DD290879B5 - Process for the preparation of carbamoylpyridylium compounds - Google Patents

Description

The invention relates to a process for the preparation of i-carbamoyl-pyrid ^ -ylium alkanesulfonaten in pure form. 1-carbamoyl-pyrid-4-ylium compounds are known to be obtained by reacting pyridine or a substituted pyridine with a carbamoyl halide (DE 2 225 230, DE 2 439 551). When using pyridine and N, N-dialkylcarbamoyl chloride z. B. oily products (GB 1 535 809).

These oily products can be removed by cleaning methods, e.g. B. mixing with a non-polar solvent, are brought to crystallization, which means an additional stage. It is also possible to make compounds of this type in substance and to purify the oily products by sublimation. In DE 2 439 551, pyridine in dimethylformamide is reacted with carbamoyl chlorides in the presence of sodium methylate-methanol.

In this procedure, the carbamoyl compounds are obtained in admixture with sodium chloride. The yields in carbamoyl-pyridylium compounds are low, because acylpyridylium - including carbamoyl-pyridylium compounds can react violently with alcohols or amines.

Therefore, the reaction in Akohol, as described in Chem. Ber. 40.1831 (1907) is not recommended. Carbamoylpyridylium compounds decompose in acetonitrile into the starting products pyridine and carbamoyl chloride (J. Phys. Chem. 68, 3149 [1964]).

i-carbamoyl-pyrid-4-ylium compounds are preferably used as hardening agents for gelatin layers in silver halide recording materials.

This requires that they be dissolved in water or in an organic, water-miscible solvent. This is very unfavorable for oily products.

Due to the significant influence on the photographic properties of silver halide emulsions by chloride, bromide or iodide ions, it is of great disadvantage to introduce salts of these compounds in the photographic layer.

In some patents z. For example, CH 596 577, the chloride is exchanged for tetrafluoroborate, which requires additional effort. In addition, salts on the surface of the photographic layer may crystallize after drying, which is extremely detrimental to the optical clarity of the cured photographic materials.

The aim of the invention is to produce i-carbamoyl-pyrid-4-ylium-alkanesulfonates in a simple manner.

The invention has for its object to develop a process for the preparation of i-carbamoyl-pyrid-4-ylium-alkanesulfonaten from Pyridinalkylsulfonsäuren and the corresponding carbamoyl chlorides, which works with high efficiency.

According to the invention, the object is achieved by reacting a Pyridinalkansulfonsäure the general formula

R ¹ = hydrogen, alkyl, subst. Alkyl, alkenyl, subst. Alkenyl, cycloalkyl, aryl, subst. Aryl and heterocycle R ² = alkylene, preferably in the range C 1 to C 4

mean,

in acetonitrile as a solvent such with a carbamoyl chloride of the general formula

^R3 Cl

N-C

R ³ , R ⁴ = identical or different alkyl, aryl, subst. Aryl, heterocycle or R ³ and R ⁴ together are the atomic group necessary to complete an optionally substituted piperidine, piperazine or morpholine ring

implements that the product formed crystallized in the hot reaction solution and the resulting excess heat can be dissipated in a sufficient manner. According to the invention, an auxiliary base is used, that of the general formula

corresponds and in which

R ¹ to R ^{3 are the} same or different alkyl, subst. Alkyl, aryl, subst. Aryl or cycloalkyl, wherein R ¹ and R ^{3 is} a carbocyclic

Ring can mean.

Contrary to the statement of J. phys. Chem. 68.3149 (1964), the reaction in acetonitrile without loss of yield is possible. Since the hydrochlorides of the auxiliary bases used here in acetonitrile are readily soluble in heat, they can be easily separated from the product.

It is advantageous to provide the solvent acetonitrile with the auxiliary base and add the pyridine sulfonic acid with stirring. Here, the i-carbamoyl-pyrid-4-ylium alkanesulfonate fall in pure form and not in admixture with sodium chloride or other salts, as described in the patent literature. The curing agents are very demanding in terms of their chemical purity, since even the smallest amounts of impurities have a negative effect on the photographic performance of the systems. Therefore, it is particularly favorable that pure products are obtained here. In all cases, they are white, crystalline substances which dissolve in water in high concentrations without leaving any residue. The auxiliary bases used in this process are obtained as hydrochlorides and can be worked up in a suitable manner to the free amines.

Also, the acetonitrile required for the reaction can be used again after distillation and drying.

With the process according to the invention, i-carbamoylpyrid-4-ylium alkanesulfonates can be prepared in a simple manner or without additional steps in comparison with the prior art. A particular advantage is that these carbamoyl compounds are obtained pure and not as usual, in admixture with z. For example, sodium chloride, so that they are particularly suitable for the photographic industry.

The following list is exemplary in nature and is not intended to limit the scope of the invention.

CH ₂ -SO,

VSTV

CH-

Me- N

me

-4-290 embodiments

In the comparative example, it was attempted to prepare the sodium salt of 2- (1-morpholinocarbamoyl-pyrid-4-ylium) ethane-1-sulfonate.

example 1

(Comparative Example) A suspension of 1.04 g of sodium in 200 ml of methanol is added dropwise with stirring to a mixture of 8.45 g of p-pyridinethanesulfonic acid and 200 ml of dry DMF.

Then 7.50 g of morpholino-carbamoyl chloride are added dropwise and the reaction solution is allowed to stand overnight.

The product is then precipitated in 650 ml of ether and filtered with suction.

M.p .: 143-147 ⁰ C. Yield .: 9.63 g (60%) The product is obtained here as a double salt with NaCl in a relatively low yield.

Example 2

1.87 g (0.01 mol) of pyridine-4-ethane-2-sulfonic acid are dissolved with 1.45 ml (0.01 mol) of triethylamine in 10 ml of acetonitrile and heated to reflux.

Then added dropwise to 1.50 g (0.01 mol) of morpholino-carbamoyl chloride.

After a brief yellowing of the solution, a white solid precipitates. This is filtered off with suction after refluxing for one hour, and the cake is again boiled in 15 ml of acetonitrile.

M.p .: 178-181 ° C. Yield: 2.33 g (77.6%) The zwitterionic product is obtained in pure form in the form of acicular crystals.

Example 3

The procedure is analogous 26.88 g of dimethylaminocarbamoyl chloride and 46.78 g of pyridine-4-ethane-2-sulfonic acid are used. A short time after its addition, the product precipitates and is sucked hot. After repeated boiling in 100 ml of acetonitrile to give a white crystalline solid.

M.p .: 175-178 ⁰ C. Yield .: 47.53 g (73.60%)

Claims (1)

Process for the preparation of carbamoyl-pyridylium compounds of the general formula R ¹ = hydrogen, alkyl, subst. Alkyl, alkenyl, subst. Aryl and heterocycle, R ² = alkylene, preferably in the range of C 1 to C 4, R ³ , R ⁴ = alkyl, alkylene, aryl, subst. Aryl or together to complete an optionally subst. Piperidine, piperazine or morpholine ring form required atomic groups mean, by reacting a Pyridinalkansulfonsäure the general formula wherein R ¹ SCLH Hydrogen, alkyl, subst. Alkyl, alkenyl, subst. Alkenyl, cycloalkyl, aryl, subst. Aryl and heterocycle, Alkylene, preferably in the range of C 1 to C 4, mean, with a carbamoyl chloride of the general formula wherein R ³ , R ⁴ identical or different alkyl, aryl subst. heterocycle or R ³ and R ⁴ = taken together to complete an optionally subst. piperidine, Piperazin- or Morpholinringes necessary atomic group, characterized in a solvent in the presence of a tertiary amine characterized in that as the solvent acetonitrile and as a tertiary amine an auxiliary base of the general formula .R ² used in which R ¹ to R ^{3 are the} same or different alkyl, subst. Alkyl, aryl, subst. Aryl and cycloalkyl.