Imidazole 4-ethyl-5-methyl

The diglycidyl ether (DGEBA) and the polyglycidyl compound (PGCBA) were mixed and heated to about 120 °C. The stoichiometric amount of bisphenol A was dissolved in the resin and, after cooling to about 60 °C, 0,1% by weight of 2-ethyl-4-methyl-imidazol was added to the mixture. The well stirred composition was degassed in a vacuum oven in order to remove trapped air. Afterwards, the reactive mixture was poured into preheated moulds and cured for two hours at 140 °C followed by two hours at 180 °C. 

CN ( )-l-[2-[[(4-chlorophenyl)methyl]thio]-2-(2,4-dichlorophenyl)ethyl]-177-imidazole mononitrate... 

Because silylation with HMDS 2/TCS 14 in acetonitrile at ambient temperature converts the unreactive a-chloroketone moiety of 743 into an /Z-mixture of reactive alkyl 4-chloro-3-trimethylsilyloxycrotonates 746a, b [230, 231] which can be isolated and distilled, if humidity is excluded, silylation of 743a, b in the presence of ami dine salts such as 745 gives the desired ethyl or methyl imidazole(4,5)-acetates 748a, b via IMz and 747b. The reaction of formamidine acetate with 746a,b affords 745 (with R=H) in up to 70% yield [232, 233] (Scheme 5.79). As side reactions one must, e.g., take into account the reaction of 746 with ammonia to give 755 which subsequently dimerizes to the pyrazine 756, as discussed in Section 5.5.3. 

Bouwman synthesized complexes of tridentate ligand A,A-bis(2-ethyl-5-methyl-imidazol-4-ylmethyl)aminopropane (5). [Zn L2]2+ complexes were synthesized with IR spectroscopic data indicating octahedral coordination.118... 

Wird die Ringerweiterung statt mit Bortrifluorid mit Meerwein-Reagens durchgefuhrt, so erhalt man mit Benzonitril aus 2-Methyl-3-phenyl-2H-azirin hauptsachlich l-Ethyl-2,5-diphe-nyl-4-methyl-imidazol und aus 3-Methyl-2-phenyl-2H-azirin 1-Ethyl-2,4-diphenyl-5-methyl-imidazol44°. 

Eine mit der C - f y cl r o x y me thylierung (s.S. 127ff.) verwandte Reaktion ist die Kondensation von zwei Molekiilen 2-Ethyl-4(5)-methyl-imidazol unter Basen-Katalyse mit einem Molekiil Formaldehyd zu Bis-[2-ethyl-4(5)-methyl-imidazol-5(4)-yI -methan (93%)846. 

SchlieBlich sei die photochemische 1-Hydroxy-alkylierung von Imidazolen mit Ketonen ge-nannt. Auf diese Weise kann /,2-Dimethyl-4-( 1-hydroxy-1-methyl-ethyl)-imidazol aus 1,2-Di-methyl-imidazol mit Aceton in 70% Ausbeute hergestellt werden. Imidazol selbst reagiert unter analogen Bedingungen jedoch nicht. Mit 2-Methyl- bzw. 1-Methyl-imidazol bleiben die Aus-beuten unter 10% und aucb die Umsetzung von 1,2-Dimethyl-imidazol mit aromatischen Ketonen wie z. B. Acetophenon oder Benzophenon verlauft nur in Ausbeuten unter 10%768. 

Analog erhalt man aus 4,5-Diiod-l-methyl-imidazol nach Halogen-Metall-Austausch mit Ethyl-magnesiumbromid und anschlieBender Umsetzung mit Triethoxy-methan 5-(Diethoxy-methyl) -4-iod-l-methyl-imidazol (68%), das mit weiterem Ethyl-magnesiumbromid und Triethoxy-methan zu 4,5-Bis-[diethoxy-methyl]-l-methyl-imidazol (58%) umgesetzt werden kann1048. 

Der Austausch des Sauerstoff-Atoms in 1-substituierten Imidazol-3-oxiden durch Nukleophile verlauft unter Angriff des Nukleophils in 2-Position. So erhalt man z. B. aus 1-Benzyl-4,5-dimethyl-imidazol-3-oxid mit Kaliumcyanid/Dimethylsulfat I-Benzyl-2-cyan-4,5-dime thy l-imidazol (65%), mit Phosphoroxychlorid l-Benzyl-2-chlor-4,5-dimethyl-imidazol (72%) bzw. mit Butindisaure-dimethylester l-Benzyl-2- (1,2-dimethoxycarbonyl-2-oxo-ethyl)-4,5-dimethyl-imidazol (83%)962. Analog wird l-Benzyl-5-methyl-imidazol-3-oxid mit z.B. Kaliumcyanid/Dimethylsulfat zu l-Benzyl-2-cyan-5-methyl-imidazol (75%) umgesetzt962. 

Die Umsetzung von l-(2-Hydroxy-ethyl)-2-methyl-5-nitro-imidazol (Metronidazol) mit 2-Ami-no-ethanthiol fiihrt bei pH 5 in Wasser in 98% Ausbeute zu 4-(2-Amino-ethylthio )-l-(2-hydroxy-ethyl)-2-methyl-imidazol, wahrend bei pH 9,5 in 67% Gesamtausbeute Gemiscne aus dem zuvor genannten Produkt und dem regioisomeren 5-(2-Amino-ethylthio)-l-(2-hydroxy-ethyl) -2-methyl-imidazol entstehen978. 

Dabei entstchcn aus 1-substituierten Imidazolen wie z.B. l-Benzyl-2-methyl- oder 1,2-Dime-thyl-imidazol unter Verbrauch von zwei Aquivalenten Benzoesaure-chlorid die 1-substituierten 2-(2-Benzoyloxy-2-phenyl-ethenyl)-imidazole wie z.B. 2-(2-Benzoyloxy-2-phenyl-etheny1)-l-benzyl- (97%) oder 2-(2-Benzoyloxy-2-phenyl-ethenyl)-l-methyl-imidazol (93%), die zu 1-Ben-zyl-2-(2-oxo-2-phenyl-ethyl)- bzw. l-Methyl-2-(2-oxo-2-phenyl-ethyl)-imidazol hydrolysiert werden konnen 766 768. 

Aus 2-Methyl-imidazol selbst entsteht unter Verbrauch von drei Aquivalenten Benzoesaure-chlorid l-Benzoyl-2-(2-benzoyloxy-2-phenyl-e(henyl)-imidazol (85%), dessen Hydrolyse 2-(2-Oxo-2-phenyl-ethyl)-imidazol (83%) liefert767 ... 

These compounds can initiate anionic polymerisation of epoxides, and when R, = H the secondary amine can react by addition to an epoxide group. Farkas and Strohm 64> have studied the reaction of 2-ethyl-4-methyl imidazole with phenyl glycidyl ether and BADGE resin using chemical analysis and proton NMR spectroscopy. They found that the imidazole readily forms adducts with epoxide of 1 1 and 1 2 molecular ratio ... 

The separation of cimetidine and its metabolites is usually carried out by extraction of the biological medium with 1-octanol fran an aqueous alkaline pH solution followed by mixing, addition of an internal standard and centrifugation. The extraction with octanol is repeated and the combined extracts are re-extracted with dilute hydrochloric acid. The aqueous acid solution is then separated, ethanol is added and mixed. This is then followed by saturating the mixture with a large amount of potassium or sodium carbonate to "salt out" the ethanol layer which contains the cimetidine and its metabolite, the sulfoxide. Several different internal standards have been used Metiamide, 1-methyl-3-[2-[[(5-methyl-imidazole-4-yl) -methyl] thio]ethyl]-2-thiourea,19 31 39 (N-cyano-N1-methy1-N"-(3-(4-imidazolyl)-propyl)guanidine32, and 13-hydroxy-theophylline. 0 After extraction the samples are either evaporated to dryness and reconstituted with a known amount of ethanol, injected directly or dissolved in the mobile phase for the HPLC analysis. 

The gas-phase proton affinity of the IV-heterocyclic carbene l-ethyl-3-methyl-imidazol-2-ylidene has been determined as 251.3 4 kcalmol-1 using the kinetic method, a value which makes the carbene one of the strongest bases reported thus far.160 Density functional theory calculations have been carried out at the B3FYP/ 6-31+G(d) level to compare the high experimental value with that estimated theoretically. 

A mixture of (+/-)-cis-2-[2-(4-chlorophenyl)ethyl]-2-(imidazol-l-yl)methyl-4-(methylsulfonyloxy)methyl-l,3-dioxolane (31.0 g), 4-aminothiophenol (12.6 g) and anhydrous potassium carbonate (23.1 g) in acetone (250 ml) was stirred overnight under reflux under nitrogen. The reaction mixture was then evaporated to dryness, and the resulting residue was extracted with methylene chloride (300 ml) and filtered. The solid filter cake was then washed with methylene chloride (200 ml). The methylene chloride extracts were then combined and concentrated and flash chromatographed on a silica gel eluting with methylene chloride followed by 30% acetone in methylene chloride. The pure product was dissolved in a minimum amount of hot ethyl acetate (125 ml), the solution diluted with an equal volume of hot hexane and seeded to give 30.0 g of (+/-)-cis-2-[2-(4-chlorophenyl)ethyl]-2-(imidazol-l-yl)methyl-4-(4-amino-phenylthio)methyl-l,3-dioxolane, melting point 121°-122.5°C. 

In an initial step, 2-chloroacetic acid ethyl ester is reacted with formamide to give 5-methylimidazole-4-carboxylic acid ethyl ester. Then sodium in ammonia is used to convert that to 4-hydroxymethyl-5-methylimidazole-hydrochloride. Cysteamine HCI (HSCH2CH2NH2-HCI) is then reacted to give 4-(2-aminomethyl)-thiomethyl-5-methyl-imidazole dihydrochloride. Then N-cyanamido-5,5-dimethyl-dithio-carbonate (from cyanamid, KOH, CS2 and ((CH3)2S04) is reacted to give a further intermediate which is finally reacted with methylamine to give cimetidine. 

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]. 

The 2-ethyl-4-methyl-imidazole (EMI) is not a tertiary amine however, it is used in the same manner as a single catalyst or as an accelerator. EMI is a substituted imidazole that is a liquid at room temperature (4000 to 8000 cP at 25°C) with a high boiling point. 

Ac, acetyl AIBN, azobis(isobutanonitrile) All, allyl AR, aryl Bn, benzyl f-BOC, ferf-butoxycarbonyl Bu, Butyl Bz, benzoyl CAN, ceric ammonium nitrate Cbz, benzyloxycarbonyl m-CPBA, m-chloroperoxybenzoic acid DAST, diethylaminosulfur trifluoride DBU, l,8-diazabicyclo[5.4.0]undec-7-ene DCC, /V. /V - d i eye I oh e x y I c ar bo -diimide DCM, dichloromethyl DCMME, dichloromethyl methyl ether DDQ, 2,3-dichloro-5,6-dicyano-l,4-benzoquinone DEAD, diethyl azodicarboxylate l-(+)-DET, L-(+)-diethyl tartrate l-DIPT, L-diisopropyl tartrate d-DIPT, D-diisopropyl tartrate DMAP, 4-dimethylaminopyridine DME, 1,2-dimethoxyethane DMF, /V./V-dimethylformamide DMP, 2,2-dimethoxypropane Et, ethyl Im, imidazole KHMDS, potassium hexamethyldisilazane Me, methyl Me2SO, dimethyl sulfoxide MOM, methoxymethyl MOMC1, methoxymethyl chloride Ms, methylsulfonyl MS, molecular sieves NBS, N-bromosuccinimide NIS, /V-iodosuccinimide NMO, /V-methylmorpho-line N-oxide PCC, pyridinium chlorochromate Ph, phenyl PMB, / -methoxvbenzyl PPTs, pyridiniump-toluenesulfonate i-Pr, isopropyl Py, pyridine rt, room temperature TBAF, tetrabutylammonium fluoride TBS, ferf-butyl dimethylsilyl TBDMSC1, f-butylchlorodimethylsilane Tf, trifhioromethylsulfonyl Tf20, trifluoromethylsulfonic anhydride TFA, trifluoroacetic acid THF, tetrahydrofuran TMS, trimethylsilyl TPAP, tetra-n-propylammonium perruthenate / -TsOH. / -toluenesulfonic acid... 

Telluran [2-(2,5-Dioxo-tetrahydro-imidazol-4-yl)-ethyl]-methyl-E12b, 393 [(H3C)2Te2 + Na-R] Tellurinane 3,5-Bis-[hydroximino]-2-methyl- E12b, 450 (Oxo ->Oxim)... 

ETHATO-7-(2-HYDROXY-3-((l-METHYLETHA L)AMINO)PROPOXY)-4-BENZOFUKANAT) ETHANONE see ELI600 a-ETHYL-p-(HYDROXYMETHYL)-l-METHYL-IMIDAZOLE-5-BUTYRIC ACID, y-LACTONE see PIFOOO... 

The quaternization of 1-substituted imidazoles is a facile reaction which leads to a stable quaternary salt via an 5n2 reaction (Scheme 16) which may be affected by steric factors. It has been shown (78AHC(22)7l) that the effects of fV-aryl substituents on rate constants for the quaternization of imidazoles can be correlated using a Hammett equation. The value of p (-0.45) for the ethylation of imidazoles shows little sensitivity to substituent effects, but this is to be expected since the basic pK values of the fV-aryl compounds do not vary widely, and the rate of alkylation must depend on the basicity of the nitrogen being quaternized. Certainly the expected sequence of reactivities, 1-methyl > 1-benzyl > 1-phenyl, is observed in the ethylation of 1-substituted imidazoles with iodoethane in ethanol or acetone, and although only qualitative observations are available, l-methyl-4-and -5-chloroimidazoles react less readily than 1-methylimidazole. Considerable experimental difficulty is experienced in quaternizing nitro-substituted imidazoles. 

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