Here's some more shit on this synthesis. Have fun!
Phenylalanine Properties:
Phenylalanine, dl- CAS# 150-0-1
Phenylalanine, l- CAS# 63-91-2
From-
http://ntp-server.niehs.nih.gov/htdocs/CHEM_H&S/NTP_Chem6/
Radian63-91-2.html
[for l-phenylalanine]
*SOLUBILITIES:
WATER : 10-50 mg/mL @ 25 C (RAD)
DMSO : <1 mg/mL @ 25 C (RAD)
95% ETHANOL : <1 mg/mL @ 25 C (RAD)
METHANOL : Very slightly soluble [031,295]
ACETONE : <1 mg/mL @ 25 C (RAD)
TOLUENE : Not available
OTHER SOLVENTS:
Ether: Very slightly soluble
Post 043 (not existing) Alcohol: Very slightly soluble [043,295]
Dilute mineral acids: Very slightly soluble
Post 295 (not existing)From-
www.chemfinder.com[for L-phenylalanine]
water solutblity: 1-5 g/100 mL at 25 C
@
http://esc.syrres.com/interkow/webprop.exe?CAS=63-91-2
[for L-Phenylalanine]
Water Solubility:
Value : 2.69E+004 mg/L
Temp : 25 deg C
Type : EXP
Ref : YALKOWSKY,SH & DANNENFELSER,RM (1992)
End of Properties-
==================
From "Topics in Currnet Chemistry" Volume 152, Electrochemistry IV,
edited by E. Stekhan, LoC# QD1. F58 v.152
page 93
"The yield and selectivity of the Kolbe electrolysis is determined by
the reaction conditions and structure of the carboxylate. ...
Experimental factors that influence the the outcome of the Kolbe
electrolysis are the current density, the temperature, the pH,
additives, the solvent, and the electrode material.
High current densities and high carboxylate concentrations favor the
formation of dimers. This is due to a high radical concentration at
the elctrode surface that promotes dimerization. Furthemore, at high
current densities the so called critical potential of about 2.4
(vs NHE) is reached [28] above which the Kolbe dimerization proceeds
smoothly. ... There is, however, no need for potential control in
Kolbe electrolysis as the critical potential is already exceeded at 1
to 10 mA/cm^2. This is much below the usually applied current density,
which should be as high as possible, normally equal to or greater than
250 mA/cm^2. ...
...
A nuetral, or even better a weakly acidic medium seems to be
prefferable for the Kolbe reaction. This is achieved by nuetralizing
the carboxylic acid to an extent of 2 to 5%, in some cases up to 30%,
by an alkali metal hydroxide or alkoxide. ... The endpoint of the
electrolysis is indicated by a change of the electrolyte to an alkaine
pH. ...
In aqueous solution an elevated pressure favors the Kolbe-coupling
against non-Kolbe products [37]. ...
Temperature has some effect on Kolbe electrolysis. Higher temperatures
seem to support disproportionation against the coupling reaction and
intramolecular additions to double bonds against a competing inter-
molecular coupling (Chap. 6). ...
Additives can strongly influence the Kolbe-reaction. Foreign anions
should be definitively excluded, because they seem to disturb the
formation of the necessary carboxylate layer at the anode. Their
negative effect increases with the charge of the anion. ...
Foreign cations can increasingly lower the yield in the order of
Fe(+2), Co(+2) < Ca(+2) < Mn(+2) < Pb(+2) [22]. Alkali and alkaline
earth metal ions, alkylammonium ions and also zinc or nickel cations do
not effect the Kolbe reaction [40] and are therefore counter ions of
choice in preparative applications. Methanol is the best sutied
solvent for Kolbe electrolysis [7, 43]. ... The following
electrolytes with methanol as a solvent have been used: MeOH-sodium
carboxylate [44], MeOH-MeONa [45, 46], MeOH-NaOH [47],
MeOH-Et3N-pyridine [48]. The yield of the Kolbe dimer decreases in
media that contains more than 4% water.
In aqueous solutions especially, the current yield is distinctly lower;
furthermore, solublity problems can occur when the salt-deficit method
is used. In aqueous solution, alpha-amino- or alpha-phenyl subsituted
carboxylates lead mainly to decomposition products, whilst in dry
methanol or methanol-pyridine, coupling products were obtained with
alpha-phenyl- and alpha-acetylaminocarboxylates [49].
...
As anode material, smooth platinum in the form of a foil or net seems
to be most univerisally applicable [32, 33]. ...
...
The nature of the cathode material is not critical in the Kolbe
reaction. ...
...
In summary the following general experimental conditions should be
applied for a sucussful dimerization of carboxylic acids: An undivided
beaker type cell can be used equipped with a smooth platinum anode and
a platinum, steel or nickel cathode in close ditance; a current
density of 0.25 A/cm^2 or higher should be provided by regulated power
supply, a slightly acidic or nuetral electrolyte, prefferable methanol
as solvent and a cooling device to maintain temperatures between 10 to
45 C should be employed. With this simple procedure and equipment
yields of coupling product as high as 90% can be obtained, provided
the intermediate radical is not easily further oxidized (see Chap. 7)."
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