Helping San Diego, California and beyond since 1997.
Do you need
volunteer, community service, work, military or court hours?
|
|
Helping San Diego, California and beyond since 1997.
|
|
Click here and add this page to your favorites!
|
Encyclopedia Britannica - Main :: FRA-GAE |
|
|
FUMARIC AND MALEIC ACIDS , two isomeric unsaturated acids of composition C4H4O4. Fumaric acid is found in fumitory (Fumaria officinalis), in various fungi (Agaricus piperatus, &c.), and in Iceland moss
heating
heating
Kekule , Ann., 1864,130, p. 21). It may also be obtained by boiling monobromsuccinic acid with water; by the action of dichloracetic acid and water on silver malonate (T. Komnenos, Ann., 1883, 218, p. 169) ; by the cyanide synthesis from acetylene di-iodide; and by heating maleic acid to 210 C. (Z. Skraup, Monats. f. Chemie, 1891, 12, p. 112). It crystallizes in small prisms or needles, and is practically insoluble in cold water. It sublimes to some extent at about 200 C., being partially converted into maleic anhydride and water, the reaction becoming practically quantitative if dehydrating agents be used. Reducing agents (zinc and caustic
Kekule and R. Anschutz, Ber., 1881, 14, p. 713). By long-continued heating with caustic
Maleic acid is obtained by distilling malic or fumaric acids; by heating fumaric acid with acetyl chloride to oo C.; or by the hydrolysis of trichlorphenomalic acid ((3-trichloracetoacrylic acid) [A. Kekule, Ann., 1884, 223, p. 18s]. It crystallizes in monoclinic prisms, which are easily soluble in water, melt at 130 C., and boil at 16o C., decomposing into water and maleic anhydride. When heated with concentrated hydrobromic or hydriodic acids, it is converted into fumaric acid. It yields an anilide; oxidation converts it into mesotartaric acid. Maleic anhydride is obtained by distilling fumaric acid with phosphorus pentoxide. It forms triclinic crystals which melt at 6o C. and boil at 196 C. Both acids are readily esterified by the action of alkyl halides on their silver salts, and the maleic ester is readily transformed into the fumaric ester by warming with iodine, the same result being obtained by esterification of maleic acid in alcoholic solution by means of hydrochloric acid. Both acids yield acetylene by the electrolysis of aqueous solutions of their alkali salts, and on reduction both yield succinic acid, whilst by the addition of hydrobromic acid they both yield monobromsuccinic acid (R. Fittig,Ann., 1877, 188, p. 98). From these results it follows that the two acids are structurally identical, and the isomerism
Wislicenus
ISOMERISM
HCCO2H HCCO2H HCCO2H Maleic acid. HO2C:6H These account for maleic acid readily yielding an anhydride, whereas fumaric acid does not, and for the behaviour of the acids towards bromine, fumaric acid yielding ordinary dibromsuccinic acid, and maleic acid the isomeric isodibromsuccinic acid.End of Article: FUMARIC AND MALEIC ACIDS If you wish, you can link directly to this article.
<a href="http://jcsm.org/StudyCenter/Encyclopedia/FRA_GAE/FUMARIC_AND_MALEIC_ACIDS.html"> FUMARIC AND MALEIC ACIDS </a> |
|
|
(Previous) FUM, or FUND HWANG |
(Next) FUMAROLE |
|
Sponsored Advertisements