Epoxides aminophenols

Epichlorohydrin is reacted with a variety of hydroxy, carboxy, and amino compounds to form monomers with two or more epoxide groups, and these monomers are then used in the reaction with bisphenol A [Lohse, 1987]. Examples are the diglycidyl derivative of cyclohex-ane-l,2-dicarboxylic acid, the triglycidyl derivatives of p-aminophenol and cyanuric acid, and the polyglycidyl derivative of phenolic prepolymers. Epoxidized diolefins are also employed (Sec. 9-8). 

Treatment of aminophenols with alkylating agents can yield either O- or N-alky-lated products, depending on the type of electrophile used and on the reaction conditions. If weak bases and hard electrophiles are used, either clean O-alkylation or mixtures of products can result (Scheme 6.20). Acid-catalyzed alkylation of aminophenols with epoxides usually yields N-alkylated products [47] (Scheme 6.12). Selective N-alkylation of aminophenols can also be achieved by using softer electrophiles or by conversion of the aminophenol into a dianion, followed by treatment with one... 

Epoxy resins based on glycidylation of bisphenols, cresol and phenol novolacs, polycarboxylic acids, polyols, amines, and aminophenols have been long known. Epoxidized linear and cyclic olefins have also been used as specialty epoxy resins. More recently, glycidylated heterocycles have been introduced, initially as specialty resins promising improved resistance to weathering. One heterocycle in particular, the hydantoin ring, has become of particular interest as an epoxy substrate (J ). 

Polyfluoro-2,3-epoxyalkanes are a convenient building block for the construction of heterocyclic systems. Nucleophilic attack on the central carbon of the epoxide ring of polyfluoro-2,3-epoxyalkanes gives rise to amides or ethers of the corresponding acids. Further reaction of a second nucleophile with the C = O may follow. So, ortho-aminophenole and polyfluoro-2,3-epoxypropane in the presence triethylamine give 2-(pentafluoroethyl)benzoxazole (90IZV2338) (Scheme 181). 

Figure 12.5 shows an example of the cured structure of a thermoset resin using two different epoxide monomers with two different amine hardeners. The epoxies are triglycidyl p-aminophenol (TGAP) and tetraglycidyl 4,4-diaminodiphenylmethane (TGDDM), which are tri- and tetra-fiinctional, respectively (n = 3 and n = 4, respectively) and the two hardeners are 4,4-diamino-diphenylsulphone (DDS) and dicyandiamide (DICY). 

A variety of biochemical pathways are known which may lead to reactive quinoid derivatives. They include dihydroxylation of aromatic or heterocyclic compounds and epoxide formation and hydrolysis to -diphenolic compounds (Booth and Boyland 1957) o- and p-hydroxylations of phenols or arylamines (In-SCOE et al. 1965 Miller et al. 1960 Booth and Boyland 1957) and rearrangement of -hydroxyarylamines to o-aminophenols (Miller and Miller 1960). It now appears that aromatic hydroxylations proceed via highly reactive arene oxides, i.e., compounds in which a formal aromatic double bond has undergone epoxidation. Depending on the compound, arene oxides may give rise to other electrophilic reactive species, including quinoid structures, but react as such readily with nucleophiles and thus provide a basis for understanding covalent attachment of aromatic hydrocarbon derivatives to protein and nucleic acids (Jerina and Daly 1974). 

Saeedi et al. modified aeyl ehloride MWCNTs with different amines - 1,4-diaminobenzene (DAB), 4-aminophenol (AP) and 4-aminothiophenol (ATP) -in order to introduee nueleophilie groups on the support to promote the axial anchorage of [Mn(salophen)Cl]. The materials were effieient catalysts in the epoxidation of alkenes, at room temperature in acetonitrile with sodium periodate, leading to 44-100% substrate conversion and 41-100% epoxide yield. The reeyelability of the heterogeneous catalysts was examined in the epoxidation of eyelo-oetene in four further runs. In the first three cycles, a small amount of leaching of the complex was detected and the epoxide yields deereased from 99 to 90%, 100 to 89% and 97 to 84% for the... 

Triglycidyl Ether of p-Aminophenol. The triglycidyl derivative of p-aminophenol was originally developed by Union Carbide (58) and is currently marketed by Huntsman under the designation MY 0500 and 0510. Epoxidation of p-aminophenol is carried out with a large excess of epichlorohydrin under carefiilly controlled conditions, since the triglycidylated resin exhibits limited thermal stability and polymerizes vigorously under the influence of its tertiary amine moiety. 

Glycidyl amine resins are prepared hy reaction of epichlorhydrin with either primary diamines, monoamines or aminophenols. Each primary amine gives rise to two epoxide substituents. The reaction again involves two steps reaction of the epichlorhydrin with an active hydrogen to form the chlorohydrin, followed by ring closure with sodium hydroxide to generate the new epoxide. The common glycidyl amines are the reaction products of epichlorhydrin with diamino diphenyl methane and with p-aminophenol. 

Table 10.6 Comparison of some stoichiometric, fully cured epoxide-amine networks Tg, glass transition temperature [Ar], aromatic group concentration F, flex parameter (see text) n, crosslink density and [OH], hydroxyl concentration. Note DGEBD = diglycidyl ether of butane diol DGEBA = diglycidyl ether of bisphenol A (i = degree of polymerization) and TGAP = triglycidyl derivative of p-aminophenol ...

Saloutina LV, Zapevalov AY, Saloutin VI, Kodess MI, IGrichenko VE, Pervova MG, Chupakhin ON (2006) Reactions of epoxides derived from internal perfluoroolefins with o-phenylenediamine and 2-aminophenol. Russ J Org Chem 42 558-566... 

---