Maleic anydride

Whilst it is obviously valuable to measure the solubility of reagents in the SCF, it is important to be aware that the solubility in a multicomponent system can be very different from that in the fluid alone. It is also important to note that the addition of reagents and catalysts can have a profound effect on the critical parameters of the mixture. Indeed, at high concentrations of reactants, the mole fraction of C02 is necessarily lower and it may not be possible to achieve a supercritical phase at the temperature of interest. Increases in pressure (i.e. further additions of C02) could yield a single liquid phase (which would have a much lower compressibility than scC02). For example, the Diels-Alder reaction (see Chapter 7) between 2-methyl-1,3-butadiene and maleic anydride has been carried out a pressure of 74.5 bar and a temperature of 50 °C, assuming that this would be under supercritical conditions as it would if it were pure C02. However, the critical parameters calculated for this system are a pressure of 77.4bar and a temperature of 123.2 °C, far in excess of those used [41]. 

Polyquaternium-11 (quaternium-23—Gafquat) is a copolymer of vinyl pyrrolidone and dimethylaminoethyl melliacrylate quaternized with dimethyl sulfate. This polymer is related to the quaternized copolymer of PVP depicted in Table 7-2. One mousse product in retail sale contains both of these cationic polymers. Others contain one cationic polymer and either a neutral or an anionic resin such as polyvinyl pyrrolidone and vinyl acetate copolymer, or a resin such as the butyl ester of polyvinyl methyl ether, a maleic anydride copolymer. 

Reaction Conditions. After stirring the reaction mixture at room temperature for 15 min, begin monitoring the system byTLC (plates with fluorescent indicator). Using as a solvent system ethyl acetate hexane (3 2) and a UV lamp for visualization, the Revalue for maleardlic add is 0.2.The Revalues for aniline and maleic anydride are 0.73 and 0.67, respectively. Once complete as judged by TLC, cool the reaction mixture in an ice bath for 5-10 min. 

Monomers with electron-rich double bonds produce one-to-one copolymers with monomers having electron-poor double bonds in reaction systems that also contain certain Lewis acids. These latter are halides or alkyl halides of nontransition metal elements, including AlCb, ZnCh, SnCL, BF3, AI(CH2CH3)Cl2, alkyl boron halides, and other compounds. The acceptor monomer generally has a cyano or carbonyl group conjugated to a vinyl double bond. Examples are acrylic and methacrylic acids and their esters, acrylonitrile, vinyl ketones, maleic anydride, fumaric esters, vinylidene cyanide, sulfur dioxide, and carbon monoxide. The variety of donor molecules is large and includes various olefins, styrene, isoprene, vinyl halides and esters, vinylidene halides, and allyl monomers [30]. 

Thermoplastic starch can also be blended with polyolefins [131 ]. In this case about 50% of thermoplastically processable starch is mixed with 40% of polyethylene and 10% of ethyl acrylate-maleic anhydride copolymer. During this mixing process an esterification reaction takes place between the maleic anydride groups in the copolymer and the free hydroxyl groups in starch. 

Unsaturated polyesters are the most versatile class of thermosetting polymers. They are macromolecules made up of an unsaturated component, (i.e., maleic anhydride or its trans isomer, fumaric acid, which provides the sites for further reaction) and a saturated dibasic acid or anhydride with dihydric alcohols or oxides (typically phthalic anhydride which can be replaced by aliphatic acid, like adipic acid, for improved flexibility). If blends of phthalic anydride (or isophthalic acid) and maleic anhydride/fumaric acid are used, ortho (or iso) resins (Figure 6.18) are obtained. On the other hand, if propoxylated or ethoxylated bisphenol A is used with fumaric acid, bisphenol A fumarates are obtained, if a blend of chlorendic... 

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