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Ethylene functional group

Fig. 25. Schematic representation of imprinting (a) cross-linking polymerization ia the presence of a template (T) to obtain cavities of specific shape and a defined spatial arrangement of functional groups (binding sites. A—C) (b) cross-linked polymer prepared from the template monomer and ethylene... Fig. 25. Schematic representation of imprinting (a) cross-linking polymerization ia the presence of a template (T) to obtain cavities of specific shape and a defined spatial arrangement of functional groups (binding sites. A—C) (b) cross-linked polymer prepared from the template monomer and ethylene...
Formation and Elimination of Multiple Bond Functionalities. Reactions that involve the formation and elimination of multiple bond functional groups may significantly effect the color of residual lignin in bleached and unbleached pulps. The ethylenic and carbonyl groups conjugated with phenoHc or quinoid stmctures are possible components of chromophore or leucochromophore systems that contribute to the color of lignin. [Pg.139]

Many functional groups are stable to alkaline hydrogen peroxide. Acetate esters are usually hydrolyzed under the reaction conditions although methods have been developed to prevent hydrolysis.For the preparation of the 4,5-oxiranes of desoxycorticosterone, hydrocortisone, and cortisone, the alkali-sensitive ketol side chains must be protected with a base-resistant group, e.g., the tetrahydropyranyl ether or the ethylene ketal derivative. Sodium carbonate has been used successfully as a base with unprotected ketol side chains, but it should be noted that some ketols are sensitive to sodium carbonate in the absence of hydrogen peroxide. The spiroketal side chain of the sapogenins is stable to the basic reaction conditions. [Pg.14]

When formation of either the five- or six-membered ring was possible for N-chloroamine 37, only the five-membered ring was conducive under the Hofmann-Ldffler-Freytag reaction conditions, forming exclusively 6-ethyl-6-aza-bicyclo[3.2.1]-octane (38). No 2-ethyl-2-aza-bicyclo[2.2.2]-octane (39) was observed. On the other hand, 2-methyl-2-aza-bicyclo[2,2.2]octan-6-one (41) was installed by UV irradiation of a solution of A -chloroamine 40 in TFA. Ironically, when the ketone functionality on 40 was protected as its ethylene ketal group, the resultant steric interactions completely prohibited the classic Hofmann-Loffler-Freytag reaction. [Pg.93]

More recent work in this series demonstrated that a carbonyl group can be interposed between the side-chaincarrying aromatic ring and the ethylene function with full retention of activity. Claisen condensation of benzoate with 2-tetralone affords the e-diketone Reaction of... [Pg.70]

A monomer is a reactive molecule that has at least one functional group (e.g. -OH, -COOH, -NH2, -C=C-). Monomers may add to themselves as in the case of ethylene or may react with other monomers having different functionalities. A monomer initiated or catalyzed with a specific catalyst polymerizes and forms a macromolecule—a polymer. For example, ethylene polymerized in presence of a coordination catalyst produces a linear homopolymer (linear polyethylene) ... [Pg.302]

Figure 3.1 The reactions of ethylene and menthene with bromine. In both molecules, the carbon-carbon doublebond functional group has a similar polarity pattern, so both molecules react with Br2 in the same way. The size and complexity of the remainders of the molecules are not important. Figure 3.1 The reactions of ethylene and menthene with bromine. In both molecules, the carbon-carbon doublebond functional group has a similar polarity pattern, so both molecules react with Br2 in the same way. The size and complexity of the remainders of the molecules are not important.
Ether An organic compound containing the —O— functional group, 590-593,591t Ethyl alcohol, 43t, 595 Ethyl butyrate, 596t Ethyl formate, 596t Ethylene... [Pg.687]

Linear step-growth polymerizations require exceptionally pure monomers in order to ensure 1 1 stoichiometry for mutually reactive functional groups. For example, the synthesis of high-molecular-weight polyamides requires a 1 1 molar ratio of a dicarboxylic acid and a diamine. In many commercial processes, the polymerization process is designed to ensure perfect functional group stoichiometry. For example, commercial polyesterification processes often utilize dimethyl terephthalate (DMT) in the presence of excess ethylene glycol (EG) to form the stoichiometric precursor bis(hydroxyethyl)terephthalate (BHET) in situ. [Pg.13]

Other commercially relevant monomers have also been modeled in this study, including acrylates, styrene, and vinyl chloride.55 Symmetrical a,dienes substituted with the appropriate pendant functional group are polymerized via ADMET and utilized to model ethylene-styrene, ethylene-vinyl chloride, and ethylene-methyl acrylate copolymers. Since these models have perfect microstructure repeat units, they are a useful tool to study the effects of the functionality on the physical properties of these industrially important materials. The polymers produced have molecular weights in the range of 20,000-60,000, well within the range necessary to possess similar properties to commercial high-molecular-weight material. [Pg.460]

Dendrimer micelles of this type have been formulated as drug delivery vehicles. Dendrimers with a hydrophobic interior have been used to entrap a hydrophobic drug such as indomethacin. This is retained because of the hydrophilic periphery containing ethylene glycol functional groups, and is released slowly because of the collapsed configuration of the interior, through which molecular diffusion is obstructed. [Pg.138]

A carbon-carbon double bond is a reactive functional group because of its iz electrons. Remember from Chapter 10 that ethylene has a CDC bond made up of one a bond plus one itt bond. As shown in Figure 13-1. the electrons in the iTrbond are located off the bond axis, making them more readily available for chemical reactions. Moreover, 71 electrons are less tightly bound than a electrons. Consequently, the reactivity patterns of ethylene are dominated by the chemistry of its n electrons. Polyethylene is one familiar polymer whose monomer is ethylene. We describe the polymerization reaction of ethylene and other monomers containing CDC bonds in Section 13-1. [Pg.890]

The polymers listed above, and all other linear polymers as well, are formed from monomers which enter into two, and only two, linkages with other structural units. This statement corresponds to the previous remark that the structural units of linear polymers necessarily are bivalent. The interlinking capacity of a monomer ordinarily is apparent from its structure it is clearly prescribed by the presence of two condensable functional groups in each monomer in the third and fourth examples above. The ability of the extra electron pair of the ethylenic linkage to enter into the formation of two bonds endows styrene with the same interlinking capacity. In accordance with the functionality concept introduced by Carothers, all monomers which when polymerized may join with two, and only two, other monomers are termed bifunctional. Similarly, a hifunctional unit is one which is attached to two other units. It follows that linear polymers are composed exclusively (aside from terminal units) of bifunctional units. ... [Pg.31]

The strength of ion binding is enhanced when the arrangements of the functional groups permit chelate formation (Begala Strauss, 1972). Thus, magnesium is more firmly bound to poly(vinyl methyl ether-maleic acid) than to either poly(acrylic acid) or poly(ethylene maleic add). [Pg.71]


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See also in sourсe #XX -- [ Pg.83 , Pg.84 ]




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