Phenol production figures

NIH shift. This indicates that formation of an epoxide intermediate has occurred, and is one method of determining whether such an epoxide intermediate is involved. The phenolic products, 1- and 2-naphthols, retain various proportions of deuterium, however. The proposed mechanism involves the formation of an epoxide intermediate, which may break open chemically in two ways, leading to phenolic products (figure 4,5). 

Phenolic compounds are commonplace natural products Figure 24 2 presents a sampling of some naturally occurring phenols Phenolic natural products can arise by a number of different biosynthetic pathways In animals aromatic rings are hydroxylated by way of arene oxide intermediates formed by the enzyme catalyzed reaction between an aromatic ring and molecular oxygen... 

Table 4 shows the worldwide and U.S. production figures and prices for phenol since the mid-1980s. Because the cumene process accounts for more than 95% of the world s phenol supply, the economics of phenol production are closely tied to this production method. In the cumene process 615 kg of acetone are coproduced with each ton of phenol produced. Thus, the economics of phenol production are influenced by acetone (qv). 

In turn the oxazoline-containing polymer may then react very rapidly (e.g. at 240°C) with such groups as carboxyls, amines, phenols, anhydrides or epoxides, which may be present in other polymers. This reaction will link the two polymers by a rearrangement reaction similar to that involved in a rearrangement polymerisation without the evolution of water or any gaseous condensation products (Figure 7.14). 

Because bis-phenol A is somewhat unstable at elevated temperature it is desirable to work with an excess of diphenyl carbonate so that the bis-phenol A is rapidly used up. The reaction may be conveniently carried out using twice or more than twice the theoretical quantity of diphenyl carbonate so that the initial reaction product is the bisfphenyl carbonate) of bis-phenol A (Figure 20.4 (a)). 

We have also investigated other oxalate esters as a potential means to improve the efficiency. The most commonly used oxalates are the 2,4,6-trichlorophenyl (TCPO) and 2,4-dinitrophenyl (DNPO) oxalates. Both have severe drawbacks namely, their low solubility in aqueous and mixed aqueous solvents and quenching of the acceptor fluorescence. To achieve better solubility and avoid the quenching features of the esters and their phenolic products, we turned to difluorophenyl oxalate (DFPO) derivatives 5 and 6 (Figure 14). Both the 2,4- and the 2,6-difluoro esters were readily synthesized and were shown to be active precursors to DPA chemiluminescence. In fact, the overall efficiency of the 2,6-difluorophenyl oxalate 5 is higher than for TCPO in the chemical excitation of DPA under the conditions outlined earlier. Several other symmetrical and unsymmet-rical esters were also synthesized, but all were less efficient than either TCPO or 2,6-DFPO (Figure 14). 

Figures 44.1 and 44.2 report the performance in the gas-phase phenol methylation of the H-mordenite and of the Mg/Fe/O catalyst, respectively. The differences between the two catalysts concerned both the transformations occurring on methanol and the type of phenolic products obtained. The H-mordenite was very active at 350°C the conversion of phenol was 80%. A further increase of temperature led to a decrease of conversion. This can be attributed to a progressive deactivation of the catalyst, due to...

Evidence corroborating the formation of phenolic products in weathered PC is shown in Figure 6. In this figure, the differential infrared spectrum of a 10 mil PC film weathered for one year at Schenectady shows a strong phenolic peak at 3500 cm 1. 

Generally phenol formation is the major reaction path however, relatively minor modifications to the structure of the carbene complex, the alkyne, or the reaction conditions can dramatically alter the outcome of the reaction [7]. Depending on reaction conditions and starting reactants roughly a dozen different products have been so far isolated, in addition to phenol derivatives [7-12], In particular, there is an important difference between the products of alkyne insertion into amino or alkoxycarbene complexes. The electron richer aminocarbene complexes give indanones 8 as the major product due to failure to incorporate a carbon monoxide ligand from the metal, while the latter tend to favor phenol products 7 (see Figure 2). 

On co-adsorbing phenol and methanol, the protonation of methanol occurs on the active acid sites as the labile protons released from the phenol reacted with methanol. Thus protonated methanol became electrophilic methyl species, which undergo electrophilic substitution. The ortho position of phenol, which is close to the catalyst surface, has eventually become the substitution reaction center to form the ortho methylated products (Figure 3). This mechanism was also supported by the competitive adsorption of reactants with acidity probe pyridine [79]. A sequential adsorption of phenol and pyridine has shown the formation of phenolate anion and pyridinium ion that indicated the protonation of pyridine. 

In Curie-point Py-LVMS studies of maceral concentrates (22). vitrinitic moieties were shown to be the main source of the hydroxy aromatic components. Thus, the hydroxy aromatic signals observed in Figure 2d appear to be primarily derived from vitrinite-like components by means of pyrolytic processes. Presumably, therefore, the "nonmobile phase", rather than the "mobile phase , is the main source of the phenols observed in TG/MS and Py-MS studies of Pittsburgh 8 coal (9,16). Further support for this conjecture comes from the observation that phenolic products are also observed in Py-MS analysis of pyridine extracts of Pittsburgh 8 coal known to contain colloidal matter whereas the corresponding tetrahydrofuran extracts, free of colloidal material, produced no phenols (21). 

Figure 3. Partial 13C NMR spectra of (A) the steam explosion lignin and (B) its phenolated product.

From pulse radiolysis lifetimes of phenol radical cations between 300 and 500 ns are known [4, 9]. Laser photolysis (3 ns, 266nm up to 15 mJ) ofN2-purged solutions of up to 10 3 mol dm 3 phenols yields phenoxyl radicals as dominating products (Figure 2). In the spectrum only a little hint for the phenol radical cations exists. The inset shows that the phenoxyl radical formation does not depend linearly from the energy but appears by biphotonic absorption contradictory to the fs-experiments described above. 

Flavonoids, products of the shikimate pathway from the phenylalanine and acetate pathways,11 share a diphenylpropane (C6-C3-C6) structure of three phenolic rings (Figure 2.1). Flavonoids are ubiquitous in plant foods—for example, flavonols like... 

The data in Figure 2 for trialkylated phenol products are similar to those in Figure 1, with two important differences. The abrupt change in effectiveness of the trialkylated phenols occurs when R is Ci0H2i to C12H25. Although in the more severe tests these compounds are about as effective as the 2,6-dialkyl-p-cresols, in the least severe test they are considerably less effective. It is evident that 2,4,6-trioctadecylphenol is also a very potent antioxidant. 

Many natural products display structural motifs biosynthetically derived from ortho-quinol precursors, and some even feature ortho-quinol moieties in their final structural arrangement [1, 6]. Asatone (7) and related neolignans can be put forward as classic examples of complex natural products derived from cyclodimerization of oxidatively activated simple phenol precursors (Figure 5) biomimetic syntheses of 7 have accordingly been accomplished by anodic oxidation (Section 15.2.1) and by Pelter oxidation (Section 15.2.2) of the naturally occurring phenol 9 [34, 36]. 

The humulones 23a-d have been known for many years, but they can still be considered as a topical family of natural products (Figure 8). Found in hop resins and brewing hops, these natural ortho-quinols aroused early interest because of their antibiotic and tuberculostatic properties. Oxidative dearomatizing hydroxylation of their phenolic parents 24a-d was used in their synthesis [1]. 

Aldehydes which contain electron-releasing substituents in the ortho or para position give phenol products via a formate intermediate. This reaction is known as the Dakin reaction, the oxidation of salicylaldehyde being a classic example (Figure 3.42).215... 

It is worthwhile to review the U.S. market size for the four principal resins currently used in wood-panel products today (4 )- These are phenol-formaldehyde (PF), urea-formaldehyde (UF), melamine-formaldehyde (MF), and resorcinol-formaldehyde (RF) (Table III). When these production figures are compared to the quantities of lignin potentially available (Table II), it is immediately obvious that all wood adhesives could be replaced by only a very small fraction of the lignin produced annually during chemical woodpulping processes. 

The only tannins in the world currently being commercially exploited for adhesive applications are those isolated by hot- (or cold-) water extraction of Acacia meamsii bark in the province of Natal, South Africa. Approximately 100,000 tons of mimosa tannin were being produced annually as reported in 1980, the latest year for which production figures were available (41)- Of this amount, about 10,000 tons were used in adhesive applications mainly in South Africa, Australia, and New Zealand. While this number is not large in light of the 300,000 to 400,000 tons of phenol used annually in resins, it does provide evidence that bark tannins can be economically used for adhesives. This application is facilitated by the relatively high cost of phenol and resorcinol in... 

The mechanism of aromatization of deuterated and otherwise substituted arene 1,2-oxides to phenolic products has been studied in detail (Figure 13). Pathways leading to phenols A and B correspond to substituent loss, whereas phenols C and D represent substituent migration. Type A phenols are most commonly formed and have been isolated from aromatization of a range of monosubstituted arene 1,2-oxides for example, 33 and 34, 35 and 36, 37, 38, 39, and... 

Figure 11.15 (from Stone, 1987) illustrates that the rate of oxidation of various substituted phenols by Mn02 can be correlated with the half-wave potentials, of these phenols. The half-wave potentials, measure the tendency of the anode to oxidize the phenols. The half-wave potential corresponds in first approximation to the redox potential of the phenol and its one-electron oxidation product. Figure 11.15 implies that the thermodynamic tendency of an electrode to oxidize a certain phenol relates to the kinetic tendency of Mn02 to oxidize this phenol. 

Resoles. Resoles are phenolic resins produced under alkaline conditions with a molar excess of formaldehyde, HCHO, over phenol in the reaction mixture. The initial reaction is the substitution of phenol with methylol (-CH2OH) groups, as shown in Figure 1, both at the ortho (I) and para (II) positions. Furthermore, because more than 1 mol of formaldehyde is used for each mole of phenol, products carrying two or three methylol groups (HI, IV) are also formed. The ortho para substitution ratio depends on the type of catalyst and pH, and decreases from 1.1 at a pH of 8.7 to 0.38 at a... 

As with condensation polymers many examples of biochemically formed vinyl addition polymers, such as the poly-cis-isoprene found in the sap of rubber trees, were known long before we were able to replicate these materials even in the laboratory. Our ability to initiate and control the preparation of vinylic polymers on a laboratory scale came in the early 1930s, substantially later than the commercialization of phenol-formaldehyde condensation polymers. Since then, however, starting with the synthesis of polyethylene, then poly(vi-nyl chloride) (PVC), synthetic rubbers and polystyrene, the scale of production of this class of polymer has outstripped the polycondensation class by more than an order of magnitude. Table 23.1 displays some representative production figures to illustrate this. 

Chlorophenols are a class of pesticide substances, e.g. fungicides, used for wood preservation, in pulp production and other miscellaneous applications. The substances were introduced in the 1930s and have been used in very large amounts. Today, the consumption has decreased and the substances are banned in many countries. The main active substance in chlorophenol products is pentachloro-phenol (PCP Figure 3.10). The substance is moderately lipophilic and persistent, yet readily absorbed and accumulated in biota and expresses a rather high acute toxicity. The metabolism and breakdown of this envirotoxicant in biota and in the environment are rather slow, resulting in successively dechlorinated metabolites. 

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