DE1921957C3 - Process for the preparation of 1,1'-disubstituted 4,4'-bipyridylium salts - Google Patents

Description

has, in which R is either an alkyl group with 1 to 12 carbon atoms or a phenyl radical means by reacting a corresponding pyridinium salt in the absence of oxygen with a dissociable cyanide and oxidation of the resulting from this reaction Reaction product to the bipyridylium salt, thereby characterized in that the reaction with the cyanide takes place in aqueous acetone.

As is known, 4,4'-bipyridyl is obtained by reacting pyridine with alkali metals. Magnesium or aluminum and subsequent oxidation (compare, for example, Annalen, 154 [1870], pp. 270 to 286). In this process, the pyridine is used in large excess, the reaction is generally carried out under pressure and the 4,4'-bipyridyl is obtained with the aid of multiplied separation operations. Another known process (Versleiche Ber .. 54 [1921], pp. 2934 to 2942, and 55 [1922], pp. 3693 to 3697) is used to obtain 4,4'-bipyridyl. ^c Pyridine with acetic anhydride and zinc and subsequent oxidation of the Ι, Γ-diacetyltetrahydro-4,4'-bipyridyl obtained in this way. According to French Patent 1,390,773 and Hungarian Patent 152,499, 4,4'-bipyridyl can be reacted in an aqueous medium with a methyl halide or in the presence of an alkali acetate with dimethyl sulfate to give a 1,1'-dimethyl-4,4'-bipyridylium salt. However, this reaction must be carried out under pressure. Which, in addition to the above-described disadvantages of the first process stage for obtaining 4,4'-bipyridyl, means a further disadvantage for the industrial production of 1,1'-dimethyl-bipyridylium salts.

From J. Am. Chem. Soc, 86, pp. 5524-5527 (1964). it is also known to be l-methy! -4-cyanpyridinium iodide in alkaline aqueous solution with sodium dithionite to l, r-dimethyl-4,4'-bipyridyliumdijodiil oxidize, but this process requires the prior recovery and isolation of the 1-methyl-4-cyanopyridinium iodide in advance. Finally, in Tetrahedron Letters, 24 (1967), pp 2313-2315, the Manufacture of U'-DidodecyM ^ '- bipyridylium dibromide by direct reaction of dodecylpyridinium bromide with an aqueous sodium cyanide solution known. Working in aqueous solution leads to relatively low yields.

The object of the invention was therefore to obtain 1,1'-disubstituted 4,4'-bipyridylium salts directly from the corresponding Starting from pyridinium salts in a technically simple manner and in better yield than before.

The inventive method for the production of U'-disubstituted 4,4'-mpynayimmsaken, their Cation the general formula

has, in which R is either an alkyl group with 1 to 12 carbon atoms or a pbenyl radical means by implementing a corresponding Pyridmium salt in the absence of oxygen with is a dissociable cyanide and oxidation of the this reaction resulting reaction product to the bipyridylium salt is characterized by that the reaction with the cyanide takes place in aqueous acetone. . .

The starting compound can be, for example, N-methylpyridinium iodide or N-phenylpyridinium chloride use. Useful dissociable cyanides are the alkali or alkaline earth cyanides, ammonium cyanide and organoammonium cyanides. In doing so, nitrogen is passed through the reaction medium, to clear it of oxygen.

The disubstituted 4,4'-bipyridylium salts obtained according to the invention can be used as herbicides. Hydrating agents, photographic materials, redox indicators, oxidizing agents, medicinal products for Treatment of coccidiosis in poultry, for the determination of small amounts of oxygen gas and as Aerobic Cyclic Phosphorylation Catalysts.

example 1

1.1 '-DimethyM ^' - bipyridylium ^^ '- diaminostilbcn-2,2'-disulfonate

2.00 g (9.05 mmol) of N-methylpyridinium iodide, 1.0 g (20 mmol) of sodium cyanide and 20 ml of a mixture of acetone and water (3: 1 parts by volume). The solution was purged with nitrogen and the neck of the flask was sealed. The flask was placed in a steam bath and heated for 21 hours. After about 5 minutes a characteristic blue color developed, the visible spectrum was characteristic for the l, r-dimethyl-4,4'-bipyridylium cation. The flask was cooled, broken and 3 ml of concentrated hydrochloric acid added. The reaction mixture was placed in a 150 ml beaker and allowed to oxidize in air until the blue color disappeared. Concentrated ammonium hydroxide was then added until the solution had a pH of about 9. A solution was then added which contained 2.0 g (5.4 mmol) of 4,4'-diaminostilbene-2,2'-disulfonic acid, dissolved in 50 ml of a 10% ammonium hydroxide solution. A dark bluish green precipitate immediately formed which was collected, dried under vacuum and weighed. Yield 0.576g (23%). The empirical formula of the 4,4'-diaminostilbene * 2,2'-disulfonic acid salt is C ₂₆ H ₂₈ N ₄ O ₆ S ₂ . This yield is a minimum because no attempt has been made to recover unreacted N-methylpyridinium salt.

\ 921

Example 2

1,1 '-DiphenyM ^' - bipyridylium dibromide

100 ml of 5 a mixture of acetone and water in a volume ratio of 1: 1 and 5.0 g (26 mmol) of N-pbenylpyridinium chloride given. The flask was placed in a container with an inert gas atmosphere, which contained oxygen-free nitrogen. Then, oxygen-free nitrogen was passed through the solution for 5 minutes directed to free them from the dissolved oxygen. 2.5 g were then added to this solution (51 mmol) sodium cyanide added to the Srienmeyer flask was closed with a cork stopper, sealed tightly and placed in a nitrogen atmosphere Left to stand for 6 days at room temperature. When the sodium cyanide was added, the solution became instantaneous cloudy, and a dark red solid appeared within 5 minutes. After standing, the

Solution filtered and the solid reaction product collected.

The collected solid material was added to a solution of 7.0 g of iodine in 100 ml of 95% igero Ethyl alcohol oxidizes. The solution thus obtained, which still contained some solid, was passed through an ion exchange column sent, which had previously been saturated with bread nions. The insoluble solid Material was in a bite mixture of Acetoniüil and water (volume ratio 9: 1) dissolved and also sent through the ion exchange column. In order to ensure a complete ion exchange of iodide for bromide, the Pass the solution through a fresh ion exchange column one more time. The resulting solution was evaporated to give a solid which was obtained twice from a mixture of acetonitrile, water and ethyl acetate was recrystallized. The solid was dried under vacuum at 100 ° C. yield 3.81 g l.r-DiphenyM, 4'-bipyndy! Hymdibromide.

Claims (1)

Claim: Process for the preparation of ϊ, Γ-disubstituted 4,4'-BipvridyliurasaIzen, their cation the general formula R-N NO