Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C201/00—Preparation of esters of nitric or nitrous acid or of compounds containing nitro or nitroso groups bound to a carbon skeleton
  • C07C201/06—Preparation of nitro compounds
  • C07C201/08—Preparation of nitro compounds by substitution of hydrogen atoms by nitro groups

Definitions

• the invention relates to the production of a dinitronaphthalene isomer mixture with an increased proportion of 1,5-dinitronaphthalene (hereinafter called 1,5-DNN) by the nitration of pure 1-nitronaphthalene or a raw nitronaphthalene mixture.
• 1,5-dinitronaphthalene is a key compound for the production of the 1,5-diammonaphthalene (hereinafter called 1,5-NDA).
• 1,5-NDA 1,5-diammonaphthalene
• Desmodur 15® The 1,5-NDI is used as an isocyanate component in polyurethanes.
• nitrated aromatics has long been known (G.A. Olah et al., Nitration: Methods and Mechanism, VCH, New York, 1989).
• Corresponding nitroaromatics have been produced industrially for decades by nitration with a mixture of sulfuric and nitric acid (so-called mixed or nitrating acid).
• mixed or nitrating acid a mixture of sulfuric and nitric acid
• Multiple nitriding, for example dinitriding is usually carried out on an industrial scale today using a two-stage nitriding (Kirk-Othmer; Encyclopedia of Chemical Technology, 1981, Vol. 15 and Ulimann; Encyclopedia of
• naphthalene Houben-Weyl; Methods of Organic Chemistry, 1971, Vol. 10, pages 492-495
• naphthalene provides a mixture of isomers of 1 -nitronaphthalene and 2-nitronaphthalene in a ratio of about 95: 5.
• the nitration of the isomerically pure 1-nitronaphthalene with a mixture of sulfuric and nitric acid produces a mixture of 1,5- and 1,8-dinitronaphthalene in a ratio of about 1: 2 in addition to about 5% of the other isomers (e.g. 1, 6- and 1.7-DNN).
• the unfavorable selectivity of the reaction preferably leads to a high and undesirable proportion of 1,8-DNN in the production of the 1,5-DNN.
• DE-A 11 50 965 describes the increase in selectivity through rapid and intensive mixing of the 1-nitronaphthalene dissolved in sulfuric acid with nitrating acid.
• the disadvantage of this process is the considerable amount of sulfuric acid which is used as a solvent and whose workup is very complex and cost-intensive.
• considerable amounts of trinitrated products can arise in this process, which both significantly reduce the 1.5-DNN yield and are also critical from a safety point of view; in particular in the adiabatic reaction described in the prior art mentioned.
• WO 94/19310 describes nitrations of nitroaromatics on aluminum silicates, sometimes known as clay cops, doped with heavy metals, so-called clay cops, which provide high yields of dinitrated products with small amounts of trititroaromatics.
• nitrations of 1 -nitronaphthalene carried out using this process provide isomer ratios as in classic nitrations with mixed acid.
• Nitrations with nitric acid in organic solvents e.g. Dichloroethane and azeotropic removal of the water of reaction are described in DE-A 24 53 529. They provide dinitronaphthalene in high yields without affecting the isomer ratio.
• the object was therefore to find a process for the preparation of a dinitronaphthalene isomer mixture with a high proportion of 1,5-dinitronaphthalene by nitration of 1 -nitronaphthalene, in which it is not necessary to use mixed or nitrating acid which is difficult to work up.
• the invention thus relates to a process for the preparation of a dinitronaphthalene isomer mixture by nitration of nitronaphthalene, in which nitronaphthalene, if appropriate in an inert organic solvent with 1 to 20 times the equivalent amount, based on nitronaphthalene, of 50 to 100% nitric acid in the presence of a solid, perfluorinated, strongly acidic ion exchanger.
• the 1-20 times the equivalent amount corresponds to 33% by weight to 92% by weight, based on the solution, for a 65% nitric acid, and 26% for a 100% nitric acid. % to 88% by weight
• the DNN isomer mixtures produced according to the invention contain a surprisingly high proportion of the 1,5-DNN isomer.
• the 1,5-DNN content is usually above 30% by weight, in particular between 34 and 50% by weight.
• the content of other by-products, in particular other dinitronaphthalene isomers and highly intruded products is lower than in comparable nitrations with mixed acid
• Pure 1 -nitronaphthalene or a crude nitronaphthalene mixture, such as is obtained as a crude product in the nitration of naphthalene, can be used as the starting product
• the fixed perfluorinated strongly acidic ion exchangers catalyzes the conversion to 1,5 -Dinitronaphthalin enriched final product perfluorinated
• strongly acidic ion exchangers are known in the art and, for example, under the trade names Nafion ® is commercially obtainable
• an ion exchange resin under the name Nafion ® NR50 Superacid Catalyst (Dupont) used
• the ion exchanger used as a catalyst is chemically inert and can easily be removed from the reaction mixture, e.g. by filtration.
• Working up as in the case of the diluted and organically contaminated sulfuric acid resulting from nitrations with mixed acid (nitric acid / sulfuric acid mixture) is omitted in the process according to the invention in advantageously
• the concentration of nitric acid is between 50% and 100%, preferably between 60% and 80%.
• the amount of nitric acid added is between 1 equivalent and 20 equivalents based on the amount of nitronaphthalene used. In the case of 65% nitric acid, this corresponds to 33 to 92% by weight.
• Amounts of nitric acid between 3 equivalents (for 65% nitric acid: 62.7% by weight) and 12 equivalents (corresponding to 87.0% by weight 65% nitric acid) are preferably used.
• the process is usually carried out at temperatures between 20 ° C. and 100 ° C., preferably 80 ° C.
• reaction is carried out with thorough mixing of the reaction e.g. by intensive stirring for a reaction time between 20 minutes and 8 hours, e.g. 3 hours.
• the process according to the invention can be carried out without further solvent only in an excess of nitric acid or, if appropriate, also after adding a solvent.
• the 1,5 selectivity can surprisingly be increased even further in the presence of an inert organic solvent.
• the process according to the invention is therefore preferably carried out in the presence of an inert organic solvent.
• solvents are polar compounds which are inert in the reaction medium. Examples of such solvents are e.g. Sulfolane or nitroalkanes such as nitromethane.
• the process according to the invention is preferably carried out in the presence of sulfolane as the organic solvent. Unreacted nitronaphthalene, excess nitric acid and solvent can be returned to the process.
• the amount of organic solvent added is between OJ and 20 parts, based on the amount of nitronaphthalene used, preferably between 0.5 and 3 parts.
• the concentration of the nitric acid is adjusted to the amount of solvent added and is between 50% and 100%, preferably 60-80%.
• the "dinitronaphthalene isomer mixture can be separated by fractionated crystallization in the isomeric dinitronaphthalenes in a known manner, for example.
• the invention further relates to isomer mixtures containing 1,5- and 1,8-dinitronaphthalene and containing 1,5-dinitronaphthalene in excess of 30% by weight, in particular between 34 and 50% by weight.
• dinitronaphthalene isomer mixtures are preferably obtainable by the process according to the invention described above.
• the 1,5-DNN can be separated off from the isomer mixture according to the invention in a known manner and used to prepare 1,5-NDA and 1,5-NDI.
• NR 50 Superacid Catalyst (Fa DuPont) is only briefly called Nafion in the following examples
• the isomer composition of the residue was determined by gas chromatography (HP 5890, column 25 m SE30, injector 300 ° C, detector (FID) 320 ° C, temperature program start 100 ° C, heating rate 10 ° C / min,
• Table 1 shows the experimentally determined isomer compositions. Nitrion nitriding results in a higher 1,5-yield and an improved (1,5) / (1,8) -DNN ratio. This corresponds to a corresponding increase in the 1.5 selectivity in the nitration.
• Table 1 Composition of the product mixture during the nitration of 1 -nitronaphthalene with nitric acid (Examples 1J to 1.4); the equivalents of nitrating agent, the concentration of the nitric acid used and the reaction temperature are indicated.
• Table 2 shows the experimentally determined isomer compositions. When the solvent is added, higher ratios (1.5) / (1.8) -DNN result. This corresponds to a corresponding increase in the 1.5 selectivity in the nitration.
• Table 2 Composition of the product mixture during the nitration of 1 -nitronaphthalene with nitric acid and addition of a solvent (Examples 2J to 2.2); the equivalents of nitrating agent, the concentration of the nitric acid used and the reaction temperature are indicated.

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• 1997
  • 1997-09-08 DE DE19739202A patent/DE19739202C1/de not_active Expired - Lifetime
• 1998
  • 1998-08-26 WO PCT/EP1998/005408 patent/WO1999012887A1/de not_active Ceased
  • 1998-08-26 JP JP2000510700A patent/JP4283990B2/ja not_active Expired - Fee Related
  • 1998-08-26 DE DE59812746T patent/DE59812746D1/de not_active Expired - Lifetime
  • 1998-08-26 AU AU93470/98A patent/AU9347098A/en not_active Abandoned
  • 1998-08-26 US US09/486,686 patent/US6242656B1/en not_active Expired - Lifetime
  • 1998-08-26 EP EP98946431A patent/EP1015414B1/de not_active Expired - Lifetime
  • 1998-08-26 ES ES98946431T patent/ES2241165T3/es not_active Expired - Lifetime

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