Hydrolysis epoxide group

Intercalation of BPDE. Several groups have studied the reversible intercalative binding of BPDE to DNA. The fluorescence quantum yield of BPDE is much lower than that of BP derivatives which do not contain an epoxide group and fluorescence techniques have not been widely used to study BPDE physical binding to DNA (4). Association constants for the DNA intercalation of BPDE have been obtained by measuring red shifts in the UV absorption spectra of BPDE which occur upon the formation of intercalated complexes and from fluorescence studies (8) of the kinetics of DNA catalyzed hydrolysis of BPDE. The hydrolysis reaction is conveniently monitored by following the fluorescence of the hydrolysis product, BPT, which has a quantum yield many times greater than BPDE. 

The principal side reaction to epoxide coupling is hydrolysis. Particularly at acid pH values, the epoxide ring can hydrolyze to form adjacent hydroxyls. This diol can be oxidized with periodate to create a terminal aldehyde residue with loss of one molecule of formaldehyde (Chapter 1, Section 4.4). The aldehyde then can be used in reductive amination reactions. The reaction of an epoxide group with an ammonium ion generates a terminal primary amine group that also can be used for further derivatization. 

Limonene (10.128) is an analogue of 4-vinylcyclohexene, and, like the latter, it undergoes epoxidation of both the C(1)=C(2) and C(8)=C(9) bonds. Like in the dioxide 10.127, the two epoxide groups are hydrated at different rates by EH. Indeed, incubations in rat liver microsomes showed that hydrolysis of limonene 1,2-epoxide was 70 times slower than that of the 8,9-epoxide, a much larger difference than that observed for the dioxide 10.127 [192], Comparison of EH-catalyzed hydration of the four epoxy groups in 4-vinyl-cyclohexene and limonene confirmed that the relative rates decreased with increasing steric hindrance at these groups. 

Open-cell PolyHIPE materials have also been prepared from hydrophilic methacrylates which, on hydrolysis, yield hydrophilic polymethacrylic acid-based species [155]. Stable HIPEs containing high levels of glycidyl methacrylate can also be formed, from which porous polymers can be made. These have considerable potential for further exploitation due to the reactive epoxide group [156],... 

Derivatives of 2-deoxyglycuronic acids have been obtained by catalytic oxidation193 of suitably protected alcohols, and by hydroformylation194 of terminal epoxide groups in aldonic acids. 6-Deoxyhepturonic acids or derivatives thereof have been obtained by cyanide displacement of a 6-sulfonyloxy group from derivatives of hexoses and hydrolysis of the resulting nitriles.195... 

Females of the lymantriid, Porthetria dispar, the gypsy moth, liberate cls-7,8-epoxy-2-methyloctadecane (disparlure) as a sex pheromone (78). The probable precursor of the epoxide, (Z)-2-methyl-7-octadecene, is present in the gland in large quantities, and it has been demonstrated that the olefin is epoxidized in vivo (79). Disparlure is rapidly adsorbed on the male antennae and quickly converted to two more polar metabolites (80), probably as a consequence of hydrolysis of the epoxide group. 

The first step in the formation of the leukotrienes is cleavage of arachidonic add from membrane phospholipids. 5-I.ipoxygcnasp, which is a calcium-dependent enzyme, catalyzes the introductionof Oi into the arachidonic add and the conversion of the resulting hydroperoxide to an epoxide. Leukotriene A, contains an epoxide group. Leukobiene (LTA ) can be converted to leukotriene B (LTB4) by enzymatic hydrolysis. LTB is a dihydroxy fatty acid it regulates the functions... 

The acid-catalyzed hydrolysis of p-phenyl-substituted cyclohexene oxides 49a-d yields diols resulting from cis and "trans addition of water to the epoxide group (Scheme 14). It was initially reported that the cis/trans diol ratio correlates well with the electronic effect of the / -substituent, and varied from 7.5 93.5 for p-nitro-sub-stituted oxide 49d to 95.3 4.7 for p-methoxy-substituted epoxide 49a.56 58 Later work established that methoxy-substituted diols 50a and 51a underwent isomerization under the conditions of acid-catalyzed epoxide hydrolysis, and that the cis/ trans diol ratios for hydrolysis of 49a-c are quite similar.59... 

In exploring, as a model case, the conversion of A -cholestene-3-one (3) into cholestane-3,6-dione (7), a Merck group" converted 750 mg. of the 3-ethyleneketal (4) into the 5a,6a-epoxide (5) by reaction with perbenzoic acid and treated a solution of (5) in tetrahydrofurane with 3 N aqueous perchloric acid solution at room temperature to effect hydrolysis of both the ethyleneketal group at Cd and the 5a,6o -epoxide group. Treatment of (6) with base effected dehydration and isomerization to the... 

Esters, Carboxylic Acids, and Ethers.—The rates of hydrolysis of 3(3- and 6(3-acetoxy-4 ,5 -epoxides and 1 a-acetoxy-2(3,3 (3-epoxides were observed to be accelerated relative to those acetates not containing a neighbouring epoxide group.24 Bile acid methyl esters were readily prepared from the carboxylic acids by reaction with methanol in the presence of toluene-p-sulphonic acid.25 Bile acids were readily converted into the amino-amides (14) by successive reaction with Bu N-... 

The presence of the two epoxide groups was indicated by the C n.m.r. spectrum. Hydrolysis of senecicannabine yielded (+)-retro-necine (1), and the proposed structure (41) was confirmed by X-ray analysis. 

The absolute configuration of the epoxide group of insect JHs was determined by spectroscopy and circular dichroism [29], In the first method, perchloric acid was used to catalyze the hydrolysis of the epoxide in the presence of H2180. The resulting v/c-diol was analyzed by mass spectroscopy and definitively demonstrated the 10/ , 115 chirality of the epoxide [30]. The chirality was confirmed by circular dichroism. The epoxide was hydrolyzed by sulfuric acid and tetrahydrofuran and the circular dichroism cotton effect of the resulting acyclic glycol was measured in the presence of tris(dipivaloylmethanato)praseodymium [31]. 

The origin of the additional carbon atoms of insect juvenile hormone (49) is not yet settled. Methionine seemed to be incorporated only into the ester methyl group. - Mevalonate was incorporated into farnesol but not into juvenile hormone. A slight incorporation of [2- " C]acetate into the chain was noted but not of [l- C]acetate. Metabolism of the ester includes hydrolysis to the corresponding acid and possibly formation also of the corresponding diol from the epoxide group. 

As indicated earlier, another powerful tool for upgrading polymer properties is the postpolymerization reaction of preformed polymers. These reactions may occur on reactive sites dispersed in the polymer main chain. Such reactions include chain extensions, cross-linking, and graft and block copolymer formation. The reactions may also occur on reactive sites attached directly or via other groups/chains to the polymer backbone. Reactions of this type are halogenation, sulfonation, hydrolysis, epoxidation, surface, and other miscellaneous reactions of polymers. In both cases these types of reactions transform existing polymers into those with new and/or improved properties. 

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