Ethyl-5-phenylimidazole

Imidazole (12.8g, 0.2mol), triethyl orthoformatc (118.4g, 0.8mol) and p-toluenesulfonic acid (Ig) are heated at 130°C until no more ethanol distils from the mixture. Excess orthoformatc is then removed in vacuo, solid sodium carbonate (1 g) is added, and the residue is fractionally distilled to give the acetal (28.2 g, 82%) as a colourless oil, bo.02 52°C. 

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The N-coordinated compound [AuCljL] (L= l-ethyl-2-phenylimidazole) with silver tetrafluoroborate gives the cycloaurated species 102, which on further reaction with triphenylphosphine and sodium tetrafluoroborate or ammonium hexafluorophosphate forms the cationic complexes 103 (X = BF., PF,) (00JCS(D)271). 

In the direct alkylation of 4-phenylimidazole the desired l-ethyl-5-phenylimidazole is obtained only as a minor product [1]... 

Epoxynovolak resin and BPA/DC-BMI prepolymer, tert.butyl peroxide and Zn acetate [106, 107] or 2-phenylimidazole and other catalysts [108] were filled with wollastonite. Carbon-fiber reinforced composites were obtained using a binder, which consisted of BPA/DC, BMI, an epoxynovolak, 2-ethyl-4-methylimidazole and an organic solvent [109]. A BPA/DC-BMI prepolymer in methylethylketone was mixed with middle-molecular-weight epoxide resin (Epikote 1001), 2-ethyl-4-methyl-imidazole, Zn acetate and triethylenediamine thermal shock resistant GRP was thus obtained [110]. 

Dimerization of ethyl 2-amino-2-cyanoacetate gives diethyl 5-aminoimidazole-2,4-dicar-boxylate (92) as in Scheme 53. At reflux temperatures in propanol, 1,1-dimethyl-1-phenacyl-hydrazinium bromide is converted into 2-benzyl-4-phenylimidazole (93). Again the cycliz-ation is a dimerization process (Scheme 53) (80AHC(27)24l). 

Triphenyloxazole (5g), formamide (40g) and liquid ammonia (lOOtnl) are heated in an autoclave at 200-210°C (5h). The brownish reaction product is poured into water, and the flocculent precipitate is filtered, washed with water and recrystallized from ethanol (4.3 g, 85%), m.p. 273°C. Similarly prepared are 2,5-diethyl-4-phenyl- (25%), 2-methyl-4,5-dipropyI-(70%) [41], 4-eihyl-5-phenyl- (50%), 4-phenyl-5-propyl- (40%) and4-benzyl-5-ethyl imidazoles (5%) [40]. From 2-methyloxazole-4-carboxylic acid boiled at 150°C in a sealed tube with aqueous ammonia is obtained 2-methylimidazole (22%) boiling with aniline gives 2-methyl-l-phenylimidazole (67%) [52]. 

To a solution of 1-methylimidazole (5g, 61 mmol) in acetonitrile (60 ml) is added sequentially benzoyl chloride (7.1 ml, 8.6 g, 61 mmol) and triethylamine (8.5 ml, 6.2 g, 61 mmol). After 15h at 25°C the triethylamine hydrochloride is filtered off, the acetonitrile is rotary evaporated, and the residue is boiled (30 min) with aqueous sodium carbonate. Continuous extraction with chloroform of the alkaline solution yields, after removal of the dried solvent, an oil which is distilled to give a pale yellowish liquid (4.2 g, 37%), bi 149°C. Similarly prepared are ethyl l-methylimidazole-2-carboxylate (bo.os 60°C), 2-bcnzoyl-l-phenylimidazole (61%, b2 210°C) and 2-benzoyl-1-benzylimidazole (68%, m.p. 66°C). 

Quatemization is sometimes difficult to avoid but can be used positively. Quatemization can provide entry into 5-substituted A-alkylated imidazoles. For example, A-ethylation of iV-benzoyl-4-phenylimidazole with a powerful alkylating agent like triethyloxonium tetrafluoroborate provides the salt that undergoes hydrolysis under mildly basic conditions to provide 5-phenyl-iV-ethylimidazole. ... 

Dry HCl-gas passed 2 hrs. at room temp, into a soln. of 2-benzylideneamino-3-methylthiocrotononitrile in abs. ether, and allowed to stand overnight 4-daloro-5- l-methylthio)ethyl-2-phenylimidazole. Y 86%. F. e. s. K. Hartke and B. Seib, Pharmazie 25, 517 (1970). 

Compounds such as 2-methylimidazole 41, 2-undecylimidazole, 2-ethyl-4-methylimidazole 42 are highly reactive materials. It has been stated that soluble imidazoles are too reactive to permit their use in one-part adhesive systems stable at ambient temperature [12]. Among the other compounds, the less reactive 4-phenylimidazole 43 would be a convenient curing agent at elevated temperature, alfliough file reaction still occurs over a few days of storage at 25 C. 4-Methyl-... 

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