Modification epoxides

Terminal modification Epoxide on PPE, phenoxy, PMMA Anhydride on PS, PP, PSF, PAES Carboxylic acid on PS, NBR ester on PPS Hydroxyl on NBR, PS, PSF, PA6 Amine on NBR, PS, PIP, SAN Isocyanate on polyamides, carbodiintide on PPE For both addition and condensation polymers... 

Additives. Because of their versatility, imparted via chemical modification, the appHcations of ethyleneimine encompass the entire additive sector. The addition of PEI to PVC plastisols increases the adhesion of the coatings by selective adsorption at the substrate surface (410). PEI derivatives are also used as adhesion promoters in paper coating (411). The adducts formed from fatty alcohol epoxides and PEI are used as dispersants and emulsifiers (412). They are able to control the viscosity of dispersions, and thus faciHtate transport in pipe systems (413). Eatty acid derivatives of PEI are even able to control the viscosity of pigment dispersions (414). The high nitrogen content of PEIs has a flame-retardant effect. This property is used, in combination with phosphoms compounds, for providing wood panels (415), ceUulose (416), or polymer blends (417,418) with a flame-retardant finish. 

The third and newest modified natural mbber available is epoxidized natural mbber (ENR). This modification was actually discovered as early as 1922 (50), although the elimination of ring opening and side reactions to give a purely epoxidized material took another 50 years or so to achieve (51). The resulting polymer is a new material, with properties totally different from natural mbber, as iadicated ia Table 5. 

Other modifications of the polyamines include limited addition of alkylene oxide to yield the corresponding hydroxyalkyl derivatives (225) and cyanoethylation of DETA or TETA, usuaHy by reaction with acrylonitrile [107-13-1/, to give derivatives providing longer pot Hfe and better wetting of glass (226). Also included are ketimines, made by the reaction of EDA with acetone for example. These derivatives can also be hydrogenated, as in the case of the equimolar adducts of DETA and methyl isobutyl ketone [108-10-1] or methyl isoamyl ketone [110-12-3] (221 or used as is to provide moisture cure performance. Mannich bases prepared from a phenol, formaldehyde and a polyamine are also used, such as the hardener prepared from cresol, DETA, and formaldehyde (228). Other modifications of polyamines for use as epoxy hardeners include reaction with aldehydes (229), epoxidized fatty nitriles (230), aromatic monoisocyanates (231), or propylene sulfide [1072-43-1] (232). 

More recent work in the corticosteroid senes has involved modification of the dihydrox-yacetone side chain at the 17 position Activity is retained, for example, when the hydroxyl group at the 17 position is omitted Thus, addition of the elements of hypobromous acid to tnene 36 [8], gives the bromohydnn 37, treatment with base leads to internal elimination to form the p-epoxide 38, opening of the oxir.ine with hydrogen fluoride gives desoximetasone, 39, [9]... 

C. Karavasilis, S. Bebelis, and C.G. Vayenas, Non-Faradaic Electrochemical Modification of Catalytic Activity 10. Ethylene epoxidation on Ag deposited on stabilized Zr02 in presence of chlorine moderators, J. Catal. 160, 190-204 (1996). 

Electrochemical promotion, or non-Faradaic Electrochemical Modification of Catalytic Activity (NEMCA) came as a rather unexpected discovery in 1980 when with my student Mike Stoukides at MIT we were trying to influence in situ the rate and selectivity of ethylene epoxidation by fixing the oxygen activity on a Ag catalyst film deposited on a ceramic O2 conductor via electrical potential application between the catalyst and a counter electrode. 

Modification of the cyclohexenyl moiety has been carried out by use of the cyclohexadiene epoxides 243 and 244, which were coupled with methyl 4-amino-4-deoxy- and -4,6-dideoxy-0 -D-glucopyranoside (385a and 385b) to give the isomers (395 and 396). 

Vitamin K is the cofactor for the carboxylation of glutamate residues in the post-synthetic modification of proteins to form the unusual amino acid y-carboxygluta-mate (Gla), which chelates the calcium ion. Initially, vitamin K hydroquinone is oxidized to the epoxide (Figure 45-8), which activates a glutamate residue in the protein substrate to a carbanion, that reacts non-enzymically with carbon dioxide to form y-carboxyglut-amate. Vitamin K epoxide is reduced to the quinone by a warfarin-sensitive reductase, and the quinone is reduced to the active hydroquinone by either the same warfarin-sensitive reductase or a warfarin-insensitive... 

In this work, highly active epoxidation catalysts, which have hydrophobic surface of TS-1, were synthesized by the dry gel conversion (DGC) method. Ti-MCM-41 was synthesized first by a modifed method and the TS-l/MCM-41 catalysts were subsequently synthesized by the DGC method. The catalysts were characterized by the XRD, BET, FT-IR, and UV-VIS spectroscopy. TS-l/MCM-41 catalysts were applied to the epoxidation of 1-hexene and cyclohexene with aqueous H202to evaluate their activities for the epoxidation reaction. ... 

This is not discussed in detail since mechanisms of resistance have been carefully reviewed (Ghannoum and Rice 1999). It was pointed out that resistance has not been associated with modification of the structure. For the 1,2,4-triazoles that have been widely used, their effect is due to inhibition of the synthesis of ergosterol that is the dominant component of fungal cell membranes. Resistance is generally associated with modification of the target enzymes, for example, the epoxidation of squalene (Terbinafine) or 14a-demethylase (Fluconazole). Resistance of Candida albicans to the azole antifungal agent fluconazole demonstrated, however, the simultaneous occurrence of several types of mechanism for resistance (Perea et al. 2001) ... 

For example, the block copolymers can be modified with a vinyl monomer [281 ]. In addition, diglycidyl ethers [282], that is, precondensates for epoxides, can be used as modifiers. Another possibility is modification with polyamines. 

An alternative synthesis producing a chiral-substituted 3-azoniaspirooctane, 153 has been published by Liu and co-workers where a modification of the Payne rearrangement was applied to amine epoxide 152 (Equation 35) <1997JCS(P1)511>. 

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