By reacting α-substituted pyridines with sodium amide in inert solvents, 2-Amino-6-alkyl pyridines can be generated in the Tschitschibabin process. Because sodium amide is used, it is important to be careful that water is absolutely excluded when this is done.
This, however, requires substantial security measures expenditure. Another downside of the reaction is that inert conditions which are correlated with the additional expense, the sodium hydride produced must also be destroyed. Opt 2-Amino-6-methylpyridine.
In the presence of cobalt-containing catalysts, the reaction of α-picoline and ammonia according to Japanese patent Application No. 54/95 576 (1979) produces 2-amino-6-methylpyridine. However, this reaction only produces very small quantities of 2-amino-6-methylpyridine.
In addition, α-amino-pyridines are known from the German Offenlegungsschrift 2,032,403 to be prepared by reaction of corresponding hydroxy compounds with ammonia. For 2-amino-6-methylpyridine, only a 27 percent yield is added to the amination stage and in addition, the starting agents of an α-alkyl axy-hydroxypyridine are not readily available.
Moreover, European brevet specification No. 0,082,613 states that aniline can be reordered into α-picoline over the zeolites of ZSM-5 at 510°C. Selectivities of just 32,6 to 56,6% are achieved with α-picoline also for aniline conversions of just 8,3 to 27,7 percent. In addition, toluidines, xylidines, diphenylamine, indoles, and quinolines, other compounds that contain nitrogen are formed abundantly.
Catalytically isomerized at high temperatures
Alkyl radicals are those with 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms (methyl, ethyl, n-propyl, Iso-propyl, n-butyl, tert-butyl, n-pentyl, iso-pentyl, tert-Pentyl, hexyl radical), preferably methyl, ethyl, n-propyl, and iso-propyl radicals. Radically speaking, they can be alkyl atomic.
A cycloalkyl-radical, preferably cyclohexyl-radical radical; anarchy-radical, preferably those with 7 to 12 carbon atoms; preferably 7 to 9 carbon-based atoms such as benzyl- and methylbenzyl-radical; and an aryl-benzyl radical, are the preferential radicals for cyclo-cyclohexyl; (and, if any, aryl-benzyl-radical);
Examples are 1,3-diaminobenzene, 2,6-diamino toluene, 2,4-diamino toluene, and 3,5-diaminobenzene, preferably 1,3-diaminobenzene, which can be used in the process according to the invention.
The method is usually carried out at temperatures from about 250°C to 500°C, preferably at 300°C to 450°C, according to the invention. Particularly at 350° to 400° C, preferable. Under regular or increased pressure, for example, less than 10 to 250 bar and ideally 30 to 190 bar, the process can be performed in accordance with the invention.
In order to conduct the process according to the invention in an inert solvent and/or diluent, such as water, toluene, and/or ammonia, the respective 1,3-diaminobenzene is usually taken up, ideally in ammonia, excess solvent and/or diluent being used generally.
The amount of solvent and/or diluent to be used is not crucial and can differ across a wide range of bounds. Preliminary experiments can easily measure the required number. The solvent or diluent is typically used for more than 5 to 120 mol per mol of 1,3-diaminobenzene. Ideally from 10 to 60 moles per mol.
In the liquid or gas phase, ideally during the gas phase, the invention process may be performed. An inert gas like nitrogen and/or argon can be a midget in the reaction mix to increase the rate of flow.
The reaction may be carried out either in parallel or continuously according to the invention.
For instance, a mix of ammonia and the respective 1,3-diaminobenzene is passed over the catalyst under pressure to conduct the process according to the invention. The reaction mixture is then treated, after leaving the reactor, in a manner known per se, such as by fractional distillation. The unreacted 1,3-diaminobenzene can be recycled in reaction with almost no loss. Opt 2-Amino-pyridine.