O Nitrobenzaldehyde

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). 

The undermentioned reductions may be carried out by simple adaptations to the procedures chloral to trichloroethj 1 alcohol m-nltroacetophenone of a-methyl-3-nitrobenzyl alcohol and o-nitrobenzaldehyde to o-nitroben l alcohol. 

A two-step synthesis of indoles from o-nitrobenzaldehydes proceeds by condensation with nitromcthanc followed by reductive cyclization. Like the Leim-gruber Batcho method, the principal application of the reaction is to indoles with only carbocyclic substituents. The forniation of the o,p-dinitrostyrenes is usually done under classical Henry condensation conditions but KF/18-crown-6 in propanol was found to be an advantageous reaction medium for acetoxy-substituted compounds[1]. The o,p-dinitrostyrenes can also be obtained by nitration of p-nitrostyrenes[2]. 

Uses. (9-Nitrotoluene is used in the synthesis of intermediates for azo dyes, sulfur dyes, mbber chemicals, and agriculture chemicals. Typical intermediates are o-toluidine, o-nitrobenzaldehyde, 2-nitro-4-chlorotoluene, 2-nitro-6-chlorotoluene, 2-amino-4-chlorotoluene (Fast Scarlet TR Base), and 2-amino-6-chlorotoluene (Fast Red KB Base). -Nitrotoluene is used principally in the production of intermediates for azo and sulfur dyes. Typical intermediates are -toluidine, -nitrobenzaldehyde, and 4-nitro-2-chlorotoluene. 

The synthesis of benzo[6]thiophenes from o-nitrobenzaldehydes or o-nitrobenzonitriles and methyl thioglycollate can be viewed as an extension of the foregoing approach (Scheme 64) (72JOC3224). 

The first 1,2-benzisoxazole, 3-phenyl-l,2-benzisoxazole, was obtained from the treatment of o-bromobenzophenone oxime with alkali in 1892 (1892CB1498,1892CB3291). 2,1-Benzisoxazole has been known since 1882, being obtained as a reduction product of o-nitrobenzaldehyde with tin and hydrochloric acid (1882CB2105). In general, benzisoxazoles behave much like substituted isoxazoles. Numerous structural ambiguities occur in the early literature of these two systems, and these have been discussed in the above reviews. 

Aryl-l,2-benzisoxazoles can also be prepared by the reaction of o-nitrobenzaldehydes and an aromatic hydrocarbon catalyzed by sulfuric acid (67AHC(8)277). Cyclization of (576) by Zn/HOAc gave (577) sulfuric acid cyclization gave (578) and (579) (62JOC3683, 66DIS(B)102). 

BAEYER - DREWSON Indoxyl Synfhesis Conversion of o-nitrobenzaldehyde and ketones to indoxyls. 

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

An old and satisfactory method is the Riedel synthesis in which o-nitrobenzaldehyde is converted to its bisformaraido derivative followed by reductive cyclization with zinc and acetic acid, or with iron and hydrochloric acid. This synthesis has been used to make... 

Anthranilic acid, or o-amidobenzoic acid, C H (NH2)(COOH),. is the-acid constituent of the ester found in neroli, petit-grain, jasmin, and mandarin oils. It is a solid crystalline substance melting at 145°. It is prepared artificially, and then converted into synthetic methyl anthranilate.. To prepare anthranilic acid, o-nitrobenzaldehyde is reduced by tin and hydrochloric acid to anthranil,... 

Tench and Coppens (Ref 13) photolyzed o-nitrobenzaldehyde, nitrobenzene, and nitroben-zoic acid with light > 3500A. ESR measurements revealed the presence of radicals for o-nitrobenzaldehyde (in solns and powder), with no radicals observed with nitrobenzene and... 

Category 3. Intramolecular Rearrangement. Two examples are the rearrangement of the trimesityl compound (1) to the enol ether (2), " and irradiation of o-nitrobenzaldehydes (3) to give o-nitrosobenzoic acids (4)." ... 

Rates of photodegradation of copolymer films were measured in air using a filtered medium pressure Hg arc as the source of radiation and o-nitrobenzaldehyde as the actinometer. Table 1 gives the dosage levels incident on these films. 

B. o-Nitrobenzaldehyde. A suspension of 51.6 g. of the diacetate in a mixture of 500 g. (272 ml.) of concentrated hydrochloric acid, 450 ml. of water, and 80 ml. of alcohol is stirred and refluxed for 45 minutes. The mixture is then cooled to 0°, and the solid is filtered with suction and washed with water (Notes 6 and 7). The crude product is purified by rapid steam distillation through a 100-cm. Allihn condenser into a cooled receiver. About 3.5 1. of distillate is collected during 30 minutes the cooled distillate is filtered, and the o-nitrobenzaldehyde is dried in a desiccator over calcium chloride. It weighs 23.7 g. (74%) and melts at 44-45°. 

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. 

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