 using Raney nickel provided indole 22. Acylation of the 3-position... 

L Plienylalanine 10 Synthesis from phenyl acetaldehyde and resolution ... 

Enzymatic processes also advance in the area of large-scale pharma intermediates /flactam antibiotics can now be produced in a fully biotechnological process, including the semi-synthesis from the /flactam core to the penicillin or cephalosporin. A precursor to ephedrine, long produced by a whole-cell process in yeast, can be obtained from benzaldehyde and acetaldehyde with the help of pyruvate dehydrogenase acting as a carboligase. 

Disulfiram (Antabuse) inhibits aldehyde dehydrogenase irreversibly, causing an increase in the level of acetaldehyde, formed from ethanol by the enzyme alcohol dehydrogenase. This results in nausea, vomiting, and other symptoms in the human—hence its use as a deterrent in alcoholism. Inhibition by disulfiram appears to be irreversible, the level returning to normal only as a result of protein synthesis. 

Highly ry//-selective aldol synthesis from cr-iodo ketones is promoted under aqueous conditions by a distannane system, (BujSnb, Bu2SnF2, and HMPA. Aqueous solutions of acetaldehyde or formaldehyde provide /3-hydroxy ketones.272 The ate complex Li+[//-Bu2Snl ( generated from Lil and -Bu2SnI2 leads to the highest class of syn-diastereoselectivity in the Reformatsky-type reaction (Equation (106)).273... 

Dipterine, the iVb-methyl derivative of tryptamine, occurs in two Asiatic members of the family Chenopodiaceae, Girgensohnia diplera Bge. (71, 72) and Arthrophytum leptocladum Popov (73), and also in the bark of Piptadenia peregrina Benth. (73a). Arthrophytum leptocladum also contains a closely related base, leptocladine (74), identified as Nb-methyltetrahydroharman by synthesis from dipterine and acetaldehyde (73). 

Acrolein and condensable by-products, mainly acrylic acid plus some acetic acid and acetaldehyde, are separated from nitrogen and carbon oxides in a water absorber. However in most industrial plants the product is not isolated for sale, but instead the acrolein-rich effluent is transferred to a second-stage reactor for oxidation to acrylic acid. In fact the volume of acrylic acid production ca. 4.2 Mt/a worldwide) is an order of magnitude larger than that of commercial acrolein. The propylene oxidation has supplanted earlier acrylic acid processes based on other feedstocks, such as the Reppe synthesis from acetylene, the ketene process from acetic acid and formaldehyde, or the hydrolysis of acrylonitrile or of ethylene cyanohydrin (from ethylene oxide). In addition to the (preferred) stepwise process, via acrolein (Equation 30), a... 

Compound 60 is a mixture of diastereomers, and the structures were proposed on the basis of spectral data and proved to be correct by synthesis from indole-3-acetaldehyde and L-cysteine. It was demonstrated that tryptamine is first converted by MAO to indole-3-acetaldehyde, which spontaneously cyclizes with free L-cysteine present in brain tissues 142). The reaction was strongly inhibited by addition of the MAO inhibitor pargyline, indicating participation of the enzyme in the formation of the aldehyde, but not in the condensation with L-cysteine, which was found to be pH-dependent and probably nonenzymatic 143). It seems possible that compound 60 is identical with material obtained during metabolic degradation of tryptamine in brain tissue 144,145). 

Do optically active 1-methyl-TIQs, as sketched in Fig. 32 for the synthesis of (7 )-salsolinol, originate from a Pictet-Spengler reaction of dopamine with acetaldehyde derive from ethanol, or are they the result of a Pictet-Spengler reaction of biogenic amines with pyruvic acid, as sketched in Fig. 33 Based on the accumulated data it seems reasonable to propose that optically active TIQs are formed by the pyruvic acid pathway, and that the pyruvic acids may be derived from an impaired glucose metabolism or an impaired amino acid metabolism. Whether the intermediate TIQ-1-carboxylic acids 91a,b are enzymatically decarboxylated to afford 64a,b in a different enantiomeric ratio, or whether optically active TIQs are formed by oxidative decarboxylation of TIQ 91 to DIQ 120, followed by an asymmetric reduction, remains open to question. 

Acrylonitrile and methacrylonitrile can be obtained from petro-chemical olefins [2] by the noncatalytic reactions of HCN with acetaldehyde, acetone (cyanohydrin is the intermediate in these processes) or oxiranes (Z-cyanoetltanol being the intermediate in the acrylonitrile synthesis from ethylene oxide). 

OSTROMISLENSKY Butadiene Synthesis CatalyHc butadiene synthesis from ethanol and acetaldehyde. 

M. Simpson and A. Gautier, Compt. rend., 65, 414 (1867) J. Wislicenus had accomplished the synthesis from acetaldehyde, hydrocyanic acid and hydrochloric acid without isolating the cyanohydrin, Ann., 128, 22 (1863). 

Reaction Mechanism. Any mechanism proposed for the vinylation of acetic acid by the hexenes must be able to account for the production of the high boiling products, 1,2-hexandiol mono- and diacetates (VIII, IX and X), and possibly hexylidene diacetate, as well as the hexenyl acetates. The currently accepted mechanism for synthesizing vinyl acetate from ethylene and acetic acid is derived from that postulated by Henry (i, 19), based on studies of the Wacker acetaldehyde synthesis. The key step in this mechanism is an insertion reaction (18). 

Rearrangement of a two-carbon insertion product could also lead to intermediates of these structures. Similar one-carbon insertion products have recently been proposed for the Wacker acetaldehyde synthesis (i, 27, 39). Elimination of a proton and palladium could occur from the intermediates XVIIa and XVIIb in a manner analogous to that proposed for the two-carbon insertion product in Reaction 13. This proposed pathway conforms with all observations, including the deuterium studies (36, 54),... 

Although alcohol has been produced by the hydrogenation of acetaldehyde obtained from the hydration of acetylene, this source is relatively unimportant ordinarily. It does, however, furnish a means for the synthesis of ethanol from such sources of carbon as calcium carbide, methane, the carbon arc, etc., which might become of importaice during periods of war, or in locations where very cheap electric power is available. Experiments on a technical scale78 in Switzerland have shown the process to be successful but at a cost too high to make the process competitive. 

Many of (he effects of chronic alcohol abuse arc due either to the toxicity of acetaldehyde and/or the failure of one or more of the many homeostatic and synthetic mechanisms in the liver. One of the earliest signs of chronic alcohol abuse is hepatomegaly. This results from the accumulation of triglyceride due to increased synthesis from the carbohydrate load and reduced protein synthesis. Continued high ethanol intake may cause the following sequelae ... 

Farrell, Me Isaac, Arch. Biochem. Biophys. 94, 543 (1961). Synthesis from 5-mcthoxytryptamine and acetaldehyde Mclsaac, Biochim. Biophys. Ada 52, 607 (1961) Meek ef o/.v Chem. dc Ind. (London) 1964, 622-... 

Horinouchi, N., 1. Ogawa, T. Sakai, T. Kawano, S. Matsumoto, M. Sasaki, Y. Mikami, and S. Shimizu. 2003. Construction of deoxyriboaldolase-overexpressing Escherichia coli and its application to 2-deoxyribose 5-phosphate synthesis from glucose and acetaldehyde for 2 -deoxyribonucleoside production. Appl. Environ. Microbiol. 69 3791-3797. 

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