| 释义 |
parabanic, a. Chem.|pærəˈbænɪk|
[f. para-: see below.]
In parabanic acid, a dibasic acid, CO·2(NH·CO), produced by the action of nitric acid on uric acid or alloxan; crystallizing in colourless prisms. When boiled with dilute acids, it is converted into oxalic acid and urea, whence it is sometimes called oxalyl carbamide or oxalyl urea. Hence ˈparaban, a proposed substitute for the name parabanic acid, to express its parallelism to alloxan. ˈparabanate, a salt of parabanic acid, as argentic parabanate, CO·2(NAg·CO).
1857Miller Elem. Chem. III. 635 Parabanic acid forms salts which are exceedingly unstable: parabanate of silver being the only salt which is permanent. 1866Odling Anim. Chem. 43 Paraban and alloxan are products of the oxidation of uric acid. 1873C. H. Ralfe Phys. Chem. p. xxviii, Kreatin is a monureide, and so are paraban and alloxan, which are obtained by the oxidation of uric acid. 1888I. Remsen Org. Chem. 203 Parabanic acid is formed by boiling uric acid with strong nitric acid and other oxidizing agents.
[Note. The term parabanic was introduced by Liebig and Wöhler in 1838 (Annalen XXVI. 285), but without any explanation of its formation. As they made parabanic acid by a reaction in which they expected to obtain alloxan, it is prob. that para- was used in the sense ‘instead of’, ‘opposed to’, the ending being that of allox-an, -anic, and the b merely euphonic. It has been suggested that the latter is a residue of carb-, and that the term was formed to express parallelism of constitution to urea or carbamide, CO·2(NH2), and to alloxan, CO·2(NH·CO)CO; but as a fact, it was not till much later that the identity of urea and carbamide was discovered.] |