Bisphenols, substituted formaldehyde reaction

The diarylation reaction is especicdly common with phenols (the diaryl product here is called a bisphenol). The reaction is normally carried out in alkaline solution on the phenolate ion. The hydroxymethylation of phenols with formaldehyde is called the Lederer-Manasse reaction. This reaction must be carefully controlled, since it is possible for the para and both ortho positions to be substituted and for each of... 

Bisphenol F Resins. Diglycidyl ether resins based on bisphenol F (DGEBF) have been developed to provide cured epoxy resins with greater flexibility and lower softening temperatures than conventional DGEB A epoxy resins. The preparation of bisphenol F resins is from formaldehyde and phenol. Three isomers are possible because substitution can occur at the ortho-, meta-, or para- positions. The proportion of isomers depends upon the pH of the reaction medium. 

In contrast to aliphatic alcohols, which are mostly less acidic than phenol, phenol forms salts with aqueous alkali hydroxide solutions. At room temperature, phenol can be liberated from the salts even with carbon dioxide. At temperatures near the boiling point of phenol, it can displace carboxylic acids, e.g. acetic acid, from their salts, and then phenolates are formed. The contribution of ortho- and -quinonoid resonance structures allows electrophilic substitution reactions such as chlorination, sulphonation, nitration, nitrosation and mercuration. The introduction of two or three nitro groups into the benzene ring can only be achieved indirectly because of the sensitivity of phenol towards oxidation. Nitrosation in the para position can be carried out even at ice bath temperature. Phenol readily reacts with carbonyl compounds in the presence of acid or basic catalysts. Formaldehyde reacts with phenol to yield hydroxybenzyl alcohols, and synthetic resins on further reaction. Reaction of acetone with phenol yields bisphenol A [2,2-bis(4-hydroxyphenyl)propane]. 

---