Ammonia, aldehyde reaction

A very efficient and universal method has been developed for the production of optically pue L- and D-amino adds. The prindple is based on the enantioselective hydrolysis of D,L-amino add amides. The stable D,L-amino add amides are effidently prepared under mild reaction conditions starting from simple raw materials (Figure A8.2). Thus reaction of an aldehyde with hydrogen cyanide in ammonia (Strecker reaction) gives rise to the formation of the amino nitrile. The aminonitrile is converted in a high yield to the D,L-amino add amide under alkaline conditions in the presence of a catalytic amount of acetone. The resolution step is accomplished with permeabilised whole cells of Pseudomonas putida ATCC 12633. A nearly 100% stereoselectivity in hydrolysing only the L-amino add amide is combined with a very broad substrate spedfidty. 

This MCR chemistry began in 1850 when the Strecker reaction S-3CR of ammonia, aldehydes, and hydrogen cyanide was introduced. Since 1912 the Mannich reaction M-3CR of secondary amines, formaldehyde, and (3-protonated ketones is used. 

Further methods [205] successfully employed to synthesize fuUeropyrroUdines include acid-catalyzed [213] or thermal [214] desilylation of trimethylsilyl amino derivatives, tautomerization of a-aminoesters of immonium salts [215] and imines [216, 217], reaction with aldehydes in the presence of aqueous ammonia [218], reaction with oxazolidinone [204] or photochemical reaction with some amino derivatives [219-223], The reaction with amino acids and aldehydes was also carried... 

The great majority of 1,4-dihydropyridines are prepared using classical Hantzsch pyridine synthesis or one of its variants. The first dihydropyridine was in fact isolated back in 1882 as a stable intermediate from that method. In its simplest form, the synthesis involves heating an aldehyde such a orf/io-nitrobenzaldehyde (12-1) with ethyl acetoacetate (12-2) and ammonia. The reaction almost certainly involves, as the first... 

As distinguished from the union of aldehyde with ammonia, this reaction is wholly general, and is frequently of great value in dealing with the aldehydes of the aromatic series. It should be noticed in this connection, that the ketones, which are closely related to the aldehydes, show similar reactions ... 

Pyridine bases such as 3-picoline and MEP are predominantly manufactured by the Chichibabin reaction, where a mixture of aldehydes or ketones is reacted with ammonia. Thus, formaldehyde, acetaldehyde and ammonia react in the gas phase to produce a mixture of pyridine and 3-picoline. By choosing the appropriate aldehyde or ketone, catalyst and phase (liquid or gas phase), the composition of the mixture can be varied at will, depending on the desired end-product. In the gas phase, silica alumina catalysts are often used, while in the liquid phase acid catalysts based on phosphoric or acetic acid are employed. In the 1990s, Reilly patented MET and BEA-based zeolite catalyst compositions for ammonia-aldehyde conversions to pyridine, picolines and alkyl pyridines. 

A pathway leading to the formation of pyridines by aldolization of aldehydes, reaction with ammonia and intramolecular cyclization has been proposed by Vernin (1981). Mottram (1991) explained the formation of 2-alkylpyridines by reaction of ammonia on dienals. 

AMMONIUM CHROMATE (7788-98-9) Not combustible but will enhance an existing fire. A powerful oxidizer. A heat- and shock-sensitive explosive. Contact with strong reducing agents such as hydrazine, alcohols, or ethers can cause explosion. Contact with water produces an alkaline solution, with evolution of free ammonia. Violent reaction with combustible materials, finely divided metals, organic substances. Aqueous solution is incompatible with organic anhydrides, acrylates, alcohols, aldehydes, alkylene oxides, substituted allyls, cellulose nitrate, cresols, caprolactam solution, epichlorohydrin, ethylene dichloride, isocyanates, ketones, glycols, nitrates, nitromethane, phenols, vinyl acetate. Exothermic decomposition with maleic anhydride. 

In 1882, Hantzsch achieved the synthesis of symmetrically substituted dihydropyridines (DHPs) by reacting ammonia, aldehydes, and two equivalents of yS-ketoest-ers [27]. Since then, interest in these types of compound has grown, because of their pharmacological activity [28]. The Hantzsch reaction has successfully been used for synthesis of a wide range of DHPs and is still a popular tool for the construction of members of this class of heterocycles [29]. The classical multicomponent synthesis may require extended reaction times and yields can be low if sterically hindered aldehydes are used [30]. 

In this reaction, the course of condensation and the type of products formed depend on several factors, such as the nature of hydroxyaromatic compounds, amines, aldehydes, and the actual ratio of the components in the reaction system. For examples, besides the initial ammonia, this reaction has been extended successfully to both primary amines and secondary amines and among the secondary amines, the reaction particularly works for dimethylamine, diethylamine, and piperidine. In addition, when one of the secondary amines exists in large excess or when dimethylamine or ammonia is removed from the reaction system via vaporization, good yields of pure products are often achievable. Besides the commonly used -naphthol, many other hydroxyaromatic compounds are suitable for this reaction as well, such as phenols, and quinolinols. " It is found that among kojic acid, 8-quinolinol, and 8-hydroxquinaldine, kojic acid is the most reactive compound for the Betti reaction, which reacts with benzylideneaniline in less than 1 day... 

Recently, Kobayashi and co-workers reported an interesting variant for the synthesis of homoallylic amines, dubbed an ammonia fixation reaction [128]. With this method, allylboronates are reacted with aldehydes in a solution of ethanolic ammonia. Despite the highly basic conditions, optically pure protected a-hydroxy aldehydes such as 89 can be employed without any observed racemization, and this approach was apphed to the synthesis of aminosugar derivatives via aminoalcohol product 90 (Equation 47). Unfortunately, the addition of a chiral camphor-based allylboronate to benzaldehyde led only to a low enantioselectivity (34% ee). Reactions with the ( )- and (2)-pinacol crotylboronates lead to the same diastereoselectivity seen in the corresponding reactions with aldehydes, affording the respective anti and syn products from a reaction mechanism that most likely involves the intermediacy of primary imines. 

A regioselective synthesis of 1,4-dienes (69) from a,/3,7,5-unsaturated ketones, e.g. (68), proceeds in excellent yield on alkylation with organolithium reagents followed by reduction with lithium in liquid ammonia. The reaction is not successful with the corresponding aldehydes and the lithamide reduction product must be quenched with ethanol or t-butyl alcohol rather than with conventional protic sources such as ammonium chloride. Where applicable, the 1,4-diene is formed as a mixture of the E- and Z-stereoisomers at the newly developed double bond. 

In crude cell extracts containing added NAD", 2-aminomuconic semialdehyde is degraded with concomitant release of ammonia. The reactions have not been studied in detail so it is not known whether the NAD" is required for oxidation of the aldehyde before replacement of the amino group. The mechanism involved in the release of ammonia is also unknown (31). 

Cobalt has an odd number of electrons, and does not form a simple carbonyl in oxidation state 0. However, carbonyls of formulae Co2(CO)g, Co4(CO)i2 and CoJCO),6 are known reduction of these by an alkali metal dissolved in liquid ammonia (p. 126) gives the ion [Co(CO)4] ". Both Co2(CO)g and [Co(CO)4]" are important as catalysts for organic syntheses. In the so-called oxo reaction, where an alkene reacts with carbon monoxide and hydrogen, under pressure, to give an aldehyde, dicobalt octacarbonyl is used as catalyst ... 

The Fischer Indolisation Reaction occurs when the phenylhydrazone of a suitable aldehyde or ketone undergoes cyclisation with loss of ammonia, under the influence of various reagents, such as zinc chloride, ethnnolic hydrogen chloride, or acetic acid. For example, the phenylhydrazone of acetophenone (p. 257) when heated with zinc chloride gives 2 phenylindole. ... 

This reaction consists of the condensation of two molecular equivalents of a 1,3 diketone (or a J3-keto-ester) with one equivalent of an aldehyde and one of ammonia. Thus the interaction of ethyl acetoacetate and acetaldehyde and ammonia affords the 1,4-dihy dro-pyridine derivative (1), which when boiled with dilute nitric acid readily undergoes dehydrogenation and aromatisation" to gb e the diethyl ester of collidine (or 2,4,6-trimethyl-pyridine-3,5 dicarboxylic acid (II)). For the initial condensation the solid aldehyde-ammonia can conveniently be used in place of the separate reagents. 

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