Chemistry Reference
In-Depth Information
way express the positions of these atoms in the compounds''. Therefore, several
types of formulas coexisted in the literature for at least two decades.
A final and decisive progress was contributed by Pasteur [
9
-
11
] (1822-1895)
and van t'Hoff (1852-1908) [
12
]. Pasteur was troubled as a student by a report that
salts of tartaric acid and paratartaric acid (i.e., the racemate) differed from each
other by the optical rotation of tartrate solutions and absence of optical rotation in
the case of ''paratartrates'', although these salts had identical properties in all other
aspects. Careful examination of numerous salts of racemic tartaric acid led to an
extremely important discovery. In the case of sodium-potassium or sodium
ammonium salts he found equal amounts of hemihedral crystals which contained
either the laevorotatory or the dextrorotatory molecules. In other words, he was
able to separate the optical enantiomers in their crystalline form. About 20 years
later Paterno published a rarely cited paper [
13
] in which he presented a tetrahedral
C
3
H
4
O
2
Lactic acid as
formulated by
O
2
H
A.Wurtz 1858
CO
C
2
H
4
H
O
O
H
2
HO
2
C
2
O
2
,O
HO C
4
H
H. Kolbe 1859
Wislicenus 1863
Me
CHO
OC
Me
K
2
CO
3
2
Br
CH
CO
2
H
CO
- 2 KBr , - CO
2
, - H
2
O
OCH
Me
x
ClH
2
CCO
2
Na
OCH
2
CO
x
- x NaCl
Me
Me
T
- x H
2
O
H
OCH
2
C
CO
OH
x
x
HO CH
2
C
CO
2
H
Me
Me
Formula 2.1
