4-hydroxyphenyl imidazole

Poly(arylene ether)s containing phenylimidazole units were initially prepared from the reaction of 2-phenyl-4,5-di(4-hydroxyphenyl)imidazole and various activated aromatic difluoro compounds according to Eq. (4) [20]. The dihydroxyimidazole was first prepared from the reaction of 4,4 -dimethoxyben-zil, benzaldehyde and ammonium acetate in refluxing acetic acid followed by... 

To the product from Step 2 (5.3 mmol) dissolved in 5 ml DMSO was added l-(4-hydroxyphenyl)imidazole (5.8 mmol) and CS2CO3 (5.6mmol) and the mixture heated to 90 °C 18 hours. The reaction mixture was partitioned between water and EtOAc, concentrated, purified by chromatography on silica gel using EtOAc/hexanes, and the product isolated. 

The A -imidazolyl sterol amaranzole A was isolated from extracts of the marine sponge Phorbas amaranthus. The C24-A -(4-hydroxyphenyl)imidazole-5-yl stmcture was elucidated by spectroscopic data [307] (Figure 5.84). 

The various tautomers and rotamers of alloxan have been examined in detail by the MNDO method and it is predicted that the keto form is most important in the gas phase, although in solution the monohydroxy forms are also thought to contribute. A mass spectral study has been used to investigate the enol-keto tautomeric equilibria of a series of substituted salicylaldehyde and 2-hydroxynaphthaldehyde Schiff bases. In neutral, ethanolic solutions, the cis- and trans-tm forms of 4,5-dimethyl-2-(2 -hydroxyphenyl)imidazoles (393) and (394) have been found to exist in equilibrium in the ground state. However, in neutral aqueous solutions, the trans-eao and keto forms (394) and (395) were the only species detected. Deuterium isotope effects on... 

Fores M., M. Duran, M. Sola, and L. Adamowicz. 1999. Excited-state intramolecular proton transfer and rotamerism of 2-(2 -hydroxyvinyl) benzimidazole and 2-(2 -hydroxyphenyl) imidazole. 7. Phys. Chem A, 103(22) 4413 420. 

K. Schipschack, H. Wagner, J. Beger, R. Neumann. The efficiency of 2-(2-hydroxyphenyl)imidazole derivatives as copper deactivators in radiation crosslinked low density polyethylene. Polymer Degradation and Stability 42(3), 253-261 (1993). 

Imidazole, l-(p-hydroxyphenyl)-pK 5, 384 (B-76MI4070I, 70AHC(12)I03, 80AHC(27)24I), 448 (70CHE194) rate constants, 5, 448 (70CHEI94)... 

B) A mixture of 2.4 parts of 1 acetyl-4-(4-hydroxyphenyl)piperazine, 0.4 part of sodium hydride dispersion 78% 75 parts of dimethylsulfoxide and 22.5 parts of benzene is stirred for one hour at 40°C. Then there are added 4.2 parts of cis-2-(2,4-dichlorophenyl)-2-(1 H-imidazol-1 -ylmethyl)-1,3-dioxolan-4-ylmethyl methane sulfonate and stirring is continued overnight at 100°C. The reaction mixture Is cooled and diluted with water. The product is extracted with 1,1 -oxybisethane. The extract is dried, filtered and evaporated. The residue Is crystallized from 4-methyl-2-pentanone. The product is filtered off and dried, yielding 3.2 parts (59%) of cis-1-acetyl-4-[2-(2,4-dichlorophenyl)-2-(1 H-imidazol-1-ylmethyl)-13-di-oxolan-4-ylmethoxy] phenyl] piperazine MP 146°C. 

As compounds exhibiting enhancing effects on CL reactions, a variety of phenols, e.g., firefly luciferin and 6-hydroxybenzothiazole derivatives [12,13], 4-iodophe-nol [14], 4-(4-hydroxyphenyl)thiazole [15], 2-(4,-hydroxy-3 -methoxy-benzyli-dene)-4-cyclopentene-l,3-dione (KIH-201) [16], and 2-(4-hydroxyphenyl)-4,5-diphenylimidazole (HDI) and 2-(4-hydroxyphenyl)-4,5-di(2-pyridyl)imidazole (HPI)[17] (Fig. 6A), and phenylboronic acid derivatives, e.g., 4-phenylylboronic acid [18], 4-iodophenylboronic acid [19], and4-[4,5-di(2-pyridyl)-l //-imidazol-2-yl]phenylboronic acid (DPPA) [20] (Fig. 6B), in the luminol/hydrogen peroxide/peroxidase system are well known. Rhodamine B and quinine are used as sensitizers in the CL-emitting reaction between cerium (IV) and thiol compounds. This CL reaction was successfully applied to the sensitive determination of various thiol drugs [21-32],... 

Figure 6 Representative (A) phenol-type and (B) phenylboronic acid-type enhancers for luminol/hydrogen peroxide/peroxidase system. KIH-201, 2-(4 -hydroxy-3 -methoxy-benzylidene)-4-cyclopentene-1,3-dione HDI, 2-(4-hydroxyphenyl)-4,5-diphenylimida-zole HPI, 2-(4-hydroxyphenyl)-4,5-di(2-pyridyl)imidazole DPPA, 4-[4,5-di(2-pyridyl)-lH-imidazol-2-yl]phenylboronic acid).

An interesting approach to maleimide-terminated phenoxy resin has recently has described (42). para-Maleimidobenzoic acid was reacted with diglyci-dylbisphenol-A epoxy resin in the presence of catalyst to provide the bismale-imide of Fig. 13. Instead of diglycidyl bisphenol-A, linear epoxy resin pre-polymers can be used in this reaction to form a maleimide terminated phenoxy resin. Another suitable functionalized monomaleimide is m- or p- N-(hydroxyphenyl) maleimide which is synthesized from maleic anhydride and m-aminophenol in DMF as a solvent at 70 °C. The purified hydroxyphenyl maleimide was reacted with epoxy resin to form novel BMIs as outlined in Fig. 14. The new BMI and phenoxy oligomers polymerize at temperatures of 200-220 °C, but the cure temperatures can be significantly lowered when catalysts such as imidazoles or triphenylphosphine are added. The cured homopolymers show Tg of 140 and 230 °C for the n = 2 and the n = 1 polymer, respectively(43). 

Chemical Name a-[5-(l,l-Dimethylethyl)-2-hydroxyphenyl]-l-methyl-5-nitro-lH-imidazole-2-methanol... 

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