DE1932297B2 - Process for the preparation of benzimicfazole-2-carbamic acid esters - Google Patents

Description

X-

-NH-C-OR

NH NH-C —O —R Ό

I! ο

in which X door hydrogen. Halogen. Alkyl with 1 to 4 carbon atoms or alkoxy with! until 4 carbon atoms and R is alkyl of 1 to 12 carbon atoms. Cycloalkyl from 5 to 8 carbon atoms as well as aralkyl stands, thereby characterized in that one phenylenediamines of the general formula in which X is hydrogen, halogen. Alkyl with 1 to 4 carbon atoms or alkoxy with 1 to 4 carbon atoms and R. for alkyl of 1 to 12 carbon atoms. Cycloalkyl of 5 to 8 carbon atoms and aralkyl is obtained when o-phenylenediamines of the general formula II

NH,

NH,

NH,

NH ₂

(H)

in which X has the meaning given above, with N-dichloromethylene-carbamic acid ester of the general Formula III

in which X has the meaning given, with N - dichloromethylene - carbamic acid - esters of general formula

R-O-C-N =

Il ο

Cl

egg

(III)

Cl

R-O-C-N = C

(III)

Cl

in which R has the meaning given above. at temperatures between -10 and +40 ⁰ C in the presence of bases and the molar ratio used of the compounds according to the general formulas II and III and the base used is 1: 1: 2.

The present invention relates to a chemically peculiar process for producing largely known benzimidazole-2-carbamic acid esters, which are known to be used as fungicides (U.S. Patent 2,593,504).

It has already become known that 2-anilinobenzimidazoles obtained when o-phenylenediamines with aromatic isocyanide dichlorides in a molar ratio 1: 1 implemented (Belgian patent 632 578).

It is also known that benzimidazole-2-carbamic acid esters are obtained when o-phenylenediamine is reacted with N-cyano-alkyl carbamates (South African patent specification 67/6589). However, this method has a number of disadvantages. So sitid to achieve larger bulging excesses of N-cyanoalkyl carbamates and longer reaction times or higher reaction temperatures required in which R has the meaning given, at temperatures between -10 and + 40 ⁰ C in the presence of bases and the molar ratio of the compounds used according to the general Formulas II and III and the base used is 1: 1: 2.

40. It can be described as extremely surprising that, in this reaction, side reactions, in particular an aminolysis of the ester group, do not occur and accordingly no by-products are formed will. It is known that carbamic acid

45. esters are aminolysed by amines (.H ouben-Weyl, Vol. VIII, pp. 161 and 162 [1952]). The inventive method therefore has a number of Benefits on. The benzimidazole-2-carbamic acid esters are in high purity and quantitative yield obtained without an excess of one or the other component being necessary. Also unnecessary a higher energy supply, as the conversion takes place quickly even at low temperatures. If you use o-phenylenediamine and methoxy

carbonyl isocyanide dichloride as starting materials, the course of the reaction can be given by the following equation be reproduced:

NH ₂ Cl

60

NH ₂ Cl

= NC-OCH ₁

Il

base

NH NH-COOCH,

In the general formula II X represents vorzuasweise fir hydrogen, chlorine, alkyl having 1 to 3 carbon atoms "■ ie methyl, Isopropyi, and alkoxy having 1 to ~> C-Atonen. like methoxy. Examples are O-phenylenediamine, 1,3,4-tolylenediamine, 4-chloro-O-phenylenediamine, 4-methoxy-o-phenylenediamine

In the general formula III, R preferably stands for alkyl with 1 to 8 carbon atoms, such as methyl ° ethyl isopropyl, η-butyl, n-octyl; Cyclohexyl; Phenylalkvi Biit 1 to 3 carbon atoms in the alkyl radical, e.g. B. Benzyl and Phenylethyl.

Examples of these compounds are: K - dichloromethylene - carbamic acid - methyl ester • ethyl ester, isopropyl ester, n-butyl ester, n-octyl ester. • cyclohexyl ester, benzyl ester and phenylethyl ester "

The N-dichloromethylene carbamic acid esters are not yet known. However, they can be prepared in a simple manner by reacting the already known dichloromethylene carbamic acid chloride with alcohols or phenols in the presence of an inert organic solvent such as ether. Dioxane, tetrahydrofuran, benzene, toluene, at temperatures between 0 and + 4O ⁰ C.

An example is the production of ethyl dichloromethylene carbamate specified:

To the solution of 300 g of dichloromethylene carbamic acid chloride (= 1.88 mol) in 350 ml of ether (dried over Na) are added 86.5 g of ethanol (abs.) (= 1.88 Mol), (reaction ^{temperature between 15 and 20 0} C). The solution is kept at room temperature for a further 2 hours, the ether is distilled off and the product is rectified. The main fraction of 267 g (= 84% of theory) (b.p. ₂₀ 55 to 68 °) is distilled again through a column: 230 g (= 72% of theory) b.p. ₂₀ 68 °.

For the preparation of the compounds according to the general formula III, a Patent protection not sought.

All inert organic solvents are suitable as diluents. These include Hydrocarbons such as gasoline or toluene, chlorinated hydrocarbons such as chloroform, ethers such as diethyl ether or dioxane. But it can also be water or aqueous mixtures with organic solvents, such as dioxane, acetone or tetrahydrofuran can be used.

The reaction according to the invention is carried out in the presence of bases. As such, can Alkali and alkaline earth hydroxides, carbonates and hydrogen carbonates, or tertiary organic bases are used. Examples are: sodium hydroxide, potassium carbonate, potassium hydrogen carbonate, triethylamine and pyridine.

The reaction temperatures must be in the range between -10 and +40 ⁰ C, preferably between ^{0 and} +30 0 C, are.

When carrying out the process according to the invention, 1 mol of the o-phenylenediamine is used Presence of 2 moles of base with 1 mole of the isocyanide &> dichlorids around.

The still new carbamic acid esters can be used as fungicides in the same way as those already known be used.

example 1

NH NH-C- OCH,

A solution of 15.6 g of methoxycarbonyl isocyanide dichloride in 50 ml of chloroform is added dropwise with stirring to a mixture of 10.8 g of o-phenylenediamine, 20.2 g of triethylamine and 300 ecm of chloroform, the temperature being kept ^{at about 20 ° C. by ice cooling} will. After stirring for a further 10 minutes, the mixture is filtered off with suction and the precipitate is washed with chloroform. After drying, 19 g of the ester are obtained. The product decomposes somewhat at 215 to 220 ^° C., but remains solid.

Example 2

NH NH-C-OC ₂ H ₅

10.8 g of o-phenylenediamine are dissolved together with 8 g of sodium hydroxide in a mixture of 200 ecm of water and 50 ecm of dioxane. 17.0 g Äthoxycarbonylisocyaniddichlorid the temperature being maintained by cooling below 20 ⁰ C are added dropwise in a mixture with 50 cc of dioxane in the cooled to 10 ⁰ C solution. After stirring for 10 minutes, the mixture is filtered off with suction, the precipitate is washed with water and acetone and dried. 20 g ester, melting point: 320 ° C (Z).

Example 3

C ₄ H ₉

NH NH-C-OCH ₃

16.4 g of 4-n-butyl-o-phenylenediamine are dissolved together with 8 g of sodium hydroxide in a mixture of 200 ecm of water and 50 ecm of dioxane. In the cooled to 1O ⁰ C solution is added dropwise 15.6 g Methoxycarbonylisocyaniddichlorid, which was dissolved in 50 cc of dioxane in advance, the temperature being kept below 20 ⁰ C by ice-cooling. After the reaction has ended, the mixture is stirred for a further 10 minutes, filtered off with suction, washed with water and acetone and dried. 23 g ester that can be purified from dimethylformamide / water. Melting point: 223 to 225 ° C.

In an analogous way the following are obtained:

Benzimidazole-2-carbamic acid n-butyl ester,
Melting point: 220 ⁰ C (Z), then solidifies again, benzimidazole ^ -carbamic acid-n-octyl ester,
Melting point: 170 ⁰ C (Z), then solidifies again, benzimidazole-2-carbamic acid benzyl ester,
Melting point: 250 ° C (Z), then solidifies again.

Claims (1)

Claim: Process for the preparation of benzimidazole-2-jarbamic acid esters the general formula! It has now been found that the largely known BtnzimidazolO-carbamic acid ester of generally formula I.