Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
2003-02-28
2004-05-18
Parsa, J. (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C568S928000, C568S930000, C564S415000, C560S359000
Reexamination Certificate
active
06737554
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to the production of a dinitronaphthalene isomer mixture with a high proportion of 1,5-dinitronaphthalene by the nitration of naphthalene, 1-nitronaphthalene or a crude nitronaphthalene mixture. 1,5-Dinitronaphthalene is a key compound for the production of 1,5-diaminonaphthalene. This is, among other things, useful as the starting compound for the production of 1,5-diisocyanatonaphthalene (trade name: Desmodur® 15). 1,5-Diisocyanatonaphthalene is used as an isocyanate component in polyurethane production.
The production of nitrated aromatics has been known for a long time (G. A. Olah et al., Nitration: Methods and Mechanisms, VCH, New York, 1989). For decades, corresponding nitroaromatics have been produced industrially by nitration with a mixture of sulfuric and nitric acids (so-called mixed or nitrating acid).
The mononitration of naphthalene yields an isomer mixture of 1-nitronaphthalene and 2-nitronaphthalene in a ratio of about 95:5. The direct dinitration of naphthalene, as well as the further nitration of 1-nitronaphthalene, produces 1,5-dinitronaphthalene and 1,8-dinitronaphthalene in a ratio of about 1:2 (Houben-Weyl: Methoden der Organischen Chemie, 4
th
edition, 1971, vol. X/1, pp. 492-495). Other dinitronaphthalene isomers are also formed to a lesser extent (about 5%), e.g., 1,6- and 1,7-dinitronaphthalene. The unfavorable selectivity of the reactions means that, in the production of 1,5-dinitronaphthalene, a high and undesirable proportion of 1,8-dinitronaphthalene is preferentially formed.
In DE-OS-11 50 965, the production of dinitronaphthalenes starting from 1-nitronaphthalene is described. An increase in selectivity in favor of the desired 1,5-dinitronaphthalene is achieved by rapid and intensive mixing of the 1-nitronaphthalene dissolved in sulfuric acid with nitrating acid. A disadvantage of this process is the considerable quantity of sulfuric acid and its complex and cost-intensive reprocessing. In addition, considerable quantities of trinitrated products can be formed in this process. Such trinitrated products clearly reduce the yield of 1,5-dinitronaphthalene and are to be regarded as significant from a safety point of view, particularly with the adiabatic reaction described in the above prior art.
In WO-99/12886, a process for the production of a dinitronaphthalene isomer mixture with a high proportion of 1,5-dinitronaphthalene from nitronaphthalene is described. Here, the reaction of the nitronaphthalene with nitric acid takes place in a nitroalkane or sulfolane as solvent. In this process, however, product mixtures are obtained which still contain considerable proportions of the unreacted educt 1-nitronaphthalene. Another disadvantage lies in the low yields of 1,5-dinitronaphthalene, which is only contained in the product mixtures at a maximum of 28.3%.
WO-99/12887 also discloses a process in which nitronaphthalene is used to produce a dinitronaphthalene isomer mixture with a high proportion of 1,5-dinitronaphthalene. Here, the reaction of the nitronaphthalene with nitric acid takes place in the presence of a solid, perfluorinated, strongly acidic ion exchanger. In general, this process has the disadvantage that the resulting dinitronaphthalene isomer mixture has to be separated off from the catalyst by extraction with dioxane at 90° C. The dioxane then has to be removed by an additional distillation step. Another disadvantage of the process lies in the fact that, to achieve high conversions of the educt 1-nitronaphthalene, the nitric acid has to be added in a large excess (6 to 8 equivalents). The fact that the product mixtures with a relatively high proportion (>30%) of 1,5-dinitronaphthalene always contain still higher proportions of 1,8-dinitronaphthalene is also disadvantageous.
DE-OS-24 53 529 describes the production of dinitronaphthalenes by nitration of naphthalene or 1-nitronaphthalene with nitric acid in an organic solvent, e.g., dichloroethane, with the azeotropic removal of the water of reaction. This process yields dinitronaphthalene in high yields, but without influencing the isomer ratio.
WO-94/19310 describes nitration of aromatics on aluminum silicates partially doped with heavy metals, so-called “claycops”, as solid catalysts. The nitration of naphthalene carried out by this process gives dinitronaphthalene in a high yield, but with an isomer ratio like that of classic nitrations with mixed acid.
In DE-A1-199 58 389, a process for the production of a dinitronaphthalene isomer mixture with an increased proportion of 1,5-dinitronaphthalene is described. In this process, naphthalene is reacted with nitric acid in the presence of at least one ionic liquid. However, these ionic liquids are very expensive and therefore unsuitable for use on an industrial scale. Another disadvantage of the process lies in the fact that very high excesses of nitric acid (8 to 22 equivalents per nitro group to be introduced) are used. Furthermore, the isomer proportion of the undesired 1,8-dinitronaphthalene, at 50 to 53%, is always clearly higher than that of 1,5-dinitronaphthalene (36.5 to 39%).
SUMMARY OF THE INVENTION
The object of the present invention is therefore to provide a simple and economic process for the production of a dinitronaphthalene isomer mixture by which a mixture of dinitronaphthalenes can be obtained in high yields and with a large proportion of 1,5-dinitronaphthalene.
It has been found that, when a zeolite is used as the catalyst in the nitration of naphthalene and/or 1-nitronaphthalene with nitric acid, a shift of the isomer ratio towards 1,5-dinitronaphthalene is possible.
DETAILED DESCRIPTION OF THE INVENTION
The invention provides a process for the production of a dinitronaphthalene isomer mixture, in which naphthalene and/or 1-nitronaphthalene is reacted with nitric acid in the presence of a zeolite.
The dinitronaphthalene isomer mixtures produced according to the invention contain a surprisingly high proportion of 1,5-dinitronaphthalene. The proportion of 1,5-dinitronaphthalene that can be achieved in the process is about 60 wt. %, based on the mixture of 1,5-dinitronaphthalene and 1,8-dinitronaphthalene. The content of other by-products, particularly other dinitronaphthalene isomers and products with a higher degree of nitration, is small.
In the process, naphthalene, pure 1-nitronaphthalene or else a crude nitronaphthalene mixture, as is obtained as a crude product in the mononitration of naphthalene, can be used as the starting product.
The process according to the invention is carried out in the presence of at least one zeolite. Mixtures of different zeolites can also be used.
In terms of their basic structure, zeolites are crystalline aluminosilicates, which are built up from a network of SiO
4
and AlO
4
tetrahedrons. The individual tetrahedrons are linked together with oxygen bridges at the vertices and form a spatial networks which is uniformly traversed by channels and cavities. As compensation for the negative charge of the lattice, exchangeable cations are included. Aluminum can be partially replaced by other elements, such as B, Ga, In, Fe, Cr, V, As, Sb or Be. In addition, silicon can be replaced by other tetravalent elements, such as Ge, Ti, Zr or Hf. The zeolites can additionally contain e.g. H, NH
4
, Li, Na, K, Mg, Ca, Cu, Zn, rare earth metals, Ti, Zr, Sn(IV), Cr(III), Fe(II), Mn(II), Co or Ni as exchangeable cations.
Zeolites of the structure types MFI, MOR, BEA, FAU, MEL, EMT, MTW, LTL, MWW, RHO, FER or HEU (according to the structural classification from W. M. Meier, D. H. Olson, Ch. Baerlocher, Atlas of Zeolite Structure Types, 4
th
Edition, Elsevier, London, 1996) are preferably used in the acidic H
+
form. Individually, the zeolites H-beta, H—Y, H-mordenite and H-ZSM-5 are particularly suitable. Zeolites of the H—Y type are particularly preferably used.
Zeolites in the acidic H
+
form and their production are described in detail in the literature (R. Szostak, Handbook of Molecular Sieves, Van Nostrand Reinhold, New York, 1992).
The zeo
Brandt Matthias
Klein Stephan
Wegener Gerhard
Gil Joseph C.
Parsa J.
Whalen Lyndanne M.
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