Maleic acid structure

Maleic acid, structure of, 753 Malic acid, structure of, 753 Walden inversion of, 359-360 Malonic ester, carboxylic acids from, 856-858... 

Both acids 3deld succinic acid, m.p. 185°, upon catalytic reduction (see Section 111,150), thus establishing their structures. Maleic and fumaric acids are examples of compounds exhibiting cis-trans isomerism (or geometric isomerism). Maleic acid has the cm structure since inter alia it readily 3delds the anhydride (compare Section 111,93). Fumaric acid possesses the trans structure it does not form an anhydride, but when heated to a high temperature gives maleic anhydride. 

Nucleophilic addition of 2-aminothiazole to the double bond of di-maleic acid hydrazine has been reported (206). No spectroscopic proof, however, is given to establish the proposed structure (60) for the resulting product (Scheme 41). 

Catalytic dehydrogenation using palladium/maleic acid has been used to convert tetrahydro-j8-earbolines of general structure 142 into the dihydro-jS Carbolinium salts (143) A similar transformation has been carried out by oxidation with iodine. ... 

Maleic acid and fumaric acid are the cis- and trans- isomers, respectively, of QH COOH) a dicarboxylic acid. Draw and label their structures. 

This intramolecular bonding in maleic acid, (8), halves its ability to form intermolecular bonds. In fumaric acid, on the other hand, all of the hydrogen bonds form between molecules (intermolecular bonds) to give a stronger, interlinked crystal structure. 

Comparison of the Mossbauer I Agxp I values with those calculated on the basis of the pqs formalism revealed that the organotin(IV) moiety has Tbp geometry, and in certain cases geometry too. Some of the complexes contain the organotin(IV) cation in two different environments. Finally, the local structure of the maleic acid complex formed with [Bu2Sn(IV)l was determined by an EXAFS method.The structural data are collected in Table 6. Similar studies... 

There are numerous possible monomers that can be used in the backbone of the polyester prepolymer. However, typical monomers are 1,2-propanediol, as just mentioned, with maleic acid (usually added as the anhydride) to provide the sites of unsaturation, and phthalic acid (again usually added as the anhydride) to act as the second of the two diacid species. The structures of these latter two substances are shown in Figure 4.1. 

Figure 4.1 Structures of (a) maleic acid and (b) phthalic acid...

The formation of a stable hydrogen-bonded ring structure as in poly(itaconic acid) and in poly(maleic acid) has also been shown to affect hydration states (Muto, Komatsu Nakagawa, 1973 Muto, 1974). 

The pH dependence of the rate of modification shows that the pKa of Asp-32 is less than 3.165 It is seen in the high-resolution crystal structures that the carboxyl groups of the two aspartate residues are hydrogen-bonded to each other. This is similar to the ionization of maleic acid, which has pKa values of 1.9 and 6.2 (equation 16.30). 

Several polymer and random copolymers of fluoroalkyl acrylates have been studied,76 including (1) Poly-1,1-dihydroperfluoroheptylacrylate (PFHA), (2) copolymer of 1,1-dihydroperfluoroheptylacrylate (PFHA) with acrylic acid (PFHA-AA, 1 1), and (3) copolymer of the monoester of 1,1-dihydroperfluor-oheptyl alcohol and maleic acid (PFHM) with vinyl acetate (PFHM-VA, 1 1). The average degree of polymerization was found to be about ten for all the polymers tested. The tendency of polymers to form well-ordered two-dimensional structures on the water surface was demonstrated. Polymers were deposited as... 

Figure 1. Chemical structures of (a) 4,4 -diazidodi-phenyl methane and (b) poly(styrene-co-maleic acid half ester).

Fig. 1 Chemical structures of the polymers commonly used for preparation of beads poly (styrene-co-maleic acid) (=PS-MA) poly(methyl methacrylate-co-methacrylic acid) (=PMMA-MA) poly(acrylonitrile-co-acrylic acid) (=PAN-AA) polyvinylchloride (=PVC) polysulfone (=PSulf) ethylcellulose (=EC) cellulose acetate (=CAc) polyacrylamide (=PAAm) poly(sty-rene-Wocfc-vinylpyrrolidone) (=PS-PVP) and Organically modified silica (=Ormosil). PS-MA is commercially available as an anhydride and negative charges on the bead surface are generated during preparation of the beads...

Infrared spectra of propene and isobutene on different catalysts were measured by Gorokhovatskii [143]. Copper oxide, which converts olefins to butadiene and aldehydes, shows adsorption complexes different from structures on a V2Os—P2Os catalyst which produces maleic acid anhydride. Differences also exist between selective oxidation catalysts and total oxidation catalysts. The latter show carbonate and formate bands, in contrast to selective oxides for which 7r-allylic species are indicated. A difficulty in this type of work is that only a few data are available under catalytic conditions most of them refer to a pre-catalysis situation. Therefore it is not certain that complexes observed are relevant for the catalytic action. 

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