Kevlar
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Breaking azeotropes
Beyond the general instant information you can research on this subject, when it comes to boiling points 20 - 30 degrees apart. It soon gets difficult
to get great seperation!
Some notable examples are
H2O + C2H5OH,
H2O + H2SO4,
CH3NO2 + CH3OH, to name a few.
In the first example H2O + C2H5OH, you can reach 96% ethanol. But distilation no longer will work, so the use of drying agents in needed here, first
and best choice is 3A mol sieves. This will get you anhydrous ethanol!
The second example H2O + H2SO4, I personally know no way to break this azeotrope. Or why you would need/want to, no doubt there are applications that
need and use anhydrous H2SO4.
The last example CH3NO2 + CH3OH, I could only think of a few methods that could work. Salting out one of the solvents, or using a dean stark
apparatus. This and the first example I have used some of these methods, but these 3 examples are but a few of many ways (excluding *2) which I could
not find a way to achieve anydrous H2SO4.
I'm sure theres people who are struggling to break azeotropes, and people who have knowledge on methods.
It would be good to compile a list of concise methods for common combinations that have little accessible information on methods and ways to break
azeotropes.
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Texium
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Quote: Originally posted by Kevlar  | | The second example H2O + H2SO4, I personally know no way to break this azeotrope. Or why you would need/want to, no doubt there are applications that
need and use anhydrous H2SO4. |
The solution to this problem is not to break the azeotrope, but to add
SO3 to react with the remaining water, giving anhydrous sulfuric acid, or oleum if excess SO3 is added.
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unionised
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In principle, you can break any azeotrope by redistilling at a different pressure.
https://www.chemeurope.com/en/encyclopedia/Ethanol_purificat...
[Edited on 17-2-24 by unionised]
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chornedsnorkack
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| Quote: Originally posted by Kevlar | Beyond the general instant information you can research on this subject, when it comes to boiling points 20 - 30 degrees apart. It soon gets difficult
to get great seperation!
Some notable examples are
H2O + C2H5OH,
H2O + H2SO4,
CH3NO2 + CH3OH, to name a few.
In the first example H2O + C2H5OH, you can reach 96% ethanol. But distilation no longer will work, so the use of drying agents in needed here, first
and best choice is 3A mol sieves. This will get you anhydrous ethanol!
The second example H2O + H2SO4, I personally know no way to break this azeotrope. Or why you would need/want to, no doubt there are applications that
need and use anhydrous H2SO4.
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How about freezing?
http://www.sulphuric-acid.com/techmanual/Properties/properti...
Azeotrope is 98,3%. Eutectic is not the same - eutectic is 94%.
A practical issue with concentrated sulphuric acid is that it is viscous and has tendency to supercool.
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solo
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Reference Information
AZEOTROPIC DATA
L. H. HORSLEY
The Dow Chemical Co., Midland, Mich.
Discription
This table of azeotropes and nonazeotropes si a revision of the wt o pre-
vious tables published in Analytical Chemistry, August 1947 and July 1949
(167, 168), together with approximately 6000 new systems, bringing the total number of systems to over 14,000.
The table is arranged in two parts: (1) table of binary systems and (2) table of ternary systems, followed by a formula index and bibliography. As in
the previous tables, the individual systems are arranged according to empirical formula using the Chemical Abstracts system, except that inorganic
compounds are listed first ni alphabetical order, followed by or ganic systems in the order carbon, hydrogen, bromine, chlorine, fluorine, iodine,
nitrogen, oxygen, sulfur.
For a given binary system the lower ordercompound according to for-
mula is chosen as the A-component and under each A-component the B-
components are likewise arranged according to empirical formula. For
ternary systems the same arrangement is used, using the lowest order for-
mula as A-component, the next lowest order as B-component, and the high- est order formula as C-component.
To facilitate finding al systems containing a given component a for- mula index is included at the end of the tables listing the systems contain- ing
a given component.
The following abbreviations are used in the table:
Min. b.p. V-1.
Vol.
M m .
Minimum boiling point azeotrope with no data given Vapor-liquid equilibrium data are given i nthe original reference
Azeotropic concentration is given i nvolume per cent. so indicated, all concentrations are weight per cent
Pressure in mm. of mercury absolute Approximate
Greater than
Lesst h a n
Unless
For systems for which more than one literature reference is available, an attempt has been made to select those data that are most reliable and
complete. The auxiliaryreferences for which no data have been given are listed with an asterisk. Where there is appreciable discrepancy in the data of
two references, both sets of data have been included.
Because Lecat has published identical data on most of his systems in two or more journals, only his most recent reference is listed here, except where
there are large discrepancies ni hisdata, in which case both sets of data have been included.
https://annas-archive.org/slow_download/76e0a17644ca607bdda9...
or,....
Attachment: phpAtLk4q (4.8MB)
This file has been downloaded 150 times
[Edited on 19-2-2024 by solo]
It's better to die on your feet, than live on your knees....Emiliano Zapata.
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chornedsnorkack
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What file type is it? What softwares open it?
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bnull
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DjVu. DjVuLibre (https://sourceforge.net/projects/djvu/) opens it.
Quod scripsi, scripsi.
B. N. Ull
P.S.: Did you know that we have a Library?
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