Phenolic chemistry phenol reaction

Solvent Fractionation. To facilitate later structural analysis, we separated the coal into structural types by solvent fractionation. Some other workers using the phenol depolymerization method to solubilize coal have used gas chroma-tography/mass spectroscopy (GC/MS) techniques to identify individual compounds (11, 13). However, with material containing large amounts of phenol and other polar groups, elaborate preparation and separation schemes have to be used to avoid contamination of the chromatography columns. As the emphasis of the present work was on structural characterization of the whole coal rather than on detailed examination of small parts of it in order to elucidate the chemistry of the phenolation reaction, we used the relatively simple scheme shown in Figure 1. 

In other work related to bleaching chemistry, the reactions of chlorine dioxide with monomeric [44] and dimeric [45] lignin model compounds have been studied computationally. These studies closely parallel experimental work in which oxidation mechanisms were proposed [46-51]. In accord with the experimental work, which reports higher reactivity of phenolic compounds, the heats of reaction for these compounds are lower than those for etherified models. The experimentally based mechanisms were generally found to be energetically feasible, but in some cases the electronic results were not consistent with the proposed mechanisms. 

We examine here a number of reaction pathways for nitric oxide, with the emphasis on assessing their biological relevance. To date, the fastest reaction for nitric oxide with clear toxicological significance is that with superoxide to produce ONOO" (Huie and Padmaja, 1993). Thus, the chemistry and reactivity of ONOO" are discussed at length. In addition, the interaction between ONOO" and nitric oxide is examined with respect to its effects on nitric oxide half-life as well as effects on peroxynitrite reactivity toward phenol. Reaction mechanisms are proposed to account for the nitrated, hydroxylated, and nitrosated phenolic products seen. 

Similarly, alcoholysis of Mo(NMc2)4 allows a ready entry into Mo alkoxide chemistry, although reactions with silanols and phenols typically produce adducts in which the liberated dimethyl-amine remains coordinated to the metal center (equation 12). 

Kraszewski et al. [208] have developed a new, efficient method for the synthesis of phosphorothioate diester, based on the H-phosphonate chemistry. The reaction of aryl nucleoside H-phosphonate with elemental sulfur furnished the corresponding aryl nucleoside phosphorothioate. The synthesis of phosphorothioates can be carried out as a four-components-one-pot reaction, by allowing nucleoside H-phosphonate to react with phenols in the presence of diphenyl phosphorochloridate to furnish aryl nucleoside H-phosphonates, which react with elemental sulfur. 

In the petroleum (qv) industry hydrogen bromide can serve as an alkylation catalyst. It is claimed as a catalyst in the controlled oxidation of aHphatic and ahcycHc hydrocarbons to ketones, acids, and peroxides (7,8). AppHcations of HBr with NH Br (9) or with H2S and HCl (10) as promoters for the dehydrogenation of butene to butadiene have been described, and either HBr or HCl can be used in the vapor-phase ortho methylation of phenol with methanol over alumina (11). Various patents dealing with catalytic activity of HCl also cover the use of HBr. An important reaction of HBr in organic syntheses is the replacement of aHphatic chlorine by bromine in the presence of an aluminum catalyst (12). Small quantities of hydrobromic acid are employed in analytical chemistry. 

Although phenolic resins have been known and widely utilised for over 60 years their detailed chemical structure remains to be established. It is now known that the resins are very complex and that the various structures present will depend on the ratio of phenol to formaldehyde employed, the pH of the reaction mixture and the temperature of the reaction. Phenolic resin chemistry has been discussed in detail elsewhere and will be discussed only briefly here. 

Phenolic resins were the first totally synthetic plastics invented. They were commercialized by 1910 [I]. Their history begins before the development of the structural theory of chemistry and even before Kekule had his famous dreams of snakes biting their tails. It commences with Gerhardt s 1853 observations of insoluble resin formation while dehydrating sodium salicylate [2]. These were followed by similar reports on the behavior of salicylic acid derivatives under a variety of reaction conditions by Schroder et al. (1869), Baeyer (1872), Velden (1877), Doebner (1896 and 1898), Speyer (1897) and Baekeland (1909-1912) [3-17]. Many of these early reports appear to involve the formation of phenolic polyesters rather than the phenol-aldehyde resins that we think of today. For... 

Murray, G.S., An Investigation into the Chemistry of the Reactions of Phenol-Fonnaldehyde Compounds with Novel Crosslinking Agents, Ph.D. The.sis. Portsmouth University, Portsmouth, 1993. 

In the first century of "organic" chemistry much attention was given to the structures of carbogens and their transformations. Reactions were classified according to the types of substrates that underwent the chemical change (for example "aromatic substitution," "carbonyl addition," "halide displacement," "ester condensation"). Chemistry was taught and learned as transformations characteristic of a structural class (e.g. phenol, aldehyde) or structural subunit... 

A method that has been the standard of choice for many years is the Lowry procedure. This method uses Cn ions along with Folin-Ciocalteau reagent, a combination of phosphomolybdic and phosphotnngstic acid complexes that react with Cn. Cn is generated from Cn by readily oxidizable protein components, such as cysteine or the phenols and indoles of tyrosine and tryptophan. Although the precise chemistry of the Lowry method remains uncertain, the Cn reaction with the Folin reagent gives intensely colored products measurable spectrophotometrically. 

The predominance of a-substituted products in the reaction of 2,4,6-tribromopyridine in phenol solution may result from competitive attack by free phenol in preference to attack by the phenoxide ion reagent involving structures 18 (B = base) or 19. A wealth of chemistry awaits elucidation by physical-organic studies. 

A reaction which has proved to be of much use in synthetic organic chemistry is the formation of the ortho and/or the para isomers of a hydroxyketone (CVI and CVTI) by treatment of a phenolic ester (CV) with an acid catalyst, viz. 

The reaction between acid chlorides and aliphatic alcohols or phenolic compounds commonly takes place at low to moderate temperature (—10 to 100°C) in solution or by interfacial or dispersion polymerization techniques. It has been widely applied to polyester synthesis. Reviews and books are available on the polymerization techniques as well as on the chemistry of this reaction.2,207 294... 

Today microemulsions are used in catalysis, preparation of submicron particles, solar energy conversion, extraction of minerals and protein, detergency and lubrication [58]. Most studies in the field of basic research have dealt with the physical chemistry of the systems themselves and only recently have microemulsions been used as a reaction medium in organic synthesis. The reactions investigated to date include nucleophilic substitution and additions [59], oxidations [59-61], alkylation [62], synthesis of trialkylamines [63], coupling of aryl halides [64], nitration of phenols [65], photoamidation of fluoroolefins [66] and some Diels-Alder reactions. 

Spectroscopy of the PES for reactions of transition metal (M ) and metal oxide cations (MO ) is particularly interesting due to their rich and complex chemistry. Transition metal M+ can activate C—H bonds in hydrocarbons, including methane, and activate C—C bonds in alkanes [18-20] MO are excellent (and often selective) oxidants, capable of converting methane to methanol [21] and benzene to phenol [22-24]. Transition metal cations tend to be more reactive than the neutrals for two general reasons. First, most neutral transition metal atoms have a ground electronic state, and this... 

Heteropoly acids can be synergistically combined with phase-transfer catalysis in the so-called Ishii-Venturello chemistry for oxidation reactions such as oxidation of alcohols, allyl alcohols, alkenes, alkynes, P-unsaturated acids, vic-diols, phenol, and amines with hydrogen peroxide (Mizuno et al., 1994). Recent examples include the epoxidations of alkyl undecylenates (Yadav and Satoskar, 1997) and. styrene (Yadav and Pujari, 2000). 

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