Hydroxymethylated phenols

A somewhat different approach to the production of thermoplastic polyolefin rubbers has been adopted by Allied Chemical with their ET polymers. With these materials butyl rubber is grafted on to polyethylene chains using a phenolic material such as brominated hydroxymethyl phenol. The initial grades of these polymers, which were introduced commercially towards the end of the 1970s, had polyethylene butyl rubber ratios of 50 50 and 75 25. Both low-density and high-density polyethylene-based varieties were produced. 

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 second phase in resole formation is reaction of the activated phenol with the aldehyde to form the phenol alcohol derivative. When the aldehyde is formaldehyde, the derivative is a hydroxymethyl phenol and the process is known as methylolation. Scheme 2 illustrates this reaction. Since resoles are usually made with excess aldehyde, more than one substitution may be made on the ring. When the reactants are phenol and formaldehyde, up to three methylol groups may be substituted. This reaction has been extensively studied and the rates of... 

The final phase of resole manufacture is known as the condensation stage (Scheme 3). This is the actual process by which molecular weight is developed and involves the combination of the hydroxymethyl phenol intermediates to form oligomers. It can be reasonably well separated from the resole methylolation reaction in practice by maintaining reaction temperatures below about 70°C. The activation energy for condensation is higher than that for methylolation. This is not to say that condensation does not occur at temperatures below 70°C. It simply means that the methylolation is much faster than condensation at this temperature. 

Sprung and Gladstone were the first to show the formation of dibenzyl ether linkages during the condensation of hydroxymethyl phenols, as depicted in Scheme 4c [152], These results have been corroborated by a number of researchers since [128,144,147,148], This condensation was reportedly second-order and takes place at pH conditions near neutral and at temperatures less than 130°C [128,147,153], At temperatures of 160°C the dibenzyl ethers are converted to something else, most likely to methylene linkages and formaldehyde [132],... 

Kim et al, observed a number of facts gleaned from C-NMR that led to an overall picture of the reactivity of various hydroxymethyl phenols (HMPs) [144, 148], Grenier-Loustalot and co-workers did a number of important experiments that expanded Kim s findings and clearly delineated the reactivity of the various functional groups position-by-position [128], The two studies show excellent agreement. The materials that follow are drawn from these two reports without further citation. As shown in Scheme 5, the condensation of 2-HMP at pH 8 and 60°C resulted in only one product. This product is the result of p-attack on the ring by the hydroxymethyl group. 

Novolacs are prepared with an excess of phenol over formaldehyde under acidic conditions (Fig. 7.6). A methylene glycol is protonated by an acid from the reaction medium, which then releases water to form a hydroxymethylene cation (step 1 in Fig. 7.6). This ion hydroxyalkylates a phenol via electrophilic aromatic substitution. The rate-determining step of the sequence occurs in step 2 where a pair of electrons from the phenol ring attacks the electrophile forming a car-bocation intermediate. The methylol group of the hydroxymethylated phenol is unstable in the presence of acid and loses water readily to form a benzylic carbo-nium ion (step 3). This ion then reacts with another phenol to form a methylene bridge in another electrophilic aromatic substitution. This major process repeats until the formaldehyde is exhausted. 

Hydroxyl number, 94 Hydroxymethylated compounds, 403 Hydroxymethylated phenol, 378. See also Hy droxy me thy lphenol Hydroxymethyl condensation reactions, 399-400... 

Hydroxymethyl-4,6-dimethylphenol, 406 Hydroxymethylphenol. See also Hydroxymethylated phenol reaction with melamine, 411 reaction with urea, 410 Hydroxymethyl substituents, condensation reactions of, 403... 

Hydroxymethyl-phenol reagiert mit Nitro-alkanen in einer Triethylamin/m-Xylol-Lo-sungzu 4-(2-Nitro-alkyl)-phenolen, 1,1 -Bis-[4-hydroxy-phenyl]-l -nitro-alkanen und in sehr geringen Ausbeuten zu 1-Nitro-l, 1,1 -tris-[4-hydroxy-phenyl]-me-than1 ... 

Hydroxymethylated phenols cannot be isolated, and the reaction continues ... 

Diphenyl-(2-hydroxy-benzyl)-phosphanoxid 33 Eine Losung von 8,1 g 2-Hydroxymethyl-phenol in 10 ml was-serfreiem THF wird tropfenweise bci 20° zu einer Losung von 15,0 g Diphenylphosphinigsaure-ethylester in 25 ml THF gegeben, wobei die Temp, auf 60° ansteigt. AnschlicBend erhitzt man 2 Sldn. und dampft ein Aus-beute 18,0 g (90°/ ) Schmp. 178-179°. 

Whether the 2- or the 6-hydroxymethyl phenol is used as the starting compound depends mainly on its accessibility.185 Sometimes a direct hydroxymethylation in the 6-position is possible in a selective way. In other cases, the 6-position is protected by bromination, to direct the hydroxymethylation to the 2-position. Reduction of the appropriate salicylic acid derivative is another possibility. 

In several deamination reactions, formation of the hydroxymethyl derivatives 243 (Fig. 90) is frequently reported instead of the expected unsaturated product. Thus, deamination of para-aminomethyl phenols (242, R = p-hydroxyphenyl) produces an intermediate methylenequinonc, which then evolves to hydroxymethyl phenol by reaction with water, - whereas deamination of aminome-thane sulfonates (242, R = SO Na) proceeds through an Sn2 attack by water on the zwit-terionie form of the Mannich base to yield the hydroxylated derivative. - "... 

HYDROXYMETHYL)PHENOL see HMKIOO HYDROXYMETHYLPHENYDURSINE OXIDE see HMK200... 

Resins are prepared commercially that have extraordinarily low monomer content (less than 0.1% of either phenol or formaldehyde) (9). The molecular weight distribution of the typical resin shows very small amounts of bis(hydroxymethyl) and tris(hydroxymethyl) phenols, with the bulk of the product being larger condensation products (9). 

Spiro-epoxy-2,4-cyclohcxadienones. Oxidation of ort/io-hydroxymethylphcnols having at least one bulky substituent by sodium periodate leads to spiro-epoxy-2,4-cyclohexadienones in good yield.1 Thus oxidation of 2,4-di-r-butyl-6-hydroxymethyl-phenol (1) in methanol by a slight excess of sodium periodate in water gives (2) in 95% yield. In the absence of a bulky substituent the product undergoes a spontaneous... 

Little is known about the overall mechanism of cyclic oligomer formation, although the mechanism of the initial stages of the sequence seems fairly clear. The first chemical event is the reaction of formaldehyde (formed in the Petrolite procedures by depolymerization of paraformaldehyde) with phenol to form 2-hydroxy-methyl- and 2,6-6w(hydroxymethyl)phenols in a base-catalyzed process, as shown in Fig. 3. Such compounds were characterized many years ago50), obtained from the action of aqueous formaldehyde on phenol in basic solution at room temperature. Subsequent condensation between the hydroxymethylphenols and the starting phenol occurs to form linear dimers, trimers, tetramers, etc. via a pathway that might involve o-quinonemethide intermediates which react with phenolate ions in a Michael-like reaction, as portrayed in Fig. 4. The condensation of hydroxymethyl-... 

The Petrolite method for calixarene synthesis also leads to dihomooxacalix[4]arenes, as represented by the p-tert-butyl compound 9. Proton-NMR spectra and TLC data indicate that the mixture obtained from p-terf-butylphenol and paraformaldehyde contains appreciable amounts of 9, but it is difficult to obtain a pure sample of 9 from this mixture 23,2, 28>. Compound 9 is much more readily accessible by the thermally-induced dehydration of the (u. v(hydroxymethyl)tetramer 46 which can be readily prepared by the convergent synthesis outlined in Scheme 5 followed by bis hydroxymethylation 62), as shown in Scheme 6. Other oxacalixarenes can also be obtained by thermally-induced dehydration. For example, 2,6-6 (hydroxymethyl)-phenols (42) yield hexahomotrioxacalix[3]arenes (43)28,62,101 > j cfroxymethyl)... 

A regular incorporation of the phenolic units into calix[4]arenes has been observed, if 2-or 6-hydroxymethyl derivatives of 3,4-disubstituted phenols (including cyclic compounds like S-naphthol) are condensed under these conditions (Scheme 5). The resulting calix[4]arenes 8 assume an inherently chiral, C4-symmetrical cone conformation which can be fixed by O-alkylation (see below). In an analogous manner a 2-hydroxymethyl phenol substituted at the 4-position with a porphyrin moiety has been converted to the corresponding calix[4]arene 9 in 60% yield by treatment with NaOH in refluxing diphenyl ether. ... 

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