Carbonation of phenols

Therefore the attack by I ion breaks O-CHg bond to form CH 3I. Phenols do not react further to give halides because the sjf hybridised carbon of phenol cannot undergo nucleophlfic substitution reaction needed for conversion to the halide. 

Phenol groups are determined by the difference of the neutralization reactions between sodium hydroxide and sodium carbonate which are common for carboxylic and phenolate groups. Oxidized carbons (typically in air at 700 K) contain equal amounts of these two functional groups. Activated carbons contain up to 800/zeqg-1 carbon of phenolate groups. The volumetric determinations are also sensitive to both carboxylic and phenolate groups so that specific deri-vatization processes are needed to reliably discriminate the two types of groups. 

The first product of the interesting pentaphenylation is o-phenylphenol (50). It was found that o-phenylphenol (50) undergoes not only monophenylation, but also diphenylation on treatment with iodobenzene at the C-2 positions to give 51 and 52 by the use of PdCb and CS2CO3. The fact that the monoarylated product 51 (25 %) and the diarylated product 52 (62 %) were obtained by the treatment of 2-phenylphenol (50) with 4 equivalents of iodobenzene shows that the arylation of benzene ring is faster than the arylation of ortho carbon of phenol under these conditions [16]. Similarly, when the reaction of bromobenzene with 50 in xylene was stopped after a short time, 2-(biphenyl-2-yl)phenol (51) was obtained in high yield, but 2,6-diphenylphenol was not formed [15]. 

Phenolic resin foam is an interesting material for the cellular insulation industry because of its high temperature resistance, fire resistance, and very low smoke generation [16]. The aqueous resole is crosslinked in the presence of a surfactant and a low boiling liquid, that volatizes during the increase ofviscosity or plasticity of the mixture. The surfectant is necessary to develop a uniform fine cellular foam stracture [1,6], Carbonization of phenolic foams yields carbon foams with an excellent thermal resistance, that are applied as high temperature insulation materials for the production of filters for corrosive agents and catalyst supports [1]. 

Glassy or polymeric carbon is obtained by carbonization of phenolics. This material shows excellent chemical resistance and impermeability to gases. Therefore, it has been used for laboratory equipment, for medical applications, for the automotive industry, and for the aerospace industry [1]. 

Following the same synthesis principle, Jaroniec et al. reported the preparation of a series of CS by carbonization of phenolic resin spheres via the modified Stober method. As shown in Fig. 2.17, all samples show spherical morphology with the average diameter of 570, 420, 370, and 200 nm for as-synthesized CS-6, CS-6-CD-4, CS-6-CD-8, CS-6-CD-12 carbon spheres, respectively. The particle... 

Gierszal KP, Jaroniec M (2006) Carbons with extremely large volume of uniform mesopores synthesized by carbonization of phenolic resin film formed on colloidal silica template. J Am Chem Soc 128 10026-10027... 

Siebold RW, Carbonization of phenolic resins, SAMPE National Symposium, San Diego, California, 20, 327, 1975. 

Porous carbon composite support (TFC) with high surface area is obtained by decomposition and carbonization of phenolic resin mixed with graphite fiber. ... 

During this carbonization cycle, the cross-linked polymeric chains do not break down and, unlike coke materials, do not go through a mesophase. The carbonization of phenolic polymers follows a similar pathJ i... 

During the carbonization of phenolic resins, complex structures are formed. Different preparation and storage conditions will lead to different carbonization processes. Some of the major reactions during the carbonization process are shown in Figure 7.25 [1]. 

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