JP2001181265A - Method for producing mercaptotetrazole compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for readily and safely producing a highly pure crystalline mercaptotetrazole compound in high yield. SOLUTION: This method for producing the mercaptotetrazole compound is characterized in that the mercaptotetrazole compound is produced by reacting an azide with an isothiocyanate compound in an aqueous solvent, extruding the objective compound from the reaction mixture with an organic solvent under a neutral to acidic condition, subjecting the resultant organic layer to an extraction operation with water under an alkali condition, and crystallizing the objective material from the obtained aqueous layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a simple method for producing a high-purity mercaptotetrazole compound.

[0002]

2. Description of the Related Art Mercaptotetrazole compounds are useful as intermediates for pharmaceuticals, agricultural chemicals and photographic chemicals, but have recently become more and more diversified in the field of photography and have become more sophisticated. There is a demand for one having stable purity and quality.

[0003] Various methods are known for synthesizing mercaptotetrazole compounds. At present, a method obtained by reacting an azide compound and an isothiocyanate compound is the most economical method from an industrial viewpoint. It is considered.

However, conventionally, the mercaptotetrazole compound produced by this method contains many impurities, and an extremely complicated purification operation was required to remove the impurities. Further, at the time of its production, an organic solvent was used as a main reaction solvent, so that it was necessary to heat and concentrate the reaction solution in the treatment after the reaction. Since the reaction solution contains highly explosive and highly toxic azide compounds,
Heating this has increased the risk of explosion, and has caused the generation of hydrogen azide gas, thereby deteriorating the working environment.

[0005] In order to avoid the need for heat treatment,
A method of performing the reaction using water as a main reaction solvent and obtaining a target product by crystallization was also attempted, but extracting crude crystals from a mother liquor containing an azide compound still poses a danger. Since the obtained crude crystals contain impurities such as residual raw materials and sulfur, there has been a problem that the use of the crude crystals requires further complicated purification work such as recrystallization.

[0006]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above situation, and has as its object to provide a method capable of easily and safely producing a high-purity crystalline mercaptotetrazole compound in a high yield. Aim.

[0007]

According to the present invention, an azide compound and an isothiocyanate compound are reacted in an aqueous solvent, and then the target substance is extracted with an organic solvent under neutral or acidic conditions. A method for producing a mercaptotetrazole compound, comprising subjecting a layer to an extraction operation with water under alkaline conditions, and crystallizing a target substance from the obtained aqueous layer.

The azide compound used in the method of the present invention includes, for example, alkali metal azide compounds such as lithium azide, sodium azide and potassium azide.
Examples thereof include alkaline earth metal compounds such as beryllium azide, magnesium azide, calcium azide, and barium azide.

As the isothiocyanate compound, for example, a compound represented by the general formula [1]:

[0010]

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(Wherein, R represents an alkyl group, a haloalkyl group, an acyl group, an alkoxy group, an optionally substituted aryl group, an arylthio group, or a sulfur atom which may have a sulfur atom; X represents a bond, or a divalent hydrocarbon group optionally having an oxygen atom or a sulfur atom.).

In the general formula [1], the alkyl group of the alkyl group optionally having a sulfur atom represented by R may be linear, branched or cyclic, and usually has a carbon number of 1-18, preferably those having 1-6 carbon atoms, specifically, for example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, sec-butyl group, n-pentyl group, isopentyl group, neopentyl group, tert-
Pentyl group, 1-methylpentyl group, 3,3-dimethylbutyl group, 1,1-dimethylbutyl group, n-hexyl group, isohexyl group, 2-methylpentyl group, 3-methylpentyl group, n-heptyl group, Isoheptyl group, n-
Octyl group, isooctyl group, 2-ethylhexyl group,
Nonyl, decyl, undecyl, dodecyl, hexadecyl, octadecyl, cyclopropyl, cyclopentyl, cyclohexyl, 2-cyclohexylethyl and the like.

As an alkyl group having a sulfur atom
Has usually 1 to 3 sulfur atoms in the alkyl group.
And specifically, for example, CH_Three-S-CH
_Two-, CH _ThreeCH_Two-S-CH_Two-, CH_ThreeCH (CH_Three) -S-CH_Two-, CH_Three-S-CH_TwoC (C
H_Three)_TwoCH_Two-S-CH_Two-, CH_ThreeCH_Two-S-CH_Two-S-CH_Two-S-CH_Two-Etc.
Can be

As the haloalkyl group, there can be mentioned those in which one or more, preferably 1 to 17, hydrogen atoms of the above-mentioned alkyl group have been replaced by halogen atoms such as fluorine, chlorine, bromine and iodine. For example, fluoromethyl group, trichloromethyl group, bromomethyl group, 1,1-difluoroethyl group, 1,2-dichloroethyl group, perfluoropropyl group, 3,3,3-trichloropropyl group, perfluorobutyl group, Fluorohexyl group,
And perfluorooctyl groups.

Examples of the acyl group include an acyl group derived from an aliphatic saturated monocarboxylic acid, an acyl group derived from an aliphatic unsaturated monocarboxylic acid, and an acyl group derived from an aromatic monocarboxylic acid. The acyl group derived from the aliphatic saturated monocarboxylic acid may be linear, branched or cyclic, and usually has 2 to 18 carbon atoms, preferably 2 to 6 carbon atoms, and specifically, Examples thereof include an acetyl group, a propionyl group, a butyryl group, an isobutyryl group, a valeryl group, an isovaleryl group, a hexanoyl group, a cyclohexanecarbonyl group, a pivaloyl group, a lauroyl group, a myristoyl group, a palmitoyl group, and a stearoyl group. The acyl group derived from the aliphatic unsaturated monocarboxylic acid may be linear or branched, and usually has 3 to 18 carbon atoms.
Preferred are those having 3 to 6 carbon atoms, and specific examples include an acryloyl group, a propioyl group, a crotonoyl group, and an oleoyl group. Examples of the acyl group derived from an aromatic monocarboxylic acid include a benzoyl group, a toluoyl group, a hydroatropoyl group, an atropoyl group, and a cinnamoyl group.

The alkoxy group may be linear, branched or cyclic, and usually has 1 to 18 carbon atoms, preferably 1 to 6 carbon atoms. Ethoxy, n-propoxy, isopropoxy, butoxy, isobutoxy, sec-butoxy, tert-butoxy, pentyloxy,
Isopentyloxy group, sec-pentyloxy group, t
ert-pentyloxy group, neopentyloxy group, hexyloxy group, cyclohexyloxy group, heptyloxy group, cycloheptyloxy group, octyloxy group,
Nonyloxy group, decyloxy group, dodecyloxy group,
Examples include a pentadecyloxy group, a heptadecyloxy group, and an octadecyloxy group.

The aryl group of the aryl group which may have a substituent generally has 6 to 10 carbon atoms. Specifically, for example, a phenyl group, an o-tolyl group, an m-tolyl group
-Tolyl group, p-tolyl group, 2,3-xylyl group, 2,4
-Xylyl group, 2,5-xylyl group, 2,6-xylyl group, 3,5-xylyl group, naphthyl group, anthryl group and the like.

The aryl group having a substituent includes:
For example, those in which usually 1 to 3 hydrogen atoms of the above aryl group are substituted with a halogen atom such as chlorine, bromine, iodine, fluorine and the like, a nitro group and the like are mentioned.
For example, an o-chlorophenyl group, a p-chlorophenyl group,
m-chlorophenyl group, o-fluorophenyl group, p-
Fluorophenyl group, m-fluorophenyl group, o-nitrophenyl group, p-nitrophenyl group, m-nitrophenyl group, 1-chloro-5-methylphenyl group, 4-nitro-2-
Examples include a methylphenyl group and a 3-chloro-2,4-dimethylphenyl group.

The arylthio group usually has 6 to 6 carbon atoms.
10, specifically, for example, phenylthio group, o-tolylthio group, m-tolylthio group, p-tolylthio group, 2,3-xylylthio group, 2,4-xylylthio group, 2,5-xylylthio group Groups, 2,6-xylylthio group, 3,5-xylylthio group, naphthylthio group, anthrylthio group and the like.

Examples of the aralkyl group of the aralkyl group which may have a sulfur atom include those in which a hydrogen atom of the above-mentioned alkyl group is substituted with an aromatic ring. Specifically, for example, a benzyl group, a phenethyl group, a phenylpropyne group Benzyl group, methylbenzyl group, methylphenethyl group, ethylbenzyl group and the like.

Examples of the aralkyl group having a sulfur atom include phenylthiomethyl, benzylthio, benzylthiomethyl, phenethylthio, phenylthiopropyl, benzylthioethyl, methylbenzylthio, methylbenzyl A thiomethyl group, a methylbenzylthioethyl group, an ethylbenzylthiomethyl group and the like.

In the general formula [1], examples of the divalent hydrocarbon group of the divalent hydrocarbon group optionally having an oxygen atom and / or a sulfur atom represented by X include carbon Number 1
-20, preferably 1-10 alkylene groups, and divalent aromatic groups and divalent araliphatic groups. The alkylene group may be linear, branched, or cyclic, and specifically includes, for example, a methylene group, an ethylene group, a trimethylene group, a propylene group, a tetramethylene group, a butylene group, a 2-methylpropylene group, and a pentane group. Methylene group, pentylene group, 2,2-dimethylpropylene group, 2-ethylpropylene group, hexamethylene group, hexylene group, heptylene group, octylene group, 2-ethylhexylene group, nonylene group, decylene group, cyclopropylene group , cyclopentylene group, cyclohexylene group, adamantane-diyl group, a tricyclo [5.2.1.0 ^2.6] decanediyl group, a norbornanediyl group, methyl norbornane-diyl group, iso norbornane-diyl group, Dekarinjiiru group and the like. Examples of the divalent aromatic group include an o-phenylene group, an m-phenylene group, a p-phenylene group, a diphenylene group, a p-xylene-α, α′-diyl group, and the like. Examples of the divalent araliphatic group include -CH _{2
-C 6 H 4 -, - CH} 2 -C 6 H 4 -CH 2 - , and the like.

As a divalent hydrocarbon group having an oxygen atom
Is, for example, a -O- group in the chain forming the alkylene group.
And, specifically, for example, -C
H_Two-O-CH_Two-, -CH_TwoCH_Two-O-CH_Two-, -CH_Two-O-CH_Two-O-CH_Two-, -CH_Two
CH_Two-O-CH_TwoCH_Two-, -CH_TwoCH_Two-O-CH_Two-O-CH_TwoCH_Two-, -CH_Two-O-CH_Two
-O-CH_Two-O-CH_Two-, -CH_Two-O-CH (CH_TwoCH_Three) -CH_Two-, -CH_TwoCH_Two-O-C
H (CH_Three) -O-CH_Two-And so on. Divalent with sulfur atom
As the hydrocarbon group of, for example, the above alkylene group is formed
And those containing 1 to 3 -S- in the chain
Typically, for example, -S-CH_Two-, -CH_Two-S-CH_Two-, -CH_TwoCH_Two-S-CH
_Two-, -CH_Two-S-CH_TwoCH _Two-S-CH_Two-, -CH_Two-S-CH_Two-S-CH_Two-, -CH_TwoC
H_Two-S-CH_TwoCH_Two-, -CH_TwoCH_Two-S-CH_Two-S-CH_TwoCH_Two-, -CH_Two-S-CH_Two-
S-CH_Two-S-CH_Two-, -CH_Two-S-CH (CH_TwoCH_Three) -CH_Two-, -CH_TwoCH_Two-S-CH
(CH_Three) -S-CH_Two-And so on. Oxygen and sulfur atoms above
When mixed in the chain forming the alkylene group
As a body example, for example, -CH_TwoSCH_TwoCH_TwoOCH_Two-, -CH_TwoSCH_TwoCH_TwoC
H_TwoOCH_TwoCH_Two-, -CH_TwoSCH_TwoC (CH_Three)_TwoCH_TwoOCH_Two-And so on
You.

Isocyanation represented by the general formula [1]
Specific examples of the compound include, for example, methyl isothiocyanate
G, ethyl isothiocyanate, n-propyl isothio
Cyanate, isopropyl isothiocyanate, n-butyl
Tyl isothiocyanate, isobutyl isothiocyanate
G, sec-butyl isothiocyanate, tert-butyl
Tyl isothiocyanate, n-pentyl isothiocyane
, Isopentyl isothiocyanate, tert-paper
Nethyl isothiocyanate, neopentyl isothiocyan
, N-hexyl isothiocyanate, 1-methyl
Pentyl isothiocyanate, cyclohexyl isothio
Cyanate, phenyl isothiocyanate, naphthyl
Sothiocyanate, o-tolyl isothiocyanate,
2,6-xylyl isothiocyanate, 3,5-xylyl
Isothiocyanate, benzyl isothiocyanate,
Hydryl isothiocyanate, phenethyl isothio
Cyanate, trityl isothiocyanate, CH_ThreeCH_TwoCH_TwoO
CH_TwoCH_Two-NCS, CH_ThreeCH_TwoOCH (CH _Three) CHOCH_Two-NCS, CH_ThreeC (CH_Three)_TwoCH
_TwoCH_TwoSCH_Two-NCS, (CH_Three)_TwoCCH_TwoSCH_TwoSCH_TwoCH_TwoSCH_TwoCH_Two-NCS, CH
_ThreeCH_TwoSCH_TwoCH_TwoCH_TwoOCH_TwoCH_Two-NCS, CH_ThreeCH_TwoSCH_TwoC (CH_Three)_TwoCH_TwoOCH
_Two-NCS and the like.

The mercaptotetrazole compound obtained by the method of the present invention includes, for example, a compound of the general formula [2]

[0026]

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(Wherein R and X are as defined above), specifically, for example, 1-methyl-5-mercaptotetrazole, 1-ethyl-5-mercaptotetrazole, n-propyl-5-mercaptotetrazole, 1-isopropyl-5-mercaptotetrazole, 1-n-butyl-5-mercaptotetrazole, 1-isobutyl-5-mercaptotetrazole,
1-sec-butyl-5-mercaptotetrazole, 1
-Tert-butyl-5-mercaptotetrazole, 1
-N-pentyl-5-mercaptotetrazole, 1-isopentyl-5-mercaptotetrazole, 1-sec
-Pentyl-5-mercaptotetrazole, 1-ter
t-pentyl-5-mercaptotetrazole, 1-neopentyl-5-mercaptotetrazole, 1-n-hexyl-5-mercaptotetrazole, 1-isohexyl-5-mercaptotetrazole, 1-cyclohexyl-
5-mercaptotetrazole, 1-naphthyl-5-mercaptotetrazole, 1-phenyl-5-mercaptotetrazole, 1-o-tolyl-5-mercaptotetrazole, 1-p-tolyl-5-mercaptotetrazole,
1- (2,6-xylyl) -5-mercaptotetrazole, 1- (3,4-xylyl) -5-mercaptotetrazole, 1-benzyl-5-mercaptotetrazole,
1-benzhydryl-5-mercaptotetrazole, 1
Phenethyl-5-mercaptotetrazole, 1-trityl-5-mercaptotetrazole,

[0028]

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[0029]

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[0030]

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[0031]

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[0032]

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[0033]

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And the like.

The method for producing a mercaptotetrazole compound of the present invention is specifically carried out as follows.

That is, an azide compound is dissolved in an aqueous solvent,
While the solution is being heated, the isothiocyanate compound is added as it is or dissolved in a solvent to be used, and the mixture is allowed to react.Then, the reaction solution is neutralized to acidic by adding an acid, and then an organic solvent is added to perform an extraction operation. . After adding a base to the obtained organic layer, an extraction operation is performed by adding water, or a basic aqueous solution is added to the organic layer, and an extraction operation is performed, and a target substance is crystallized from the obtained aqueous layer. Thus, a high-purity mercaptotetrazole compound is obtained.

If the amount of the azide compound is too small,
Since a decomposed product of the isothiocyanate compound is easily generated, it is usually equimolar to 2 moles to the isothiocyanate compound.
The molar amount is twice as much, preferably equimolar to slightly excess.

As the aqueous solvent, water is most preferred.
For example, it may contain a water-soluble organic solvent such as alcohols such as methanol, ethanol, isopropanol, and butanol; nitriles such as acetonitrile; amides such as N, N-dimethylformamide; and ethers such as tetrahydrofuran. . In this case, when the proportion of the organic solvent increases, not only the post-treatment becomes complicated, but also depending on the type of the contained organic solvent, a side reaction proceeds preferentially. Is usually at most 50%, preferably at most 20%, more preferably at most 10%.

The amount of the aqueous solvent used is usually 1 to 50 times, preferably 2 to 10 times the weight of the azide compound used.

If the reaction temperature is too low, the reaction rate is reduced, so that the reaction temperature is usually 40 to 120 ° C., preferably 60 to 120 ° C.
0 ° C.

When reacting the azide compound with the isothiocyanate compound, an exothermic reaction occurs rapidly when the entire amount is reacted at once. Therefore, the azide compound is first dissolved in a solvent, and the isothiocyanate compound is added dropwise thereto. It is desirable to react.

The reaction time is generally 5 minutes to 5 hours, preferably 10 minutes to 2 hours.

As the acid added to the reaction solution after the reaction is completed, for example, mineral acids such as hydrochloric acid, sulfuric acid, phosphoric acid, and nitric acid, and sulfonic acids such as methanesulfonic acid, ethanesulfonic acid, p-toluenesulfonic acid, and the like. No.

The purpose of using an acid is to make the target substance a free substance and transfer it to the organic layer by making the reaction solution neutral or acidic. Therefore, the amount of the acid used is an amount necessary to make the target substance a free body.

The acid may be added before the extraction solvent is added to the reaction solution as described above, or may be added after the extraction solvent is added.

Examples of the extraction solvent include hydrocarbons such as hexane, toluene, xylene and benzene, halogenated hydrocarbons such as methylene chloride, 1,2-dichloroethane and chloroform, and esters such as ethyl acetate and butyl acetate. Examples thereof include ketones such as ethyl methyl ketone and methyl isobutyl ketone, and ethers such as dioxane, diethyl ether, diisopropyl ether and t-butyl methyl ether. These may be used alone or in combination of two or more.

The amount of the extraction solvent is usually 1 to 20 times the theoretical amount of the mercaptotetrazole compound to be finally obtained.

When the organic layer containing the target substance is further subjected to an extraction operation with water, the extraction is performed under alkaline conditions, whereby the target substance moves from the organic layer to the aqueous layer. As the base added to make the liquid alkaline, any base may be used as long as it forms a water-soluble salt. Specifically, for example, triethylamine, diisopropylethylamine, N, N-dimethylaniline, piperidine , Pyridine, 4-dimethylaminopyridine, 1,5-diazabicyclo [4.3.0] non-5-ene, 1,8-diazabicyclo [5.4.0] undec-7-ene, tri-n-butylamine, N-methyl Organic bases such as morpholine, alkali metal hydroxide compounds such as sodium hydroxide, alkali metal carbonate compounds such as sodium carbonate, alkali metal bicarbonate compounds such as sodium hydrogen carbonate and the like can be mentioned. When these bases are used as an aqueous solution, they may be added as an aqueous layer to the organic layer and extracted.

Further, by passing the obtained water layer through an adsorbent such as activated carbon, for example, sulfur and the like as impurities can be efficiently adsorbed and removed, such an operation may be performed as a post-treatment. .

Crystallization of the target product may be carried out by a method generally used in this field, for example, by adding a crystallization solvent to the obtained aqueous layer and then adding an acid.

Examples of the crystallization solvent to be added include water-soluble organic solvents such as acetonitrile, acetone and tetrahydrofuran.

The amount of the crystallization solvent is usually 0.1 to 20 times the theoretical amount of the mercaptotetrazole compound to be finally obtained.

Examples of the acid used for crystallization include mineral acids such as hydrochloric acid, sulfuric acid and phosphoric acid, and sulfonic acid derivatives such as p-toluenesulfonic acid. When the acid is added to the reaction solution, a higher purity mercaptotetrazole compound can be obtained by slowly adding the acid dropwise than by adding the entire amount at once.

The amount of the acid used for crystallization is an equimolar amount or a slight excess with respect to the base remaining in the water tank.

After the target product is crystallized, the crystallized product is washed with a mixed solvent of water and a water-soluble organic solvent, for example, by kneading, to easily obtain a higher-purity mercaptotetrazole compound. Can be

After the crystallization, the target substance may be obtained by draining the liquid and subjecting it to a usual method such as drying under reduced pressure and drying with air.

In the method of the present invention, the temperature during the post-treatment is usually 0 to 50 ° C., preferably 10 to 40 ° C.
When the reaction solution generates heat, the above-mentioned temperature range may be maintained by cooling or the like.

Other reaction operations and post-treatment methods, etc.
What is necessary is just to carry out according to the same kind reaction normally performed.

As described above, the present invention does not require a heating operation at a high temperature, which requires solvent concentration, which is performed by a conventional method at the time of the post-treatment of the reaction, and the desired mercaptotetrazole is obtained by extraction and crystallization. The advantage of obtaining a compound is that the risk of explosion of azide during manufacturing can be avoided, and the exposure to toxic gas, hydrogen azide, can be avoided, resulting in significantly improved work safety. Having.

Further, according to the method of the present invention, a high-purity crystalline mercaptotetrazole compound which is easy to handle can be easily obtained in a high yield.

Thus, the mercaptotetrazole compound obtained by the method of the present invention can be used very effectively also as a development inhibitor for photography requiring high purity and stable quality.

Hereinafter, the present invention will be described specifically with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

[0063]

[Embodiment 1] 48.1 g of sodium azide in water 150
After dissolving in 100 ml, the mixture was heated to 90 ° C., and 100 g of phenyl isothiocyanate was added dropwise thereto over about 30 minutes.
The mixture was stirred and reacted for minutes. After completion of the reaction, the reaction solution was water-cooled to about 30 ° C., 400 ml of ethyl acetate and 74.5 g of hydrochloric acid were added, and the mixture was separated to extract a desired product. 130 g of a 25% aqueous sodium hydroxide solution, 150 ml of water and 180 ml of hexane were added to the obtained organic layer,
Liquid separation was performed again to extract the desired product. Activated carbon in the resulting water layer
After adding 3 g and adsorbing impurities, activated carbon was filtered using 30 ml of water. After 100 ml of acetonitrile was added to the reaction solution, 81 g of hydrochloric acid was added dropwise thereto under water cooling over about 30 minutes.
After the completion of the dropwise addition, the mixture was allowed to stand for about 1 hour to crystallize the desired product. The crystallized product was filtered and blown dry to obtain 122 g of 1-phenyl-5-mercaptotetrazole (yield: 93%).

FIG. 1 shows the results of HPLC analysis of the obtained compound. However, HPLC measurement conditions are as follows.

<HPLC measurement conditions> Column: Wakosil 5C18 (trade name of Wako Pure Chemical Industries, Ltd.)
4.6 × 150 mm Eluent: acetonitrile / water / 70% HClO ₄ = 500/500/1 Wavelength: λ = 254 nm Flow rate: 1.5 ml / min Preparation: 0.1 g of sample crystal was eluted to 10 ml, and 0.1
Make up to 20 ml with the eluent.

Comparative Example 1 According to the method described in JP-A-58-23681, a mercaptotetrazole compound was produced as follows. After dissolving 6.6 g of sodium azide in a solution consisting of 24 ml of ethanol and 6 ml of water, the mixture was heated to 70 ° C., and 13.5 g of phenylisothiocyanate was added thereto for about 3 hours.
The mixture was added dropwise over 5 minutes, and then reacted with stirring for about 2 hours. After completion of the reaction, the reaction solution was cooled with water to about 30 ° C., and concentrated by heating under reduced pressure (4.
(0-60 ° C) to remove ethanol. After 12 g of hydrochloric acid and 50 ml of water were added to the residue, 100 ml of ethyl acetate was added, and the mixture was separated to extract the desired product. 15 g of anhydrous sodium sulfate was added to the obtained organic layer, followed by drying and filtration.
The mixture was concentrated under reduced pressure to obtain 17.3 g of 1-phenyl-5-mercaptotetrazole (yield: 97%).

FIG. 2 shows the results of HPLC analysis of the obtained compound. The HPLC measurement conditions are the same as in Example 1.

Comparative Example 2 37 g of sodium azide in 350 ml of water
After dissolving in phenyl isothiocyanate 70 g
Over about 5 minutes, and then heated to about 100 ° C.
The mixture was stirred and reacted for hours. After the completion of the reaction, the reaction solution was cooled with water to about 35 ° C., and 64 g of hydrochloric acid was added dropwise to the reaction solution. After standing overnight, the obtained crystallized product was washed with water, dehydrated, and dried with 1-phenyl-5-methylbenzene.
118 g (wet) of crude crystals of mercaptotetrazole were obtained.

FIG. 3 shows the results of HPLC analysis of the obtained compound. The HPLC measurement conditions are the same as in Example 1.

The mercaptotetrazole compound obtained in Example 1 was found to be of very high purity from the fact that only one peak appeared in the analysis by HPLC as apparent from FIG.

On the other hand, the mercaptotetrazole compound obtained by the method of Comparative Examples 1 and 2, which is a conventional method, has a plurality of peaks in HPLC analysis as apparent from FIGS. It can be seen that there are many impurities and the purity is low as compared with the compound obtained by the method.

In Comparative Examples 1 and 2, toxic hydrogen azide gas is generated particularly when the reaction solution is concentrated by heating or when crystallizing with an acid, and safety measures such as working with a ventilation mask are used. However, in Example 1, there was no danger of gas generation or explosion in the whole process, and it was found that the mercaptotetrazole compound could be produced extremely safely.

[0073]

According to the present invention, there is provided a method for easily obtaining a high-purity mercaptotetrazole compound in a crystalline form. According to the method of the present invention, a problem in the conventional method, for example, Produces the desired high-purity mercaptotetrazole compound easily and in high yield without worrying about the danger of toxic gas generation or its explosion caused by using azide compounds as raw materials I can do it.

[Brief description of the drawings]

FIG. 1 shows the results obtained by Example 1 which is the method of the present invention.
3 shows the results of HPLC analysis of -phenyl-5-mercaptotetrazole.

FIG. 2 shows 1- obtained by Comparative Example 1 which is a conventional method.
3 shows the results of HPLC analysis of phenyl-5-mercaptotetrazole.

FIG. 3 shows 1- obtained by Comparative Example 2 which is a conventional method.
3 shows the results of HPLC analysis of phenyl-5-mercaptotetrazole.

Claims (1)

[Claims] 1. A reaction between an azide compound and an isothiocyanate compound in an aqueous solvent, followed by extraction of the target substance with an organic solvent under neutral or acidic conditions, and the resulting organic layer is diluted with water under alkaline conditions. A method for producing a mercaptotetrazole compound, comprising subjecting an intended operation to crystallization from an aqueous layer obtained by performing an extraction operation.