WO2010041614A1

WO2010041614A1 - 2-benzyl-4-(2,4-dichlorophenyl)-5-methylimidazole compound

Info

Publication number: WO2010041614A1
Application number: PCT/JP2009/067308
Authority: WO
Inventors: Takayuki Murai; Masayuki Miyazaki; Hirohiko Hirao
Original assignee: Shikoku Chemicals Corporation
Priority date: 2008-10-06
Filing date: 2009-09-29
Publication date: 2010-04-15
Also published as: TW201014828A; MY158622A; KR20110073498A; CN102171382A; KR101602985B1; JP5368241B2; TWI435870B; CN102171382B; JP2011016785A

Abstract

An object is to provide a 2-benzyl-4-(2,4-dichlorophenyl)-5-methylimidazole compound useful as an antioxidant for copper surface, a curing agent for epoxy resins, or an intermediate for medicaments and agricultural chemicals. A 2-benzyl-4-(2,4-dichlorophenyl)-5-methylimidazole compound represented by the formula (I). The compound can be synthesized by reacting a 2-halogenated 2',4'-dichloropropiophenone compound with an arylacetamidine compound under heating in the presence of a dehydrohalogenating agent in an organic solvent. (I) wherein X₁ and X₂ are the same or different and represent a hydrogen atom, a chlorine atom, or a bromine atom.

Description

DESCRIPTION

2-BENZYL-4- (2 ,4-DICHLOROPHENYL) -5-METHYLIMIDAZOLE COMPOUND

Technical Field

The present invention relates to a novel 2-benzyl- 4- (2 , 4-dichlorophenγl) -5-methγlimidazole compound.

Background Art

As an imidazole compound similar to the compound of the invention, for example, 2- (2 , 4-dichloro-benzyl) -5- (3,4-dichloro-phenyl) -lH-imidazole is disclosed in Patent Document 1. However, in the document, an imidazole compound wherein a methyl group is bonded to the 4 (5) - position of the imidazole ring is not disclosed.

Citation List

Patent Literature [PLT 1] JP-T-2003-500357 (page 7, page 51)

Summary of Invention

An object of the invention is to provide a novel 2- benzyl-4- (2 , 4-dichlorophenyl) -5-methylimidazole compound. In order to solve the foregoing problem, the present inventors made extensive and intensive investigations. As a result , the present inventors have found that a novel 2-benzyl-4- (2,4-dichlorophenyl) -5- methylimidazole compound represented by the formula (I) can be synthesized and thus they have accomplished the invention.

That is, the present invention includes the following aspects in its broadest configurations: (1) A 2-benzyl-4-(2,4-dichlorophenyl) -5- methy1imidazole compound represented by the formula (I) :

wherein X₁ and X₂ are the same or different and represent a hydrogen atom, a chlorine atom, or a bromine atom.

The 2-benzyl-4- (2 , 4-dichlorophenyl) -S- methylimidazole compound of the invention is useful as an antioxidant for the surface of a metal, particularly a copper (including a copper alloy) and a curing agent or a curing accelerator of an epoxy resin and also as an intermediate raw material in medicinal and agricultural chemical fields.

Description of Embodiments The following will describe the invention in detail The 2-benzyl-4- (2 ,4-dichlorophenyl) -5- methylimidazole compound of the invention is one represented by the following formula (I) and examples thereof include : 2-benzyl-4- (2 ,4-dichlorophenyl) -5-methγlimidazole,

2- (2-chlorobenzyl) -4- (2 ,4-dichlorophenyl) -5- methylimidazole ,

2- (3-chlorobenzyl) -4- (2 ,4-diσhlorophenγl) -5- methylimidazole , 2- (4-chlorobenzyl) -4- (2 ,4-dichlorophenyl) -5- methylimidazole,

2- (2,3-dichlorobenzyl) -4- (2 ,4-dichlorophenyl) -5- methylimidazole ,

2- (2,4-dichlorobenzyl) -4- (2 ,4-dichlorophenyl) -5- methylimidazole,

2- (2,5-dichlorobenzyl) -4- (2 ,4-dichlorophenyl) -5- methylimidazole ,

2- (2,6-dichlorobenzyl) -4- (2 ,4-dichlorophenyl) -5- methylimidazole , 2- (3,4-dichlorobenzyl) -4- (2 ,4-dichlorophenyl) -5- methylimidazole ,

2- (3,5-dichlorobenzyl) -4- (2 , 4-dichlorophenyl) -5- methylimidazole ,

2- (2-bromobenzyl) -4- (2 ,4-dichlorophenyl) -5- methylimidazole,

2- (3-bromobenzyl) -4- (2 ,4-dichlorophenyl) -5- methylimidazole ,

2- (4-bromobenzyl) -4- (2 , 4-diσhlorophenyl) -5- methylimidazole , 2- (2 ,3-dibromobenzyl) -4- (2 ,4-dichlorophenyl) -5- methylimidazole ,

2- (2 ,4-dibromobenzyl) -4- (2 ,4-diσhlorophenyl) -5- methylimidazole ,

2- (2 , 5-dibromobenzyl) -4- (2 ,4-dichlorophenyl) -5- methylimidazole,

2- (2 , 6-dibromobenzyl) -4- (2 ,4-dichlorophenyl) -5- methylimidazole ,

2- (3,4-dibromobenzyl) -4- (2 ,4-dichlorophenyl) -5- methylimidazole , 2- (3, 5-dibromobenzyl) -4- (2 ,4-dichlorophenyl) -5- methylimidazole ,

2- (3-bromo-2-chlorobenzyl) -4- (2 , 4-dichlorophenyl) -5- methylimidazole ,

2- (4-bromo-2-chlorobenzyl) -4- (2 ,4-dichlorophenyl) -5- methylimidazole, 2- (5-bromo-2-chlorobenzγl) -4- (2 , 4-dichlorophenγl) -5- methylimidazole ,

2- (2-bromo-6-chlorobenzγl) -4- (2 , 4-dichlorophenγl) -5- methylimidazole, 2- (2-bromo-3-chlorobenzγl) -4- (2 ,4-dichlorophenyl) -5- methylimidazole ,

2- (4-bromo-3-chlorobenzγl) -4- (2 ,4-dichlorophenyl) -5- methγlimidazole ,

2- (5-bromo-3-chlorobenzyl) -4- (2 ,4-dichlorophenyl) -5- methylimidazole,

2- (2-bromo-5-chlorobenzyl) -4- (2 ,4-dichlorophenyl) -5- methylimidazole ,

2- (2-bromo-4-chlorobenzyl) -4- (2 ,4-dichlorophenyl) -5- methγlimidazole, and 2- (3-bromo-4-chlorobenzyl) -4- (2 ,4-dichlorophenyl) -5- methylimidazole .

wherein X_x and X₂ are the same or different and represent a hydrogen atom, a chlorine atom, or a bromine atom. The 2~benzγl-4- (2 , 4-dichlorophenγl) -5- methylimidazole compound of the invention can be synthesized in accordance with known methods. For example, as shown in the following reaction scheme, the compound can be synthesized by reacting a 2-halogenated 2 ' ,4 ' -dichloropropiophenone compound with an arylacetarnidine compound under heating in the presence of a dehydrohalogenating agent in an organic solvent.

wherein X₁ and X_∑ are the same as described above and X₃ represents a chlorine atom, a bromine atom, or an iodine atom. In the above-mentioned reaction, the amount of the arylacetamidine compound to be used is preferably in a ratio of 0.8 to 1.5 times moles , more preferably 0.9 to 1.1 times moles relative to the 2-halogenated 2 ',4'- dichloropropiophenone compound. The amount of the dehydrohalogenating agent to be used is preferably in a ratio of 1 to 10 times equivalents relative to the 2- halogenated 2 ' , 4 ' -dichloropropiophenone compound.

As the above 2-halogenated 2', 4'- dichloropropiophenone compound, there may be mentioned 2,2' ,4' -trichloropropiophenone, 2-bromo-2' ,4'- dichloropropiophenone, and 2-iodo-2' , 4' - dichloropropiophenone .

The 2-halogenated 2' ,4' -diσhloropropiophenone compound is obtained by halogenating the 2-position of 2' ,4' -dichloropropiophenone. As the halogenation, chlorination or iodination is also possible but a bromination reaction wherein an equimolar amount of bromine is reacted with 2' ,4' -dichloropropiophenone is most simple and convenient.

As 2' ,4' -dichloropropiophenone, a commercially available one as a reagent can be used.

The above arylacetamidine compound can be obtained by reacting an arylacetamidine hydrochloride with an alkali agent and removing hydrogen chloride. In the above-mentioned synthetic reaction of the imidazole compound, it is also possible to use an arylacetamidine hydrochloride or a salt of the arylacetamidine compound with a conventionally known inorganic acid or organic acid instead of the arylacetamidine compound.

The arylacetamidine hydrochloride can be synthesized in accordance with known methods. For example, as shown in the following reaction scheme, the arylacetamidine hydrochloride can be synthesized by reacting a benzyl cyanide compound with hydrogen chloride gas and a lower alcohol such as ethanol to effect conversion into an arylacetimidate hydrochloride and further reacting it with ammonia.

HClZC₂H₅OH

wherein X₁ and X₂ are the same as described above . Examples of the hydrochloride of the arylacetamidine compound obtained through such reactions include : phenylacetamidine hydrochloride , (2-chlorophenyl) acetamidine hydrochloride, (3-chlorophenyl)acetamidine hydrochloride, (4-chlorophenyl) acetamidine hydrochloride, (2 , 3-dichlorophenyl) acetamidine hydrochloride , (2 ,4-dichlorophenyl) acetamidine hydrochloride, (2 ,5-dichlorophenyl) acetamidine hydrochloride, (2 , 6-dichlorophenyl) acetamidine hydrochloride , (3,4-dichlorophenyl) acetamidine hydrochloride, (3 , 5-dichlorophenγl) acetamidine hydrochloride , (2-bromophenyl) acetamidine hydrochloride, (3-bromophenyl) acetamidine hydrochloride, (4-bromophenyl) acetamidine hydrochloride, (2 , 3-dibromophenγl ) acetamidine hydrochloride , (2,4-dibromophenyl) acetamidine hydrochloride , (2 , 5-dibromophenyl ) acetamidine hydrochloride , (2 , 6-dibromophenyl ) acetamidine hydrochloride , (3,4 -dibromophenyl ) acetamidine hydrochloride , (3 , 5-dibromophenyl ) acetamidine hydrochloride , (3-bromo-2-chlorophenyl) acetamidine hydrochloride, (4 -bromo-2-chlorophenyl) acetamidine hydrochloride, (5-bromo-2-chlorophenyl) acetamidine hydrochloride, (2-bromo-6-chlorophenγl) acetamidine hydrochloride, (2-bromo-3-chlorophenyl) acetamidine hydrochloride, (4-bromo-3-chlorophenyl) acetamidine hydrochloride, (5-bromo-3-chlorophenyl) acetamidine hydrochloride, (2-bromo-5-chlorophenyl) acetamidine hydrochloride,

(2-bromo-4-chlorophenyl) acetamidine hydrochloride, and (3-bromo-4 -chlorophenyl) acetamidine hydrochloride .

As the above dehydrohalogenating agent, any known one can be used without limitation. Examples of such a dehydrohalogenating agent include inorganic alkali compounds such as sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate; organic base compounds such as triethylamine and 1,8- diazabicyclo [5.4.0] -7-undecene (DBU); metal alkoxide compounds such as sodium methoxide and potassium tert- butoxide; and the like.

As the above organic solvent, any known one can be used without limitation as long as it can dissolve the 2- halogenated 2' ,4' -dichloropropiophenone compound and the arylaαetamidine compound and a salt thereof and is not involved in the reactions . Examples of such a solvent include alcohols such as isopropyl alcohol and tert- butanol ; hydrocarbons such as hexane and toluene; halogenated hydrocarbons such as chloroform and chlorobenzene ; esters such as ethyl acetate; nitriles such as acetonitrile; ethers such as tetrahydrofuran, dioxane, and ethylene glycol dimethyl ether; amides such as N,N-dimethylformamide (DMF) and N,N-dimethylacetamide (DMAC) ; dimethyl sulfoxide (DMSO) ; and the like. These solvents may be used in combination .

The reaction temperature is preferably from room temperature to refluxing temperature and the reaction time is preferably from 1 to 10 hours. The reaction may be usually carried out under atmospheric pressure.

The 2-benzγl-4- (2 , 4-dichlorophenγl) -5- methylimidazole compound formed under the above reaction conditions can be isolated by usual post-treatment . For example, a crude product of the compound can be obtained by partitioning the reaction mixture after completion of the reaction between an aqueous layer and an organic solvent layer and evaporating the organic solvent after washing the organic solvent layer with water, and the crude product can be further purified by recrystallization operation or the like.

Examples

The following will specifically describe the present invention with reference to Examples but it should not be construed that the invention is limited thereto. Incidentally, Reference Examples 1 and 2 show synthesis examples of phenylacetamidine hydrochloride and 2-bromo-2' ,4' -dichloropropiophenone, respectively.

Reference Example 1

(Synthesis of phenylacetamidine hydrochloride)

Into a solution consisting of 117.8 g (1.006 mol) of phenylacetonitrile and 55.8 g (1.21 mol) of dry ethanol was introduced 44.6 g (1.22 mol) of hydrogen chloride gas over a period of 4 hours at 5 to 10⁰C. When the reaction solution was allowed to stand at 4°C for 1 day and further at room temperature for 2 days , ethyl phenylacetimidate hydrochloride precipitated as a white solid. After ethyl phenylacetimidate hydrochloride collected by filtration was crushed, a solution consisting of 35.6 g (2.09 mol) of ammonia and 246 g of dry ethanol was added portionwise thereto with shaking under ice-cooling. Then, the mixture was stirred under ice cooling for 2 hours and further at room temperature overnight. After insoluble matters of a white solid were filtered off, the filtrate was concentrated to dryness under reduced pressure to obtain 172.5 g (1.011 mol, yield 100.5%) of phenylacetamidine hydrochloride in a pale yellow thick syrup form. Reference Example 2 (Synthesis of 2-bromo-2' ,4' -dichloropropiophenone)

To a solution consisting of 62.4 g (0.307 mol) of 2' ,4' -dichloropropiophenone and 70 g of methanol was added dropwise 49.8 g (0.312 mol) of bromine over a period of 45 minutes at 60 to 65°C. The reaction solution was concentrated to 115 g under reduced pressure and the concentrate was partitioned between 120 g of toluene and 150 g of water. After the toluene layer was washed with water and dried over magnesium sulfate, the solvent was evaporated under reduced pressure to obtain 84.8 g (0.301 mol, yield 98.0%) of 2 -bromo-2' ,4' -dichloropropiophenone as a pale yellow viscous substance.

Example 1

(Synthesis of 2-benzyl-4- (2,4-dichlorophenyl) -5- methylimidazole)

After a suspension consisting of 42.7 g (0.250 mol) of phenylacetamidine hydrochloride, 86.4 g (0.625 mol) of potassium carbonate, and 120 ml of N,N-dimethylformamide was stirred at 50°C for 40 minutes, a solution consisting of 70.5 g (0.250 mol) of 2-bromo-2' ,4' - dichloropropiophenone and 80ml of N,N-dimethylformamide was added dropwise thereto over a period of 1 hour 20 minutes at the same temperature, followed by stirring at 60°C for another 3 hours.

Then, after the reaction suspension was cooled, it was partitioned between 1000 ml of water and 200 ml of toluene. After the toluene layer was washed twice with water, toluene was evaporated under reduced pressure. Subsequently, 120 ml of acetonitrile was added thereto and the whole was stirred under heating to precipitate crystals. After cooling, the crystals were collected by filtration and washed with acetonitrile to obtain a milky white powder. The powder was subjected to recrystallization from acetonitrile to obtain 28.7 g (0.090 mol , yield 30.0%) of colorless needle-form crystals .

Melting point, Rf value on thin layer chromatography, and ¹H-NMR and mass spectral data of the obtained crystals were as follows, •mp. 167-169°C

^•TLC (silica gel, acetone) : Rf = 0.59 -¹H-NMR (de-DMSO) δ: 2.09 (s, 3H), 3.95 (s, 2H), 7.21-7.62 (m, 8H)

^•MS m/z (%) : 318 (M+2 , 62) , 316 (M⁺, 100), 301 (3), 281 (8), 239 (3), 190 (2), 171 (5), 136 (3) , 122 (7), 103 (6) , 91 (6) , 77 (3) .

Based on these spectral data, the obtained compound was identified as 2-benzyl-4- (2 ,4-dichlorophenyl) -5- methylimidazole represented by the following formula,

Example 2 (Synthesis of 2- (2-chlorobenzyl) -4- (2 , 4-dichlorophenyl) - 5-methylimidazole)

First, (2-chlorophenyl) acetamidine hydrochloride was synthesized in accordance with the method of Reference Example 1, changing phenylacetonitrile of Reference Example 1 to (2-chlorophenyl) acetonitrile . Next, white powdery crystals were obtained by carrying out a synthesis experiment in accordance with the method of Example 1 , changing phenylacetamidine hydrochloride of Example 1 to (2-chlorophenyl) acetamidine hydrochloride.

Melting point, Rf value on thin layer chromatography, and ¹H-NMR and mass spectral data of the obtained crystals were as follows . •mp. 161-163°C •TLC (silica gel, ethyl acetate) : Rf = 0.85

-¹H-NMR (de-DMSO) δ: 2.09 (s, 3H) , 4.06 (s, 2H), 7.26-7.60

(m, 7H) .

•MS m/z (%) : 352 (M+2 , 16), 350 (M⁺, 16), 317 (63), 315

(100) , 279 (3) , 243 (2) , 171 (2) , 137 (3) , 122 (6) , 101

(4).

Based on these spectral data, the obtained compound was identified as 2- (2-chlorobenzyl) -4- (2 ,4- dichlorophenyl) -5-methylimidazole represented by the following formula.

Example 3 (Synthesis of 2- (3-chlorobenzyl) -4- (2 ,4-dichlorophenyl) 5-methylimidazole)

First, (3-chlorophenyl) acetamidine hydrochloride was synthesized in accordance with the method of Reference Example 1, changing phenylacetonitrile of Reference Example 1 to (3-chlorophenyl) acetonitrile. Next, white powdery crystals were obtained by carrying out a synthesis experiment in accordance with the method of Example 1, changing phenylacetamidine hydrochloride of Example 1 to (3-chlorophenyl) acetamidine hydrochloride.

Melting point, Rf value on thin layer chromatography, and ¹H-NMR and mass spectral data of the obtained crystals were as follows . •mp. 143-146°C -TLC (silica gel, ethyl acetate): Rf = 0.75

-¹H-NMR (de-DMSO) δ: 2.09 (s, 3H), 3.96 (s, 2H), 7.24-7.62 (m, 7H) .

^•MS m/z (%) : 352 (M+2 , 93), 350 (M⁺, 100), 315 (18), 279 (3), 239 (5), 190 (2), 173 (3), 164 (5), 137 (6), 122 (9), 102 (6) , 89 (4) .

Based on these spectral data, the obtained compound was identified as 2- (3-chlorobenzyl) -4- (2,4- dichlorophenyl) -5-methylimidazole represented by the following formula.

Example 4 (Synthesis of 2- (4-chlorobenzγl) -4- (2 , 4-dichlorophenyl) -

5-methylimidazole)

First, (4-chlorophenyl) acetamidine hydrochloride was synthesized in accordance with the method of

Reference Example 1, changing phenylacetonitrile of Reference Example 1 to (4-chlorophenyl) acetonitrile. Next, white powdery crystals were obtained by carrying out a synthesis experiment in accordance with the method of Example 1, changing phenylacetamidine hydrochloride of Example 1 to (4-chlorophenyl) acetamidine hydrochloride .

Melting point, Rf value on thin layer chromatography, and ¹H-NMR and mass spectral data of the obtained crystals were as follows.

^•mp. 198-199°C -TLC (silica gel, ethyl acetate) : Rf = 0.85 -¹H-NMR (de-DMSO) δ: 2.08 (s, 3H) , 3.93 (s, 2H), 7.28-7.60 (m, 7H) .

•MS m/z (%) : 352 (M+2 , 91), 350 (M⁺, 100) , 315 (20), 279 (3), 239 (3) , 190 (3), 164 (4), 137 (7), 122 (10), 102 (6) , 89 (3) .

Based on these spectral data, the obtained compound was identified as 2- (4-chlorobenzγl) -4- (2,4- dichlorophenyl) -5-methylimidazole represented by the following formula.

Example 5 Synthesis of 2- (2 ,4-dichlorobenzγl) -4- (2 ,4- dichlorophenyl) -5-methylimidazole)

First, (2,4-dichlorophenyl)acetamidine hydrochloride was synthesized in accordance with the method of Reference Example 1, changing phenylacetonitrile of Reference Example 1 to (2,4- dichlorophenyl) acetonitrile.

Next, milky white powdery crystals were obtained by carrying out a synthesis experiment in accordance with the method of Example 1 _/ changing phenylacetamidine hydrochloride of Example 1 to (2,4- dichlorophenyl) acetamidine hydrochloride.

Melting point, Rf value on thin layer chromatography, and ¹H-NMR and mass spectral data of the obtained crystals were as follows . -rnp. 164-165°C

^•TLC (silica gel, acetone) : Rf = 0.66

-¹H-NMR (d₆-DMSO) δ: 2.10 (s, 3H), 4.06 (s, 2H), 7.35-7.60

(m, 6H)

^•MS m/z (%) : 388 (M+4, 14), 386 (M+2, 29), 384 (M⁺, 22), 351 (94) , 349 (100), 316 (20), 314 (31), 299 (2), 279 (2) ,

193 (2), 171 (5), 159 (5), 136 (7), 121 (4), 101 (3).

Based on these spectral data, the obtained compound was identified as 2- (2,4-dichlorobenzyl) -4- (2 ,4- dichlorophenyl) -5-methylimidazole represented by the following formula.

Example 6

(Synthesis of 2- (2 , 6-dichlorobenzγl) -4- (2 ,4- dichlorophenyl) -5-methylimidazole)

First , (2 , 6-dichlorophenyl ) acetamidine hydrochloride was synthesized in accordance with the method of Reference Example 1, changing phenylacetonitrile of Reference Example 1 to (2,6- dichlorophenyl) acetonitrile.

Next, white powdery crystals were obtained by carrying out a synthesis experiment in accordance with the method of Example 1, changing phenylacetamidine hydrochloride of Example 1 to (2,6- dichlorophenyl) acetamidine hydrochloride .

Melting point, Rf value on thin layer chromatography, and ¹H-NMR and mass spectral data of the obtained crystals were as follows. ^•mp. 240-241°C

•TLC (silica gel, hexane: ethyl acetate = 1:1) : Rf = 0.52

-¹H-NMR (d₆-DMSO) δ: 2.05 (s, 3H), 4.25 (s, 2H), 7.31-7.62

(m, 6H)

•MS m/z (%) : 388 (M+4 , 13), 386 (M+2 , 27), 384 (M⁺, 21),

351 (99), 349 (100), 314 (32), 299 (3), 279 (3), 243 (3),

193 (4), 171 (7), 159 (7), 139 (11), 121 (9), 101 (6), 89

(2), 75 (3).

Based on these spectral data, the obtained compound was identified as 2- (2 , 6-dichlorobenzyl) -4- (2 ,4- dichlorophenγl) -5-methylimidazole represented by the following formula .

Example 7

(Synthesis of 2- (3,4-dichlorobenzγl) -4- (2 ,4- dichlorophenyl) -5-methylimidazole)

First , (3 , 4-dichlorophenyl) acetamidine hydrochloride was synthesized in accordance with the method of Reference Example 1 , changing phenylacetonitrile of Reference Example 1 to (3,4- dichlorophenyl) acetonitrile.

Next, white powdery crystals were obtained by carrying out a synthesis experiment in accordance with the method of Example 1, changing phenylacetamidine hydrochloride of Example 1 to (3,4- dichlorophenyl) acetamidine hydrochloride.

Melting point, Rf value on thin layer chromatography, and ¹H-NMR and mass spectral data of the obtained crystals were as follows . •mp. 184-185°C

^•TLC (silica gel, ethyl acetate): Rf = 0.80 -¹H-NMR (dβ-DMSO) δ: 2.08 (s, 3H), 3.96 (s, 2H), 7.26-7.61 (m, 6H)

•MS m/z (%) : 388 (M+4 , 48), 386 (M+2 , 100), 384 (M⁺, 80), 349 (13) , 314 (9) , 239 (5) , 212 (2) , 190 (3) , 171 (8) , 159 (6) , 136 (10) , 121 (5) , 101 (3) .

Based on these spectral data, the obtained compound was identified as 2- (3,4-dichlorobenzyl) -4- (2 ,4- dichlorophenyl) -5-methylimidazole represented by the following formula.

Example 8

(Synthesis of 2- (4-bromobenzγl) -4- (2, 4-dichlorophenyl) -5- methylimidazole)

First, (4-bromophenyl) acetamidine hydrochloride was synthesized in accordance with the method of Reference Example 1, changing phenylacetonitrile of Reference Example 1 to (4-bromophenyl) acetonitriIe.

Next, white powdery crystals were obtained by carrying out a synthesis experiment in accordance with the method of Example 1 , changing phenylacetamidine hydrochloride of Example 1 to (4-bromophenyl) acetamidine hydrochloride .

Melting point, Rf value on thin layer chromatography, and ¹H-NMR and mass spectral data of the obtained crystals were as follows. -mp. 206-207⁰C •TLC (silica gel, hexane:ethyl acetate = 1:1): Rf = 0.38 -¹H-NMR (d₆-DMSO) δ: 2.07 (s, 3H), 3.92 (s, 2H), 7.24-7.63 (m, 7H)

•MS m/z (%) : 398 (M+4 , 47), 396 (M+2 , 100), 394 (M⁺, 64), 361 (6) , 315 (11) , 299 (3) , 279 (3) , 239 (5) , 198 (4) , 183 (3), 171 (11), 136 (6), 122 (20), 102 (17), 89 (8), 75 (5) .

Based on these spectral data, the obtained compound was identified as 2- (4-bromobenzyl) -4- (2 , 4- dichlorophenyl) -5-methylimidazole represented by the following formula .

Example 9

Surface treating liquids containing each of the imidazole compounds synthesized in Examples 1 to 8 and, other than these compounds, 2-phenylimidazole as an effective ingredient were prepared. A chemical film was formed on the surface of copper by bringing each of the treating liquids into contact with copper and wetting time of molten solder to copper was measured, thereby antioxidation performance to the copper surface on which the imidazole compound acted being measured. In this case, it was judged that the shorter the wetting time is, the more excellent the antioxidation performance of the imidazole compound is.

Details of the evaluation test are as follows. (1) Preparation of surface treating liquid:

After the imidazole compound, an acid, a metal salt, and a halogen compound were dissolved in ion-exchanged water so as to achieve composition described in Table 1, pH was adjusted with ammonia water to prepare a surface treating liquid.

(2) Surface treatment method:

A test piece whose material was metallic copper (a copper plate having a size of 5 mm x 50 mm x 0.3 mm) was degreased and then subjected to soft etching. After the test piece was immersed in a surface treating liquid at a predetermined temperature for a predetermined time to form a chemical film on the surface of copper, the test piece was washed with water and dried. (3) Measurement of wetting time:

The test piece subjected to the surface treatment was immersed in a post flux [trade name "JS-64MSS" manufactured by Koki Co., Ltd.] and solder wetting time (sec) was measured by a solder wetting tester (SAT-2000, manufactured by Rhesca Corporation) . The solder used was a tin-lead eutectic solder (trade name: H63A, manufactured by Senju Metal Industry Co., Ltd.) and the measurement conditions were as follows: soldering temperature 240°C, immersion depth 2 mm, immersion speed 16 mm/sec.

In this connection, the test pieces on which the solder wetting time was measured were (A) one immediately after the surface treatment, (B) one after allowed to stand in a constant-temperature constant-humidity chamber at a temperature of 40⁰C and a humidity of 90% RH for 96 hours, and (C) one after further heated at 200°C for 10 minutes .

The obtained test results were as shown in Table 1.

Table 1

CO

According to the test results shown in Table 1, since the surface treating liquids containing a 2-benzyl- 4- (2,4-dichlorophenyl) -5-methylimidazole compound of the invention as an effective ingredient can form a chemical film excellent in moisture resistance and heat resistance on the surface of copper, they are useful for antioxidation of copper surface.

Industrial Applicability The present invention can provides a 2-benzyl-4-

(2 ,4 -dichlorophenyl) -5-methylimidazole compound useful as an antioxidant for the surface of a metal, particularly copper including a copper alloy and a curing agent or a curing accelerator for epoxy resins and also as an intermediate raw material in medicinal and agricultural chemical fields .

While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the scope thereof.

This application is based on Japanese patent application No. 2008-259661 filed on October 6, 2008, and Japanese patent application No. 2009-138853 filed on June 10, 2009, the entire contents thereof being hereby incorporated by reference.

Claims

1. A 2-benzyl-4- (2 ,4-dichlorophenyl) -5-methylimidazole compound represented by the formula (I) :