Catechol-formaldehyde resins

For patients hypersensitive to p-fert-butylphenol-formaldehyde resin, for whom no clinically relevant contact to this resin can be found, patch testing with p-ferf-butyl catechol can be indicated. Patch testing with p-ferf-butylphenol-formaldehyde resin is not sufficient to detect hypersensivity to phenol-formaldehyde resins based on other phenols. A more complete patch testing for allergies to this group of resins should include testing with phenol-formaldehyde resin and the patients own resins/materials. Extracts of finished products can be useful for patch testing. Resins based on phenol and p-ferf-butylphenol can be tested as a mix. (Bruze 1985, 1988)... 

Baumann also examined the details of the reaction of silicic acid with catechol (163c) as well as with a catechol-formaldehyde condensate which acted as a polyphenol (163d). The latter resin, when not too highly cross-linked, removes soluble silica from slightly alkaline water. 

Phenolic ion exchangers derived from a phenol-formaldehyde condensation reaction appeared in the first generation of ion-exchange polymers. More recently, styrene-divinylbenzene copolymers incorporating azo-substituted cresol and salicylic acid, catechol, hydroquinone, and benzoquinone have been described. The quinone-type polymers selectively sorb Hg(III) and the catechol resins sorb Cr(VI). 

Many phenolic compounds other than phenylpropanoids can be obtained from plants catechol, guaiacol, syringic acid, syringaldehyde, gallic acid, vanillin, and vanillic acid are obtained from plants. These phenolic compounds have become candidates for monomers used in the polymer industry. They undergo oxidative polymerization and serve as monomers for phenol-formaldehyde type resins, and some compounds having a hydroxyl group and a carboxylic acid serve as monomers for polycondensation. 

Cardanol is a main component of thermally treated cashew nut shell liquid (CNSL), and is a phenolic compound with a long unsaturated hydrocarbon chain substituted in the meta position (Figure 2.17a). Urushiol, which is obtained from lacquer tree, poison ivy, poison oak, and poison sumac (Toxicodendron), and used for a raw material of a lacquer (urushi) in East Asia, is also a phenolic compound of catechol with a long unsaturated or saturated hydrocarbon chain (Figure 2.17b). Cardanol-based polymers have been reported very often, while there are a few research reports on urushiol-based polymers. Research on polymers synthesized from cardanol or CNSL are reviewed elsewhere.In the late 1980s, cardanol or CNSL-based polymers began to be reported as novel phenol-formaldehyde type resins and novel epoxy resins.Thereafter, Pillai and his co-workers have vigorously studied synthesis of various type of cardanol-based polymers polymers obtained... 

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