Process for producing 1-(2-chlorphenyl)-5(4H)-tetrazolinone

Abstract: There are provided a novel compound 1-(2-chlorophenyl)-5-chlorotetrazole of the formula: a process for producing 1-(2-chlorophenyl)-5(4H)-tetrazolinone which comprises hydrolyzing said compound, as well as a process for producing 1-(2-chlorophenyl)-5(4H)-tetrazolinone which comprises reacting 2-chlorophenylisocyanide dichloride with sodium azide and then hydrolyzing the resulting compound as such without being subjected to isolation and purification.

Description: The present invention relates to a process for producing 1-(2-chlorophenyl)-5(4H)-tetrazolinone and to a novel intermediate therefor. 1-Substituted-5(4H)-tetrazolinones, in general, have been synthesized by processes represented by the following reaction equation A. These processes have problems as mentioned below and hence they are not adequately useful for an industrial production process. (i) A reaction of an anhydrous system is employed, and thus it is difficult to conduct handling and to set up reaction conditions. (ii) In the above reaction (1) using aluminum chloride, while 1 mole of sodium azide only is reacted with 1 mole of isocyanate, the remaining 2 moles of sodium azide are decomposed and wasted. Furthermore, sodium azide is expensive. Therefore, it is uneconomical. (iii) Aluminum chloride used as a catalyst in the above reaction (1) has difficulties in draining work. (iv) Azidotrimethylsilane used in the above reaction (2) is more expensive than sodium azide. Further, in some cases, the yield is low even when the reaction time is extended (cf. EP-0638561 and documents cited therein). Nucleophilic substitutions at the C-5 of tetrazoles are generally known, for example the hydrolysis of 2-methyl-5-bromo-tetrazole to give 2-methyl-5(1H)-tetrazolinone (A.R. Katritzky et al., Comprehensive Heterocyclic Chemistry, Vol. 5, Ch.4.13 (1984); page 817, scheme 19). This substitution reaction is commonly used also on 1-(substituted or unsubstituted phenyl)-5-chloro-tetrazole derivatives (cf. EP-0029183; FR-2387969; US-3489763). It has now been found that 1-(2-chlorophenyl)-5(4H)-tetrazolinone can be obtained when 1-(2-chlorophenyl)-5-chlorotetrazole is hydrolyzed, in the presence of a base selected from the group consisting of the hydroxides of alkaline metals and alkaline earth metals and in the presence of water, at a temperature of 50 °C to 160 °C, the reaction time ranging from 1 minute to 10 minutes. In the process of the invention, the handling and the setting up of reaction conditions are simpler and the solvent and the base used are more inexpensive as compared with the above-mentioned known production processes. Furthermore, according to the invention, since by-products are alkali chlorides alone and the objective compound with high purity can be synthesized in a high yield, various advantages can be obtained such that it is easy to conduct purification treatment after the reaction . Therefore, the process of the invention is extremely suitable for producing 1-(2-chlorophenyl)-5(4H)-tetrazolinone on an industrial scale. In the process of the invention, it is possible to obtain 1-(2-chlorophenyl)-5(4H)-tetrazolinone in a high yield under the high temperature and high alkaline conditions, even though this compound is susceptible to decomposition under such high temperature and high alkaline conditions. The process of the invention is shown by the following equation when, for example, sodium hydroxide is used as a base. The process of the invention is carried out in the presence of a base selected from the group consisting of the hydroxides of alkaline metals and alkaline earth metals (e.g. lithium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide and magnesium hydroxide). The process of the invention can be carried out at a temperature within the range of 50 °C to 160 °C, preferably 80 °C to 140 °C. Usually, the process of the invention should desirably be conducted under normal pressure but it may optionally be conducted under elevated or reduced pressure. In the process of the invention, the reaction time is usually ranging from 1 minute to 10 minutes under the above-mentioned reaction conditions. According to the process of the invention, 1-(2-chlorophenyl)-5(4H)-tetrazolinone can be obtained, for instance, by hydrolyzing 1-(2-chlorophenyl)-5-chlorotetrazole in the presence of an equimolar amount to four-fold molar amount of the base (such as sodium hydroxide) and in the presence of water. 1-(2-Chlorophenyl)-5-chlorotetrazole which is used as a starting material in the above-mentioned process of the invention is a novel compound, and thus the invention also relates to 1-(2-chlorophenyl)-5-chlorotetrazole. 1-(2-Chlorophenyl)-5-chlorotetrazole can quantitatively be obtained when 2-chlorophenylisocyanide dichloride is reacted with sodium azide, in the presence of inert solvents. The reaction is shown by the following reaction equation C. This reaction can be conducted, for example, by a process similar to that described in Journal of Organic Chemistry, Vol. 32, No. 11, pp. 3580-93; see also EP-0149269 and EP-0278542, and Example 2 below). 2-Chlorophenylisocyanide dichloride used as the starting material in the above reaction is a compound which is known per se [described in Angew. Chem., Vol. 74, page 861 (1962)], and which can be produced by the process described in the literature (see also the Reference Example below). The formed 1-(2-chlorophenyl)-5(4H)-tetrazolinone can be isolated and purified by a method which is known per se, such as extraction, chromatography or recrystallization. Then, the following examples illustrate the processes of the invention, but they should not be regarded as limiting the invention in any way. Example 1 A solution of sodium hydroxide (13 g, about 45% by weight) in water, 1-(2-chlorophenyl)-5-chlorotetrazole (12.9 g) in water (6.5 ml) were mixed and the mixture was heated to 110 °C. The reaction was initiated and the temperature increased to 115 °C. After 3 minutes from the initiation of the reaction, the temperature was lowered to room temperature and then water (20 ml) was added. The insoluble matter was extracted with toluene (10 ml) and the aqueous solution was adjusted to a pH of 1. The solid matter was collected by filtration followed by washing with water and drying to obtain as pale tan solid 1-(2-chlorophenyl)-5(4H)-tetrazolinone (11.3 g) (yield: 96%). melting point: 123-125 °C Example 2 (production of the starting material used in Example 1) To a solution of sodium azide (3.9 g) in water (20 ml) 2-chlorophenylisocyanide dichloride (12.9 g) dissolved in acetone solution (50 ml) was added under stirring. As the reaction proceeded, the temperature was elevated and reached about 50 °C. After stirring 15 minutes while maintaining the temperature of 50 °C, the mixture was heated for 30 minutes under refluxing. Acetone was distilled off under reduced pressure, and water (20 ml) was added to the residue to collect the product by filtration under reduced pressure. After washing, this was dried to obtain colorless 1-(2-chlorophenyl)-5-chlorotetrazole (12.9 g) (yield: quantitative). melting point: 101-103 °C Reference Example (production of the starting material used in Example 2 and 3) To a mixture of thionyl chloride (150 ml) and sulfuryl chloride (67.5 g) N-(2-chlorophenyl)-formamide (77.5 g) was added at a temperature of 15-20 °C. After stirring the mixture for 3 hours at room temperature, it was heated to 80 °C and stirred for 30 minutes. After completing the reaction, thionyl chloride was distilled off under reduced pressure to obtain 2-chlorophenyl-isocyanide dichloride (yield: 86.7%). boiling point: 104-106°C/10mmHg (13.3 mbar).

Claims: A process for producing 1-(2-chlorophenyl)-5(4H)-tetrazolinone which comprises hydrolyzing 1-(2-chlorophenyl)-5-chlorotetrazole, in the presence of a base selected from the group consisting of the hydroxides of alkaline metals and alkaline earth metals and in the presence of water, at a temperature of 50 °C to 160 °C, the reaction time ranging from 1 minute to 10 minutes. The process according to claim 1, wherein the hydrolysis is conducted at a temperature of 80 °C to 140 °C. 1-(2-Chlorophenyl)-5-chlorotetrazole of the formula:

Inventors: MAURER FRITZ DR, MAURER, FRITZ, DR.
Applicants: BAYER AGROCHEM KK, NIHON BAYER AGROCHEM K.K.
Application year: 1996
Main classification: C07D257
IPC codes: B01J23, C07D257, B01J27