Epoxides amines

The alcohol B is a typical amine-epoxide adduct, and the acid A is a 1,3-dioxygenated compound ... 

Strong bases, such as potassium acetate, potassium 2-ethylhexoate, or amine—epoxide combinations are the most useful trimerization catalysts. Also, some special tertiary amines, such as 2,4,6-tns(A7,A7-dimethylarninomethyl)phenol (DMT-30) (6), l,3,5-tris(3-dimethylaminopropyl)hexahydro-j -triazine (7), and ammonium salts (Dabco TMR) (8) are good trimerization catalysts. 

Amination Epoxides in alkali, including ethylene oxide, propylene oxide, glycidol (2,3-epoxypropan-l-ol). Scheme 10.58 shows glycidyltrimethylammonium chloride Glycidyltrimethylammonium chloride marketed to enhance dyeability with direct and reactive dyes... 

An alternative synthesis producing a chiral-substituted 3-azoniaspirooctane, 153 has been published by Liu and co-workers where a modification of the Payne rearrangement was applied to amine epoxide 152 (Equation 35) <1997JCS(P1)511>. 

Many different pathways, mechanisms, and enzymes are associated with activation. These include dehalogenation, AT-nitrosation of secondary amines, epoxidation, conversion of phosphothionates to phosphate, metabolism of phen-oxyalkanoic acids, oxidation of thioethers, hydrolysis of esters and peroxides. The following is a summary. 

To attain the requirements of an epoxy matrix utilized in filament-wound C-fiber-epoxy composites we have considered the characteristics required of the amine curing agent molecule. To ensure long gel times at 23 °C requires that the primary amine-epoxide (P.A.-E) reaction rate is considerably greater than the rate of the secondary amine-epoxide (S. A.-E) reaction, and that the S.A. reaction does not occur at low temperatures. Furthermore, to attain low 23 °Cr s and low post-cure temperatures... 

Fig. 21. Primary amine-epoxide reaction ((i) and (ii) — sites for E-OH and SA-E reactions respectively...

Fig. 22a and b. (i) Epoxide-hydroxyl and (ii) secondary amine-epoxide reactions that form (a) inter-molecular crosslinks and (b) intramolecular rings... 

These reactions are catalysed by acids such as Lewis acids, phenols, and alcohols. The hydroxyl groups formed by the amine epoxide addition are active catalysts, so that the curing reaction usually shows an accelerating rate in its early stages, typical of auto catalysis. In some cases when the amine is present in less than stoichiometric concentrations, reaction of epoxide and hydroxyl may occur to produce an ether group ... 

A study of the reaction of PGE and aniline using high purity reagents and excluding traces of hydroxylie materials, has been reported by Enikolopiyan 56). This demonstrated that amine-epoxide addition can occur in the absence of acidic catalysts, and the observed overall rate was second-order in amine concentration. 

Schechter 55) proposed that the catalytic effect of hydroxyl groups on the epoxide-amine addition reaction involved a termolecular activated complex formed in the concerted reaction of amine, epoxide and hydroxyl. Smith 57) suggested a modified mechanism in which the same activated complex is formed in a bimolecular reaction between an adduct formed from epoxide (E) and the proton donor (HX), and the amine ... 

The interpretation of the kinetics is based on the mechanisms proposed by Schechter et al.55) and Smith 57), for the reaction of secondary amines with epoxides, extended to include the primary amine reaction. The rate-determining step is assumed to be the reaction of amine, epoxide and hydroxyl or other proton-donor species, HX, to form a termolecular complex, Eq. (3-13). The proposed reaction scheme is ... 

Better fits were obtained for n = 1 which gave linear reduced rate-conversion plots up to 20-30 % conversion, followed by a downward curvature. The apparent preexponential factors and activation energies associated with Kt and K2 were A, = 6.53 x 10s s-1, E, = 80.4kJ/mole, A2 = 3.01 x 10s s 1, and E2 = 71.3 kJ/mole. These kinetics can be explained in terms of a bimolecular rate-determining step between hydroxylic catalyst species and either amine or a rapidly-formed amine-epoxide adduct. An analysis similar to that of Horie et al. yields the kinetic Eq. 

A kinetic model which includes both amine-epoxide and hydroxyl-epoxide addition reactions, with hydroxyl autocatalysis has been proposed by Zukas 103,104). The starting point was an expression for the rate of consumption of epoxide by reaction with primary or secondary amine and hydroxyl groups... 

CARBON SKELETON. The technique of precolumn catalytic hydrogenation can be applied to reduce certain unsaturated compounds to their parent hydrocarbons. Compounds analyzed by this technique include esters, ketones, aldehydes, amines, epoxides, nitriles, halides, sulfides, and fatty acids. Fatty acids usually give a hydrocarbon that, is the next lower homolag than the parent acid. For most systems utilizing hydrogenation, hydrogen is also used as the carrier gas. Usually 1% palladium or platinum on a non-adsorptive porous support such as AW-Chromosorb P is used as the catalytic packing material. 

On comparing the spectrum of the epoxy resin in Fig. 4a with that obtained after reaction with APS dried at 25°C (Fig. 4b), one can see the disappearance of the epoxide peak at 912 cm and the appearance of a strong band at 3500 cm-1 due to —OH groups, as expected from the above reaction. However, after reaction for the same duration with APS dried at 170°C, the disappearance of the epoxide peak at 912 cm"1 and the appearance of the hydroxyl band at 3500 cm 1 are both less significant. The ratio of peak intensities, 912/3500 cm, remains high, indicating inhibition of the amine-epoxide reaction when APS is dried at 170°C. 

It thus seems that there is no direct link between volumetric and elastic properties in the glassy state and that the anomalous density variations cannot be attributed to a crosslink density effect, either direct (on molecular packing) or indirect (through internal antiplasticization as discussed below). It seems reasonable to correlate this behavior with the presence of unreacted epoxides. The density would be (in the systems under consideration) a continuously increasing function of the amine/epoxide ratio, owing to the... 

Figure 11.11 Cole-Cole plots for networks resulting from the condensation of diglycidyl ether of bisphenol A (DGEBA) and diethyltoluenediamine (ETHA), with various amine/epoxide molar ratios (numbers on the figures). Reprinted from Tcharkhtchi et at. 1998. Copyright 2001 with permission from Elsevier Science.

A comparison of results obtained for several networks based on the same epoxide-amine pair, but with variable amine/epoxide molar ratios, and thus variable crosslink densities, is shown in Table 11.3 (Tcharkhtchi et al., 1998). Havriliak-Negami and Perez models cannot be distinguished from one another by the quality of the fit of experimental curves, within experimental uncertainty. From a mathematical point of view, the Havriliak-Negami model is better than the Perez model because it has less parameters to fit (four parameters against five). In contrast, physical arguments could favor the Perez model, for which the parameters have a physical interpretation. 

Table 11.3 Havriliak-Negami and Perez (see text) parameters for the glass transition region of DGEBA-ETHA networks differing in the amine/epoxide molar ratio. (After Tcharkhtchi et a/., 1998.)... 

L-24 as a ligand, up to 85—90% yield. The linking reaction of a poly(tBA) with a bromide terminal was also possible with divinylbenzene, whereas the other two divinyl compounds led to side reactions.328 The yield of star polymers can be increased up to 95% with the use of additives. The a-end-functionalized linear polymers afford surface-functionalized star polymers with various functional groups such as alcohols, amines, epoxides, and nitriles. 

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