Epoxy nitrile

Another pertinent case is the formation of a tertiary fluoride from treatment of P,(1-disubs titu ted [Pg.91]

The most striking aspect about ring formation of epoxy nitriles is their stereochemical requirements. For example, the 2-hydroxymethylcyclobutanecarbonitrile 11 was formed exclusively from the m-epoxide cy.v-10, but reaction of the corresponding Orw.v-epoxide lrans-10 gave a mixture of cyclobutane 11 and cyclopentane 12.12... 

The reaction of 5-silyl-y,5-epoxypentanenitrile derivatives with a base and an alkylating agent gives (Z) - 3 - s i I o x y- y, 3 -u n saturated pentanenitrile derivatives via a tandem process that involves the formation of a cyclopropane derivative by epoxy nitrile cyclization followed by Brook rearrangement and an anion-induced cleavage of the cyclopropane ring (Scheme 105).152... 

The early aerospace adhesives were primarily based on epoxy resin chemistry. However, unique applications requiring high temperatures and fatigue resistance have forced the development of epoxy-phenolic, epoxy-nitrile, epoxy-nylon, and epoxy-vinyl adhesives specifically for this industry. The aerospace industry has led in the development and utilization of these epoxy-hybrid adhesives. 

Epoxy-nitrile Nitrile-epoxy adhesives are composed of solid epoxy resin modified with carboxyl-terminated butadiene nitrile (CTBN) copolymer. The CBTN is introduced into die epoxy resin at elevated temperatures. The modification provides toughness and high peel strength without sacrificing heat and chemical resistance. The film adhesives are widely used in the aerospace industry in the construction of jetliners. 

Vinyl-phenolic Nitrile-phenolic Epoxy-phenolic Epoxy-nylon Epoxy-nitrile 3000-4500 15-35 3000-4500 15-60 2000-3200 6-12 5500-7200 80-130 3700-6000 22-90... 

The epoxy-nitrile adhesives were introduced commercially in the late 1960s. They consisted primarily of DGEBA epoxy resin modified with carboxyl-terminated butadiene nitrile (CTBN) rubber. These first nitrile copolymers were available from B.F. Goodrich under the trade name of Hycar. The most convenient form of epoxy nitrile adhesive, especially when one is bonding large parts (aircraft structures), is a supported film. However, solvent solutions of epoxy-nitrile adhesives have also been commercially available. 

However, the single-phase epoxy nitrile adhesive achieves its high peel strength by bulk elongation. Other properties, such as heat and chemical resistance, are generally degraded as they are when other flexibilizers or plasticizers are added to the epoxy. The two-phase version of this adhesive hybrid solves many of these problems. 

Typically tape or film epoxy adhesives are modified with synthetic thermoplastic polymers to improve flexibility in the uncured film and toughness in the cured adhesive. Epoxy resins can also be blended with phenolic resins for higher heat resistance. The most common hybrid systems include epoxy-phenolics, epoxy-nylon, epoxy-nitrile, and epoxy-vinyl hybrids. These hybrid film adhesives are summarized in Table 13.2, and structural properties are shown in Table 13.3. 

Epoxy-nitrile adhesives have also been developed for the purpose of toughening conventional epoxy adhesives. These early adhesives were made from homogeneous blends of nitrile elastomer and epoxy resin. They are not similar to the modern-day CTBN toughened epoxy adhesive where the nitrile phase consists of discrete particles. An advantage of the... 

The toughness of an epoxy-nitrile adhesive is nearly equivalent to that of an epoxynylon adhesive. However, the epoxy-nitrile system has much better hydrolytic stability. Also, the low-temperature properties of an epoxy-nitrile adhesive are superior to those of epoxy-nylon adhesive. Table 7.3 illustrates the effect of nitrile addition on tensile shear and peel strength. 

Epoxies, nitriles, and phenolics show relatively low diffusion rates and are less susceptible to moisture attack than most other polymers. As a result, these materials are often used in adhesive and sealant formulations where resistance to moisture is essential. 

C cured film (nitrile-phenolic, vinyl-phenolic, novolac-epoxy) 120°C cured film (modified epoxy, nitrile-epoxy, nylon-epoxy)... 

Epoxy-nitrile 1500 60°C, 100% RH All samples failed before 2 months... 

Vinyl-phenolic Nitrile-phenolic Vinyl-phenolic Neoprene-phenolic Nylon-phenolic Modified epoxy Nitrile-phenolic Epoxy... 

Various adhesives can be used to bond polyphenylene oxide to itself or to other substrates. Parts must be prepared by sanding or by chromic acid etching at elevated temperature. Methyl alcohol is a suitable solvent for surface cleaning. The prime adhesive candidates are epoxies, modified epoxies, nitrile phenolics, and polyurethanes. Epoxy adhesive will provide tensile shear strength on abraded polyphenylene oxide substrates of 600 to 1300 psi and 1300 to 2200 psi on etched (chromic acid) substrates.71... 

Marshall has applied the reductive decyanation-elimination of /3, -y-epoxy-nitriles to allylic alcohols212 in a synthesis of cis- and trans-pulegol (Scheme 11) which is converted into ( )-pulegone.213... 

Urea-Formaldehyde Adhesives used are epoxies, nitrile-phenolics, phenol-formaldehyde, resorcinol-formaldehyde, furan, polyesters, butadiene-nitrile rubber, neoprene, cyanoacrylate, and phenolic-polyvinyl butyral (1). 

Ishii, K., Abe, M., and Sakamoto, M., Photochemical reactions of nitrile compounds. Part 2. Photochemistry of an a,P-unsaturated 7,S-epoxy nitrile and Y,8-cyclopropyl nitrile, J. Chem. Soc., Perkin Trans. 1, 1937, 1987. 

Kotera, M., Ishii, K., and Sakamoto, M., Photocyclization reactions of epoxy nitriles via carbonyl ylides. Formation of spiroketals, spiroethers, and a spirolactone, Chem. Pharm. Bull., 43, 1621, 1995. 

FM . [Ant Cyanatnid] Epoxy, nitrile, phenolic, or polyimide resins foam and adhesive api cs. 

Epoxy nitriles and esters generated in situ from chloroketones can be readily transformed into the corresponding allylic alcohols with LDA, proving a rapid route to hydroxy amino acids. 

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