Aldehyde Condensation Polymers

Among the polymeric stabilizers may be listed poly-condensed polymers based on alkyl phenols, aldehydes, and ketones of the aliphatic series, where = 1 - 8 and R,R means alkyl [24], Na, K, Ca phenolates of poly-condensed polymers [25], and also products of epichlor-ide with one or more aliphatic amines C3—C30 [26]. 

In far too many instances trade-name polymer nomenclature conveys very little meaning regarding the structure of a polymer. Many condensation polymers, in fact, seem not to have names. Thus the polymer obtained by the step polymerization of formaldehyde and phenol is variously referred to a phenol-formaldehyde polymer, phenol-formaldehyde resin, phenolic, phenolic resin, and phenoplast. Polymers of formaldehyde or other aldehydes with urea or melamine are generally referred to as amino resins or aminoplasts without any more specific names. It is often extremely difficult to determine which aldehyde and which amino monomers have been used to synthesize a particular polymer being referred to as an amino resin. More specific nomenclature, if it can be called that, is afforded by indicating the two reactants as in names such as urea-formaldehyde resin or melamine-formaldehyde resin. 

Melt poly condensation is also the most popular method for other thermotropic condensation polymers, including the polyazomethines where the reaction between aromatic aldehydes or ketones and primary amines with elimination of water leads to azomethine (Schiffs base) formation 48). 

The synthesis of optically active polymers is an important area in macromolecular science, as they have a wide variety of potential applications, including the preparation of CSPs [31-37]. Many of the optically active polymers with or without binding to silica gel were used as CSPs and commercialized [38]. These synthetic polymers are classified into three groups according to the methods of polymerization (1) addition polymers, including vinyl, aldehyde, isocyanide, and acetylene polymers, (2) condensation polymers consisting of polyamides and polyurethanes, and (3) cross-linked gels (template polymerization). The art of the chiral resolution on these polymer-based CSPs is described herein. 

The second known possibility is the reaction of (Si a) with aldehyde or acetales under acidic conditions in CHCI3 (Eq. 39) The mechanism of the condensation is analogu-ous to the reaction of phenols with aldehydes. Condensation at the /8-position of 83 a) leads over dimer and trimer to the polymer 85) (yield < 30%). The yield of 85) may be optimized using a solvent with a higher solubility for the polymer. The limitation is the low yield of 4.3% for the one step synthesis of 83 a). 

Aniline—form aldehyde resins were once quite important because of their excellent electrical properties, but their markets have been taken over by newer thermoplastic materials. Neverthd.ess, some aniline resins are stiU used as modifiers for other resins. Acrylamide (qv) occupies a unique position in the amino resins field since it not only contains a formaldehyde reactive site, but also a polymerizable double bond. Thus it forms a bridge between the formaldehyde condensation polymers and the versatile vinji polymers and copolymers. 

Polyvinyl - methyl- ether Vinyl chloride polymers Urea- and melamineform-aldehyde condensates (uncured) Crosslinked (cured, vulcanized) polymers... 

Formaldehyde/urea condensate Formaldehyde/urea copolymer Form-aldehyde/urea polymer Formaldehyde/urea precondensate Formaldehyde/urea epolymer Formaldehyde/urea resin. See Urea-formaldehyde resin... 

Thus, it is possible to form the very reactive, aldehyde-functionalized polymers by functionalization of polymeric organolithium compounds with 4-morpholinecarboxaldehyde. The key to the success of this procedure is due to the formation of a stable, tetrahedral intermediate that does not decompose to form the aldehyde group until work-up with alcohol. Work-up with acidic methanol is the preferred procedure to prevent dimer formation from base-catalyzed aldol condensation, primarily for functionalizations of poly(dienyl)lithiums. 

Specifically, the adhesives described by Briggs and Muschiatti employ chlorosulfonated polyethylene or mixtures of sulfonyl chlorides and chlorinated polymers as the toughening system. The toughener is dissolved in methyl methacrylate and an amine/aldehyde condensation product is used as the curative. These compositions are described as useful with or without the traditional hydroperoxide initiator. Compositions without hydroperoxide are noticeably slower to cure. 

The calixarenes (from the Greek calix, meaning chalice) are a family of structures that have seen extensive use in many contexts. Shown below is the remarkable, one-step synthesis of the prototype calixarene. This condensation reaction is a variant of the phenol-aldehyde condensation that produces bakelite, the first synthetic polymer. Early workers spent considerable effort to optimize this synthesis, biasing the product toward the calixarene... 

This volume continues in the tradition of Volume I in presenting detailed laboratory instructions for the preparation of various types of polymers such as urea, melamine, benzoguanamine/aldehyde resins (amino resins-amino-plasts), phenol/aldehyde condensates, epoxy resins, silicone resins, alkyd resins, polyacetyls/polyvinyl acetals, polyvinyl ethers, polyvinyl pyrroli-dones, polyacrylic acids, and polyvinyl chloride. Polyvinyl acetate and related vinyl esters, allyl polymers, acetylene polymers, maleate and fumarate polymers, and several other addition-condensation polymer types will be covered at a later date in Volume III. 

Although the plastics industry uses both classes of polymers, most thermoset plastics are based on heterochain polymers such as the urethane, epoxy, and aldehyde condensation resins. Thermoplastics, however, are mainly based on carbon chain polymers (with the notable exceptions of polyesters, nylons, and a few others). 

Phenol - aldehyde polymers. L. Baekland (1909) first demonstrated the possibilities of the reaction between phenol and formaldehyde from the commercial view point. Condensation in the presence of either... 

Aldehydes fiad the most widespread use as chemical iatermediates. The production of acetaldehyde, propionaldehyde, and butyraldehyde as precursors of the corresponding alcohols and acids are examples. The aldehydes of low molecular weight are also condensed in an aldol reaction to form derivatives which are important intermediates for the plasticizer industry (see Plasticizers). As mentioned earlier, 2-ethylhexanol, produced from butyraldehyde, is used in the manufacture of di(2-ethylhexyl) phthalate [117-87-7]. Aldehydes are also used as intermediates for the manufacture of solvents (alcohols and ethers), resins, and dyes. Isobutyraldehyde is used as an intermediate for production of primary solvents and mbber antioxidants (see Antioxidaisits). Fatty aldehydes Cg—used in nearly all perfume types and aromas (see Perfumes). Polymers and copolymers of aldehydes exist and are of commercial significance. 

In a dedicated combinatorial approach, Strohmeier and Kappe have reported the rapid parallel synthesis of polymer-bound enones [33]. This approach involved a two-step protocol utilizing initial high-speed acetoacetylation of Wang resin with a selection of common /i-ketoesters (Scheme 7.13) and subsequent microwave-mediated Knoevenagel condensations with a set of 13 different aldehydes (see Section 7.3.6). 

The synthesis of 4,5-disubstituted triazoles shown in Scheme 208, carried out on a polymer support with microwave assistance, is based on a similar principle. In the first step, sulfinate 1248 is converted to sulfone 1249. Condensation with aldehydes provides vinyl sulfones 1250. Cyclocondensation of sulfones 1250 with sodium azide generates corresponding triazoline intermediates that eliminate sulfinate 1248 to provide triazoles 1251 in moderate to good yield <2006OL3283>. 

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