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sparkgap
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@solo: Pd/C is definitely not powerful enough a catalyst to strip fluorine off from a fluoroaliphatic. It might reduce any multiple bonds present
(e.g. this), but no fluorine removal can happen.
sparky (~_~)
"What's UTFSE? I keep hearing about it, but I can't be arsed to search for the answer..."
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solo
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Quote: Originally posted by sparkgap  | @solo: Pd/C is definitely not powerful enough a catalyst to strip fluorine off from a fluoroaliphatic. It might reduce any multiple bonds present
(e.g. this), but no fluorine removal can happen.
sparky (~_~) |
......I was afraid of that.....thanks , solo
It's better to die on your feet, than live on your knees....Emiliano Zapata.
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manimal
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Can I use sodium carbonate or bicarbonate and ammonium sulfate to create concentrated ammonia solution? I supposed that the reaction would be slow,
because due to the weak acidity of ammonium sulfate, only a small percentage of it would be deprotonated at a given time in order to acidify the
carbonate.
I tried mixing bicarbonate and amm. sulfate and bubbles were indeed evolved, although slowly, and the odor of ammonia became noticeable after a few
minutes. I am wondering what percentage of the ammonia will react with the CO2 to form ammonium carbonate, and what can be done to minimize excape of
nh3 gas.
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Paddywhacker
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| Quote: Originally posted by manimal | Can I use sodium carbonate or bicarbonate and ammonium sulfate to create concentrated ammonia solution? I supposed that the reaction would be slow,
because due to the weak acidity of ammonium sulfate, only a small percentage of it would be deprotonated at a given time in order to acidify the
carbonate.
I tried mixing bicarbonate and amm. sulfate and bubbles were indeed evolved, although slowly, and the odor of ammonia became noticeable after a few
minutes. I am wondering what percentage of the ammonia will react with the CO2 to form ammonium carbonate, and what can be done to minimize excape of
nh3 gas. |
With heat, ammonium sulphate will evolve ammonia with almost any basic compound, including metallic oxides such as magnesium and zinc oxides. With
carbonates you will also get CO2 evolved. This is the dry powders, mixed. Trap and dissolved the NH3 in water.
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sakshaug007
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Hello everyone,
I have recently become very interested in Kolbe electrolysis particularly concerning alkyl halide synthesis. I want to attempt a kolbe electrolysis of
a solution of sodium acetate and potassium iodide to form methyl iodide and would like to ask your advice for optimizing efficiency of the
electrochemical cell so that I get the most methyl iodide with the least amount of ethane and methanol byproducts. For instance, should the solution
be hot or cold? Should I have it stirring or not? Should I have divided cells? Should I use a dilute or saturated solution of iodide and acetate (I
assume saturated)? What voltage, current density etc.
I have read previous posts concerning reaction conditions for Kolbe electrolysis and it was stated that the highest yields are obtained using smooth
platinum electrodes (which I of course don't have). I will instead use graphite electrodes which have shown to produce moderate yields of the kolbe
products (i.e. ethane). I thought about platinized titanium electrodes but they are apparently detrimental to the reaction (not sure why). Does anyone
know where I can get "cheap" (Ha ha!) platinum?
If anyone could provide references or textbook information regarding Kolbe electrolysis would be very helpful as well.
Thank you very much
"If everyone knew everything what would be the point?"
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Sedit
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Does any one know of a way to cleave the methoxy down to benzene? If nothing else Phenol? I faintly remeber seeing SeO2 used for this reason but I
cant find additional information on it.
[Edited on 20-4-2009 by Sedit]
Knowledge is useless to useless people...
"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the
fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story
before."~Maynard James Keenan
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DJF90
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With HBr or HI then the ether is cleaved on the alkyl side, leaving you with phenol. You could then react this with zinc dust at elevated
temperatures to form benzene.
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Sedit
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What exactly is elevated temperatures? Do I need a tube furnace or is reflux sufficiant? Sorry for being persistant Iv just always wanted to know how
to cleave a methoxy and cant find any good data on it. Will this work with carbon substitutes on the ring also.
Knowledge is useless to useless people...
"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the
fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story
before."~Maynard James Keenan
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Bolt
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The selenium dioxide method is mentioned in Love Drugs. I doubt that it works well (if at all). As for the demethylation, search for demethylation,
and you will find lots of schemes.
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DJF90
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I'm not entirely sure to be honest, If I were going to try it I would make sure the phenol and zinc dust were mixed homogeneously (as much as
possible) and then heat the distillation flask until benzene starts (and finishes) coming over.
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Bolt
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I doubt it works. I believe that "The Chemistry of Phenols" is around here somewhere.
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Sedit
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It wasnt in Love Drugs that I seen the SeO2 method it was a fleeting pictogram in a threed somewhere here at SM. I will have to look at Love Drugs to
see if there is any additional information about the SeO2 process. Iv seen many schemes for the demethylation but they all proceed thru the phenol so
if there is a way to do away with that It would be nice.
Knowledge is useless to useless people...
"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the
fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story
before."~Maynard James Keenan
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Formatik
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What is the oxidation potential of H2SO5? S2O8(2-) in acidic solution is 1.96V (Wiberg, Holleman) and USP6032682 gives 2V for H2S2O8. I suspect it is
more than H2S2O8, since H2SO5 instantly liberates I2 from aq. KI, but H2S2O8 only slowly, though I can't find the value of H2SO5.
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DJF90
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Peroxodisulfate is a very strong oxidiser, but it is also quite slow. I assume this to be a kinetic effect, as adding a suitable catalyst ( I think we
used a silver (I) salt (nitrate?) in the lab ) produces a much more rapid oxidising action. I believe it is a stronger oxidiser than the
monopersulfate, and I don't think judging the oxidising capability on the speed at which the substance can liberate iodine from KI is a reliable
method.
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Formatik
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| Quote: Originally posted by DJF90 | | Peroxodisulfate is a very strong oxidiser, but it is also quite slow. I assume this to be a kinetic effect, as adding a suitable catalyst ( I think we
used a silver (I) salt (nitrate?) in the lab ) produces a much more rapid oxidising action. |
True, AgNO3 will catalyse at least some persulfate oxidations.
| Quote: | | I believe it is a stronger oxidiser than the monopersulfate, and I don't think judging the oxidising capability on the speed at which
the substance can liberate iodine from KI is a reliable method. |
Do you have anything to corroborate the speculation that that might be the case?
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DJF90
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From what I remember, there isnt alot down that end of the table, and I only remember a few redox couples with a higher potential (although admittedly
I dont remember seeing peroxymonosulfate at all).
The table has the S2O8(2-)/ 2 SO4(2-) couple at +2.010V. Wikipedia lists the standard electrode potential for HSO5(-) / HSO4(-) as +1.44 V; I
know its wikipedia but its better than nothing eh?
[Edited on 21-4-2009 by DJF90]
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Formatik
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K2S2O8 was also given as 2.01 in this journal. But as to HSO5(-), I've found the following a paper concerning the KHSO5 triple salt, putting the value up higher:
Oxone (2KHSO5.KHSO4.K2SO4) is a triple salt of potassium and may be regarded as a mono-substituted derivative of hydrogen peroxide. However, it
has an oxidation potential greater than that of hydrogen peroxide (E HSO5-/HSO4- = 1.82 eV compared to E H2O2/H2O = 1.77 eV). (link)
And then something in a paper picked up by search engine about : Addition of successive aliquots of hydrogen peroxide at the last step increases
the oxidation potential of sulfuric acid to 1.81 V by forming monopersulfuric acid, H2SO5 (Caro’s acid) [19]. (link), putting the lower value of H2SO5 at 1.81.
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chemrox
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Has anyone here made the citrate of a solid amine? I noted the three acid positions and am asuming appropriate solvents are found and the acid is
added in 1:3 molar concentration. I'm struggling with the solvents and would appreciate access to a compendium of solute/solvents.
"When you let the dumbasses vote you end up with populism followed by autocracy and getting back is a bitch." Plato (sort of)
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Panache
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| Quote: Originally posted by chemrox | | Has anyone here made the citrate of a solid amine? I noted the three acid positions and am asuming appropriate solvents are found and the acid is
added in 1:3 molar concentration. I'm struggling with the solvents and would appreciate access to a compendium of solute/solvents.
|
i think you would find the formed salt very very unstable if attempts were made to isolate it from solvent, perhaps you could do it at cryo
temperatures, may hang around for a few milliseconds then.
When you say solid amine i assume you mean 'solid at STP' amine, not say methyl amine at -150C, which would be solid.
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Paddywhacker
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| Quote: Originally posted by chemrox | | Has anyone here made the citrate of a solid amine? I noted the three acid positions and am asuming appropriate solvents are found and the acid is
added in 1:3 molar concentration. I'm struggling with the solvents and would appreciate access to a compendium of solute/solvents.
|
You mean like stearamine? The amine should dissolve in an aqueous solution of the acid. I would expect an increase in viscosity of the salt aqueous
solution.
The high MW amines are only weakly basic, so expect only the 1:1 ratio salt to be easily formed.
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Nicodem
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| Quote: Originally posted by Sedit | | It wasnt in Love Drugs that I seen the SeO2 method it was a fleeting pictogram in a threed somewhere here at SM. |
You probably mean this.
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Sedit
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Thats not the one but helpful indeed. Sadly I did know know the potential hazards associated with SeO2 so I think that method is out the window.
Knowledge is useless to useless people...
"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the
fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story
before."~Maynard James Keenan
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Maja
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I have some 70% acetic acid + 30% water solution and would like to convert this to glacial acetic acid. Distillation with 95% sulfuric acid will
achieve this ? Or I need to go via acetates route + H2SO4 ? Thank you.
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querjek
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Does anybody have a range around which an ethanol flame burns? How about isopropanol?
it's all about chemistry.
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not_important
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| Quote: | | Does anybody have a range around which an ethanol flame burns? |
Do you mean flame temperature or flammabilitry limits? Get this PDF for answers for both measurements.
http://www.vrac.iastate.edu/ethos/files/ethos2005/pdf/stokes...
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