Epoxy amine

Hydroxyazetidines. 2,3-Epoxy amines undergo isomerization (cyclization). The reaction is stereoselective. 

Payne reaction. Recent methodology takes advantage of the same anchimeric activity in optically active 2,3-epoxy sulfides and 2,3-epoxy amines (82 and 85), whereby treatment with Lewis acid induces rearrangement to the corresponding thiiranium and aziridinium ions (83 and 86) as reactive intermediates which react efficiently with a variety of nitrogen-based nucleophiles to give functionalized hydroxy sulfides (84) or hydroxy amines (87) <97SL11>. 

Scheme 10.S Aza-Pavne rearrangement of representative 2.3-epoxy amines.

Aziridine rings constitute a vital sub-structure of biologically active molecules. This renders the synthesis of such compounds through aza-Payne rearrangement of aziridinemethanols 28 and 2,3-epoxy amines 29 of much interest in connection with the synthesis of bioactive compounds. 

When 2,3-epoxy amine 5, structurally related to epoxyalkanes 1 and 2 was treated with trimethylsilyl trifluoromethanesulfonate (TMSOTf) in CDCI3 at - 40°C, and the reaction mixture was allowed to warm to room temperature, the H-NMR spectrum of the resulting solution clearly showed the formation of a new compound 6, stable at room temperature (Scheme 6.2). Compound 6 was very reactive in the presence of nucleophiles yielding, after hydrolysis, products with the structure of aminoalcohols. 

Alkyl-2,3-epoxy amines react with the azide ion of trimethylsilyl azide at C(3) when the Lewis acid is either Bp3-Et20 or ZnCl2 but at C(2) when the Lewis acid is Ti(OPr-1)4. The regiospecificity is >95 5 when either BF3 or ZnCl2 is used but is completely reversed at <5 95 when the Lewis acid is Ti(OPr-i)4. The yields range from 76 to 98% in the three reactions. 

Asphalt, unmodified Coal tar Coal tar— epoxy Coal tar— nretlianes Epoxy phenolic- baked Epoxy amine- cnred Epoxy ester Fnrfnryl alcohol Phenolics, baked Polyesters (nnsati i-rated) Polyvinyl cliloracetates Vinyl ester Urethanes Vinylidene cliloride Clilorinated rubber... 

Material used to activate resins to promote hardening. For polyesters, organic peroxides are used primarily. For epoxies, amines and anhydrides are used. 

After rinsing and dry-off, the primer is applied. In most modern plants this means electrodeposition of the primer (Section 14.1). The most widely used primers are cathodic. The body shell is made the cathode and current flows between it and inert anodes in the electropaint bath. The paint is formulated so that the resin is basic and, when neutralised with an acid such as lactic acid, becomes positively charged. The most widely used resins are epoxy-amine adducts ... 

Figure 1. Three main epoxy - amine curing reactions.

Figure 2. Mechanism and reaction rates for the epoxy - amine cure.

Epoxy (Amine-Cured) Bisphenol A-based epoxy resins used for composite fabrication are commonly cured with multifunctional primary amines. For optimum chemical resistance these generally require a heat cure or postcure. The cured resin has good chemical resistance, particularly to basic environments, and can have good temperature resistance. 

Mailhot B, Morlat-Therias S, Bussiere P-O, Gardette J-L (2005) Study of the degradation of an epoxy/amine resin, kinetics and depth-profiles. Macromol Chem Phys 206 585-591... 

For imperfect epoxy-amine or polyoxypropylene-urethane networks (Mc=103-10 ), the front factor, A, in the rubber elasticity theories was always higher than the phantom value which may be due to a contribution by trapped entanglements. The crosslinking density of the networks was controlled by excess amine or hydroxyl groups, respectively, or by addition of monoepoxide. The reduced equilibrium moduli (equal to the concentration of elastically active network chains) of epoxy networks were the same in dry and swollen states and fitted equally well the theory with chemical contribution and A 1 or the phantom network value of A and a trapped entanglement contribution due to the similar shape of both contributions. For polyurethane networks from polyoxypro-pylene triol (M=2700), A 2 if only the chemical contribution was considered which could be explained by a trapped entanglement contribution. 

Figure 2. Theoretical curves for superimposed reduced moduli Gd /RT(mol/ cm 3) of epoxy-amine networks versus the gel fraction ws. Fraction of epoxy groups in monoepoxide is O, 0 , 0.2 A, 0.33 V, 0.5. Key O, , A, V, dry networks , A, , swollen networks value of front factor A indicated.

Two-bath, two-stage dyeing process, 9 198 Two-bladed impellers, 16 672-673 Two-color thermometers, 24 457 Two-component epoxy—amine coatings, 10 443... 

New coatings to improve impermeability o PET coating with an epoxy-amine barrier... 

Figure 6. XPS C Is (left) and 0 Is (right) spectra of the interfacial substrate surface of epoxy-amine coating on bare steel following cathodic polarization testing (solid curves). Also shown is an approximate curve resolution for each spectrum components of the C Is spectrum are, from left, alkane, ether, and carbonate principal components of the 0 Is spectrum are, from left, iron oxide, carbonate, ether, ad adsorbed water (29.) or sodium Auger ( ). Reproduced with permission from Ref. 29. Copyright 1981, Pergamon Press.

Figure 7. Paint adhesion loss in salt spray exposure (ASTM B117) as a function of ester content for chain-extended epoxy-amine and epoxy-ester resin based coatings. All coatings applied at 20-25 urn film thickness to SAE 1010 steel test panels, baked, scribed and exposed for 24 hours to salt spray conditions.

A similar example of curing inhibition In an acidic medium has been observed when moderate amounts of salicylic acid were added to epoxy-amine matrix systems. (26) Such behavior may beresponsible for the poor bond strengths observed with the NTMP-containing oxide-primer specimens. In environments containing an aggressive species (e.g.. Cl ), the anion may interact with and become incorporated into the NTMP-oxide matrix, whereby it can attack the metal surface. 

For this work, the epoxy/amine ratio was varied and the dynamic mechanical response was determined for ... 

Figure 7. Arrhenius plot for mixed system to B-stage cure glass cloth composites for several epoxy/amine ratios.

---