DE2747551A1 - Benzimidazolyl-guanidine cpds. prodn. - by neutralisation of ortho-phenylenediamine cpds. with hydrochloric acid and reaction with dicyandiamide - Google Patents

Abstract

In the prodn. of benzimidazolylguanidine cpds. of formula (I) (where R is Cl, br, H, CH3, OCH3, phenyl or NO2), (a) an o-phenylenediamine cpd. is added to HCl at such a rate that the reaction mixt. warms to >=60 degrees C; (b) dicyandiamide is added so that temp. of 120 degrees C is reached without external heating; and (c) (I) is pptd. by addn. of NaOH, sepd. from the mother liquor washed chloride-free, and dried. (I) are obtd. in high yield and purity by a process which is sparing of heat energy. this is achieved by utilising the heat of neutralisation of the o-phenylenediamine by HCl as a heat source.

Description

Process for the preparation of Benzimidazolylguanidinverbin-

dungen (2-guanidino-benzimidazole) The invention relates to a method for the production of benzimidazolylguanidine and its substituted in the benzene nucleus Compounds (2-guanidino-benzimidazoles) from the corresponding b-phenylenediamines and dicyandiamide in aqueous solution.

It is known that benzimidazolylguanidine compounds are obtained from the dihydrochloride of corresponding o-phenylenediamine compounds, after adding of the dicyandiamide to the aqueous solution of the dihydrochloride one to five hours on Reflux is boiled (US-PS 3 023 103>; KING, FE. And employees I. Chem. Soc. (London) 1948, 1366-71) These methods have the particular disadvantage that the total heat of neutralization in the isolation of the o-phenylenediamine compounds get lost. In addition, such o-phenylenediamine compounds are often very sensitive Compounds that are prone to the formation of discolored by-products, which at occur more frequently: this reduces the yield the desired benzimidazolylguanidine compounds.

The task was therefore to find a method which would do it allow such benzimidazolylguanidine compounds in increased yield, higher To produce purity and, above all, more energy-efficient.

This object of the process for the preparation of benzimidazolylguanidine compounds of the general formula I. where R can be chlorine, bromine or hydrogen atoms or represent methyl, methoxy, phenyl or nitro groups, was solved by introducing an o-phenylenediarnine compound into hydrochloric acid so quickly that the mixture warms to at least 60.degree , adds dicyandiamide to this mixture at such a rate that a temperature of 120 ° C. is reached without the supply of external heat energy, then the benzimidazolylguanidine compound formed precipitates by adding sodium hydroxide solution, separated from the mother liquor in a manner known per se, washed free of chloride with water and then dries.

The process of the invention therefore does not start with the dihydrochlorides of the o-phenyldiamine compounds, but separate from their bases themselves and uses the heat of neutralization that arises when it is introduced into the hydrochloric acid for heating up for starting the reaction of the dihydrochloride with dicyandiamide required starting temperature. It was surprising that with a correspondingly fast Dicyandiamide entry the resulting reaction temperature for a complete Implementation is sufficient and therefore the subsequent RücX river cooking is dispensed with can be. As further notable advantages of this procedure according to the invention The results were improved yields and increased purity compared to the prior art.

Accordingly, the process for the preparation of benzimidazolylguanidine compounds proceeds according to formula I in the following steps: 1. Enter the o-phenylenediamine in hydrochloric acid with stirring, the mixture warming to 60 to 70 ° C.

2. Adding dicyandiamide to the 70 ° C warm mixture, among other things Stir in such a way that the temperature does not exceed 120 ° C.

3. Addition of NaOH after the reaction has ended to precipitate the formed Benzimidazolylguanidine compound.

4. Cooling the mixture, separating the solid from the mother liquor, Wash out until it is free of chloride and then dry in a known manner.

The reaction mixture is used for the heat-economically favorable implementation in steps 1 and 2 not or only insignificantly heated from the outside and heat losses largely prevented by the reacting mixture. The implementation is thus preferably carried out under essentially adiabatic conditions.

The present method is most beneficial in a combination carried out by two agitator tanks, the first of which is well insulated and heatable, the second is not insulated and water-cooled.

The following examples are intended to explain the invention in greater detail serve: Example 1 In a stirred tank with a capacity of 1,200 parts by volume, which is isolated and is provided with a reflux condenser, 175 parts by weight of hydrochloric acid (29.3 %) and 10 parts by volume of water and then 77.2 parts by weight of o-phenylenediamine registered.

After entering the mixture has a temperature of 68 OC then 60 parts by weight of dicyandiamide are added over the course of 20 minutes, the temperature rises to 122 OC. After completing the entry and briefly stirring (5 to 10 minutes) the benzimidazolylguanidine is formed by adding sodium hydroxide solution (20%) set in freedom. The resulting mixture is drained into a R: your factory container, cooled to room temperature and the precipitated product spun off. After this The product is washed out with water until it is free of chloride at 90 to 100 ° C dried in vacuum.

There are 105 parts by weight of product with 39.9% N and 0.4% moisture, corresponding to a yield of 84%.

Example 2 As in Example 1, 175 parts by weight of hydrochloric acid are used (29.3%) with 10 parts by volume of water and 102.7 parts by weight of 1,2-diamino-5-chlorobenzene mixed. The mixture then reaches a temperature of 60 to 70 OC 60 parts by weight of dicyandiamide are entered within 20 minutes. One moves Further as in Example 1. After drying, 115 parts by weight of 5-chlorobenzimidazolylguanidine are obtained with 32.0% N and 0.3% H20, corresponding to a yield of 76.5%.

Example 3 As in Example 1, 175 parts by weight of hydrochloric acid are used (29.3%) with 86 parts by weight of 1,2-diamino-5-methylbenzene and 60 parts by weight of dicyandiamide used.

106 parts by weight of 5-methylbenzimidazolylguanidine at 35.8 are obtained % N and 0.5% H20, corresponding to a yield of 80.0%.

Example 4 When using 175 parts by weight of hydrochloric acid (29.3%), 107 parts by weight of 1,2-diamino-5-nitrobenzene and 60 parts by weight of dicyandiamide accordingly Example 1 gives 119 parts by weight of 5-nitrobenzimidazolylguanidine after drying with 34.9% N and 0.5% H20. The yield is 78.0%.

Examples 5-11 In the manner described in Example 1, the o-Phenylenediamines listed in the table below into the corresponding Benzimidazolylguanidinverbindungen transferred. Example o-phenylenediamine Benzimidazolyl-N content Cl-Ge Br-Ge Ausbeu no. guanidine (BIG)% hold% hold% te% 5 1,2-diamino-4,6-dichlorobenzene 4,6-dichloro-BIC 27.2 29.7 - 68 6 1,2-diamino-5,6-dichlorobenzene 4,5-dichloro-BIG 27.7 19.3-73 7 1,2-diamino-4,5,6-trichloro-4,5,6-trichloro-23.7 38.2-63 benzene BIG 8 1,2-diamino-5-bromobenzene 5-bromo-BIG 26.3-31.0 76 9 1,2-diamino-4,6-dimethylbenzene 4,6-dimethyl-BIG 33.2 - - 69 10 1,2-diamino-4,6-methoxybenzene 5-methoxy-BIG 32.3 - - 58 11 1,2-diamino-5-phenylbenzene 5-phenyl-BIG 27.0 - - 77

Claims (2)

Claims 1 Process for the preparation of benzimidazolylguanidine compounds of the general formula I. where R can be chlorine, bromine or hydrogen atoms or represent methyl, methoxy, phenyl or nitro groups, characterized in that an o-phenylenediamine compound is introduced into hydrochloric acid so quickly that the reaction mixture warms to at least 60 ° C, dicyandiamide is added to this mixture at such a rate that a temperature of 120 ° C. is established without the supply of external heat energy, then the benzimidazolylguanidine compound formed is precipitated by adding sodium hydroxide solution, separated from the mother liquor in a manner known per se, washed free of chloride and then dried. 2. The method according to claim 1, characterized in that the implementation and precipitation occurs in a different vessel than cooling.