Aldehydes 2-nitrobenzaldehyde

With propnonic aldehyde, butyraldehyde, valeraldehyde, cenanthol, myristic aldehyde, nitrobenzaldehyde, phenylacetaldehyde, furfurol, and others, the reaction can be carried out. All the compounds obtained contain the methyl groups of the two acetacetic ester molecules, but the third side-chain is different, depending upon the nature of the aldehyde employed. 

Heat a suspension of 22 g. of the diacetate in a mixture of 120 ml. of concentrated hydrochloric acid, 190 ml. of water and 35 ml. of alcohol under reflux for 45 minutes. Cool the mixture to 0°, filter the solid with suction, and wash with water. Purify the crude aldehyde by rapid steam distillation (Fig. II, 41, 3) collect about 1500 ml. of distillate during 15 minutes, cool, filter, and dry in a vacuum desiccator over calcium chloride. The yield of pure o-nitrobenzaldehyde, m.p. 44—45°, is 10 g. The crude solid may also be purified after drying either by distillation under reduced pressure (the distillate of rather wide b.p., e.g., 120-144°/3-6 mm., is quite pure) or by dissolution in toluene (2-2-5 ml. per gram) and precipitation with light petroleum, b.p. 40°-60° (7 ml. per ml. of solution). 

Potassium and sodium borohydride show greater selectivity in action than lithium aluminium hydride thus ketones or aldehydes may be reduced to alcohols whilst the cyano, nitro, amido and carbalkoxy groups remain unaffected. Furthermore, the reagent may be used in aqueous or aqueous-alcoholic solution. One simple application of its use will be described, viz., the reduction of m-nitrobenzaldehyde to m-nitrobenzyl alcohol ... 

EHRLICH - SACHS Aldehyde Synthesis Formation of o-nitrobenzaldehydes from o-nitrotoluenea. 

The behavior of aromatic aldehydes is typical. Nitration of benzaldehyde takes place several thousand times more slowly than that of benzene and yields rw-nitrobenzaldehyde as the major product. 

The AFO reaction has seen very few variations since it was first reported in 1934. However, the most significant modification was reported in 1958 by Ozawa and further elaborated by Smith and others. Prior to this modification the intermediate chalcones were purified and then subjected to hydrogen peroxide in a basic medium. With the modification, the chalcone was generated in situ, from an aldehyde and a hydroxyacetophenone, and then allowed to react with aqueous hydrogen peroxide in the presence of sodium hydroxide to deliver the flavonol. Smith and coworkers conducted a limited study to examine the scope and limitations of this modification.Flavonols were delivered in 51-67% however, no flavonols were isolated with highly reactive aldehydes such as p-nitrobenzaldehyde and when 2-hydroxy-4-methoxyacetophenone was used. 

Kinetic investigation of the reaction of cotarnine and a few aromatic aldehydes (iV-methylcotarnine, m-nitrobenzaldehyde) with hydrogen eyanide in anhydrous tetrahydrofuran showed such differences in the kinetic and thermodynamic parameters for cotarnine compared to those for the aldehydes, and also in the effect of catalysts, so that the possibility that cotarnine was reacting in the hypothetical amino-aldehyde form could be completely eliminated. Even if the amino-aldehyde form is present in concentrations under the limit of spectroscopic detection, then it still certainly plays no pfi,rt in the chemical reactions. This is also expected by Kabachnik s conclusions for the reactions of tautomeric systems where the equilibrium is very predominantly on one side. 

A useful reaction sequence has been developed for conversion of an aromatic aldehyde into the next higher homologous acid. The nitro analog of 45, prepared from m-nitrobenzaldehyde, is converted into the azide 51 by hydrazinolysis and treatment with nitrous acid. The... 

See entry NITROBENZALDEHYDES See Other ALDEHYDES, NITROARYL COMPOUNDS... 

See entry nitrobenzaldehydes See other aldehydes, nitroaryl compounds... 

Fig. 4.3 I solated yields of Biginelli dihydropyrimidine products (Scheme 4.24 a) in different reaction vessels of a 36 vessel rotor (Fig. 3.7). Outer ring, vessels 1-20 inner ring, vessels 21-36). Aldehydes a, benzaldehyde b, 2-hydroxybenzaldehyde c, 3,4-dimethoxybenzaldehyde d, 3-nitrobenzaldehyde e, 2-chlorobenzaldehyde f, 4-(N,N-dimethylamino)benzaldehyde. Adapted from [85],...

L-Rhamnosone was prepared by the action of hydrochloric acid on L-rhamnose phenylosazone9 and was identified by reconversion to the osazone. This method was later employed186 as a stage in the synthesis of the ascorbic acid analog, L-rhamnoascorbic acid. The benzaldehyde decomposition of the osazone gave a low yield of osone93 and o-nitrobenzaldehyde was not a satisfactory aldehydic substitute. 

A frequently reported spectrophotometric technique for the determination of hydralazine is based on reactions with aromatic aldehydes to form hydrazones with absorption in the visible region. Luk yanchikova et al (5 +) used p-nitrobenzaldehyde Wesley-Hadzija and Abaffy (55) and Ruggieri (56) used p-dimethylaminobenzaldehyde Luk yanchi-kova (57,58) used cinnamaldehyde Schulert (33) used p-hydroxybenzaldehyde and Zak et al (59) used p-methoxy-benzaldehyde, after testing cinnamaldehyde, salicylaldehyde, 3, +,5-trimethoxybenzaldehyde, and 1-naphthaldehyde. 

Aldehyde or ketone (5 g) (4-nitrobenzaldehyde, piperonal, naphthalene-2-carboxalde-hyde, 2-furan carboxyaldehyde, 2-thiophene carboxyaldehyde, propanal, butanal, piva-laldehyde or cyclohexanecarboxaldehyde)... 

Experiments in deoxygenated ethanol solution in the dark showed that, by stirring, 4-nitrobenz-aldehyde is obtained in 60% yield, accompanied by 13% 2-(4-nitrobenzyl)-2-nitropropane. Under the same conditions, but with sonication, the yields are 23% of 4-nitrobenzaldehyde and 48% of 2-(4-nitrobenzyl)-2-nitropropane (Einhorn et al. 1990). The importance of this result consists in the following conclusion The ultrasonic irradiation has a marked influence on the relative rates of the competing reactions and stimnlates just the ion-radical one. 

Both above mentioned complex hydrides have been successfully used for the preparation of unsaturated aldehydes from unsaturated acyl chlorides (yields 48-71%) [1011] and for the synthesis ofp-nitrobenzaldehyde from p-nitroben-zoyl chloride [775, 7077], a reduction which could hardly be achieved by applying catalytic hydrogenation. 

Nifedipin Nifedipine, dimethyl ether l,4-dihydro-2,6-dimethyl-4-(2 -nitrophenyl)-3,5-piridindicarboxylic acid (19.3.16), is synthesized by a Hantsch synthesis from two molecules of a j3-dicarbonyl compound—methyl acetoacetate, using as the aldehyde component—2-nitrobenzaldehyde and ammonia. The sequence of the intermediate stages of synthesis has not been completely established [20-23]. 

The diketothienothiophene (249b) can be condensed with aldehydes thus p-nitrobenzaldehyde gives the 2,5-bis-p-nitrobenzylidene derivative (250). ... 

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