Phenol epoxides

The methylated maleic acid adduct of phthalic anhydride, known as methyl nadic anhydride VI, is somewhat more useful. Heat distortion temperatures as high as 202°C have been quoted whilst cured systems, with bis-phenol epoxides, have very good heat stability as measured by weight loss over a period of time at elevated temperatures. The other advantage of this hardener is that it is a liquid easily incorporated into the resin. About 80 phr are used but curing cycles are rather long. A typical schedule is 16 hours at 120°C and 1 hour at 180°C. 

Semiconducting devices, switches and miniaturised v.h.f. circuits are all particularly sensitive to the slightest reaction on critical surfaces, and in devices calling for the highest levels of reliability even the most inert of the phenolic, epoxide and silicone resins are not considered to be fully acceptablecorrosion of electronic assemblies may often be enhanced by migration of ions to sensitive areas under applied potentials, and by local heating effects associated with current flows. 

Hulbert, P. B. Grover, P. L. Chemical rearrangement of phenol-epoxide metabolites of polycyclic aromatic hydrocarbons to quinone-methides. Biochem. Biophys. Res. Commun. 1983, 117, 129-134. 

The first enantioselective total synthesis of the sesquiterpenoid heliannuol D 56 has been reported by Shishido and co-workers. The key step was a base-mediated (NaOH) intramolecular cyclisation of the phenolic epoxide mixture 55 (R1 = MOM, R2 = H and R1 = H, R2 = MOM). Heliannuol D (and the eight-membered congener, heliannuol A) is an allelopathic agent isolated from cultivated sunflowers (Helianthus annuus L.SH-222) <00JCS(P 1)1807>. 

Thus, a synthetic source of promising allelochemicals is essential if we are to comprehensively study the agent s mode of activity and establish its basic structure-activity profile. The proposed work addresses this need. We will synthesize alleopathic natural products isolated from the sunflower (the heliannuols), and structurally related compounds, in optically pure form based on biomimetic phenol-epoxide cyclizations. The bioactivity of the targets and intermediates will be evaluated through laboratory tests on plant germination and growth. Bioassays will be performed on the synthetic intermediates to allow for the development of a preliminary structure-activity profile for these novel natural herbicides. 

P4 Heliannuols A, D, and K. Our preliminary results show that the biomimetic phenol epoxide cyclization route is valid for the exo cyclization products such as heliannuol D (4), and we are hopeful that... 

The products of epoxidation in vivo depend on the reactivity of the particular epoxide. Stabilized epoxides react with nucleophiles and undergo further enzymic reactions, whereas destabilized ones undergo spontaneous isomerization to phenols. Epoxides are generally reactive intermediates, however, and in a number of cases are known to be responsible for toxicity by reaction with cellular constituents. 

Phenols, epoxides, and halides can react with the tripeptide glutathione to give mercapturic acids and some steroids can react with sulfates. 

The polycyclic aromatic hydrocarbon carcinogens, which are very ubiquitous, are metabolized by the microsomal mixed-function oxidase system of target tissues to a variety of metabolites such as phenols, quinones, epoxides, dihydrodiols and dihydrodiol-epoxides ( ). The mqjor pathway of activation of benzo(a)pyrene (BP) leads to the formation of dihydrodiol-epoxide of BP which interacts predominantly with the 2-amino of guanine of DNA. The dihydrodiol-epoxide of BP appears to be the major ultimate electrophilic, mutagenic, and carcinogenic metabolite of BP ( ). Nevertheless, other metabolites such as certain phenols, epoxides and quinones may contribute to the overall carcinogenic activity of BP. In addition, a free radical mechanism may also be partly involved in its carcinogenic activity. 

Phenol epoxide Pigmented Strong acid to strong alkali Cooling water Brackish and sea water... 

Substituted phenol epoxide Pigmented Strong acid to alkali Salt solutions Cooling waters Gases Organic liquids... 

Fungi Cunninghamella bainieri Microsomes Xenobiotics Alcohol, phenols epoxides 29)... 

Yeasts S. cerevisiae Microsomes Xenobiotics Alcohols, phenols, epoxides 32)... 

The basic catalysis of the epoxide-phenol reaction has been studied by a variety of authors (12,13). In general, the conclusion has been that basic catalysis gives selectivity for the phenol-epoxide reaction over the secondary alcohol-epoxide reaction (the secondary alcohol being formed from the opening of an epoxide). Although the base catalyzed reaction has been studied, the specific mechanism for triphenylphosphine Catalysis has not been determined. We propose the mechanism shown in Reaction Scheme 3 which is consistent with our experimental results. 

Uses Catalyst increasing crosslinking speed, adhesion promoter for heatcuring coating systems based on e.g., phenolic-epoxide resins improves sulfur staining resist, of interior can coatings Properties Lt. to dk. reddish low-vise, liq. dens. = 0.88 g/cm (20 C) ... 

Uses Phenolic for heat-curable phenolic/epoxide resin combinations, can coatings, chemically resist, protective coatings Properties Dilutable with MEK, MIBK, ethyl acetate, butyl acetate, methoxypropyl acetate, methoxypropanol dens. = 1.05 g/cm (20 C) dynamic vise. 180-300 mPa S flash pt. = 43 C 63-67% NV Storage 6 mos min. shelf life stored in original containers below 25 C Phenodur PR 260/68B [Solutia]... 

Chem. Descrip. Phenolic resin (55%) in isobutanol/butanol Uses Phenolic for internal/external coating of pkg. containers, can coatings, high-adhesion chemically resist, protective coatings for apparatus, vessels, pipelines, and for heat-curing phenolic/epoxide combinations Features Unplasticized... 

Butanedioi dimethacryiate crosslinking agerd, phenolic-epoxide... 

Glucuronic acid conjugates were formed when phenols, epoxides, or dihydrodiols of BaP were incubated with uridine diphosphate glucuronic acid (UDPG) in the presence of rat liver microsomes. The conjugates were not formed when the soluble fraction was employed. Conjugates were formed most readily from the phenolic metabolites of BaP 358). 

Figure 1 shows the principal metabolic pathways of B tP (a representative PAH) and the formation of some conjugates. In the interest of simplicity, further metabolic transformations, such as the P450 catalyzed oxidation of phenols to phenol-epoxides, conversion of phenols to phenol-dihydrodiols, all the enzymatic steps, and the stereochemistry of the metabolites are omitted. 

Thermosets are based on crosslinked polymers. They harden permanently with the aid of catalysts and/or heat, and cannot be remelted without degrading their polymeric structure. The thermosetting family includes phenolics, epoxides, alkyds, polyurethanes, melamine, urea-formaldehyde and unsaturated polyesters. 

The spotting tack and/or the heat resistance of elastomeric polyurethane adhesives may he extended by adding resins (alkyl phenolic, epoxide, terpene phenolic, coumarone) or polymers (low crystallizing polyurethane, acrylic, nitrile ruhher, chlorinated ruhher, acetyl cellulose) (Penczek and Nachtkamp 1987) with low miscihility with the polyurethane. To improve adhesion together with heat resistance, reactive alkyl phenolic resins, chlorinated rubber, or other chlorine-containing polymers can be added. 

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