GB1581407A - Production of condensed triazoles - Google Patents

Description

(54) PRODUCTION OF CONDENSED TRIAZOLES (71) We, CIBA-GEIGY AG, a Swiss Body Corporate, of Basle, Switzerland, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention relates to a process for the production of condensed triazoles by reaction of an o-diamine from the series of the aromatic 6-rings with an alkyl nitrite in an organic solvent. By "series of the aromatic 6-rings" we mean series including benzene, naphthalene and heteroaromatic rings containing 6 atoms in the ring.

Processes for the production of benzotriazole in aqueous solution have already been variously described, for example by R. E. Damschroder and W. D. Peterson, Org. Synth. Coll. Vol. III, 106 (1955), by K. Gengnagel and Th. Papenfuhs in German Auselgeschrift 2,351,595, and by J. Meyer and M. Rohmer, Chemische Berichte, 33, 261 (1900). However, these aqueous processes yield coloured impure products which have to be purified additionally by a complicated decolouration procedure, by recrystallisation, or by a distillation which involves safety risks [explosion: Chem. Eng. News 34, 2450 (1956)]. Furthermore, present-day requirements regarding wastewater purification also give rise to ecological problems because of the presence of condensed triazoles and organic acids in the wastewaters.

A process for the production triazoles in organic solvents has been described by H. Sieper, Chem. Ber. 100, 1646-1654 (1967). In this process, o- or peridiamines of the benzene or naphthalene series are reacted in an organic solvent (benzene, ethanol or glacial acetic acid) at elevated temperature (700--800C) with an aromatic nitrosamine (diphenyl or ditolyl nitrosamine) in the presence of at least I equivalent of an acid (pka > 37) to give the corresponding triazole.

Surprisingly, it has now been found that condensed triazoles from the series of the aromatic 6-rings can be obtained in near colourless and very pure form and virtually quantitative yield, while simultaneously reducing the amount of wastewater, by reacting a corresponding o-diamine with an alkyl nitrite in the presence of a catalytic amount of an acid in an organic solvent.

Accordingly, the present invention provides a process for the production of condensed triazoles of the formula

wherein A represents o-arylene or heteroarylene, X is alkylene and R represents hydrogen, alkyl, aryl or aralkyl, which comprises adding an ester of nitrous acid to a reaction mixture consisting of a diamine of the formula II or a tetramine of formula IIa

wherein A, X and R have the given meanings, a catalytic amount of an acid and an organic solvent, at a temperature between -20" and +100"C.

Of particular interest for the process of the present invention are diamines of the formula II, wherein A represents o-phenylene, o-naphthylene or, as heteroarylene, represents p-pyridylene, and R represents hydrogen, C1-C20a1 kyl, phenyl which is unsubstituted or substituted by halogen, C1-C20alkyl, C1- C20alkoxy or nitro, or benzyl or phenethyl which can be substituted in the benzene ring by halogen, C1-C20alkyl, C1-20alkoxy or nitro.

As C1-C20alkyl, R is for example methyl, ethyl, propyl, isopropyl, butyl, tertbutyl, pentyl, 2,3-dimethylpropyl, 2-methylpentyl, hexyl, 2,4-dimethylpentyl, octyl, isooctyl, tert-octyl, nonyl, dodecyl, octadecyl or eicosyl.

As halogen-substituted phenyl, R is in particular phenyl which is mono- or disubstituted, but preferably monosubstituted, in the para-position by chlorine or bromine.

As alkyl-substituted phenyl, R is for example phenyl which is mono- or disubstituted, but preferably monosubstituted, in the para-position by methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, pentyl, 2,3-dimethylpropyl, 2methylpentyl, hexyl, 2,4-dimethylpentyl, octyl, isooctyl, tert-octyl, nonyl, dodecyl, octadecyl or eicosyl.

As alkoxy-substituted phenyl, R is for example phenyl which is mono- or disubstituted, preferably monosubstituted, in the para-position by methoxy, ethoxy, n-butoxy, tert-butoxy, octoxy, decyloxy, octadecyloxy or eicosyloxy.

As nitro-substituted phenyl, R is for example phenyl which is mono- or disubstituted, preferably mono-substituted, in the para-position by nitro.

As benzyl or phenylethyl which is substituted in the benzene nucleus by halogen, R is in particular benzyl or phenethyl which is mono- or disubstituted, but preferably monosubstituted, in the para-position by chlorine or bromine.

As benzyl or phenethyl which is substituted in the benzene nucleus by alkyl, R is for example benzyl or phenethyl which is mono-or disubstituted, but preferably monosubstituted, in the para-position by methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, pentyl, 2,3-dimethylpropyl, 2-methylpentyl, hexyl, 2,4-dimethylpentyl, octyl, isooctyl, tert-octyl, nonyl, dodecyl, octadecyl or eicosyl.

As benzyl or phenethyl which is substituted in the benzene nucleus by alkoxy, R is for example benzyl or phenylethyl which is mono- or disubstituted, but preferably mono-substituted, in the para-substitution by methoxy, ethoxy, nbutoxy, tert-butoxy, octoxy, decyloxy, octadecyloxy or eicosyloxy.

As benzyl or phenethyl which is substituted in the benzene nucleus by nitro, R is for example benzyl or phenylethyl which is mono- or disubstituted, but preferably monosubstituted, in the para-position by nitro.

Particularly preferred diamines of the formula II for the process of the present invention are 1,2-diaminobenzene (o-phenylenediamine) and 3,4-diaminotoluene.

Tetraaminodiphenylalkane or tetraaminodiphenylalkane derivatives can also be reacted to give bis-benzotriazole alkane or bis-benzotriazolyl alkane derivatives, for example 3,4,3',4'-tetraamino-diphenylmethane to give 5,5'-bisbenzotriazolylmethane.

The diamines to be used in the process of the invention are generally known and they are can be obtained by methods which are in themselves known.

Suitable solvents are aprotic solvents or also protic solvents which do not contain more than 40 /" by weight of water.

Aprotic solvents to be used according to the invention are preferably optionally chlorinated aromatic hydrocarbons, for example benzene, chlorobenzene, o-dichlorobenzene, toluene, ethyl benzene, isopropyl benzene, xylene and tetraline, also mineral oil fractions, aliphatic hydrocarbons containing 5 to 15 carbon atoms, for example pentane, hexane, cyclohexane, decane or pentadecane, chlorinated aliphatic hydrocarbons containing 1 to 4 carbon atoms, for example dichloroethane, carbon tetrachloride, trichloroethane or isobutyl chloride, as well as ethers or carboxylic acid esters.

Protic solvents which can be used in the process of the invention are alcohols, glycols, glycol ethers, especially low boiling alcohols, for example methanol, ethanol, propanol and isopropanol, and also ethylene glycol, ethylene glycol methyl or ethyl ether.

As catalysts there are used salts of organic or inorganic acids with the diamine employed or with additional tertiary amines.

Examples of inorganic acids are hydrochloric acid, hydrobromic acid, sulphuric acid or the different phosphoric acids.

Suitable organic acids are the carboxylic acids, for example formic acid, aliphatic mono- and dicarboxylic acids, such as acetic acid, propionic acid, butyric acid, oxalic acid, malonic acid, succinic acid, a-halogenated aliphatic carboxylic acids containing 2 to 10 carbon atoms, such as chloroacetic acid, achloropropionic acid, a-chlorobutyric acid, a-chloroisovaleric acid, achloropelargonic acid and the corresponding brominated acids, polyhalogenated carboxylic acids, such as dichloroacetic acid, trichloroacetic acid, trifluoroacetic acid and perfluorobutyric acid, and also cyanoacetic acid. From the series of the aromatic carboxylic acids mention may be made of benzoic acid and the nuclearsubstituted derivatives thereof, such as 2-, 3- or 4-chlorobenzoic acid, 2,4- or 2,5dichlorobenzoic acid, alkylated benzoic acid, such as 2-, 3- or 4-methylbenzoic acid, nitrobenzoic acids or phathalic acid, as well as phenylacetic acid.

Unsubstituted aliphatic carboxylic acids containing 1 to 10 carbon atoms are particularly preferred.

It is particularly advantageous to use as catalysts the salts of the above acids with the diamine employed. This can be best accomplished by adding the acids to the reaction mixture.

It is also possible to use the salts of the above acids with other tertiary amines, for example pyridine bases or trialkylamines, preferably those the alkyl radical of which contain 1 to 10 carbon atoms, for example trimethylamine or triethylamine.

The amount of acid to be used is advantageously 0.001 to 0.5 mole, preferably 0.01 to 0.1 mole, per mole of diamine. The optimum amount, however, is different for each acid and depends to a great extent on its dissociation constant.

Esters of nitrous acid, especially or primary or secondary alcohols containing 1 to 20 carbon atoms, are used as diazotising agents. Examples of such esters are the liquid nitrites of butyl, pentyl, isopentyl, heptyl and decyl alcohols as well as benzyl alcohol, having a boiling point above 50"C. The esters of alcohols containing 1 to 3 carbon atoms, i.e. the methyl, ethyl, propyl or isopropyl esters, which have a boiling point below 50"C and are gaseous or very readily volatile liquids, are advantageously used. It is also possible to use nitrites of polyalcohols or polyhydroxy polymers, for example ethylene glycol, polyethylene glycol or polyvinyl alcohol. The esters can be in liquid form or dissolved in a solvent, for example in the same solvent in which the reaction takes place. The low boiling solvents can also be introduced in the gaseous state.

All alkyl nitrites to be used in the invention are generally known and can be prepared by methods which are in themselves known.

The reaction temperature is between 200 and +100"C. However, it is most advantageous to carry out the reaction at a temperature between 20 and 60"C.

The triazoles obtained by the process of the invention are valuable corrosion inhibitors, especially for copper, but can also be used as intermediates for numerous syntheses.

The invention is illustrated by the following Examples.

Example 1 108.1 g of pure o-phenylenediamine are suspended in 400 ml of a xylene isomer mixture. After addition of 1.8 g of glacial acetic acid, the mixture is stirred for 30 minutes at room temperature. With efficient stirring, 61.7 g of freshly prepared gaseous methyl nitrite is introduced beneath the surface of the mixture over the course of 3 hours. The temperature is kept between 20 and 25"C with a cold water bath. Thirty minutes after the introduction of all the methyl nitrite, a check is made to ascertain whether the reaction mixture still contains free methyl nitrite and whether the phenylenediamine has been completely reacted. If not, small amounts of nitrite are introduced until the starting material can no longer be detected. If the starting material has been completely reacted, the resulting solution is heated to 700C and the volatile secondary components (methanol and water) are distilled off as an azeotrope initially under normal pressure and then under a weak vacuum. When the azeotropic distillation is complete, the reaction solution is diluted with 250 ml of xylene isomer mixture and seeded at 600C with a small amount of pure benzotriazole and stirred very vigorously at 550--600C until the crystallisation of the product is substantially complete. The crystal slurry is then cooled to 150--200C, filtered through a suction filter, and the filter cake is washed with about 150 ml of cold xylene mixture. The isolated moist product is dried in vacuo at 60"--70"C, affording 115.5 g (97 /n of theory) of 99.7 /n benzotriazole.

Melting point: 98.1"C. The mother liquor contains 2% of theory, corresponding to a reaction of 99% of theory.

Example 2 28.2 g of pure 2-aminodiphenylamine are suspended in 120 ml of o- dichlorobenzene. 0.25 g of trichloroacetic acid are added and the mixture is then heated to 600C, whereupon a solution forms. Then 18.7 g of isopentyl nitrite are added dropwise in the course of 2 1/2 hours and the reaction mixture is kept constantly at 600C. When the addition is complete, the batch is allowed to continue to react for a further 2 1/2 hours at 600C and then cooled to room temperature. The resulting solution is then concentrated by rotary evaporation in vacuo and the residue is taken up in 300 ml of cyclohexane. The solution is stirred for 15 minutes at room temperature and the precipitated product is collected by filtration, washed with 100 ml of cyclohexane and dried in vacuo at 6-70"C. Yield: 26.6 g (91 /" of theory) of dry product with a melting point of 890-900C. The mother liquor contains an additional amount of product.

Example 3 72.7 g of 4 - chloro - 1,2 - phenylenediamine (pract.) are suspended in 400 ml of chlorobenzene and the suspension is heated to 400 C, whereupon a solution is obtained. 0.72 g of hydrogen chloride gas is introduced below the surface of the solution and then, with efficient stirring, 38.3 g of freshly prepared gaseous ethyl nitrite are introduced below the surface. The temperature is kept constantly between 40 and 45"C. When the addition is complete, the mixture is reacted to completion for 1 hour at 400450C, then heated to 800 C. A clear solution is obtained. The volatile secondary components (ethanol and water) are distilled off in a weak vacuum and the reaction mixture is allowed to cool to 100C. The resulting suspension is filtered at 100C and the filter cake is washed with 100 ml of ice-cold chlorobenzene and dried in vacuo at 7800C. Yield: 62 g (81 /" of theory) of product with a melting point of 157"C. The mother liquor contains an additional amount of product.

By repeating the same procedure, but adding 2.44 g of benzoic acid instead of 0.72 g of hydrogen chloride gas, the yield of dry product is 66.9 g (87.1% of theory).

Melting point: 157"C. The mother liquor contains an additional amount of product.

Example 4 61.7 g of technical 3,4-diaminotoluene (approx. 99 / > ) are suspended in 400 ml of a xylene mixture and the suspension is heated to about 90"C, whereupon a solution is obtained. After cooling to room temperature, 0.9 g of glacial acetic acid is added as catalyst and, with efficient stirring, 32.6 g of freshly prepared gaseous methyl nitrite are introduced below the surface of the solution. The temperature is kept between 20 and 25"C with a cold water bath. The reaction is clearly exothermic and the sparingly soluble starting material gradually dissolves.

45 Minutes after the completion of the addition, a check is made to ascertain whether the reaction mixture still contains free methyl nitrite and the starting material has been completely reacted. If this is so, the resulting two-phase solution is heated to 800C and the volatile components (methanol and water) are distilled off at 80"--85"C, initially under normal pressure and then under a weak vacuum, as an azeotrope.

When the distillation is complete, the reaction solution is cooled to room temperature and completely concentrated by rotary evaporation, yielding 70 g of a liquid melt which crystallises at room temperature. The solid residue is finally taken up in 300 ml of cyclohexane and stirred for 1 hour at room temperature. The crystalline product is collected by filtration, washed with cyclohexane and dried at 60--70"C in vacuo. Yield: 66 g (99.2% of theory). Melting point: 800 C.

Example 5 216.6 g of distilled o-phenyldiamine are added to 800 ml of methanol and the mixture is heated to about 40"C, whereupon the starting material dissolves. After addition of 1.84 g of formic acid, the solution is cooled to about 35"C and 124.4 g of freshly prepared gaseous methyl nitrite is introduced below the surface over the course of 4 1/2 hours. The temperature is kept between 30 and 35"C with a cold water bath. 30 minutes after completion of the addition, a check is made to acertain whether the reaction mixture still contains free methyl nitrite and the ophenylenediamine has been completely reacted. If not, small additional amounts of methyl nitrite are introduced until the starting material can no longer be detected.

The reaction solution is then heated for about 1 hour to reflux and the remaining methyl nitrite is expelled. The resulting nitrite-free solution, which is almost golden yellow in colour and contains about 234.6 g of 100% benzotriazole (98.5% of theory), can be worked up in various ways.

To prepare very pure benzotriazole, the methanol is distilled off at about 45 50"C in vacuo and the residue is crystallised from a solvent or possibly from water.

To prepare a technical product, only the methanol is distilled of in vacuo and the residual melt (containing 48% of water) is processed mechanically in the form of granules, pellets or flakes. To prepare benzotriazole derivatives, the reaction solution is further processed direct and the methanol is removed in vacuo only after completion of the next synthesis step.

Instead of using pure methanol (800 ml), it is possible to use with equal success aqueous methanol having a water content of for example 25% by weight.

Example 6 4.56 g of 3,3' - 4,4' - tetramino - diphenylmethane are added to a mixture 67.5 ml of methanol and 7.5 ml of water. The mixture is heated to about 60"C and a clear solution is formed. This solution is cooled to about 40"C and then 0.24 g of glacial acetic acid is added. With good stirring, 2.7 g of freshly prepared gaseous methyl nitrite is then introduced below the surface. The temperature is kept constantly between 35 and 40"C. 30 minutes after completion of the addition, a check is made to ascertain whether the tetramine has been completely reacted. If not, the reaction mixture is allowed to continue to react at 350--400C for 2 to 3 hours and a further check is then made. When the reaction is complete, the resulting solution is heated to 500--550C and the remaining methyl nitrite is expelled. This solution is then diluted with 100 ml of water and the methanol is distilled off at about 40"C by rotary evaporation. The precipitated product is filtered off at room temperature, washed with 100 ml of water and dried in vacuo at 50"--60"C, affording 4.7 g of dry, virtually pure 5,5' - methylene - bis benzotriazole with a melting point of 166"C. (Literature: softening at about 150"C, melting point about 155"C, decomposition at about 230"C).

WHAT WE CLAIM IS: 1. A process for the production of condensed triazoles of the formula I or Ia

wherein A represents o-arylene or heteroarylene, X is alkylene and R represents hydrogen, alkyl, aryl or aralkyl, which comprises adding an ester of nitrous acid to a reaction mixture consisting of a diamine of the formula II or a tetramine of formula lla

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (13)

**WARNING** start of CLMS field may overlap end of DESC **. Example 5 216.6 g of distilled o-phenyldiamine are added to 800 ml of methanol and the mixture is heated to about 40"C, whereupon the starting material dissolves. After addition of 1.84 g of formic acid, the solution is cooled to about 35"C and 124.4 g of freshly prepared gaseous methyl nitrite is introduced below the surface over the course of 4 1/2 hours. The temperature is kept between 30 and 35"C with a cold water bath. 30 minutes after completion of the addition, a check is made to acertain whether the reaction mixture still contains free methyl nitrite and the ophenylenediamine has been completely reacted. If not, small additional amounts of methyl nitrite are introduced until the starting material can no longer be detected. The reaction solution is then heated for about 1 hour to reflux and the remaining methyl nitrite is expelled. The resulting nitrite-free solution, which is almost golden yellow in colour and contains about 234.6 g of 100% benzotriazole (98.5% of theory), can be worked up in various ways. To prepare very pure benzotriazole, the methanol is distilled off at about 45 50"C in vacuo and the residue is crystallised from a solvent or possibly from water. To prepare a technical product, only the methanol is distilled of in vacuo and the residual melt (containing 48% of water) is processed mechanically in the form of granules, pellets or flakes. To prepare benzotriazole derivatives, the reaction solution is further processed direct and the methanol is removed in vacuo only after completion of the next synthesis step. Instead of using pure methanol (800 ml), it is possible to use with equal success aqueous methanol having a water content of for example 25% by weight. Example 6 4.56 g of 3,3' - 4,4' - tetramino - diphenylmethane are added to a mixture 67.5 ml of methanol and 7.5 ml of water. The mixture is heated to about 60"C and a clear solution is formed. This solution is cooled to about 40"C and then 0.24 g of glacial acetic acid is added. With good stirring, 2.7 g of freshly prepared gaseous methyl nitrite is then introduced below the surface. The temperature is kept constantly between 35 and 40"C. 30 minutes after completion of the addition, a check is made to ascertain whether the tetramine has been completely reacted. If not, the reaction mixture is allowed to continue to react at 350--400C for 2 to 3 hours and a further check is then made. When the reaction is complete, the resulting solution is heated to 500--550C and the remaining methyl nitrite is expelled. This solution is then diluted with 100 ml of water and the methanol is distilled off at about 40"C by rotary evaporation. The precipitated product is filtered off at room temperature, washed with 100 ml of water and dried in vacuo at 50"--60"C, affording 4.7 g of dry, virtually pure 5,5' - methylene - bis benzotriazole with a melting point of 166"C. (Literature: softening at about 150"C, melting point about 155"C, decomposition at about 230"C). WHAT WE CLAIM IS:

1. A process for the production of condensed triazoles of the formula I or Ia

wherein A represents o-arylene or heteroarylene, X is alkylene and R represents hydrogen, alkyl, aryl or aralkyl, which comprises adding an ester of nitrous acid to a reaction mixture consisting of a diamine of the formula II or a tetramine of formula lla

wherein A, X and R have the above meanings, a catalytic amount of an acid and an organic solvent, at a temperature between -20" and +100"C.

2. A process according to claim 1 wherein a start is made from a diamine of the formula II, wherein A represents o-phenylenc,-o-naphthylene or, as heteroarylene, o-pyridylene, and R represents hydrogen, C1-C20alkyl, phenyl which is unsubstituted or substituted by halogen, C1-C20alkyl, C1-C20alkoxy or nitro, or benzyl or phenethyl which can be substituted in the benzene ring by halogen, C1- C20alkyl, C1-C20alkoxy or nitro.

3. A process according to claim 1 or claim 2 wherein the compound of formula II is 1,2-diaminobenzene.

4. A process according to claim 1 or claim 2 wherein the compound of formula II is 3,4-diaminotoluene.

5. A process according to any of the preceding claims wherein the reaction is carried out at a temperature between 20 and 60"C.

6. A process according to any of the preceding claims wherein an aprotic solvent is used as solvent.

7. A process according to claim 6 wherein toluene, ethyl benzene, isopropyl benzene, xylene or tetraline is used as aprotic solvent.

8. A process according to any of claims 1 to 5 wherein a protic solvent which contains not more than 40 /" by weight of water is used as solvent.

9. A process according to claim 8 wherein methanol, ethanol, propanol, isopropanol, ethylene glycol, ethylene glycol methyl or ethyl ether is used as protic solvent.

10. A process according to any of the preceding claims wherein 0.01 to 0.1 mole of an unsubstituted aliphatic carboxylic acid containing I to 10 carbon atoms is used per mole of the diamine.

11. A process according to any of the preceding claims wherein the ester of nitrous acid is the ester of an alcohol containing 1 to 3 carbon atoms.

12. A process according to claim 1 substantially as described in any of Examples 1 to 6.

13. Condensed triazoles of formula I defined in claim 1 whenever prepared by a process according to any of the preceding claims.