Cyclic phenol-formaldehyde

The cyclic phenol-formaldehyde resins were naturally produced in low yield as by-products of linear resins [17[. In the cyclic phenol—aldehyde resin, the end valences are joined to form a cyclic structure, for example. 

In polymer synthesis, calixarenes - cyclic phenol-formaldehyde oligomers - are rarely studied and reported. There are two main applications of calixarenes in polymer synthesis use of metal calrxarene complexes as catalysts for polymerization and star-shaped polymers with a calixarene core. 

Coreactants, in microencapsulation, 16 444 Coreactive curing agents, 10 388-389, 392-411, 418. See also Curing agents amine functional, 10 392 401 carboxylic functional polyester and anhydride, 10 401—406 cyanate ester, 10 411 cyclic amidine, 10 410 isocyanate, 10 410 melamine-, urea-, and phenol-formaldehyde resins,... 

The cyclic alkylene carbonates have also been applied as the cure-accelerators of phenol-formaldehyde (PF) [262-266] and sodium silicate [267] resin systems, which are widely used in foundry sand and wood binder applications. 

Hayes BT, Hunter RF (1958) Phenol formaldehyde and allied resins VI rational synthesis of a cyclic tetranuclear/t-cresol novolak. J Appl Chem 8 743-748. 

Alkyd and polyester resins, epoxy compounds, phenol-formaldehyde resin, urea and/or melamine-aldehyde resin, cyclic urea resin, carbamide acid ester formaldehyde resin, ketone formaldehyde resin, polyurethane, polyvinylester, polyvinyl acetate, polyvinyl chloride and polymer mixtures, polyethylene, polystryrene, styrene mixtures and graft copolymers, polyamide, polycarbonate, polyvinyl ether, polyacrylic and methacrylic acid esters, polyvinyl flouride, polyvinylidene chloride copolymers, UV and/or electron irradiated lacquers. 

The progress of the reaction was followed by monitoring the decrease in formaldehyde concentration with time. Previous studies used the hydroxylamine hydrochloride method of analysis (5 -55), but this was avoided in the current study as it requires tedious pH titrations. Instead, a colorimetric method was used that was first developed by Nash (55), involving formation of 3,5-diacetyl-1,4-dihydrolutidine, by reaction of formaldehyde with ammonia and acetyl acetone at neutral pH. The cyclic product absorbs at 412 nm with a molar extinction coefficient of 8,000 (55). Other colorimetric methods cannot be used as they all involve very strongly acidic or basic media (55), which would force the phenol-formaldehyde reaction to completion. 

Phenol-formaldehyde and allied resins VI Rational synthesis of a cyclic tetranuclear p-cresol novolak, B. T. Hayes and R. F. Hunter, J. Appl. Chem., 1958, 8, 743. 

Formaldehyde, polymer with paraformaldehyde and phenol. See Phenol-formaldehyde resin Formaldehyde protechualdehyde-3,4-cyclic acetal. See Heliotropine... 

Calixarenes, coined by C. D. Gutsche, are the cyclic oligomers produced by condensation of phenols and formaldehyde (1). In other words, they are cyclic phenol resins, but their physical and chemical properties are much different from those of linear phenol resins. Many of the calixarenes are crystalline and generally have poor solubilities in either water or in organic solvents. Their melting points are generally high, while ordinary phenol resins, novolaks, soften below 150°C. 

Formaldehyde f6r- mal-d9- hld, fer- [ISV form- + aldehyde] (1872) (formic aldehyde, methanal, oxymethylene) n. HCHO. A colorless gas with a pungent, suffocating odor, obtained most commonly by the oxidation of methanol or low-boiling petroleum gases such as methane, ethane, etc. The gas is difficult to handle, so it is sold commercially in the form of aqueous solutions (formalin), solvent solutions, as its oligomer, paraformaldehyde, and as the cyclic trimer, 1,3,5-trioxane (a-trioxym-ethyl-ene). High-molecular-weight, commercial polymers of formaldehyde are called poly-oxymethylene or acetal resin. Formaldehyde is also used in the production of other resins such as phenolic resin (phenol-formaldehyde) and amino resin (urea formaldehyde). Syn methylene oxide, methanal. See formalin. 

The most important cyclic carbonate is ethylene carbonate (EC). It is employed as a promoter in the curing of phenol-formaldehyde or epoxy resins and, in huge quantities, as a starting material for the production of DMC and DPhC. Such pro-... 

Other well known condensation polymers include phenol-formaldehyde resins, the prototype of which is Bakelite (Figure 13.15 C). Such structures were known as early as the 1870s, and in the early 20th century these tough, durable thermosets were among the first synthetic polymers of commerical importance. More modern versions of this type of polymer are known as Novolac. This chemistry is also that which make.s calixarenes (Chapter 4), which are cyclic tetramers rather than linear polymers. 

CalixLnJarenes (1) are a class of phenol-formaldehyde macrocyclic oligomers which exhibit different sizes and shapes depending on the number of phenolic units in the cyclic array and on the nature of substituents on the aromatic nucleus (R ) and on the phenolic oxygen (R ). 

The calixarenes are phenol-formaldehyde cyclic oligomers which possess hydro-phobic cavities capable of forming inclusion complexes with aromatic guest molecules in the solid state [1,2]. They also have the ability to function as ion and molecular carriers as well as enzyme mimics [1, 3,4]. 

PMR spectroscopy has been applied to the characterisation of a wide range of homopolymers including PMMA [286-289], PVC [290-294], PS [293, 295, 296], polyvinyl ethers [297-300], polyacrylic acid [301], poly(methyl-a-chloroacrylate) [302], carboxy terminated polybutadiene [303], poly(a-methyl styrene) [304], natural rubber [305-307], chlorinated polyisobutylenes [308], sulfonated PS resins [309, 310], polyvinyl phenyl ether [311], lactone polyester [312], chlorinated PVC [313], PC [314], poly 1,3 butadiene [315], poly-2-allyl phenyl acrylate [316], poly(4-methyl-pentene-1) [317], polymethacrylic acid [318], PP [296], cyclic ethers [319], polymethacrylonitrile [320], poly(a-methyl styrene) tetramer [321], PEG [322], PE [289], polyacrylamide [311], polymethylacrylamide [323], polypyrrolidone [324], polychloroprene [325], phenol formaldehyde resins [326, 327], Nylon 66 [328], polyvinylidene fluoride [329], polyvinyl formate [330], polyacrylonitrile [331], epoxy resins [332], allyl biguanide [333], poly(2-isopropyl-2-oxazollines) [334] and trehalose vinyl benzyl ether [335]. 

This issue is to celebrate the 50th anniversary of the proposal of a macrocyclic structure for the calixarenes. In February 1944, Zinke and Ziegler published an article entitled Zur Kenntnis des Hartungsprozesses von Phenol-Formaldehyde-Harzen in Chemische Berichte, volume 77, page 264. Here, they proposed a cyclic tetrameric structure (CnHi40)4 for an oligomer extracted from the condensation product mixture obtained by reacting p-tert-butylphenol with formaldehyde in the presence of sodium hydroxide. 

The functionality of precursors varying between/ = 2 and/ = 6 is considered to be low (Figure 5.2). Polyurethane networks prepared from bifunctional telechelics and trifunctional triisocyanates, diepoxide (f = 2)-diamine (f = 4) systems, diepoxide if = 4)-cyclic anhydride (/ = 2) systems, phenol (/ = 3)-formalde-hyde if = 4) resins, or melamine (/ = 6)-formaldehyde (/ = 2) resins are in this category. 

Calix[n]arenes (n=4,6,8) are cyclic condensation products of ap-substituted phenol and formaldehyde [58]. Gutsche and co-workers [59,60] have developed procedures for the synthesis of calixarenes and caHxarene derivatives. 

Dimethylsulfide is an alkyl sulfide or thioether. It is a volatile liquid (bp, 38°C) that is moderately toxic by ingestion. Thiophene is the most common cyclic sulfide. It is a heat-stable liquid (bp, 84°C) with a solvent action much like that of benzene. It is used in the manufacture of pharmaceuticals and dyes, as well as resins that also contain phenol or formaldehyde. Its saturated analog is tetrahydrothiophene, or thiophane. 

---