JP2010095509A - 2-(2,4-dichlorobenzyl)-4-phenyl-5-alkylimidazole compound - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a 2-(2,4-dichlorobenzyl)-4-phenyl-5-alkylimidazole useful as an antioxidant for a copper surface, a curing agent for an epoxy resin or an intermediate of pharmaceuticals and agrochemicals. <P>SOLUTION: The compound represented by chemical formula (I) (wherein R is a 1C-6C alkyl group) is obtained by a reaction between an alkylphenylketone compound halogenated at the 2-position and (2,4-dichlorophenyl)acetamidine or a salt thereof. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a novel 2- (2,4-dichlorobenzyl) -4-phenyl-5-alkylimidazole compound.

  As an imidazole compound similar to the present invention, for example, Patent Document 1 discloses 2- (2,4-dichloro-benzyl) -5-phenyl-1H-imidazole. However, this document does not disclose an imidazole compound in which an alkyl group is bonded to the 4 (5) position of the imidazole ring.

Japanese translation of PCT publication No. 2003-500377 (7th page, 55th page)

  An object of the present invention is to provide a novel 2- (2,4-dichlorobenzyl) -4-phenyl-5-alkylimidazole compound.

  As a result of intensive studies in order to solve the above-mentioned problems, the present inventors have obtained a novel 2- (2,4-dichlorobenzyl) -4-phenyl-5-formula represented by the chemical formula (I) of Chemical Formula 1. It was recognized that an alkylimidazole compound could be synthesized, and the present invention has been completed.

（式中、Ｒは炭素数が１〜６のアルキル基を表す。）

(In the formula, R represents an alkyl group having 1 to 6 carbon atoms.)

  The 2- (2,4-dichlorobenzyl) -4-phenyl-5-alkylimidazole compound of the present invention is an antioxidant on the surface of a metal, particularly copper (including a copper alloy) constituting a conductive part of a printed wiring board. It is also useful as a curing agent or curing accelerator for epoxy resins and as an intermediate material in the field of medicine and agrochemicals.

Hereinafter, the present invention will be described in detail.
The 2- (2,4-dichlorobenzyl) -4-phenyl-5-alkylimidazole compound of the present invention is represented by the chemical formula (I) of Chemical Formula 2, and examples of the compound include:
2- (2,4-dichlorobenzyl) -5-methyl-4-phenylimidazole,
2- (2,4-dichlorobenzyl) -5-ethyl-4-phenylimidazole,
2- (2,4-dichlorobenzyl) -4-phenyl-5-propylimidazole,
5-butyl-2- (2,4-dichlorobenzyl) -4-phenylimidazole,
2- (2,4-dichlorobenzyl) -5-pentyl-4-phenylimidazole,
2- (2,4-dichlorobenzyl) -5-hexyl-4-phenylimidazole and the like.

（式中、Ｒは炭素数が１〜６のアルキル基を表す。）

(In the formula, R represents an alkyl group having 1 to 6 carbon atoms.)

  The 2- (2,4-dichlorobenzyl) -4-phenyl-5-alkylimidazole compound of the present invention can be synthesized according to a known method. For example, as shown in the reaction formula of Chemical Formula 3, a 2-position halogenated alkylphenylketone compound and (2,4-dichlorophenyl) acetamidine are heated in an organic solvent in the presence of a dehydrohalogenating agent. Can be synthesized.

（式中、Ｒは炭素数が１〜６のアルキル基を表し、Ｘは塩素原子、臭素原子またはヨウ素原子を表す。）

(In the formula, R represents an alkyl group having 1 to 6 carbon atoms, and X represents a chlorine atom, a bromine atom or an iodine atom.)

  In the above-described reaction, the amount of (2,4-dichlorophenyl) acetamidine used is preferably 0.8 to 1.5 times mol, more preferably 0.9 to 0.1 mol with respect to the 2-position halogenated alkylphenyl ketone compound. The ratio may be 1.1 times mole. The amount of the dehydrohalogenating agent used is preferably a ratio of 1 to 10 times equivalent to the 2-position halogenated alkylphenyl ketone compound.

As the 2-position halogenated alkylphenyl ketone compound,
2-chloropropiophenone,
2-bromopropiophenone,
2-iodopropiophenone,
2-chlorobutyrophenone,
2-bromobutyrophenone,
2-iodobutyrophenone,
2-chlorovalerophenone,
2-bromovalerophenone,
2-iodovalerophenone,
2-chlorohexanophenone,
2-bromohexanophenone,
2-iodohexanophenone,
2-chloroheptanophenone,
2-bromoheptanophenone,
2-iodoheptanophenone,
2-chlorooctanophenone,
Examples include 2-bromooctanophenone and 2-iodooctanophenone.

  These 2-position halogenated alkyl phenyl ketone compounds are obtained by halogenating the 2-position of the alkyl phenyl ketone compounds. As the halogenation, chlorination or iodination can be performed, but the bromination reaction in which 1 mol of bromine is reacted with 1 mol of the alkylphenyl ketone compound is the simplest.

  2-Chloropropiophenone and 2-bromopropiophenone are also available as reagents.

  The (2,4-dichlorophenyl) acetamidine can be synthesized according to a known method. For example, as shown in the reaction formula (4), (2,4-dichlorophenyl) acetonitrile is reacted with hydrogen chloride gas and a lower alcohol such as ethanol to convert to (2,4-dichlorophenyl) acetimidate hydrochloride. Further, (2,4-dichlorophenyl) acetamidine hydrochloride can be synthesized by further reacting with ammonia.

As (2,4-dichlorophenyl) acetamidine, (2,4-dichlorophenyl) acetamidine hydrochloride obtained by the above reaction can be used, but free hydrochloric acid is removed by reacting the hydrochloride with alkali or the like. It goes without saying that arylacetamidine compounds can be used.
In addition, not only the said (2, 4- dichlorophenyl) acetamidine hydrochloride but the salt of free (2, 4- dichlorophenyl) acetamidine and a conventionally known inorganic acid or organic acid can also be used.

  Any known dehydrohalogenating agent can be used without limitation. Examples of such a dehydrohalogenating agent include inorganic alkalis such as sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, triethylamine, 1,8 -Organic bases such as diazabicyclo [5,4,0] -7-undecene (DBU), metal alkoxide compounds such as sodium methoxide, potassium tert-butoxide, and the like.

  As the reaction solvent, any known one can be used without limitation as long as it can dissolve the 2-position halogenated alkylphenyl ketone compound and (2,4-dichlorophenyl) acetamidine or a salt thereof and does not participate in the reaction. it can. Examples of such solvents 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, and nitriles such as acetonitrile. , Ethers such as tetrahydrofuran, dioxane, ethylene glycol dimethyl ether, amides such as N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAC), and dimethyl sulfoxide (DMSO). A combination of solvents may be used.

  The reaction temperature is preferably room temperature to reflux temperature, and the reaction time is preferably 1 to 10 hours. The reaction may be usually performed under atmospheric pressure.

  The 2- (2,4-dichlorobenzyl) -4-phenyl-5-alkylimidazole compound produced under the above reaction conditions can be isolated by ordinary post-treatment. For example, the reaction mixture after completion of the reaction is divided into an aqueous layer and an organic solvent layer, the organic solvent layer is washed with water, precipitated from the organic solvent as oxalate, etc., and freed with alkali to obtain the crude compound. It can be further purified by recrystallization operation or the like.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples. A synthesis example of (2,4-dichlorophenyl) acetamidine hydrochloride is shown in Reference Example 1.

[Reference Example 1]
<Synthesis of (2,4-dichlorophenyl) acetamidine hydrochloride>
Hydrogen chloride gas 27. at 25 ° C. under cooling to a solution consisting of 130.2 g (0.70 mol) of (2,4-dichlorophenyl) acetonitrile, 262 g of chloroform and 35.0 g (0.76 mol) of dehydrated ethanol. Crystals were precipitated by blowing 3 g (0.75 mol) over 80 minutes and allowing to return to room temperature for 10 hours at 5 to 10 ° C. and then standing for 2 days. By distilling off the solvent under reduced pressure, ethyl (2,4-dichlorophenyl) acetimidate hydrochloride was obtained as a white solid. The solid was crushed and a solution consisting of 17.4 g (1.01 mol) of ammonia and 122 g of dehydrated ethanol was added little by little while shaking under ice cooling. After the addition was completed, the suspension after stirring for 2 hours under ice-cooling and returning to room temperature overnight was concentrated to 200 g under reduced pressure. After cooling, the crystals were collected by filtration, washed with chloroform, and then dried. As a result, 131 g (0.55 mol, yield 78.1%) of white powdery (2,4-dichlorophenyl) acetamidine hydrochloride was obtained.

[Example 1]
<Synthesis of 2- (2,4-dichlorobenzyl) -5-methyl-4-phenylimidazole>
A suspension composed of 47.9 g (0.20 mol) of (2,4-dichlorophenyl) acetamidine hydrochloride, 75 g (0.54 mol) of potassium carbonate and 180 ml of N, N-dimethylformamide was stirred at 50 ° C. for 30 minutes. At the same temperature, a solution consisting of 42.6 g (0.20 mol) of 2-bromopropiophenone and 70 ml of chloroform was added dropwise over 1 hour, and the mixture was further stirred at 60 ° C. for 2 hours. Next, the reaction suspension is cooled and then distributed to 600 ml of water and 200 ml of chloroform. After the chloroform layer is washed twice with water, the chloroform is distilled off under reduced pressure, and the candy-like concentrate is heated and dissolved in acetone. Then, oxalic acid was added until the system became weakly acidic, and the precipitated crystals were collected by filtration and washed with acetone to obtain the target oxalate salt as skin-colored crystals. The oxalate salt was suspended in methanol under heating, and 28% sodium methoxide-methanol solution was sufficiently added until it became alkaline. Methanol was distilled off under reduced pressure, and the candy-like concentrate was washed three times with hot water. Washing gave a brown solid crude product. The solid was recrystallized from acetonitrile to obtain 27.3 g (0.086 mol, 43% yield) of milky white powdery crystals.

The melting point of the obtained crystal, the Rf value of thin layer chromatography, ¹ H-NMR and mass spectral data were as follows.
・ Mp. 113-116 ℃
・ TLC (silica gel, acetone): Rf = 0.67
・¹ H-NMR (d ₆ -DMSO) δ: 2.33 (s, 3H), 4.07 (s, 2H), 7.16-7.60 (m, 8H)
・ MS m / z (%): 316 (M ⁺ , 42), 281 (100),
265 (2), 246 (32), 231 (3), 171 (4), 159 (5), 130 (6), 123 (5), 103 (8), 89 (3), 77 (5).
From these spectral data, the obtained compound was identified as 2- (2,4-dichlorobenzyl) -5-methyl-4-phenylimidazole represented by Chemical Formula 5.

[Example 2]
<Synthesis of 2- (2,4-dichlorobenzyl) -5-hexyl-4-phenylimidazole>
A synthesis test was performed according to the method of Example 1 by replacing 2-bromopropiophenone of Example 1 with 2-bromooctanophenone, and a brown candy-like product was obtained.

The Rf value, ¹ H-NMR, and mass spectrum data of the obtained candy-like product by thin layer chromatography were as follows.
・ TLC (silica gel, acetone): Rf = 0.71
・¹ H-NMR (CDCl ₃ ) δ: 0.84 (t, 3H, J = 6.8Hz), 1.24−1.29 (m, 6H), 1.59 (br.s, 2H),
2.66 (br.s, 2H), 4.02 (s, 2H), 7.02-7.50 (m, 8H)
・ MS m / z (%): 386 (M ⁺ , 49),
371 (4), 351 (21), 329 (28), 316 (100), 281 (9), 244 (5), 159 (11), 130 (35), 115 (5),
103 (17), 89 (2), 77 (3).
From these spectrum data, the obtained compound was identified to be 2- (2,4-dichlorobenzyl) -5-hexyl-4-phenylimidazole represented by Chemical Formula 6.

Example 3
Separately, a 2- (2,4-dichlorobenzyl) -4-phenyl-5-alkylimidazole compound synthesized in Examples 1 and 2 and a surface treatment solution containing 2-phenylimidazole as an active ingredient were prepared. Then, by contacting the treatment liquid with copper, a chemical conversion film was formed on the surface of the copper, and the wetting time of the molten solder with respect to the copper was measured to evaluate the antioxidant performance to the copper surface on which each imidazole compound acts. . In this case, it is determined that the shorter the wetting time, the better the antioxidant performance of the imidazole compound.
The details of the evaluation test are as follows.
(1) Preparation of surface treatment solution After dissolving an imidazole compound, an acid, a metal salt, and a halogen compound in ion-exchanged water so as to have the composition shown in Table 1, the pH is adjusted with ammonia water to prepare a surface treatment solution. Prepared.
(2) Surface treatment method A test piece (5 mm x 50 mm x 0.3 mm copper plate) made of metallic copper is degreased, then soft-etched, and immersed in a surface treatment solution at a predetermined temperature for a predetermined time to obtain a copper surface. After the chemical conversion film was formed on, it was washed with water and dried.
(3) Wetting time measurement The surface-treated test piece was immersed in a post-flux [trade name “JS-64MSS” manufactured by Hiroki Co., Ltd.] and solder wettability tester (SAT-2000, Inc.). Solder wetting time (seconds) was measured using Resca. The solder used was tin-lead eutectic solder (trade name: H63A, manufactured by Senju Metal Industry), and the measurement conditions were a solder temperature of 240 ° C., an immersion depth of 2 mm, and an immersion speed of 16 mm / second.
In addition, the test piece which measured the solder wetting time includes (A) a sample immediately after the surface treatment, (B) a sample left in a constant temperature and humidity chamber at a temperature of 40 ° C. and a humidity of 90% RH for 96 hours, and (C ) Further, (B) is heated at 200 ° C. for 10 minutes.
The test results obtained were as shown in Table 1.

According to the test results shown in Table 1, the surface treatment liquid containing the 2- (2,4-dichlorobenzyl) -4-phenyl-5-alkylimidazole compound of the present invention as an active ingredient is resistant to moisture on the surface of copper. Therefore, it is useful for preventing the oxidation of the copper surface.

Claims (1)

A 2- (2,4-dichlorobenzyl) -4-phenyl-5-alkylimidazole compound represented by the chemical formula (I) of Chemical Formula 1.

(In the formula, R represents an alkyl group having 1 to 6 carbon atoms.)