Benzaldehyde catalytic hydrogenation

Pyrolytic Decomposition. The pyrolytic decomposition at 350—460°C of castor oil or the methyl ester of ricinoleic acid spHts the ricinoleate molecule at the hydroxyl group forming heptaldehyde and undecylenic acids. Heptaldehyde, used in the manufacture of synthetic flavors and fragrances (see Elavors and spices Perfumes) may also be converted to heptanoic acid by various oxidation techniques and to heptyl alcohol by catalytic hydrogenation. When heptaldehyde reacts with benzaldehyde, amyl cinnamic aldehyde is produced (see Cinnamic acid, cinnamaldehyde, and cinnamyl... 

In the catalytic hydrogenation of benzaldehyde to benzyl alcohol, it is very important to prevent the hydrogenolysis of the product. Nickel60-63 and copper... 

Aldoximes yielded primary amines by catalytic hydrogenation benzaldehyde gave benzylamine in 77% yield over nickel at 100° and 100 atm [803, with lithium aluminum hydride (yields 47-79%) [809, with sodium in refluxing ethanol (yields 60-73%) [810] and with other reagents. Hydrazones of aldehydes are intermediates in the Wolff-Kizhner reduction of the aldehyde group to a methyl group (p. 97) but are hardly ever reduced to amines. 

With nitrobenzene, reduction to an intermediate stage results in the formation of a complex which, as is also the case with the initial complexes formed with ferricyanide, benzoquinone, and benzaldehyde, cannot react in the manner shown in the first conclusion. These species require the presence of added alkali, which apparently effects the displacement of reduced substrate by hydroxyl anion to yield hydroxypentacyanocobaltate(III). All of the substrates mentioned have been found to undergo catalytic hydrogenation when added to the catalyst system in less than stoichiometric quantities in the presence of alkali. 

The water-soluble Ru(II) complex [Ru(i76-C6H6)(CH3CN)3](BF4)2 catalyzed the biphasic hydrogenation of alkenes and ketones with retention of the catalyst in the aqueous phase (87). However, the ruthenium complex moved to the organic phase when benzaldehyde was hydrogenated. In a benzene-D20 system, H-D exchange was observed between H2 and D20. Both monohydridic pathway and a dihydridic pathway are possible for hydrogen activation, and these two different catalytic cycles influence the yield and product distribution. 

Benzyl alcohol readily undergoes the reactions characteristic of a primary alcohol, such as esterification and etherification, as well as halide formation. In addition, it undergoes ring substitution. In the presence of acid, polymerization is observed, and the alcohol can be thermally dehydrated to toluene [108-88-3], Catalytic oxidation over copper oxide yields benzaldehyde benzoic acid is obtained by oxidation with chromic acid or potassium permanganate. Catalytic hydrogenation of the ring gives cyclohexylmethanol [100-49-2]. 

The catalytic hydrogenation of benzaldehyde is a model reaction of hydrogenations of aromatic aldehydes. The principal reaction is ... 

With aromatic and heteroaromatic aldehydes,193 4-oxo-6,7,8,9-tetra-hydro-4T/-pyrido[l,2-a]pyrimidines yielded the 9-arylmethylene derivatives,133,266 whereas with glyoxylic acid the 9-carboxymethylene derivative was formed.266,267 The primary addition product (237) could be isolated from the reaction mixture of ethyl 6-methyl-4-oxo-6,7,8,9-tetrahydro-4//-pyrido[l,2-a]pyrimidine-3-carboxylate and benzaldehyde. On dehydration the addition product (237) gave the 9-benzylidene compound.266 The 9-carboxymethylene derivatives may be transformed by catalytic hydrogenation to the 9-acetic acids, which can be esterified.266,267... 

Pyruvate decarboxylase (PDC, E.C. 4.1.1.1) accepts other substrates besides pyruvate, its natural reactant As early as 1921, Neubergand Hirsch described the reaction of yeast with benzaldehyde and pyruvate to phenylacetylcarbinol (2-keto-3-hydroxy-propylbenzene) (Neuberg, 1921) in a carboligase side reaction which yields ephedrine after reaction with methylamine and catalytic hydrogenation (Figure 7.37). 

Acid Amides can be produced by acylating ammonia with esters, acid anhydrides, or the acids themselves (above 100 °C) an important product is formamide from methyl formate. Alternatively acid amides can be synthesized by reacting acid halides with ammonia. Catalytic hydrogenation converts the acid amides to primary amines. Ammonia and aldehydes or ketones are the basis for different stable products. With formaldehyde hexamethylenetetramine (urotropine) is obtained with acetaldehyde, ammono acetaldehyde with benzaldehyde, hydrobenzamide with ethylene and propylene oxides, aqueous ammonia reacts to form ethanol- or propanolamine. 

Upon treatment with hydroxylamine mesembrine gave an oxime, isolated as a crystalline hydrochloride (6). This ketoxime was reduced with lithium aluminum hydride to a primary amine 9). By catalytic hydrogenation mesembrine yields an optically active alcohol, mesem-brinol (6, 7). Condensation with benzaldehyde formed a dibenzylidene derivative of mesembrine (9). 

The enzyme has also been used in the production of several natural amino acids such as L-serine from glycine and formaldehyde and L-tryptophan from glycine, formaldehyde, and indole [77-79], In addition, SHMT has also been used for the production of a precursor, 20, to the artificial sweetener aspartame (21) through a non-phenylalanine-requiring route (Scheme 14) [80-83]. Glycine methyl ester (22) is condensed with benzaldehyde under kinetically controlled conditions to form L-enY/ ra-p-phenylserine (23). This is then coupled enzymatically using thermolysin with Z-aspartic acid (24) to form A -carbobcnzyloxy-L-a-aspartyl-L-eryt/zro-p-phenylserine (20). and affords aspartame upon catalytic hydrogenation. 

Treatment of l-alkyl-3-t-butoxycarbonylimidazolium salts with methanol hydrolyzes the ester group <905795). Catalytic hydrogenation of l-benzyloxy-2-imidazolone converts it into the 1-hydroxy derivative, while treatment with methanolic alkali causes elimination of benzaldehyde to form 2-imidazolone <8751058). 

Now a difficulty emerged. They wanted to carry out the resolution on a large scale but enantio-merically pure 6 is expensive. The solution was to make it themselves from previously resolved cheap 2. The obvious route is reductive amination using benzaldehyde and the only danger is racemisation of the intermediate imine 7. They found that the imine 7 did not racemise as it was prepared in toluene but that some racemisation took place when NaB(CN)H3 was used for the reduction. The solution was to use catalytic hydrogenation and they prepared 53 kg batches of optically pure 7 in 98% yield by this method and used that to resolve the hydroxy acid 5. 

Compound (329), a potent inhibitor of dihydrofolate reductase, was synthesized by a Knoevenagel condensation of the ketone (326) with ethyl cyanoacetate to afford (327) in 28-81% yield. Catalytic hydrogenation of (327) over Pd/C gave almost exclusively the undesired endo isomer, whereas with lithium in liquid ammonia and phenol as proton donor the desired exo compound (328) was obtained in 71% yield.222 Knoevenagel condensation of benzaldehydes with malonodinitrile in the presence of a base leads to benzylidenemalonodinitriles. These compounds, especially the 2-chlorobenzylidenemalonodini-trile (CS, 330), are used as riot-control agents (sneeze and tear gas). 2,324... 

A further s3mthesis was described (92) in which a-picolyl hthium is treated with benzaldehyde, and the resulting phenyl (a-picolyl)-carbinol is converted to dZ-sedamine by AZ-methylation followed by catalytic hydrogenation. From the mother liquors of the crystallization of dZ-sedamine, the other diastereoisomer was obtained. It melts at... 

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