Magpie
lab constructor
Posts: 5939
Registered: 1-11-2003
Location: USA
Member Is Offline
Mood: Chemistry: the subtle science.
|
|
disodium benzene-m-disulfonate
Since I recently made 25.9g of 81% oleum I decided to use it to make the subject compound, DBmD for short. I used a 1/10 scale of the procedure in
"Fundamental Processes of Dye Chemistry," by Fierz-David and Blangey in the forum library.
Preliminary work involved making the required amounts of 20% oleum and 66% oleum. I had just enough oleum to do this. My procedure was a bit crude,
but that's only because my 81% oleum consisted of two phases, ie, mostly liquid but with some solid.
The sulfonations were carried out in a 100mL beaker on a mag-stirrer hotplate with an installed thermometer. The 20% oelum mix did not fume but the
the mix with the 66% oleum did fume. My hood was essential for working with oleum here.
The non-fuming product was was dark brown due to some carbon coming in with the oleum and some charring during the sulfonations, I would imagine.
This was poured into water then CaCO3 was added to neutralize it. Next time I would use an equivalent amount of Ca(OH)2 to avoid all the foaming due
to CO2 production. (See picture below.) I didn't measure pH here and likely added too much CaCO3.
This was then filtered, removing the CaSO4 produced. A picture of the brown translucent filtrate is shown. Then Na2CO3 was added to just turn
phenolphthalein paper red (pH 9). I was a little sloppy here too and slightly overshot the pH. This produced another insoluble residue which I took
as CaCO3. A little activated charcoal was added at this time to remove some color and the product filtered again. The filtrate was then dried on a
steam bath then in an oven at 140C. The solid flake DBmD is shown in the last picture. Yield was 13.1g; %yield = 46.5%.
    
The single most important condition for a successful synthesis is good mixing - Nicodem
|
|
|
smuv
National Hazard
Posts: 842
Registered: 2-5-2007
Member Is Offline
Mood: Jingoistic
|
|
Cool. I recently made sodium tosylate and had good results crystallizing it from concentrated NaCl(aq), you might want to give this a shot with your
product. The problem with the sulfonates is that they have such high mp's and cannot be TLCed so it is hard to say, when you have a 'pure' product.
Are you after resorcinol? if so we should compare notes, I just did p-cresol synth from sodium tosylate...
|
|
|
Magpie
lab constructor
Posts: 5939
Registered: 1-11-2003
Location: USA
Member Is Offline
Mood: Chemistry: the subtle science.
|
|
I am after resorcinol. But I didn't read the fine print on the procedure until now. A vacuum heating is required at ~12mmHg. I may have to invest
in a vacuum pump, etc, before I can proceed.
The single most important condition for a successful synthesis is good mixing - Nicodem
|
|
|
smuv
National Hazard
Posts: 842
Registered: 2-5-2007
Member Is Offline
Mood: Jingoistic
|
|
You should find another procedure. This does not need to be conducted in a vacuum; you can do it with simple alkali fusion in an open vessel. It is
true that dihydric phenols are somewhat oxidation prone, but with care taken to avoid prolonged reaction times, good yields have been reported.
afterthought: http://books.google.com/books?id=T4U-AAAAYAAJ&pg=PA694&a...
This procedure is just proof of point. However, that reaction time is unnecessarily long because they are using NaOH. The problem with sodium
hydroxide is that it does a poor job dissolving the sulfonate. If the reaction was done in KOH the reaction time should be on the order of tens of
minutes; look around and see what you find.
[Edited on 2-8-2011 by smuv]
|
|
|
Magpie
lab constructor
Posts: 5939
Registered: 1-11-2003
Location: USA
Member Is Offline
Mood: Chemistry: the subtle science.
|
|
Thanks smuv for that useful information. I will be looking for a procedure requiring only standard glassware.
The Fierz-David & Blangey procedure would require a vacuum pump, vacuum gauge, and a heated vacuum chamber. This equipment would be used for
"bake processing," a process that seems peculiar to the dye industry. Although I wouldn't mind constructing such an oven it would be another
time-consuming and expensive project. If I could forsee using it occaisionaly I might build it just for the fun of it. Also I imagine it is just a
matter of time before I need to buy a vacuum pump and gauge as my aspirator is only good down to about 75mmHg. I have managed without one for about 8
years, however.
The single most important condition for a successful synthesis is good mixing - Nicodem
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
