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Phenol-formaldehyde resins, as a group, are formed by a step-growth polymerization reaction that can be either acid- or base-catalysed.Since formaldehyde exists predominantly in solution as a dynamic equilibrium of methylene glycol oligomers, the concentration of the reactive form of formaldehyde depends on temperature and pH.
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Another method entails methylation of phenol with methanol over a solid acid catalyst, often comprising magnesium oxide or alumina. Temperatures above 300 °C are typical. Anisole converts to cresols under these conditions. [5] [6] Another isomer of cresol is called Benzyl alcohol, or alpha-cresol (α-cresol).
Phenolic, amino, and furan resins all cured by polycondensation involving the release of water and heat, with cure initiation and polymerisation exotherm control influenced by curing temperature, catalyst selection or loading and processing method or pressure – the degree of pre-polymerisation and level of residual hydroxymethyl content in ...
This pattern is illustrated by the use of formaldehyde in the production various polymers and resins from phenol-formaldehyde condensations (Bakelite, Novolak, and calixarenes). Similar crosslinking occurs in urea-formaldehyde resins. The hydroxymethylation of N-H and P-H bonds can often be reversed by base.
Melamine-formaldehyde resin forms via the condensation of formaldehyde with melamine to give, under idealized conditions, the hexa-hydroxymethyl derivative. Upon heating in the presence of acid, this or similar hydroxymethylated species undergoes further condensation and crosslinking.
Para tertiary butylphenol formaldehyde resin, also known as p-tert-butylphenol-formaldehyde resin (PTBP-FR), is a thermoplastic phenol-formaldehyde resin found in commercial adhesives, particularly glues used to bond leather and rubber. It has broad usage in a large variety of industries and can be found in many household textile products and ...
Salicyl alcohol is produced by the hydroxymethylation of phenol using formaldehyde: [4] C 6 H 5 OH + CH 2 O → C 6 H 4 OH(CH 2 OH. Air oxidation of salicyl alcohol gives salicylaldehyde. C 6 H 4 OH(CH 2 OH + O → C 6 H 4 OH(CHO) +H 2 O. Chemical sweeteners are formed by acetal formation with e.g. isovanillin (Cmp4). [5]