Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C209/00—Preparation of compounds containing amino groups bound to a carbon skeleton
  • C07C209/02—Preparation of compounds containing amino groups bound to a carbon skeleton by substitution of hydrogen atoms by amino groups
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C209/00—Preparation of compounds containing amino groups bound to a carbon skeleton
  • C07C209/30—Preparation of compounds containing amino groups bound to a carbon skeleton by reduction of nitrogen-to-oxygen or nitrogen-to-nitrogen bonds
  • C07C209/32—Preparation of compounds containing amino groups bound to a carbon skeleton by reduction of nitrogen-to-oxygen or nitrogen-to-nitrogen bonds by reduction of nitro groups
  • C07C209/36—Preparation of compounds containing amino groups bound to a carbon skeleton by reduction of nitrogen-to-oxygen or nitrogen-to-nitrogen bonds by reduction of nitro groups by reduction of nitro groups bound to carbon atoms of six-membered aromatic rings in presence of hydrogen-containing gases and a catalyst
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C209/00—Preparation of compounds containing amino groups bound to a carbon skeleton
  • C07C209/30—Preparation of compounds containing amino groups bound to a carbon skeleton by reduction of nitrogen-to-oxygen or nitrogen-to-nitrogen bonds
  • C07C209/38—Preparation of compounds containing amino groups bound to a carbon skeleton by reduction of nitrogen-to-oxygen or nitrogen-to-nitrogen bonds by reduction of nitroso groups

Definitions

• the invention relates to a process for the preparation of 4-aminodiphenylamine (4-ADFA) precursors, 4-nitrosodiphenylamine and/or 4-nitrodiphenylamine and/or salts thereof, wherein aniline with nitrobenzene reacts in a liquid medium with a base to obtain 4-ADFA precursors, i.e. 4-nitrosodiphenylamine (4-NODFA), 4-nitrodiphenylamine (4-N0 2 DFA) and/or salts thereof, providing 4-ADFA following the hydrogenation.
• 4-ADFA precursors i.e. 4-nitrosodiphenylamine (4-NODFA
• 4-nitrodiphenylamine (4-N0 2 DFA) and/or salts thereof providing 4-ADFA following the hydrogenation.
• 4-Aminodiphenylamines (4-ADFA) can be prepared by various methods, for example by reacting 4-chloronitrobenzene with aniline followed by hydrogenation, by nitrosation of diphenylamine to N-nitrosodiphenylamine and after rearrangement to 4- nitrosodiphenylamine by hydrogenation.
• 4-ADFA intermediates from both ecological and economical point of view are based on direct reaction of aniline with nitrobenzene.
• the reaction is initiated by bases, forming an anilide anion by reaction with aniline, which anilide anion subsequently substitutes the hydrogen in nitrobenzene by nucleophilic substitution [A; Wohl et al.: Ber. 34, 2442-2450 (1901) and A. Wohl: Ber. 36, 4135-4138 (1903)], wherein the use of solid potassium hydroxide as a base leads mainly to phenazine and phenazinoxide, and the use of sodium hydroxide leads also to 4-NODFA.
• U.S. Patent No. 5,420,354 discloses the reaction of nitrobenzene with aniline in the presence of hydrogen, a hydrogenation catalyst, an acid co-catalyst and a hydrogenation inhibitor, providing directly 4-ADFA, but in relatively low yields (max. 12%) and at low selectivity of reaction, like in other processes already mentioned above.
• 4-ADFA halogen-free process for the preparation of 4-ADFA is based on the reaction of aniline with 4-(phenylazo)diphenylamine in the presence of strong bases, such as potassium t-butoxid with crown ethers or quaternary ammonium hydroxides [U.S. Patent Nos. 5,382,691, 5,633,407, 5,618,979 and 5,451,702].
• strong bases such as potassium t-butoxid with crown ethers or quaternary ammonium hydroxides
• the subsequent conversion of 4- FADFA to 4-ADFA can be carried out either by catalytic hydrogenation according to U.S. Patent No. 5,451,702] or by nucleophilic substitution reaction of 4-FADFA with an amine in the presence of strong bases [U.S. Patent Nos. 5,382,691, 5,633,407 and 5,618,979].
• 4- ADFA can also be prepared [see U.S. Patent Nos. 5,618,979 and 5,633,407, and a publication by M.K. Stem at al.: J. Org. Chem. 59, 5627-5632 (1994)] in one step directly by reaction of azobenzene or azoxybenzene with aniline in the presence of strong basic catalysts.
• azobenzene is used as a starting material, which is a technically more hardly available material and, moreover, it is necessary to prepare it in advance.
• there is a lot of waste which must be either further processed or disposed of.
• reaction products could be obtained with high yields and with high selectivity only when using quaternary ammonium hydroxides.
• the mechanism of the reaction is known [M.K. Stem et al. in J. Am. Chem. Soc. 114, 9237-9238 (1992), and New J. Chem. 20, 259-268 (1996)].
• the process for the preparation of 4-aminodiphenylamine precursors by the reaction of aniline and nitrobenzene in the presence of water and a base with controlled amount of water with respect to the base according to the invention is based on the fact that the reaction is carried out in the mole ratio of water to the dosed base, obtained after extraction of organic impurities by an aromatic solvent of an aqueous phase from hydrogenation of a condensation mixture, between 3.99 and 3:1 at the start of the coupling reaction, and between 0.40 and 0.59:1 at the end of the coupling reaction (the range of water:TMAH mole ratios), thus providing 4-nitrodiphenylamine and/or 4-nitrosodiphenylamine and/or salts thereof.
• the water.TMAH mole ratios are determined by taking the samples and their analysing. The end of the reaction is indicated by full conversion of nitrobenzene or by achieving the maximum content 2 wt. % of the initial amount of nitrobenzene in the reaction mixture.
• the prepared 4-nitrosodiphenylamine (4- NODFA), 4-nitrodiphenylamine (4-N0 2 DFA) and/or salts thereof provide 4-ADFA.
• the mole ratio of aniline to nitrobenzene is preferably between 1 : 1 and 10:1, and the mole ratio of the base to nitrobenzene is between 0.7:1 and 4:1.
• Hydrogenation of the condensation product in the presence of the hydrogenation catalyst and added water is followed by separation of the hydrogenation catalyst, separation of phases into an organic phase, containing 4-aminodiphenylamine, and an aqueous phase, containing the released base.
• the aqueous phase is extracted by an aromatic solvent in order to remove 4-ADFA, aniline, azobenzene and phenazine, and this purified recycling aqueous phase can be used again in the condensation as a base after the extraction by an aromatic solvent for removing organic impurities and after supplementing the losses caused due to handling and due to base decomposition.
• tetramethylammonium hydroxide is used as a base, and toluene, ethylbenzene, aniline, nitrobenzene or mixtures thereof are used as an aromatic solvent.
• the present process for the preparation of 4-aminodiphenylamine (ADPA) precursors of the invention is advantageous particularly due to its economical attractiveness. More specifically, in its first embodiment the invention provides a process, in which the base and aniline are recycled in a way that demonstrates its economical advantageousness. It has been found out that the base and aniline can be recycled with a minimal loss of reactivity for the condensation of aniline with nitrobenzene by an appropriate controlling of impurity levels in the recycled flows. Furthermore, it has been found out that the undesired amounts of 4-ADFA from the base containing recycling aqueous phase, that get into the aqueous phase during separation of the aqueous and the organic phase after the hydrogenation, can be removed by an extraction with toluene.
• TMAH tetramethylammonium hydroxide
• the condensation reaction mixture from the previous step was added with water for dilution (in the amount corresponding to 30 wt. % of the initial condensation mixture) together with 0.6 g of commercially available dry 3% Pd/C catalyst. Then the mixture was hydrogenated in the 3.75 1 autoclave at the temperature between 65 and 80°C and the hydrogen pressure of 4 MPa. The hydrogenation reaction was stopped, when the monitored hydrogen uptake was virtually nil.
• the HPLC analysis data on intermediates and final products were used to calculate the nitrobenzene selectivity (i.e. (NODPA+NDPA moles)formed/(nitrobenzene moles)con verted).
• the hydrogenated condensation mixture was separated into an aqueous and an organic phase .
• the aqueous phase was treated by extraction with toluene (optionally ethylbenzene or xylene).
• the extraction removed 4-aminodiphenylamine present in water.
• This treated aqueous phase was returned back to carry out further condensation reaction.
• the amount of TMAH required for another reaction was supplemented to reach the original initial amount of TMAH.
• An acid-base titration method was used to determine the concentration of TMAH in the aqueous solution.
• the regenerated aniline was returned back to the subsequent reaction.
• the regeneration of aniline was carried out either by separation of the fore-runs or by returning the aniline with the fore-run into another cycle of condensation and hydrogenation.
• This example illustrates a possibility to prepare 4-nitroso- and 4-nitrodiphenylamine under the conditions of water/TMAH mole ratio lower than 0.6 in the end of the condensation reaction, also with the time period for finishing the reaction within 3 hours.
• the reaction was carried out according to Example 1, except that after adding nitrobenzene to the reaction, the operating pressure was reduced from 7.0 kPa to 2.6 kPa and a temperature of the reaction mixture was maintained at 75°C. In this way the water content of 1.15% (water/TMAH mole ratio of 0.4) was reached in the condensation mixture after 2 hours of the finishing period.
• the total selectivity of precursors to NB in the condensation was 94.1%.
• the total yield of 4-ADFA after hydrogenation of the condensation mixture was 93.4%.
• This example illustrates the preparation of 4-nitroso-/4-nitrodiphenylamine by a continuous process in a stirred-flow reactor.
• the first member was loaded with a starting condensation mixture of a composition shown in Table 3.
• a temperature of the reaction mixture was adjusted to 72°C at the pressure of 7.0 kPa.
• This condensation mixture was added with nitrobenzene at a volume rate of 0.717 ⁇ 0.008 ml/min, and the mixture of aniline/TMAH, containing 14.22 wt. % of TMAH, was added simultaneously at a volume rate of 5.0 ⁇ 0.05 ml/min.
• the aniline/TMAH mixture was tempered to 70°C.
• the mole ratio of the incoming TMAH/NB was 1.1.
• the condensation mixture from the first flow reactor flowed to the second reactor, where the conditions of pressure and temperature were identical to those in the first member of the boiler system. After separation of the condensate, the aniline distilled with water returned to the first reactor.
• a process for the preparation of 4-aminodiphenylamine precursors according to the present invention can be used in industry in the production of antioxidants.

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• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

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