Bunnett, J. F.; Rauhut, Michael M.; Knutson, David; Bussell, Geo. E. published the artcile< The conditions, scope, and mechanism of the von Richter reaction>, Recommanded Product: 2,3-Dibromobenzoic acid, the main research area is .
Experiments with D compounds showed that in the reaction of p-O2NC6H4Cl (I) with alc. KCN to form m-ClC6H4CO2H (II), and in the transformation of PhNO2 to BzOH, H exchange with the solvent occurred. Efforts to isolate a nitrile intermediate have been unsuccessful, but it is shown that nitriles are hydrolyzed rapidly under the conditions of the reaction. Br2C6H3NO2 (III) having Br ortho to the NO2 group reacted poorly, but III with unflanked NO2 groups gave fair yields. A tarry, amorphous byproduct was shown to contain CO2H groups. The optimum conditions for the reaction have been defined and the mechanism is discussed. 2,6-Br2C6H3NH2 diazotized in 9.5M HCl below 0°, and the diazonium cobaltinitrite prepared and decomposed by the method of Hodgson and Marsden (C.A. 38, 2021.8) gave 22% 2,6-III m. 81-3°. m-BrC6H4NHAc nitrated by the method of Case and Sloviter (C.A. 32, 529.9), the resulting mixed products deacetylated by acid hydrolysis, the crude mixed anilines diazotized, and the diazonium salts treated with CuBr gave 2,4-III. 3,5-III, m. 105-6°, was prepared by the method of Shepherd (C.A. 41, 4465h). The nitration of p-C6H4Br2, m. 87°, gave 2,5-III, m. 81-3°. Heating 12.5 g. p-ClC6H4NH2.HCl and 10 g. 99.5% D2O 112 h. at 120° in a sealed tube (or 24 h. at 150°), neutralizing with 6M NaOH, diluting with about 40 cc. dioxane, adding the solution slowly with stirring to a previously prepared mixture of 43 cc. cold concentrated H2SO4 and 50 g. K2S2O8, stirring 1 h. with cooling, pouring onto 300 cc. crushed ice, neutralizing with saturated aqueous Na2CO3, filtering off the light yellow, flocculent material, letting the mixture stand, filtering off a 2nd crop after 1.5 h., dissolving the combined material in 200 cc. glacial AcOH, treating the solution with 200 cc. 30% H2O2, 200 cc. glacial AcOH, and 13 g. HNO3 (d. 1.42), heating the resulting green solution 45 min. on the steam bath, pouring it into 1500 cc. H2O, and recrystallizing the flocculent precipitate from EtOH yielded 6.2 g. D-labeled I (IV), m. 81.5-2.5°, containing 1.02 atoms D/mol. In another run the contents of the sealed tube treated with dilute HCl, diazotized, the diazonium cobaltinitride formed and decomposed in the usual manner, and the product steam distilled and recrystallized from EtOH gave 2.6 g. IV, m. 83-4°, containing 0.99 atom D/mol. B(OEt)3 (10.8 g.) and 5.0 g. D2O kept overnight, and the mixture distilled gave EtOD which was stored in sealed ampuls. A series of von Richter reactions [cf. Ber. 8, 1418(1875)] was carried out by the procedure described previously (C.A. 44, 9938c) with 4.0 g. p-BrC6H4NO2 (V) each under the following conditions (time in hrs., weight of KCN used in g., aqueous solvent, % conversion, and % recovered V given). At 150° in a sealed tube: 1, 2.6, 25 cc. 50% MeOH, 12.5, 55; 1, 10.4, 25 cc. 50% MeOH, 21, 0; 1, 2.6, 25 cc. 48% EtOH, 22, 35; 1, 2.6, 25 cc. 50% PrOH, 11, 55; 1, 2.6, 25 cc. 50% iso-PrOH, 10, 72; 1, 2.6, 25 cc. 50% BuOH, 2.5, 85. At reflux temperature: 48, 8.1, 34 cc. 48% EtOH, 37, 0; 1.5, 15.0, 50 g. 95% pinacol, 1.5, 60; 2.5, 15.0, 75 cc. (HOCH2CH2)2O, 2.5, 0; 2.5, 15.0, 30 cc. 99% BuC(OH)Me2, 0, 65; 2.5, 15.0, 98% AmC(OH)MeBu, 0, 70. PhNO2 (2.5 g.) in 25 cc. 75% aqueous pyridine heated with 2.6 g. KCN 1 h. in a sealed tube at 150° gave only 96% recovered PhNO2. In a similar run in 25 cc. 80% dioxane with 5.0 g. KCN in a sealed tube during 2 h. at 160°, 88% PhNO2 was recovered. PhNO2 (2.5 g.) and 5.0 g. KCN in 25 cc. 48% aqueous EtOH heated 1.5 h. in a sealed tube at 160° yielded 10% BzOH and 12% recovered PhNO2. A series of similar runs was carried out with I (time, weight of I used in g., weight of KCN, aqueous solvent, % conversion, and % recovered I given): Sealed tube at 150°: 50 min. 2.5, 5.0, 25 cc. 48% EtOH, 38, 0. Reflux: 48 h. 3.15, 200.0, 600 cc. 48% EtOH, 42, 0; 18 h. 3.15, 10.3, 75 cc. 48% EtOH, 20, 19; 48 h., 3.15, 20.0, 75 cc. 95% EtOH, 14, 33; 48 h., 3.00, 6.45, 26 cc. 48% EtOH, 40, 0; 48 h., 3.15, 20, 75 cc. 50% MeOH, 20, 0; 48 h., 3.15, 20, 75 cc. 33% MeOH, 15, 6; 48, 3.15, 20, 75 cc. 50% iso-PrOH, 9, 47; 20 h., 3.15, 10.3, 90 cc. 53% EtOH and 22% C6H6, 0, 61; 45 h., 3.15, 20, 75 cc. 50% MeCN, 0, -. Sealed tube at 150°: 1 h., 3.15, 2.6, 75 cc. 50% glycerol-25% EtOH, 0, 79; 1 h., 3.15, 2.6, 75 cc. 50% dioxane, 7, 56. A number of aromatic nitro compounds was submitted to the von Richter reaction; the nitro compound used, the products obtained, % conversion, and % recovered starting material are given for the following reactions in a sealed tube: p-O2NC6H4I, m-IC6H4CO2H (m. 182-3°), 40, 0; 3,5-Cl2C6H3NO2 (m. 63.8-4.2°), 2,4-Cl2C6H3CO2H (m. 158.5-9.5°), 30, 0; m-O2NC6H4F, no acid, 0, 74; p-O2NC6H4F (m. 57-9°), no acid, 0, 14 (the recovered starting material was converted to p-FC6H4CONHPh, m. 182-4°, for identification); p-C6H4(NO2)2, no acid, 0, 6; 2,3-III (m. 85°), 3,4-Br2C6H3CO2H (m. 225-7°), 1, 0 (at reflux); 3,4-III (m. 56-8°), 2,3-Br2C6H3CO2H (m. 144-8°), 16, 0; 2,6-III, no acid, 0, 93; 2,4-III, 3,5-Br2C6H3CO2H (m. 219-20°), 2, 0 (amide, m. 184-6°) (reflux); 3,5-III, 2,4-Br2C6H3CO2H (m. 163-9°), 18, 32 (amide, m. 195-6°); 2,5-III, 2,5-Br2C6H3CO2H (m. 151-3°), 7, 23; 2-O2NC6H4Br, m-BrC6H4CO2H (m. 151-3°), 2, 44 (reflux). PhNO heated 1 h. at 155° with 2.6 g. KCN in 25 cc. 48% EtOH yielded 0.3 g. (PhN:)2, m. 65-6°, which was reduced with Sn and HCl to benzidine, m. 117-20°; in similar runs in 75% dioxane, azoxybenzene, m. 29-31°, was obtained. PhNO2 (5.0 g.), 5.0 g. anhydrous KCN, 5 cc. EtOD, and 5 cc. D2O heated 1 h. in a sealed tube at 150-60° gave 3 g. PhNO2 and 0.380 g. BzOH, m. 120.5-21° (from H2O); the BzOH obtained contained, after equilibration of its CO2H H atoms with H2O, 0.72 atom D/mol. The recovered PhNO2 was nearly D-free. Thus, H atoms from the solvent do become attached to aromatic C during the von Richter reaction. IV (2.2 g.) (containing 1.02 atom D/mol.), 5 g. KCN, and 30 cc. 48% EtOH heated 75 min. at 160-70° in a sealed tube gave II containing 0.42 atom D/mol. IV (containing 0.99 atom D/mol.) gave similarly II containing 0.38 atom D/mol.
Journal of the American Chemical Society published new progress about Intermediates. 603-78-1 belongs to class bromides-buliding-blocks, and the molecular formula is C7H4Br2O2, Recommanded Product: 2,3-Dibromobenzoic acid.
Referemce:
Bromide – Wikipedia,
bromide – Wiktionary