Amine-epoxide addition

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 ... 

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... 

Heterocycles aren t new at this point we ve encountered them many times in previous chapters, usually without comment. Thus, epoxides (three-membered cyclic ethers), lactones (cyclic esters), and lactams (cyclic amides) are heterocycles, as are the solvents tetrahydrofuran (a cyclic ether) and pyridine (an aromatic cyclic amine). In addition, carbohydrates exist as heterocyclic hemiacetals (Section 25.5). 

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. 

N-Hydroxysuccinimide ester N-Hydroxysuccinimide ester Addition or alkylation Reductive amination Epoxide... 

Primary cycloaUphatic amines react with phosgene to form isocyanates. Reaction of isocyanates with primary and secondary amines forms ureas. Dehydration of ureas or dehydrosulfuri2ation of thioureas results in carhodiimides. The nucleophilicity that deterrnines rapid amine reactivity with acid chlorides and isocyanates also promotes epoxide ring opening to form hydroxyalkyl- and dihydroxyalkylaniines. Michael addition to acrylonitrile yields stable cyanoethylcycloalkylarnines. 

AH of the amine hydrogens are replaced when MDA or PMDA reacts with epoxides to form amine based polyols. These polyols can be used in reactions with isocyanates to form urethanes or with additional epoxide to form cross-linked thermo set resins. 

Polymerization to Polyether Polyols. The addition polymerization of propylene oxide to form polyether polyols is very important commercially. Polyols are made by addition of epoxides to initiators, ie, compounds that contain an active hydrogen, such as alcohols or amines. The polymerization occurs with either anionic (base) or cationic (acidic) catalysis. The base catalysis is preferred commercially (25,27). 

Methylene chloride is one of the more stable of the chlorinated hydrocarbon solvents. Its initial thermal degradation temperature is 120°C in dry air (1). This temperature decreases as the moisture content increases. The reaction produces mainly HCl with trace amounts of phosgene. Decomposition under these conditions can be inhibited by the addition of small quantities (0.0001—1.0%) of phenoHc compounds, eg, phenol, hydroquinone, -cresol, resorcinol, thymol, and 1-naphthol (2). Stabilization may also be effected by the addition of small amounts of amines (3) or a mixture of nitromethane and 1,4-dioxane. The latter diminishes attack on aluminum and inhibits kon-catalyzed reactions of methylene chloride (4). The addition of small amounts of epoxides can also inhibit aluminum reactions catalyzed by iron (5). On prolonged contact with water, methylene chloride hydrolyzes very slowly, forming HCl as the primary product. On prolonged heating with water in a sealed vessel at 140—170°C, methylene chloride yields formaldehyde and hydrochloric acid as shown by the following equation (6). 

All lene Oxides and Aziridines. Alkyleneamines react readily with epoxides, such as ethylene oxide [75-21-8] (EO) or propylene oxide [75-56-9] (PO), to form mixtures of hydroxyalkyl derivatives. Product distribution is controlled by the amine to epoxide mole ratio. If EDA, which has four reactive amine hydrogens, reacts at an EDA to EO mole ratio which is greater than 1 4, a mixture of mono-, di-, tri,-, and tetrahydroxyethyl derivatives of EDA are formed. A 10 1 EDA EO feed mole ratio gives predominandy 2-hydroxyethylethylenediamine [111-41-1], the remainder is a mixture of bis-(2-hydroxyethyl)ethylenediamines (7). If the reactive NH to epoxide feed mole ratio is less than one and, additionally, a strong basic catalyst is used, then oxyalkyl derivatives, like those shown for EDA and excess PO result (8,9). 

Ethylene oxide is a highly active intermediate. It reacts with all compounds that have a labile hydrogen such as water, alcohols, organic acids, and amines. The epoxide ring opens, and a new compound with a hydroxyethyl group is produced. The addition of a hydroxyethyl group increases the water solubility of the resulting compound. Eurther reaction of ethylene oxide produces polyethylene oxide derivatives with increased water solubility. 

Epoxide/aliphatic amine or polyamide blends Air drying Addition polymerisation Blends rich in higher ketones Fairly good Very good Poor Very good Fairly good/ good Finishes need to be supplied in two separate containers and mixed just prior to use... 

Draw structures to show how addition of the triamine results in strengthening the polymer. Amines are good nucleophiles and can open epoxide rings in the same way other bases can. 

Reduction of the aromatic amine (15) is the usual source of (14), and reductive amination of (16) gives (15). There are many published routes to (15) of which addition of an activating group (17) is probably easiest on a large scale. You may also have considered using nitro compound (18) or epoxide (19). 

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