Polyfunctional phenols

The reaction of nucleophiles with chloroarene-Mn(CO)3 and fluoro arene-Cr(CO)3 complexes has been employed for the synthesis of diaryl ethers and has been particularly applied (ref. 55) to the selective arylation of polyfunctional phenols by reaction of the phenoxide formed from NaH in dimethylformamide with the 4-chlorotoluene-manganese tricarbonyl cation (as the hexafluorophosphate) in acetonitrile at ambient temperature over 18 hours. 

Novolaks cannot undergo a spontaneous curing, because they are polyfunctional phenols cross-linked by methylene bridges. Therefore the curing agents must be at least bifunctional compounds. Curing can be carried out without the elimination of water with compounds that are easily converted into methylene carbonium ions for example, hexamethylene tetramine, which is widely used commercially (Urotropin, Hexa). Dihydroxy-benzyl amine and trihydroxybezyl amine structures are also formed with the elimination of ammonia, e.g.. 

Hence it has been assumed that in the case of a polyfunctional phenolic resin, cross-linking occurs via the resin and two such chroman rings ... 

The useful Bronsted acid type curing agents for the epoxy resins are polyfunctional phenols, polyfunctional organic acids, and anhydrides of mono- and difunctional organic acids. 

Polynuclear Phenol—Glycidyl Ether-Derived Resins. This is one of the first commercially available polyfunctional products. Its polyfunctionahty permits upgrading of thermal stabiUty, chemical resistance, and electrical and mechanical properties of bisphenol A—epoxy systems. It is used in mol ding compounds and adhesives. 

As already indicated, the polycarbonates may be produced from a wide range of polyfunctional hydroxy compounds. In practice only the diphenyl compounds have proved of much interest and the only polycarbonate of commercial significance is derived from bis-phenol A 2,2-bis-(4-hydroxyphenyl) propane. 

The use of phenolic polymers in photocrosslinkable systems usually involves multicomponent systems which incorporate polyfunctional low molecular weight crosslinkers. For example, Feely et al. [9] have used hydroxymethyl melamine in combination with a photoactive diazonaphthoquinone which produces an indene carboxylic acid upon irradiation to crosslink a novolac resin. Similarly, Iwayanagi et al. [10] have used photoactive bisazides in combination with poly(p-hydroxy-sty-rene) to afford a negative-tone resist material which does not swell upon development in aqueous base. 

Use of a Difunctional Crosslinker. An alternate approach to chemically amplified imaging through electrophilic aromatic substitution is shown in Figure 6 below. In this approach a polyfunctional low molecular weight latent electrophile is used in a three component system also including a photoactive triaryl sulfonium salt and a phenolic polymer. In this case again crosslinking of the polymer is observed upon... 

The present authors studied the extraction of aromatic amines into ILs. As is seen from experimental data for [C4CiIm][PFg] (Figure 9.2), aniline, napthylamine, and o-toluidine are efficiently extracted from the alkaline aqueous solution. Thus, as in the case of phenols, neutral (molecular) forms of solutes were extracted. Another example of the same behavior is given by many polyfunctional compounds, for example, 8-hydroxyquinoline (Figure 9.3 presents a comparison of extraction pH-profile with the distribution diagram for ionic forms of the solute). 

If the monomers are bifunctional, as in the above example, then a linear polymer is formed. Terminating monofunctional groups will reduce the average degree of polymerisation. Polyfunctional monomers, such as glycerol and phthalic acid, are able to form branching points, which readily leads to irreversible network formation (see Chapter 9). Bakelite, a condensation product of phenol and formaldehyde, is an example of such a space-network polymer. Linear polymers are usually soluble in suitable solvents and are thermoplastic - i.e. they can be softened by heat without decomposition. In contrast, highly condensed network polymers are usually hard, are almost completely insoluble and thermoset - i.e. they cannot be softened by heat without decomposition. 

The condensation of furfural with resordnol in presence of hydrochloric add at 34-35 °C followed by sulfonation of the condensate affords a polyfunctional cation-exchange resin containing —SO3H, —COOH, and —OH (phenolic) groups. The carboxylic activity of this resin has been attributed to the oxidation of furfurylic... 

The first type concerns aminomcthylation giving rise to the mactomolecular network starting from polyfunctional polymeric substrates and/or amines. Hardening of phenolic novolacs-- and other resins with urotropinc belongs to this type of reaction. The process may be carried out in the presence of protcic molecules, which are thus inserted into the cured material. - Similarly, the crosslinking of collagen or other proteic macromolccules with formaldehyde, or with mixtures of aldehydes, is frequently encountered (see also Chap. HI, C.2).- - ... 

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