03-29-02 22:46
No 289581
This is a pure thought experiment employing
various tidbits of past procedures to
address amine separations. Part of this
comes from de-gaaking efforts applied
to accumulated failures of the past;
some from steaming efforts, and some
from guesswork.
Your experiences or
comments are invited.
........................................
This theoretical process arises from
questions concerning separation of
products from Kolbe processes: but
could have a more general application.
Assume you have a pile of mixed benzyl
amine material, including conjoined
molecules, and fragments. (HCl salts is
assumed.).
Assume you have an oil bath with a
candy thermometer, and a good
thermostat or a person who acts as one
by controlling the electric supply to the
hot plate heating the oil..
First, you separate the pile into two
components: that which melts at or
below 175C, and that which does not. (
I envisage this being ghetto-done in a
large test tube held at an angle, with the
powder held at “the angle of repose” in
the upper section: as the lower melting
point fraction reaches it’s melt point it
slides downhill...Remove the test tube,
cool, and take out the un melted
powder.
Remove the melted material and
repowder.
Re-do the same process: this time
collect the material that melts at, say,
below 160C, and discard it..
Now (in my mind’s eye, which is prone
to myopia and astigmatism...) the
fraction should be pretty clean,
maybe...??
..........................
All the above is not new
technique, but if a better "apparatus"
is easily done,please advise...
But now for some chromatography of a
different sort.
The fraction could be placed into a two
port vessel.
The first port would connect to your
basic aquarium pump whose exit would
be at the bottom of the vessel...
The second port would connect to a
long coiled vinyl condenser line
adjacent.
The vessel is heated again to somewhere
between 180C and 200C and fuming
should be noticeable and the bubbling of
the melt should push the vaporized
material into the condenser.
The condensed powders inside the tube
should be very well separated by
species.
Testing could be accomplished thru
making small slits in the hose at regular
intervals and washing the material with
water or alcohol into separate receiver
flasks, and testing the wash water.
Alternatively, the hose could be multi-
segmented and connected with hose
barb fittings for easy separation,
washing, and testing.
Once appropriate testing and
identification of the distance(s) of the
desirable species is ascertained, the
subsequent extractive precesses should
be quite repeatable, as long as the flow
rate of the pump, and the temperature of
the oil bath, are consistent...
Note that the flow rate of the pump is
equivalent to impressed voltage in
electrophoresis: more flow will give
more separation. Unlike
electrophoresis, however, the state
change of the gas to a solid will fix the
material from further migration.
A possible complication arises from the
reality that the desirable species may be
non-contiguous, with an unwanted
substance intervening: although I
consider it unlikely. Testing will answer
this, of course.
I propose that this technique could be
an alternative approach to the
separation of other problem
discriminations, also: such as
guaifenesin and quinine from pseudo.
Further, I will venture that refinement of
this technique could enable separation
of racemates,: ephedrine from pseudo-
ephedrine, and dextro from levo
components. Amphetamine from
methyl-amphetamine; pseudo from non-
alcoholic variations, etc.
Probably this is old hat: but it is “new
thought” for me.
Thank you for your instructive input, here
presumed":<)
dwarfer
(Distinctive Doe)
03-30-02 23:53
No 290015
I only read part, however this most likely won't work because the solid will probably bee soluable in whatever is melted and thus no separation.
Look up fractional crystallization, this is more likely to work. Its based on differing solubilities in a solvent, not on diferences in melting point. It is a common separation used in large scale pharmaceuticals and similar products such as amino acids. The products are crystallized by concentration or by changeing temps, this is more of an art than a science, perfect for you and ibeeware to work on.
foxy
Those who give up essential liberties for temporary safety deserve neither liberty nor safety
(Old P2P Cook)
03-31-02 01:00
No 290036
I only read part, however this most likely won't work because the solid will probably bee soluable in whatever is melted and thus no separation.
Yes, this is the problem with Dwarfer's scheme.
Look up fractional crystallization,
But combine melting with crystallization and you have Zone Melting (I think this is the term used, or is it Zone Refining?). Pour molten material to be purified into a glass tube and allow to freeze. Now very slowly pass the tube through the center of a thin circular heater. The heater will melt a cross-section of the material in the tube and as the tube passes through the heater this thin molten zone will travel the length of the tube. As this molten zone travels the length of the tube, with previously molten material freezing while new material is melted, it will concentrate impurities in the molten zone which is drawn to one end of the tube.
(Moderator)
03-31-02 05:05
No 290121
But combine melting with crystallization and you have Zone Melting (I think this is the term used, or is it Zone Refining?).
Both terms are correct, they're used in different fields for the same process
(Hive Addict)
04-02-02 03:32
No 291188
..... this most likely won't work because the solid will probably bee soluable in whatever is melted and thus no separation.
Yes, this is the problem with Dwarfer's scheme.
Please, I'm not getting it..
The melted mixture of liquids will be at a temperature
where they will begin to fume off: I would guess(but do not know) that for MA that would be around 200C:
I believe (in my mind) that the lower fuming fractions will
go earlier in time and longer in condenser before
precipitating...
I don't think there would be any "eutectic" considerations or other "mutual interference" problems:
but might be wrong.
Certainly,
maybe ":<),
even a small change in gas-residency
time before settling would make
a significant differential
in where the condensation would take place.
Yeah, it is a mixture of liquids...??
So does fractional distillation
start with a mixture of liquids,
separated by boiling points.
If I am overlooking something,
I'll be glad to be
dis-illusioned,
the option being to remain semi-blind.
==============================
Would this change the perspective for you?
Assume all the different amines are freebased,
and dissolved in a high temperature smoke-free oil.
The bubbles of air now rise to the sirface,
carrying molecules which then wend their routes
back to solid-ness.
Thank you again:
If GOD was on MY side,
there would be NO question....
dwarfer
(Distinctive Doe)
04-02-02 06:37
No 291269
What molecules do you expect in the mixture?
What temp do they melt?
Will they decompose at their melting point? How fast?
Kolbe = amphetamine right
I think amphetamine HCl is probably not very stable when melted with a mixture of other stuff, especially if its in contact with Oxygen. A better procedure might bee to treat the Kolbe products like a very dirty pseudo pill, give it whatever cure, then if possible distill the freebase. That seems like it might bee a good strategy, but who knows.
Those who give up essential liberties for temporary safety deserve neither liberty nor safety
(Hive Addict)
04-02-02 07:00
No 291281
Thank you Foxy:
I tend to agree with you about the oxygen thing:
but I (in part) am predicating my spurious emission
on my experience with long glass tubes, lung power, and test tubes with
1, gaak
2. unreacted stuff
3. over reacted stuff
and mouse droppings in it.
The mobility differential of the different materials,
when exposed to uncontrolled flame and heat source-
well, controlled, but you know what i mean..-
is quite remarkeable.
I think once "airborne" the molecules follow thier own
destiny as determined by their configuration.
CO2 could be used if
air did not work..
Anyway, it should befairly easy to try:
wonder if somebody has?
===========
??
dwarfer
(Distinctive Doe)
04-22-02 13:33
No 300139
Zone melting and column crystallization as analytical tools.
Schildknecht, Hermann.
Anal. Chim. Acta (1967), 38(1-2), 261-73.
Journal in English. CAN 67:39936
Abstract
A micro-zone melting app., and a developed continuous flow column crystallizer are described. The methods of freezing out the solvent (Zonenschmelzen. Verlag Chemie: Weinheim. 1964. 226 pp.; Pfann: Zone Melting, 2nd Ed. Wiley: New York. 1966. 310 pp.), multistage crystn., micro zone melting, and column crystn. are used to sep. isomers, and for sepg. and identifying compds. in plant and animal products, and in meteorites. Pure C6H6 is prepd. by means of column crystn. The column crystn. app. consists of 2 concentric tubes with a metal spiral rotating in the annular space between them. Crystals are formed by cooling the top of the column, and are scraped off and carried down the column by the spiral action. Re-melting of the crystals at the bottom of the column forms liquid phase for contacting with the descending crystals. The H2O ext. of the ovules of Oenothera (CA 58: 12856g) was concd. by freezing most of the H2O; the concd. soln. contained detectable amts. of 14 compds. reacting with ninhydrin: 5 peptides, 1 amine, and 7 amino acids were identified. By chromatographing the concd. H2O ext., sucrose and 4 reducing sugars were found. By using a multi-stage zone-melting app. with several heaters and coolers, the purification of the 2,4-dinitrophenylhydrazone of Me2CO; PhNHAc, and the sepns. of a mixt. of 3,4- and 3,5-xylenol, and of tiglic, and angelic acid are described. Palmitic acid (identified by m.p. and ir spectrum) was isolated from adipocere by means of micro-zone melting. The EtOH soln. of 1 water beetle (bladder) was chromatographed on silica gel, giving 3 mg. of colorless crystals (m.p. 110°) which sublimed, but had a complex ir spectrum. After the passage of 20 zones through a micro-ingot, 2 fractions were first obtained; further zone melting gave a low melting fraction, and a eutectic, which was sepd. by thin-layer chromatog. The 3 fractions were identified, by means of ir and uv spectra and the m.p. of the 2,4-dinitrophenylhydrazone derivs., as BzOH, p-HOC6H4CHO, and p-HOC6H4CO2Me.
C6H6, used to ext. meteorite samples, is purified continuously in the column crystallizer; 30 ml./hr. of ultrapure C6H6 (I) was prepd. from the purest C6H6 available (II). The gas chromatogram of I has 1 peak of C6H6; that of II has elution peak of C6H6, and minor peaks due to methyl cyclopentane, thiophene, and aliphatic compds. An Aerograph chromatograph, with 5% Apiezon L column, and programed temp. of 40-160° (4°/min.) was used. The C6H6 ext. (6-8 days extn.) of Essebi meteorite was concd. by freezing most of the C6H6. The thin-layer chromatogram on silica gel G, of the concd. meteorite ext. in cyclohexane gave sep. spots of alkanes, S, aromatic, and acidic compds. 12 references.
Continuous multistage fractional crystallization. I. Laboratory investigation.
Betts, W. D.; Freeman, J. W.; McNeil, D.
J. Appl. Chem. (London) (1968), 18(6), 180-7.
Abstract
Lab. scale Schildknecht rotating helix crystallizers were constructed and used for sepns. of org. (79) and aq. (4) mixts. Columns operated continuously effected sepns. equiv. to 4-5 equil. sepns. at throughputs up to 1.5 l./hr. For complete sepn. in binary mixts. which form mixed crystals, it was necessary to rerun the conc. from the 1st pass. Sepns. effected on the aq. solns. of inorg. salts and EtOH indicate that these columns could be used for the desalination of water, concn. of aq. effluents, and concn. of beers and wines. 23 references.
Those who give up essential liberties for temporary safety deserve neither liberty nor safety