Aromatic diols

A series of symmetrical aromatic 1,3-diols has been efficiently synthesized fl-om substituted aryl Grignard reagents and isopropenyl acetate in a one-step reaction that formed anti products as the major species (Scheme 8). Both experimental and theoretical studies suggested that the reaction involves the formation of a relatively stable intermediate containing a six-membered ring (17). 

Symmetrical aromatic 1,3-diols were synthesized from substituted aryl Grignard reagents and isopropenyl acetate in a one-step reaction that formed anti products as... 

The first HFIP-based polycarbonate was synthesi2ed from bisphenol AF with a nonfluorkiated aromatic diol (bisphenol A) and phosgene (121,122). Incorporation of about 2—6% of bisphenol AF and bisphenol A polycarbonate improved the dimensional stabkity and heat-distortion properties over bisphenol A homopolycarbonate. Later developments in this area concern the flame-retardant properties of these polymers (123,124). 

Polycarbonates are prepared commercially by two processes Schotten-Baumaim reaction of phosgene (qv) and an aromatic diol in an amine-cataly2ed interfacial condensation reaction or via base-cataly2ed transesterification of a bisphenol with a monomeric carbonate. Important products are also based on polycarbonate in blends with other materials, copolymers, branched resins, flame-retardant compositions, foams (qv), and other materials (see Flame retardants). Polycarbonate is produced globally by several companies. Total manufacture is over 1 million tons aimuaHy. Polycarbonate is also the object of academic research studies, owing to its widespread utiUty and unusual properties. Interest in polycarbonates has steadily increased since 1984. Over 4500 pubflcations and over 9000 patents have appeared on polycarbonate. Japan has issued 5654 polycarbonate patents since 1984 Europe, 1348 United States, 777 Germany, 623 France, 30 and other countries, 231. 

The thermotropic aromatic main chain liquid crystalline polymers are also prepared by the phase transfer catalyzed aromatic nucleophilic polymerization [87]. Polyetherification of bis(4-chloro-3-nitrophenyl) sulfone with mesogenic aromatic diols is shown below ... 

Boric acid esters provide for thermal stabilization of low-pressure polyethylene to a variable degree (Table 7). The difference in efficiency derives from the nature of polyester. Boric acid esters of aliphatic diols and triols are less efficient than the aromatic ones. Among polyesters of aromatic diols and triols, polyesters of boric acid and pyrocatechol exhibit the highest efficiency. Boric acid polyesters provide inhibition of polyethylene thermal destruction following the radical-chain mechanism, are unsuitable for inhibition of polystyrene depolymerization following the molecular pattern and have little effect as inhibitors of polypropylene thermal destruction following the hydrogen-transfer mechanism. 

The inhibitive efficiency of boric acid polyesters differs greatly. The highest efficiency is exhibited by polyesters of boric acid, aromatic diols and triols. This derives from the fact that in this case the radicals are accepted not only by boron, but also by the aromatic nucleus. Among the aromatic polyesters, most efficient is ester of boric acid and pyrocatechin due to the Frank-Rabinovich cage effect. The efficiency of inhibi-... 

These chelatoborates are synthesized by reactions of aromatic diols (e.g., pyrocate-chol), hydroxycarboxylic acids (e.g., salicylic acid), or other aromatic OH-... 

Aromatic polyesters were efficiently synthesized from aromatic diacid divinyl esters. Lipase CA induced the polymerization of divinyl esters of isoph-thalic acid, terephthalic acid, and p-phenylene diacetic acid with glycols to give polyesters containing aromatic moiety in the main chain. The highest molecular weight (7.2 x 10 ) was attained from a combination of divinyl isophthalate and 1,10-decanediol. Enzymatic polymerization of divinyl esters and aromatic diols also afforded the aromatic polyesters. ... 

The reactions of the six-membered chlorocyclophosphazene were studied with a number of aliphatic diamines (169 175), aromatic diamines (176), aliphatic diols (177-179), aromatic diols (180,181) and compounds containing amino and hydroxyl functional groups (169,170,182). This subject has been reviewed (11,16,20). There are at least five different reaction products that are possible (Fig. 19). Replacement of two chlorine atoms from the same phosphorus atom produces a spirocyclic product. Replacement of two chlorine atoms from two different phosphorus atoms in the same molecule produces an ansa product. Reaction of only one end of the difunctional reagent, resulting in the substitution of only one chlorine atom, leads to an open-chain compound. Intermolecular bridged compounds are formed when the difunc-... 

Mechanisms of Interaction of Polycyclic Aromatic Diol Epoxides with DNA and Structures of the Adducts... 

The reaction of metabolically generated polycyclic aromatic diol epoxides with DNA Ua vivo is believed to be an important and critical event in chemical carcinogenesis Cl,2). In recent years, much attention has been devoted to studies of diol epoxide-nucleic acid interactions in aqueous model systems. The most widely studied reactive intermediate is benzo(a)pyrene-7,8-diol-9,10-epoxide (BaPDE), which is the ultimate biologically active metabolite of the well known and ubiquitous environmental pollutant benzo(a)pyrene. There are four different stereoisomers of BaPDE (Figure 1) which are characterized by differences in biological activities, and reactivities with DNA (2-4). In this review, emphasis is placed on studies of reaction mechanisms of BPDE and related compounds with DNA, and the structures of the adducts formed. 

The existence of isomeric polycyclic aromatic diol epoxide compounds provides rich opportunities for attempting to correlate biological activities with the physico-chemical reaction mechanisms, and conformational and biochemical properties of the covalent DNA adduct8 which are formed. 

Tin adducts of the type Sn(C>2R) were obtained in the electrolysis of aromatic diols with tin as the sacrificial anode R(OH)2 = 1, 2-dihydroxybenzene (catechol), tetrabromo-cathechol, 2,3-dihydroxynaphthalene and 2,2/-dihydroxybiphenyl yields, based on mass loss of the anode, range within 75-94 %136. 

Polycarbonates form a rather specialised class of linear polyesters, since they are formed from a diol, usually an aromatic diol, with a derivative of carbonic acid. The commercially useful products also differ from other types of polyester in that they are generally non-crystalline, melt-processable polymers of high 7J, possessing very high optical clarity and toughness. 

It also may be prepared by extraction of weak borax brine with a kerosene solution of an aromatic diol, sucb as 2-etbyl-l,3-hexanediol or 3-cbloro-2-hydroxy-5-(l,l,3,3-tetrametbylbutyl)benzyl alcohol. The diol-borate chelate formed separates into a kerosene phase. Treatment with sulfuric acid yields boric acid which partitions into aqueous phase and is purified by recrys-taUization. 

An aromatic diol is oxidized with BaMn04 providing a 58% of the desired bisfuraldehyde. Although, a Swern oxidation provides a 75% yield, the employment of BaMn04 is preferred because of experimental simplicity. 

Anionic five-coordinated silicates have been prepared also with oxygen-containing six- and seven-membered chelate rings (16-18), using suitable aromatic diols, 1,8-dihydroxynaphthalene and 2,2 -dihydroxybiphenyl, respectively37. However, spirosilicates... 

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