Epoxide groups

The reaction of OF2 and various unsaturated fluorocarbons has been examined (35,36) and it is claimed that OF2 can be used to chain-extend fluoropolyenes, convert functional perfluorovinyl groups to acyl fluorides and/or epoxide groups, and act as a monomer for an addition-type copolymerization with diolefins. 

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. 

The most important Lewis bases are tertiary amines or polyamines converted into tertiary amines upon reaction with epoxide groups. 

Higher moleeular weight products may be obtained by reducing the amount of excess epichlorohydrin and reacting the more strongly alkaline conditions which favour reaction of the epoxide groups with bis-phenol A. If the diglycidyl ether is considered as a diepoxide and represented as... 

In addition to the resins based on bis-phenol A dealt with in preceding sections there are now available a number of other resins containing epoxide groups. These can be treated in two main groups ... 

Those which contain a ring sturcture as well as an epoxide group in the molecule—the cyclic aliphatic resins. 

Those which have an essentially linear structure on to which are attached epoxide groups—the acylic aliphatic epoxide resins. 

As with the other non-glycidyl ether resins the absence of the ether oxygen near to the epoxide group results in low reactivity with amine hardemers whereas activity with acid anhydride proceeds at reasonable rates. 

The weight in grams to provide one reactive hydrogen atom for every epoxide group in lOOg of liquid epoxide resin of epoxide equivalent 190. 

Steroids possessing an epoxide grouping in the side chain have likewise been converted to fluorohydrins. Thus, 20-cyano-17,20-epoxides of structure (19) furnish the 17a-fluoro-20-ketones (20) after treatment of the intermediate cyanohydrins with boiling collidine. The epimeric 5a,6a 20,21-oxides (21) afford the expected bis-fluorohydrins (22). The reaction of the allylic... 

Epoxy resins have a wide range of molecular weights (=1,000-10,000). Those with higher molecular weights, termed phenoxy, are hydrolyzed to transparent resins that do not have the epoxide groups. These could he used in molding purposes, or crosslinked hy diisocyanates or hy cyclic anhydrides. 

Epoxide resins are essentially long-chain polyhydric alcohols with epoxide groups at either end. They make useful building blocks because both the hydroxyl and the epoxide groups are available for reaction with other compounds. 

Figure 43 Preparation of POSS compounds containing epoxide groups.

In SBR, the benzene rings protrude like branches from the mbber backbone and absorb molecular vibrations caused by the elastomer chain touching the road surface thereby improving the traction properties. In ENR, the epoxide group performs a similar function like the benzene rings pendant from the backbone. 

It must be underlined that independently of the MS equipment characteristics, no information about stereo-chemistry can be obtained. In fact, cis and trans isomers of the corresponding carotenoid showed identical mass spectra, as did carotenoids with epoxide groups at 5,6 and 5,8 positions. In addition, special care should be taken in assigning carotenoid molecular masses to avoid confusion due to the various ions that may be formed depending on measurement conditions. 

B. Dobinson, W. Hofmann and B. P. Stark, The Determination of Epoxide Groups (Monographs in Organic Functional Group Analysis, Vol. 1), Pergamon Press, New York, 1969, p. 39. 

Water acting as a nucleophile attacks the protonated epoxide from the side opposite the epoxide group. 

Figure 8. The structures of the K-region oxides of DMBA (XI) (a, b and c), BP (XII) (d) and phenanthrene (XIII) (e). Views (c), (d) and (e) are directly onto the plane of the epoxide group.

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