Maleic acid conformation

Calcium(II) complexes maleic acid conformation, 2, 475 mandelic acid, 2, 474... 

ESR spectra, 511 Uranium(VI) complexes dioxoneocupferron, 512 Uranium hexaalkoxides physical properties, 347 Uranyl complexes cupferron, 512 formamide, 491 glycolic acid, 472 hexafluoroacetylacetone, 373, 377 photochemistry, 385 rearrangement, 384 maleic acid conformation, 467 neutral 1,3-diketones, 402 poly ketones, 399 Urea... 

Vinyls. Vinyl resins are thermoplastic polymers made principally from vinyl chloride other monomers such as vinyl acetate or maleic anhydride are copolymerized to add solubUity, adhesion, or other desirable properties (see Maleic anhydride, maleic acid, and fumaric acid). Because of the high, from 4,000 to 35,000, molecular weights large proportions of strong solvents are needed to achieve appHcation viscosities. Whereas vinyls are one of the finest high performance systems for steel, many vinyl coatings do not conform to VOC requirements (see Vinyl polymers). 

Molecular forms that arise as a result of rotation around freely rotatable bonds are known as conformers. Even small molecules can have different conformations in solution. In the two conformations of succinic acid illustrated opposite, the atoms are arranged in a similar way to fumaric acid and maleic acid. Both forms are possible, although conformation 1 is more favorable due to the greater distance between the COOH groups and therefore occurs more frequently. Biologically active mac-... 

The effect of polar groups on the diimide reaction is sensitive to the configuration of the attached groups. For example, fumaric acid (trans) is ten times as reactive as maleic acid (els ) and the ratio of reactivities of the geometrical isomers of cinnamic acid, trans/cis. is 10 3 (ref. 21b). In comparison, cis- and trans-2-butene have almost identical reactivities. The difference may be explained by a change in the degree of advancement of the transition state towards the saturated product where the eclipsed conformation would result in a greater non-bonded repulsive interaction between the cis-substituents than the trans. 

Tungsten(VI) complexes guanidine, 283 hydroxamic acids, 506 maleic acid, 475 conformation, 467 tartaric acid, 479 NMR, 468... 

While these experiments stimulated other research, it is sad to relate that the proposed explanation is not correct. It required almost seventy years, however, before it was realized that the curare-like action of the onium salts was a result of their ionic character. Other examples of the role of spatial arrangement were discovered. For example, quoting Stewart Ishizuka (1897) found that maleic acid was a much stronger poison than its stereoisomer, fumaric acid 1.94 grammes for every kilogramme in a dog s weight was a fatal dose of the former acid, while the same dose of fumaric acid was harmless. Similarly these isomers were found to have differential effects on microorganisms. Stewart also rationalized the mydriatic action of tropine and the inactivity of pseudotropine in terms of three-dimensional formulae as shown below (1 and 2). In many ways, these structural representations are close to the present-day conformational structures (pseudotropine = 3, tropine = 4) ... 

It is concluded that below the transition temperature the monomer intensity increases with increasing temperature due to excimer dissociation to excited-state monomer. Above the transition temperature the excited-state equilibrium is apparently broken because the thermal energy is sufficient to activate excimer non-radiative decay by dissociation to ground-state monomer. Consequently, the monomer emission no longer increases with increasing temperature and the isobestic point disappears. Pyrene has been used as a fluorescent probe to monitor the conformational state of maleic acid with... 

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