ractions.:
NSOLUBLE
in each other
or
0 PHASES
most
ORGAN
SOLVENTS
are
with each other,
extraction
CHOOSE IH2O
or one,
solven
or
Liquid/liquid
extraction
Criteria for the ORGANIC SOLVENT:
1 , Tnert
2 . Immiscible with H2O
3 . G o o d solvent
4 . Not too expensive
5 . Not too toxic
6 . Volatile
($$$)
benzoic acid
mp 123', pK, 4.17
naphthalene
mp 80°, neutral
2-naphthol
mp 123O, pK, 9.5
benzoic acid
mp 123', pK, 4.17
conjugate base
naphthalene
mp SO" neutral
conjugate base
The ORGANIC SOLVENT:
diethyl ether
a.k.a.,
=
ethyl ether
"ether"
1 . Inert
2 . Non-polar
3.
Immiscible with H z 0
4.
Volatile (bp -35 'C)
5 . Reasonably non-toxic
@.uy $y,o
Very flarnrnable!!!
Techniques
tips
and/or
helpful hints:
E r l e l ~ ~ r l e y e rPLASILS
for
orgarlie
solvents/solutio~is;
NOT beakers
Beakers (or flasks) for aqueous solutions
Stir solutions with glass rod;
NOT metal spatula
Spatulas for SOLIDS, not liquids/solutions
VACUUM filtration when you want the SOLID
GRAVITY filtration when you want the SOLUTION
Physical
constants:
Aldrich catalog
Handbook of Chemistry and Pllysics (CRC)
Merck Index
benzoic acid
conjugate base
naphthalene
S L 0 W acidification
of
bicarbonate
solution:
WHY ??
naphthalene
conjugate base
COOL in ICE
1
during
NEUTRALIZATION
WHY ??
1I
1
OH-
+
H~Q+
+
2H20
+
A
naphthalene
DRYING AGENTS
for
organic
solutions:
how do they work
..
33
to remove the solvent
1 . Operates at reduced
be careful !
-
2 . Think and understand
pressure;
!
3 . Use little or no heat.
Why ?
Naphthalene itself is volatile
(mothballs!).
benzoic acid
conjugate base
naphthalene
conjugate base