Bisphenolic intermediates

Foremost among the moncmiers prepcured from 2,6-DCP, however, are the bisphenolic intermediates. Several of these, along with their appropriate chemical cdsbre-viations, are illustrated below ... 

As one can see, the prinre attention for the selection of bisphenol intermediates in all mentioned applications is their purity. So, BPA of different purity is usually produced to fulfill the quality requirements of the polymer products (Table 7.12). 

PFCB Silicones From Phenols. Initial efforts toward the synthesis of siloxane containing PFCB polymers focused on the preparation of bisphenol intermediates amenable to the traditional fluoroalkylation/elimination synthetic scheme vide supra). However, this strategy was met with little success and the attempted preparation of l,3-bis(hydroxyphenyl)-l,l,3,3,-tetramethyldisiloxane by published methods, could not be accomplished in acceptable yields. 

In the reaction of phenol and bisphenol F with hexa, nmr spectra show the transient appearance of benzoxazine intermediates after 2 h at 103°C, all the benzoxazine decomposed to the diphenyknethylene and benzylamine intermediates (15). 

Halogenated intermediates based on chlorendic anhydride and alkoxylated, brominated bisphenol are quite stable and are used extensively in flame-retarded high temperature compositions, but brominated aUcychcs, such as dibromotetrahydrophthahc resin, are rapidly dehydrohalogenated at lower temperatures. 

Thioglycohc acid is recommended as a cocatalyst with strong mineral acid in the manufacture of bisphenol A by the condensation of phenol and acetone. The effect of the mercapto group (mercaptocarboxyhc acid) is attributed to the formation of a more stable carbanion intermediate of the ketone that can alkylate the phenol ring faster. The total amount of the by-products is considerably reduced (52). 

Epoxy Resins. Epoxy resins (qv) or polyether resins are thermosets used as the binder for terrazzo dooring. The epoxy resin often is made from epichlorohydrin and bisphenol A. An excess of epichlorohydrin is used to assure that the intermediate product contains terminal epoxide groups. 

Epichlorohydrin and Bisphenol A-Derived Resins. Liquid epoxy resins maybe synthesized by a two-step reaction of an excess of epichl orohydrin to bisphenol A in the presence of an alkaline catalyst. The reaction consists initially in the formation of the dichi orohydrin of bisphenol A and further reaction by dehydrohalogenation of the intermediate product with a stoichiometric quantity of alkaH. 

In the 1980s a number of copolymers became established, known as polyester carbonates, which may be considered as being intermediate between bisphenol A polycarbonates and the polyarylates discussed in Chapter 25. 

A method of converting polycarbonate (PC) to bishydroxyethyl ether of bisphenol A (BHE-BPA) was studied, with a view to recycling PC plastic wastes. Treating PC in ethylene glycol with a catalytic amount of sodium hydroxide produced the monohydroxyethyl ether of bisphenol A (MHE-BPA, 42%), BHE-BPA (11%) and BPA (42%). BHE-BPA was produced quantitatively when 1.6 mol. equiv. ethylene carbonate was added to this reaction system. The reaction of BPA with EC produced both BHE-BPA and MHE-BPA, indicating that ethylene carbonate was formed as an intermediate in the base catalysed reaction of PC with ethylene glycol. A large proportion of this ethylene carbonate formed from PC was, however, lost by decarboxylation so additional ethylene carbonate must be provided for the quantitative preparation of BHE-BPA. 12 refs. 

They are also important chemical intermediates. For example, acetone is used to make methyl methacrylate (the starting material for Plexiglas and Lucite plastics), methyl isobutyl ketone, and Bisphenol A (used in epoxy and polycarbonate resins). 

Almost all of the isopropylbenzene produced is used for making phenol and acetone. The largest use of acetone is as a chemical intermediate to methyl methacrylate and along with phenol to make bisphenol A for preparation of polymers. Acetone is also used widely as a solvent. 

The degradation of bisphenol-A by Sphingomonas sp. strain AOl is initiated by hydroxylation to intermediates that undergo fission to 4-hydroxyacetophenone and 4-hydroxybenzoate. The components have been purified, and consist of cytochrome P450, ferredoxin reductase, and ferredoxin (Sasaki et al. 2005). 

Implementation of the C5, C5 -hydroxy lation protocol as described in Scheme 7.19 above (71/72 to 73/74) provided further efficiencies. The C5,C5 -chlorination proceeded uneventfully, but the chloro to alkoxy interchange was difficult and required optimization of the reaction conditions. The catalyst system derived from Pd2dba3 and the X-phos(t-Bu) ligand proved to be effective in the coupling with KOH to provide the desired bisphenol. The resulting product was highly unstable and decomposed under a one-pot alkylation protocol. Isolation of the bisphenol under carefully controlled conditions followed by immediate benzylation (BnBr, NaH, DMF) furnished key intermediate 79 in 70 % yield. 

Selective epoxidation of one of the double bonds in dialkenes is of practical interest (Table XVI). Although monoepoxides predominate at low H2O2 concentrations, the diepoxides are also formed at higher concentrations. The diallyl epoxides of bisphenol A are major intermediates in the adhesives industry, and their synthesis in solid-catalyzed reactions in an eco-friendly manner remains a challenge. 

Precautionary action to reduce the exposure of humans and wildlife to the oestrogenic plastics intermediate bisphenol A looks closer following an EC technical meeting in March. Member States rejected risk assessments put forward by the UK which set aside evidence of low-dose effects on fish and laboratory animals. Bisphenol A is an important plastics intermediate used in polycarbonates and epoxy resins. Global manufacturing capacity stands at two million tonnes per year. 

Phenol is both a man-made chemical and produced naturally. It is found in nature in some foods and in human and animal wastes and decomposing organic material. The largest single use of phenol is as an intermediate in the production of phenolic resins. However, it is also used in the production of caprolactam (which is used in the manufacture of nylon 6 and other synthetic fibers) and bisphenol A (which is used in the manufacture of epoxy and other resins). Phenol is also used as a slimicide (a chemical toxic to bacteria and fungi characteristic of aqueous slimes), as a disinfectant, and in medicinal preparations such as over-the-counter treatments for sore throats. Phenol ranks in the top 50 in production volumes for chemicals produced in the United States. Chapters 3 and 4 contain more information. 

The two major uses of phenol in 1995 were the production of bisphenol-A (35%) and the production of phenolic resins (34%) (CMR 1996). The largest use for bisphenol-A is as an intermediate in the production of epoxy resins (Thurman 1982). Phenol-formaldehyde resins comprise over 95% of this market (Thurman 1982). The plywood adhesive industry required 26% of the total production of phenolic resins in 1977. These low-cost, versatile, thermoset resins have other major uses in the construction, automotive, and appliance industries (Thurman 1982). 

Ketones.have the characteristic -C- signature group imbedded in them. Acetone, CH3COCH3, comes from two different routes. It is a by-product in the cumene to phenol/acetone process. It is the on-purpose product of the catalytic dehydrogenation of isopropyl alcohol. Acetone is popular as a solvent and as a chemical intermediate for the manufacture of MIBK, methyl methacrylate, and Bisphenol A. 

The best performing coatings were the vinyl ester, the bisphenol A epoxy cured with an aliphatic amine, and a novolac epoxy cured with a mixed aromatic/cycl oal i phati c amine. The saturated polyester, and a bisphenol A epoxy cured with a polyamide amine showed significant deterioration of the coating material in the acid, and corrosion of the underlying steel. Two types of novolac epoxies cured with aromatic amines showed intermediate performance. 

Oxidation of several 1,1-bisphenols 78 with IBD gives spirobenzofuran derivatives of general formula 79 (Eq. 21). This approach, when applied to benzylidine l.l -bisnaphthols 80, leads to a stereospecific cyclization, thereby forming the less hindered naphtho[2,l-fi]furan-2(l//)-spiro-r-(2//)-naphthalene-2 -ones (82) [80JCS(P1)1978,80JCS(P1)1986]. The conversion 80 to 82 probably occurs through intermediate 81 (Scheme 25). 

The most widely used epoxy resin intermediates (Araldite, Epon, and Epi-Rez) are produced from the reaction of bisphenol A and epichlorohyorin, as shown in Figure 15.7,... 

Phenol is produced through both natural and anthropogenic processes. It is naturally occurring in some foods, human and animal wastes, and decomposing organic material, and is produced endogenously in the gut from the metabolism of aromatic amino acids. Phenol has been isolated from coal tar, but it is now synthetically manufactured (EPA, 2002). Currently, the largest use of phenol is as an intermediate in the production of phenolic resins, which are used in the plywood, adhesive, construction, automotive, and appliance industries. Phenol is also used in the production of synthetic fibers such as nylon and for epoxy resin precursors such as bisphenol-A. 

Oxidative stress and covalent binding to macromolecules. Oxidation to the epoxide occurs via a tetrahedral intermediate, which can form either an epoxide or a phenol directly (see the scheme below). The epoxide can covalently bind nucleophiles, such as DNA or proteins, to open up the epoxide to a phenol and make toxic covalent adducts. The phenols can be further oxidized to bisphenols, which can in turn form quinones. Quinones can cause serious oxidative damage to cells through radical pathways, or can alkylate N- or S-nucleophiles, such as glutathione and glycine. 

Allyl chloride is used to make intermediates for downstream derivatives such as resins and polymers. Approximately 90% of allyl chloride production is used to synthesize epichlorohydrin, which is used as a basic building block for epoxy resins and in glycerol synthesis. Allyl chloride is also a starting material for allyl ethers of phenols, bisphenol A and phenolic resins, and for some allyl esters. Other compounds made from allyl chloride are quaternary amines used in chelating agents and quaternary ammonium salts, which are used in water clarification and sewage sludge flocculation (Kneupper Saathoff, 1993). 

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