Center for Heterocyclic Compounds, Department of Chemistry, University of Florida, Gainesville, FL, USA
Box 42912, Indianapolis, Indiana, USA
PCT/EP96/03841 filed Sep. 2, The sulfur trioxide percentage does not have any real effect on the results. Fax: 3523929199, b
Fetching data from CrossRef. The process according to the present invention is preferably carried out in oleum having a sulfur trioxide concentration of 20 to 65%.
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Moreover, the 2,6-dichloropyridine nitration is achieved only with difficulty, so it is not surprising that, in general, a powerful nitrating agent is selected. The use of 20%-oleum is preferred for practical reasons. generation, Process for producing 2,6-dichloro-3-nitropyridine, <- Previous Patent (Continuous process f...). General knowledge of the field will enable the skilled person to select suitable substituents, e.g., alkyl, especially lower alkyl such as C1-6 alkyl, halo-alkyl, aralkyl, notably deactivated aralkyl such as nitrotoluenyl. If you are not the author of this article and you wish to reproduce material from
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Further background includes Japanese Patent Publication No. From 3-acetylpyridine the 1,2-dihydropyridine compound 8a is obtained from attack of the nucleophile in the 2-position. rmurugan@reillyind.com, c
It should be noted that this yield of 82.5% in the synthesis indicates the presence of virtually all of the theoretical amount of nitration product in the reaction mixture. Authors contributing to RSC publications (journal articles, books or book chapters)
For reproduction of material from all other RSC journals and books: For reproduction of material from all other RSC journals. It has been found that the nitration of pyridine-2,6-diamines, which is commonly performed in a mixture of nitric acid and concentrated sulfuric acid, will give a significantly higher yield (from about 50% up to more than 90%) if the reaction is carried out in a mixture of nitric acid and oleum, or by otherwise providing an inherently anhydrous medium. Theoretically, it is possible to start from less concentrated sulfuric acid and to add a larger quantity of sulfur trioxide, but in so far as free sulfur trioxide can be handled at all, it is preferred not to do so for practical reasons. If you are the author of this article you do not need to formally request permission
article provided that the correct acknowledgement is given with the reproduced material. The present application is a Continuation of Reaction of pyridine compounds in organic solvents with N2O5 gives the corresponding N-nitropyridinium nitrate. to access the full features of the site or access our, Instructions for using Copyright Clearance Center page. This is clear, for example, from the fact that with DAP it is a question of dinitration, while 2,6-dichloro-pyridine is subject only to mono-nitration reaction. If you are not the author of this article and you wish to reproduce material from
This then reacts with a regioselective migration of the NO2 group from the 1- to the 3-position. Information about reproducing material from RSC articles with different licences
Removal of various substituents by base hydrolysis is … Pouring out said reaction mixture containing a greater excess of ice gave a better yield still, 94%. If you are the author of this article you still need to obtain permission to reproduce
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80 °C whereas at lower temperatures nitration occurs in the benzene ring (Section 3.2.3.2.1). XX is the XXth reference in the list of references. The invention therefore has for its object to provide as economic process by which pyridine diamines can be nitrated with a good yield of neat product, without substantial by-products. By the term "pyridine-2,6-diamines" are meant 2,6-diaminopyridine (DAP) and derivative compounds with substitution in the pyridine ring of either or both amino groups and/or carbon atom no. The yield was 2,483 moles, 90.3% DADNP. On reaction of this with an aqueous solution of NaHSO3 unstable 1,2- and 1,4-dihydropyridine compounds are formed which react to give β-nitropyridine compounds. You do not have JavaScript enabled. You do not have JavaScript enabled. is available on our Permission Requests page. From pyridine itself compound 2 is obtained … abboud@chem.ufl.edu. to reproduce figures, diagrams etc. Conf. with the reproduced material.
Alternatively, use may be made of concentrated sulfuric acid with 20%- or 65%-oleum added thereto to obtain the desired fuming sulfuric acid concentration. Fetching data from CrossRef. do not need to formally request permission to reproduce material contained in this
The drawback to this process is that it gives a DADNP yield of not more than 50% of theory. All rights reserved. The favorable effect of this is that on conclusion of the nitration reaction the sulfuric acid is still virtually free of water. In the case of DAP this option is not at all obvious, given that the dinitration as such proceeds easily and the low yield cannot be explained just like that either. E-mail:
If so desired, instead of DAP itself there may be used in the process according to the present invention derivative compounds with substitution in the pyridine ring of either or both amino groups and/or carbon atom no. Please enable JavaScript
4 (C-4) with oleum-resistant substituents. Reproduced material should be attributed as follows: If the material has been adapted instead of reproduced from the original RSC publication
However, it cannot be derived from the background information that this specific mixture is capable of solving the above-described problem. contained in this article in third party publications
The nitration of DAP by having it react with a mixture of nitric acid and sulfuric acid is known from German Patent Publication No. RIGID ROD POLYMER BASED ON PYRIDOBISIMIDAZOLE. (1991). No. the whole article in a third party publication with the exception of reproduction
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Mononitration yields 5‐chloro‐3‐methoxy‐2‐nitro‐pyridine N ‐oxide while more drastic conditions give 3‐chloro‐5‐methoxy‐2,6‐dinitropyridine. If you are the author of this article you still need to obtain permission to reproduce
The reaction of the 1,2-dihydropyridine compounds have been studied. If you are the author of this article you do not need to formally request permission
The nitration reaction of Example 1 was performed in a 1-liter reactor at 1/3 scale (somewhat shorter times were needed because of the larger specific cooling area) using ice-water cooling. to access the full features of the site or access our. In this connection, the invention also relates to the nitration reaction of pyridine-2,6-diamines in which a pyridine-2,6-diamine is contacted with a nitrating agent in the form of a mixture of nitric acid and sulfuric acid, but where the presence of water is countered in a different fashion, e.g., by carrying out the reaction in an inherently anhydrous medium (i.e., a medium where the released water is trapped by a compound which is more strongly hygroscopic than the nitration product formed during the reaction), e.g., in the presence of polyphosphoric acid, diphosphorus pentoxide, acetic anhydride, and the like. The final concentration of the (fuming) sulfuric acid exceeds 100% and is preferably 104.5 to 114.5%. From pyridine itself compound 2 is obtained which reacts with ΔH‡ = 18(1) kcal mol–1 and ΔS
International Application No. This was confirmed with the aid of a comparable methanol filtrate: the precipitation with methanol of a sample of pure nitrated product (DADNP) in 100% sulfuric acid, collection of the solids at 10° C., and washing with water gave a yield of 83% of the product. It has been found that the nitration of pyridine-2,6-diamines, which is commonly performed in a mixture of nitric acid and concentrated sulfuric acid, will give a significantly higher yield (from about 50% up to more than 90%) if the reaction is carried out in a mixture of nitric acid and oleum, or by otherwise providing an inherently anhydrous medium. 4, 310,671 discloses the nitration of 2,6-dichloropyridine in oleum. Its rate of reaction is only marginally affected by the polarity of the reaction medium. 3,920,336. The preparation of 3‐chloro‐5‐methoxypyridine N ‐oxide and its nitration are reported. Privacy Policy Reaction of pyridine compounds in organic solvents with N 2 O 5 gives the corresponding N-nitropyridinium nitrate.