Aldehydes dehydrogenation

In Pseudomonas putida ppGl that carries the OCT plasmid, there is duplication of some of the loci. Those for alkane hydroxylation (alkA, alkB, and alkC) and for alkanol dehydrogenation (alcO) occur on the plasmid, whereas those for alcA and alcB, and for aldehyde dehydrogenation (aldA, aldB) occur in the chromosome (Grund et al. 1975). 

E. E. Blatter, D. P. Abriola, R. Pietruszko, Aldehyde Dehydrogenase. Covalent Intermediate in Aldehyde Dehydrogenation and Ester Hydrolysis , Biochem. J. 1992, 282, 353-360. 

There are recent literature reports according to which alcohols and aldehydes dehydrogenate in the presence of ammonia to form nitriles. Process are operated by Rohm Haas, Ruhrchemie, and Bayer [21-23]. Molybdenum nitrides were found most efficient as heterogeneous catalysts [15] cf. eqs. (8) and (9) (R = n-CsHv). They also effect dehydrogenation of amines, as demonstrated for -butylamine in eq. (10). 

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. 

The aniline then reacts with the ap-unsaturated aldehyde by 1 4-addition the addition product, under the influence of strong acid, cyclises to form 1 2-dihydroquinaldine. The latter is dehydrogenated by the condensation products of aniline with acetaldehyde and with crotonaldehyde simultaneously produced ( .c., ethylideneaniline and crotonylideneaniline) these anils act as hydrogen acceptors and are thereby converted into ethylaniline and n-butyl-aniline respectively. 

This is an example of the Doebner synthesis of quinoline-4-carboxylic acids (cinchoninic acids) the reaction consists in the condensation of an aromatic amine with pyruvic acid and an aldehj de. The mechanism is probably similar to that given for the Doebner-Miller sj nthesis of quinaldiiie (Section V,2), involving the intermediate formation of a dihydroquinoline derivative, which is subsequently dehydrogenated by the Schiff s base derived from the aromatic amine and aldehyde. 

Hydroqulnollnes. Pyrans formed by reactions of a,P-unsaturated aldehydes with 1-ethoxycyclohexene and treated with hydroxjiamine are converted ia good yield to 5,6,7,8-tetrahydroquiQolines (117). These compounds can be dehydrogenated to the corresponding quiaolines. The parent reduced product has been prepared by heating O-aHylcyclohexanone oxime (118). 

Rhenium oxides have been studied as catalyst materials in oxidation reactions of sulfur dioxide to sulfur trioxide, sulfite to sulfate, and nitrite to nitrate. There has been no commercial development in this area. These compounds have also been used as catalysts for reductions, but appear not to have exceptional properties. Rhenium sulfide catalysts have been used for hydrogenations of organic compounds, including benzene and styrene, and for dehydrogenation of alcohols to give aldehydes (qv) and ketones (qv). The significant property of these catalyst systems is that they are not poisoned by sulfur compounds. 

Cyanoamidines such as (10) are converted into the more useful 2-formyl-A-norsteroids (11) by reduction with lithium in methylamine (buffered with ammonium acetate) followed by hydrolysis on hydrated alumina. This yields a mixture containing approximately 5 parts of the 2j5-aldehyde and 3 parts of the 2a-aldehyde (11). Both aldehydes are smoothly dehydrogenated by 2,3-dichloro-5,6-dicyanobenzoquinone in the presence of acid to the 2-formyl--A-iiorsteroids (12). ... 

The intermediacy of dipolar species such as 186 has been demonstrated by reaction of enamines with 2-hydroxy-1-aldehydes of the aromatic series (129). The enamine (113) reacts in benzene solution at room temperature with 2-hydroxy-1-naphthaldehyde to give the crystalline adduct (188) in 91 % yield. Oxidation with chromium trioxide-pyridine of 188 gave 189 with p elimination of the morpholine moiety. Palladium on charcoal dehydrogenation of 189 gave the known 1,2-benzoxanthone (129). 

Bohlmann (207) reported the reaction of /I -dehydroquinolizidine with methyl vinyl ketone and with propargyl aldehyde forming a partially saturated derivative of julolidine 135 and julolidine (136), respectively. Compound 135 can be prepared also by mercuric acetate dehydrogenation of ketone 137, which is formed by condensation of 1-bromoethylquinolizi-dine with ethyl acetoacetate (Scheme 11). 

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