Hexahydrophthalic anhydride

Hexahydrophthalic anhydride (HHPA) is a low-melting-point (36°C) solid. It is liquefiable at temperatures of 50 to 60°C and can be mixed easily with hot epoxy resins. The mixed resins are characterized by low viscosity, long pot life, and low exotherm. Because of its low reactivity HHPA is generally used with an accelerator, usually BDMA or DMP-30. 

HHPA is generally used in a concentration between 55 and 80 pph depending on the nature of the epoxy resin. The viscosity is generally about 200 cP at 40°C when mixed with a DGEBA epoxy resin. A typical cure schedule for a 0.5 to 2 percent BDMA catalyzed system is 2 h at 80°C plus 1 h at 200°C. Typical of all the anhydride curing agents, the cured epoxy will demonstrate high heat distortion temperatures and excellent chemical resistance. 

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Alkenylsuccinic anhydrides made from several linear alpha olefins are used in paper sizing, detergents, and other uses. Sulfosuccinic acid esters serve as surface active agents. Alkyd resins (qv) are used as surface coatings. Chlorendric anhydride [115-27-5] is used as a flame resistant component (see Flame retardants). Tetrahydrophthalic acid [88-98-2] and hexahydrophthalic anhydride [85-42-7] have specialty resin appHcations. Gas barrier films made by grafting maleic anhydride to polypropylene [25085-53-4] film are used in food packaging (qv). Poly(maleic anhydride) [24937-72-2] is used as a scale preventer and corrosion inhibitor (see Corrosion and corrosion control). Maleic anhydride forms copolymers with ethylene glycol methyl vinyl ethers which are partially esterified for biomedical and pharmaceutical uses (189) (see Pharmaceuticals). 

Hexahydrophthalic anhydride (Figure 26.10 II) (Mol. Wt. 154) has a melting point of 35-36°C and is soluble in the epoxy resin at room temperature. When 0.5% of a catalyst such as benzyldimethylamine is used the curing times are of the same order as with phthalic anhydride. About 80 phr are required. In addition... 

Zhang, X.D. et al., Relationship between IgGl levels and airway responses in guinea pigs actively and passively sensitized to hexahydrophthalic anhydride. Allergy, 53, 20, 1998. 

Fig. 5. Addition reaction products from hexahydrophthalic anhydride and diisopropanol-amine rearrangement from AB2 to ABB monomer...

The glass transition temperatures determined with these polyesteramide resins appeared to be strongly dependent on the type of anhydride used and of their molecular weight. Figure 10 shows the dependence of glass transition temperature on molecular weight for hyperbranched polyesteramides based on hexahydrophthalic anhydride. In general, the Tg for HHPA- and THPA-based resins were about 45-90°C, PA based resins about 70-100°C, and SA and GA about 20-40°C. 

Besides the water absorption, the unexpected high hydrophilic character of the hydroxyl functional hyperbranched polyesteramides is also reflected in its solubility behavior. A resin, based on hexahydrophthalic anhydride and diisopropanolamine (see Fig. 7), is soluble in water/ethanol mixtures with up to 50% water By means of GPC we followed the hydrolytic stability of this resin in 50 50 water/ethanol mixtures at different pH values (4, 7, and 10) at room temperature. Even after 28 days no degradation was observed. Only under drastic conditions, such as reflux in 50 50 ethanol/water mixture at pH 14 for 16 h was the resin completely destroyed. At other pH values such as 1 or 12, but under the same conditions, the hyperbranched polyesteramide was partly degraded. 

Molecular weights of the products as measured with vapor pressure osmometry were in good agreement with the calculated ones. Interestingly, resins based on hexahydrophthalic anhydride and diisopropanolamine with tertiary amines as functional groups are soluble in water without quaternization of the... 

Uozumi has explored a series of (25, 4/ )-4-hydroxyproline-derived 2-aryl-6-hydroxy-hexahydro-lFf-pyrrolo[l,2-c]imidazolones as potential alternatives to cinchona alkaloid-based catalysts for the alcoholative ASD of meio-anhydrides (Fig. 16) [226]. Uozumi screened a small library of catalysts prepared by a four-step, two-pot reaction sequence from 4-hydroxyproline in combination with an aldehyde and an aniline. The most selective member, compound 67, mediated the methanolytic ASD of cw-hexahydrophthalic anhydride in 89% ee when employed at the 10 mol% level for 20 h at -25 °C in toluene [226]. 

Diethyl m-hexahydrophthalate has been prepared from cis-hexahydrophthalic acid, absolute ethanol, and sulfuric acid, and from cfs-hexahydrophthalic anhydride, absolute ethanol, and sulfuric acid. Diethyl cw-A -tetrahydrophthalate has been prepared from cfx-A -tetrahydrophthalic acid or its anhydride, ethanol, and sulfuric acid. Dimethyl cfx-A -tetrahydrophthalate and dimethyl cw-hexahydrophthalate have been synthesized by the procedures of this preparation. ... 

Resing and Moniz 60) cured DGEBA with three different curing agents, piperidine, hexahydrophthalic anhydride (HHPA) and nadic methyl anhydride (NMA). Spectra were collected with C-13 NMR using cross polarization and high power decoupling. 

Garroway, Ritchie, and Moniz 70 continued the characterization of epoxy polymers with respect to molecular motion using variable temperature, solid state C-13 NMR. DGEBA was the epoxy of interest. The DGEBA was cured with piperidine, m-phenylene diamine, hexahydrophthalic anhydride and nadic methyl anhydride. The piperidine cured DGEBA had the best resolved polymer spectra. This system... 

BA BuE-PA BE-HET BE-HHPA BE-MA BE-PA BE-SA CA CHX DMA DMBA DY 062 GA HEB HHPA HMTA MA MTHPA NMA benzoic acid monobutylester of phthalic acid monobenzylester of hexachloroendomethylenetetrahydrophthalic acid monobenzylester of hexahydrophthalic acid monobenzylester of maleic acid monobenzylester of phthalic acid monobenzylester of succinic acid citraconic anhydride cyclohexanol N,N-dimethylaniline dimethylbenzylamine high boiling tertiary amine (Ciba Geigy AG) gjptaric anhydride 2-hydroxy-4-(2,3-epoxypropoxy)benzophenone hexahydrophthalic anhydride hexamethylenetetramine maleic anhydride methyltetrahydrophthalic anhydride nadic methyl anhydride (methylbicyclo[2.2.1]heptene-2,3-dicarboxylic anhydride isomers)... 

Table 3. Hammett reaction constants q for the copolymerization of p-N02, p-C02CH3, p-Cl, p-H, p-CHj, and p-OCH3 substituted phenylglycidyl ethers with hexahydrophthalic anhydride initiated with tri-n-butylamine ...

Tanaka and Kakiuchi52 > analyzed the conversion curves for the copolymerization of substituted phenylglycidyl ethers with hexahydrophthalic anhydride and found a first-order dependence with respect to the initiator at the maximum reaction rate (Eq. (80)), and second-order kinetics for the region of initiation (Eq. (81)). 

Antoon and Koenig 67) found a first-order dependence with respect to the tertiary amine, but they were not able to distinguish between zero-, first-, and second-order kinetics with respect to monomers. Approximately the same fit was obtained for all mentioned orders below the gel point. Peyser and Bascom reported first-order kinetics for the curing of the diglycidyl ether of bisphenol A with hexahydrophthalic anhydride 94) and second-order kinetics with respect to the same epoxide cured with nadic methyl anhydride 93). They also pointed out the uncertainty in determining the reaction order. 

Second-order kinetics with respect to the amine and epoxide was also found by Antipova et al. 65) for the curing of epoxy resins with hexahydrophthalic anhydride, by Sorokin et al.321 for the reaction of phenylglycidyl ether with phthalic anhydride in the presence of butanol, Luston and Manasek 45 74) for the copolymerization of 2-hydroxy-4-(2,3-epoxypropoxy)benzophenone with phthalic anhydride in the absence or in the presence of proton donors, and Kudyakov et al. 98) for the curing of epoxy resins with maleic anhydride. 

Tanaka and Kakiuchi35 361 found a proportionality between the rate of curing of epoxy resins with hexahydrophthalic anhydride and the concentrations of epoxide, anhydride and tertiary amine (Eq. (82)), and also first-order kinetics with respect to the proton donors if present (Eq. (83)). 

Boos and Flauschildt90) obtained for the model copolymerization of phenylglycidyl ether with hexahydrophthalic anhydride activation energies of 96 kJ/mol up to 75% conversion and 27 kJ/mol for higher conversions. Frequency factors are also very different (log A = 13.7 and 5.5, respectively). The frequency factors as well as the temperature coefficients of the solution viscosities depended on the initiator concentration. The activation energy determined by the same authors 90) for the curing of epoxy resins at conversions lower than 75% was 86.4 kJ/mol and the frequency factor log A = 11.8 whereas at higher conversions these values were not obtained. 

Typical polyesteramide made from di-2-propanolamine, hexahydrophthalic anhydride and bis-(dimethylaminopropyl)imine. Synergists polyethyleneimine reacted with formaldehyde and caprolactam giving polymers with pendant caprolactam rings V-methyl butylamine reacted with formaldehyde and polyacrylamide... 

When 1,2,3,6-tetrahydrophthalic anhydride (4-cyclohexene-l,2-dicarboxylic acid anhydride) (36) is heated with a mixture of hydrogen sulfide and hydrogen in the presence of cobalt sulfide, it gives octahydrobenzo[c]thiophene (53%) and a trace of 4,5,6,7-tetra-hydrobenzo[c]thiophene.48 Similar treatment of hexahydrophthalic anhydride gives a mixture (69%) of cis- and (rcww-octahydrobenzo[c]-thiophene, which may be separated by VPC.48... 

After the primary amines, acid anhydrides are the next most important class of epoxy curing agents, although these are not used as often in adhesive systems as they are in casting compounds, encapsulants, molding compounds, etc. The most common types of anhydrides are hexahydrophthalic anhydride (HHPA), phthalic anhydride (PA), nadic methyl anhydride (NMA), and pyromellitic dianhydride (PMDA), although there are several others. Chemical structures of several anhydrides are illustrated in Fig. 5.6. 

Fig. 19. Critical conversion of epoxy groups at the gel point, for the stoichiometric system DGEBA-hexahydrophthalic anhydride as a function of the relative concentration of the tertiary amine catalyst (initiator), q = [lyiEJ using various analytical method and reaction condition (for details cf. Ref.------theoretical de-...

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