Phenolic condensate resins

Under comparable reaction conditions the much more reactive formaldehyde and phenol do not only give the para- but also the ortho-substituted phenol derivative. This reaction ultimately leads to the three-dimensional network of formaldehyde/phenol condensation resins such as Bakelite and to related, well-defined receptor molecules known as cahxarenes. 

PMMA Phenolic Phenol condensation resins (low Mw) miscibility with PMMA FTIR shown 25 cm shift in carbonyl frequency band 819... 

Platinum-group metals (qv) form complexes with chelating polymers with various 8-mercaptoquinoline [491-33-8] derivatives (83) (see Chelating agents). Hydroxy-substituted quinolines have been incorporated in phenol—formaldehyde resins (84). Stannic chloride catalyzes the condensation of bis(chloromethyl)benzene with quinoline (85). 

The epoxy cresol—novolak resins (2) are prepared by glycidylation of o-cresol—formaldehyde condensates in the same manner as the phenol—novolak resins. The o-cresol—formaldehyde condensates are prepared under acidic conditions with formaldehyde—o-cresol ratios of less than unity. 

The phenolics are resinous materials produced by condensation of a phenol, or mixture of phenols, with an aldehyde. Phenol itself and the cresols are the most widely used phenols whilst formaldehyde and, to a much less extent, furfural are almost exclusively used as the aldehydes. 

Since the last edition several new materials have been aimounced. Many of these are based on metallocene catalyst technology. Besides the more obvious materials such as metallocene-catalysed polyethylene and polypropylene these also include syndiotactic polystyrenes, ethylene-styrene copolymers and cycloolefin polymers. Developments also continue with condensation polymers with several new polyester-type materials of interest for bottle-blowing and/or degradable plastics. New phenolic-type resins have also been announced. As with previous editions I have tried to explain the properties of these new materials in terms of their structure and morphology involving the principles laid down in the earlier chapters. 

Prior to 1890, formaldehyde was not commercially available [2]. Thus the first phenol-formaldehyde resins were made using formaldehyde equivalents such as methylene diacetate or methylal [2,20]. The first true phenol-formaldehyde resin was made by Kleeberg at the direction of Emil Fisher in 1891 [2,21]. Saliginen (o-hydroxymethyl phenol) was recognized as a condensation product of phenol and formaldehyde in 1894 and was the subject of United States patents in 1894 and 1896 [22,23]. 

The same chemical mechanisms and driving forces presented for phenol-formaldehyde resins apply to resorcinol resins. Resorcinol reacts readily with formaldehyde to produce resins (Fig. 2) which harden at ambient temperatures if formaldehyde is added. The initial condensation reaction, in which A-stage liquid resins are formed, leads to the formation of linear condensates only when the resorcinol/formaldehyde molar ratio is approximately 1 1 [119]. This reflects the reactivity of the two main reactive sites (positions 4 and 6) of resorcinol [120]. However, reaction with the remaining reactive but sterically hindered site (2-positiori) between the hydroxyl functions also occurs [119]. In relation to the weights of resorcinol-formaldehyde condensates which are isolated and on a molar basis, the proportion of 4- plus 6-linkages relative to 2-linkages is 10.5 1. However, it must be noted that the first-mentioned pair represents two condensa-... 

A reaction vessel explosion at BASF s resins plant in Cincinnati (July 19, 1990) killed one and injured 71. The BASF facility manufactures acrylic, alkyd, epoxy, and phenol-formaldehyde resins used as can and paper-cup liner coatings. The explosion occurred when a flammable solvent used to clean a reaction vessel vented into the plant and ignited. The cleaning solvent that was not properly vented to a condenser and separator, blew a pressure seal, and fdled the 80-year-old building with a white vapor cloud. 

Synthetic resins form the heart of the paint industry. The tw o main types of synthetic resins are condensation polymers and addition polymers. Condensation polymers, formed by condensation of like or unlike molecules into a new, more complex compound, include polyesters, phenolics.. iniino resins, polyurethane, and epoxies. Addition polymers include polyvinyl acetate, polyvinyl chloride, and the acrylates,... 

Though less prevalent than addition polymerization, condensation polymerization produces important polymers such as polyesters, polyamides (nylons), polycarbonates, polyurethanes, and phenol-formaldehyde resins (Chapter 12). 

Phenol-formaldehyde resins are the oldest thermosetting polymers. They are produced by a condensation reaction between phenol and formaldehyde. Although many attempts were made to use the product and control the conditions for the acid-catalyzed reaction described by Bayer in 1872, there was no commercial production of the resin until the exhaustive work by Baekeland was published in 1909. In this paper, he describes the product as far superior to amber for pipe stem and similar articles, less flexible but more durable than celluloid, odorless, and fire-resistant. ° The reaction between phenol and formaldehyde is either base or acid catalyzed, and the polymers are termed resols (for the base catalyzed) and novalacs (for the acid catalyzed). 

A Friedel-Crafts-type reaction of phenols under basic conditions is also possible. Aqueous alkaline phenol-aldehyde condensation is the reaction for generating phenol-formaldehyde resin.34 The condensation of phenol with glyoxylic acid in alkaline solution by using aqueous glyoxylic acid generates 4-hydroxyphenylacetic acid. The use of tetraalkylammonium hydroxide instead of sodium hydroxide increases the para-selectivity of the condensation.35 Base-catalyzed formation of benzo[b]furano[60]- and -[70]fullerenes occurred via the reaction of C60CI6 with phenol in the presence of aqueous KOH and under nitrogen.36... 

Substance made of giant molecules formed by the union of simple molecules (monomers) for example, polymerization of ethylene forms a polyethylene chain, or condensation of phenol and formaldehyde (with production of water) forms phenol-formaldehyde resins. 

Cation-exchange resins are used as catalysts in the produdion of MTBE (methyl tertiary-butyl ether, 2-methoxy-2-methylpropane) and various other oxygenates and, lately, also in the dimerization of isobutene [30]. Other commercial applications of the cation-exchange resins indude dehydration of alcohols, alkylation of phenols, condensation readions, alkene hydration, purification of phenol, ester hydrolysis and other reactions [31]. The major producers of ion-exchange resins are Sybron Chemicals Incorporated [32] (Lewatit resins), Dow Chemical Company [33] (DOWEX resins), Purolite [28] (Purolite resins), and Rohm and Haas Company [27] (Amberlyst resins). 

In the development of a reactive non-chrome post-treatment, a variety of phenolic resins were synthesized and commercial phenolic resins evaluated. It was found that phenol-formaldehyde resins, creso1-forma1dehyd e condensates, ortho-novo 1 ak resins, and phenol-formaldehyde emulsions gave positive results when employed as post-treatments over zinc and iron phosphate conversion coatings. The above materials all possessed drawbacks. The materials in general have poor water solubility at low concentrations used in post-treatment applications and had to be dried and baked in place in order to obtain good performance. The best results were obtained with poly-4-vinylphenol and derivatives thereof as shown in the following structure (8,9,10)... 

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. 

Condensations with carbonyl compounds phenol-formaldehyde resins. Acid or base catalyzes electrophilic substitution of carbonyl compounds in ortho and para positions of phenols to form phenol alcohols (Lederer-Manasse reaction). 

Instead, a prepreg that is particularly suitable for the fabrication of electrical and office equipment has been developed. This prepreg consists of a thermoset, preferably a phenol formaldehyde resin, that is formulated with a MMBS resin. The MMBS resin is added to the phenolic novolak preferably at the stage of the condensation reaction of the phenolic resin. 

The first synthetic plastics were the phenol-formaldehyde resins introduced by Baekeland in 1907 [1], Melamine and urea also react with formaldehyde to form intermediate methylol compounds which condense to cross-linked polymers much like phenol-formaldehyde resins. Paper, cotton fabric, wood flour or other forms of cellulose have long been used to reinforce these methylol-functional polymers. Methylol groups react with hydroxyl groups of cellulose to form stable ether linkages to bond filler to polymers. Cellulose is so compatible with these resins that no one thought of an interface between them, and the term reinforced composites was not even used to describe these reinforced systems. 

Acid Catalyzed. Although ketonic carbonyl groups are less reactive than aldehydic carbonyls in the presence of basic catalysts, this is not the case with acid catalysts. Thus acetone undergoes aldol addition in the presence of sulfuric acid to give mesityl oxide, which then condenses with a third molecule of acetone to give a mixture ofphorone (2,6-dimethyl-2,6-heptadien-4-one) and mesitylene (1,3,5-trimethylbenzene). Ketones also condense with activated aromatic products in the presence of sulfuric acid to give coupled aromatic products. For example, acetone and phenol condense to bisphenol A (4,4 -isopropylidenediphenol), which is used in the manufacture of epoxy resins (qv) and polycarbonates (qv). 

Recovery System (MARS) for recovery of phenol from resin production condensates. Journal of Membrane Science,... 

One of the earliest commercial plastics was Bakelite , formed by the reaction of phenol with a little more than one equivalent of formaldehyde under acidic or basic conditions. Baeyer first discovered this reaction in 1872, and practical methods for casting and molding Bakelite were developed around 1909. Phenol-formaldehyde plastics and resins (also called phenolics) are highly cross-linked because each phenol ring has three sites (two ortho and one para) that can be linked by condensation with formaldehyde. Suggest a general structure for a phenol-formaldehyde resin, and propose a mechanism for its formation under acidic conditions. (Hint Condensation of phenol with formaldehyde resembles the condensation of phenol with acetone, used in Problem 26-17, to make bisphenol A.)... 

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