Phenol-aldehyde condensations

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... 

Erdtman. H. Hogberg, S. Abramson. S. Nilsson. B, Cyclooligomeric phenol-aldehyde condensation products. Tetrahedron Lett. 1968. 1679. 

Hogbeig AG (1980) Cyclooligomeric phenol-aldehyde condensation products. Stereoselective synthesis and DNMR study of two l,8,15,22-tetraphenyl[14]metacyclophan-3,5,10,12,17,19,24,26-octols. J Am Chem Soc 102 6046-6050... 

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... 

Reaction uniformity in phenol-aldehyde condensations is obtained by careful control of reaction conditions such as temperature of condensation [39], catalyst concentration, and pH. At the early stages the reaction is exothermic, and the temperature must be controlled to prevent a runaway reaction [40]. Gel permeation chromatography offers a means to monitor product uniformity. Specific catalysts (usually 1-6%) are used to obtain either a resole (alkaline catalysts or basic salts) or novolac (acid catalysts). 

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. 

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