2-Nitroaniline, iodination

The removal of iodine from 2-iodo-4-nitroaniline in refluxing hydrochloric acid (ca. 100 °C), had a first-order rate coefficient of 4.7 x 10"5, and for 2-iodo-... 

Diiodo- -nitroaniline has.been made by the action of iodine chloride on a chloroform solution 1 and also on a glacial acetic acid solution 2 of />-nitroanilinc. 

Preparation of m-nitrophenol from m-nitroaniline 557 A cold mixture of water (450 ml and concentrated sulfuric acid (330 ml) is poured, with stirring, over finely powdered ra-nitro-aniline (210 g), and ice (800 g) is added. When the mixture has become homogeneous, a solution of sodium nitrite (105 g) in water (250 ml) is run in during 8-10 min from a dropping funnel until the starch-iodine reaction remains positive. The temperature is kept between 0° and 5° and the mixture is stirred for a further 5-10 min. Then the m-nitrobenzenediazonium sulfate is allowed to settle, the supernatant liquid is poured off and the solid washed, if necessary, with water by decantation in order to purify the salt filtration is necessary only when gross impurity is present. 

Hexakis(2,6-di-0-methyl)-a-CyD complexes with a small guest molecule, such as iodine and 1-propanol, crystallize with the cage-type packing structure [185]. Compared with the structure of the corresponding -CyD complex, the guest molecules in the both complexes are shifted to the secondary hydroxyl side from the center of the cavity. 3-Iodopropionic acid [186], m-nitroaniline [187], and acetonitrile [188] are also fully accommodated in the host cage . A 3-0 acetylated host, hexakis(2,6-di-0-methyl-3-0-acetyl)-a-CyD, was crystallized from butylacetate [189]. In spite of the disruption of intramolecular hydrogen bonds, the host molecule is in a round shape because of the inclusion of butylacetate. 

Note The sulfanilic acid can also be diazotized in situ on nitrite-impregnated TLC layers in this case the chromatograms are merely sprayed with sulfanilic acid solution (2<7o in 10 mol hydrochloric acid) [5]. Diazotized 4-nitroaniline can also be used in place of diazotized sulfanilic acid [3]. In the case of clotrimazole, the layer is first sprayed with alcoholic iodine solution to cleave the imidazole ring bound to the molecule, then with sodium carbonate solution and finally with diazotized sulfanilic acid [12]. 

Fluorene Glutaric anhydride Iodine Isobutyl stearate Isophthaloyl dichloride Lithium carbonate 2,6-Lutidine a-Methylbenzyl alcohol Methyl cyanoacetate 2-Methyl-4-nitroaniline... 

The anodic chlorination in some cases allows one to achieve better regioselec-tivities than chemical alternatives (p/o ratio of chlorotoluene in chlorination of toluene anodic 2.2, chemical alternative 0.5-1.0) [215]. Anodic oxidation of iodine in trimethyl orthoformate afforded a positive iodine species, which led to a more selective aromatic iodination than known methods [216]. Aryliodination is achieved in good yield, when an aryhodide is oxidized in HOAc, 25% AC2O, 5% H2SO4 in the presence of an arene [217, 218]. Alkyl nitroaromatic compounds, nitroaromatic ketones, and nitroanilines are prepared in good yields and regioselectivity by addition of the corresponding nucleophile to a nitroarene and subsequent anodic oxidation of the a-complex (Table 13, number 11) [219, 220]. 

Of the derivatives of p-phenylenediamine, the most effective are the N, N -di-alkyl derivatives, in which the alltyl possesses a branched hydrocarbon chain on the carbon closest to the nitrogen atom [235]. They are usually produced by reductive allq lation of p-nitroaniline, p-phenyl-enediamine, p-nitrodiphenylamine, p-nitrosodiphenylamine, or p-amino-diphenylamine with aldehydes and ketones [236-252] with hydrogen at a temperature of 100-250°C and a pressure from 5 to 200 atm in the presence of catalysts. Copper-chromium catalysts (mixtures of oxides of the metals chromium, copper, barium, etc.) [241, 242, 245-247, 249, 250], iodine in the presence of HCl, HBr, or HI [253, 254], Pt/C [245, 252], and Raney nickel [244] are most often used as the catalysts. 

Similar to hydrogen sulphide and sulphides, sulphur dioxide and sulphites can be determined by titration with iodine or by oxidation to sulphate followed by gravimetric determination as barium sulphate. Additionally a spectrophotometric method was developed based on the colour of p-nitroaniline which is discharged on acidification but is restored by adding formaldehyde and sulphur dioxide or sulphite. 

---