Bob (Stranger)
07-13-04 20:06
No 519133
      refluxing problematic mixture     

I am putting a formaldehyde on a phenol, and it's not going too smoothly. Using 37% solution there's ample water in it but that should not be a problem. Far more problematic is the temperature I think is minimum 110 celsius and the formaldehyde is boiling too soon. I reflux like mad, the temperature stays at 100. I do not reflux enough, the stuff distills over. The synth says reflux, however.

After some hours of refluxing, I get a tough slime that smells of my phenol and shows little discoloration as should be the case.

What would be a good way to solve the problem? Take off the reflux and let the pressure build up?
 
 
 
 
    KidCurry
(Hive Bee)
07-13-04 20:40
No 519138
      What do you mean by "the stuff distills...     

What do you mean by "the stuff distills over"? Are you using a distillation setup for refluxing? If so, that's not right. What you should use is a simple RBF with a reflux condenser attached to it.

The boiling point of a solution of 37% formaldehyde in water is 96C, so it won't go up to 110.
 
 
 
 
    GC_MS
(Hive Addict)
07-13-04 20:45
No 519139
      o-phenol formylations     

As far as I can remember, formaldehyde-involving phenol formylations should be anhydrous. That is why paraformaldehyde is used.

Aztecunnilingus Maximus
 
 
 
 
    Rhodium
(Chief Bee)
07-13-04 20:45
No 519140
      Strange     

Could you show us the synthesis you are following, or provide a link?

If it says "reflux" and no temperature is specified, you should not try to bring it to 110°C - reflux is reflux.

I reflux like mad, the temperature stays at 100. I do not reflux enough, the stuff distills over.

??? How can stuff "distill over" when you have a vertical reflux condenser attached? Are you trying to reflux in a distillation setup, or are you overloading the vertical condenser?

The Hive - Clandestine Chemists Without Borders
 
 
 
 
    Chimitant
(Newbee)
07-13-04 20:51
No 519141
      Insufficient cooling     

I think he is using a condensor that is uncapable of condensing all the stuff that is evaporating. Do you have a horizontal condensor attached to your vertical ?

And waht do you mean with "What Take off the reflux and let the pressure build up"

Never, ever let pressure build up during reflux. You need special equipment to do so. Your regular glass set-up will not hold...

A little poison now and then: that makes for agreeable dreams.
 
 
 
 
    Osmium
(Stoni's sexual toy)
07-14-04 11:33
No 519364
      > I am putting a formaldehyde on a phenol,...     

> I am putting a formaldehyde on a phenol,

You definitely need to tell us what kind of phenol you are using and more details about the procedure, because that mixture might produce something resembling the first industrially produced polymer, Bakelite. If you do it wrong your result might resemble the reentry heat shields of the first space capsules, or the heat resistant stuff in really big rocket engine nozzles and 747 brake pads (which are all manufactured using certain phenol-formaldehyde resins too).

BUSH/CHENEY 2004! After all, it ain't my country!
www.american-buddha.com/addict.war.1.htm
 
 
 
 
    Bob
(Stranger)
07-19-04 15:18
No 520275
      The final product is a cyclic tetramer of para     

The final product is a cyclic tetramer of para t-butylphenol. There is a bridge in the ortho position of the phenol, and it consists of a single CH2 group. There is sodium hydroxide, where hydroxide is catalyst and sodium is a cation of the right size (which is really required to be sodium) to get a tetramer.

Potassium or rubidium will work too but hexamers or octamers will result.

This is an intermediate step, though, and there should first be an activated precursor. It is not there, I suppose. What exactly this precursor should be is not clear to me and I think to no one, but it should be green.

I have a setup for distillation but I close it down if I wish. The reason I let it distill is to be sure of the right reflux flow. If I close it down and reflux is not enough, I am afraid of pressure as has been said.

I am absolutely sure they do it in aquous environment though alternative synthesis exist which use paraformaldehyde in anhydrous environment. The synthesis I use does not specifically say reflux, but a erlenmeyer is heated on an oil bath of said temperature. I think a normal erlenmeyer will not stand any pressure so they must have left it open.
 
 
 
 
    Osmium
(Stoni's sexual toy)
07-19-04 23:32
No 520333
      You better look up the meaning of the term     

You better look up the meaning of the term "reflux condenser".

BUSH/CHENEY 2004! After all, it ain't my country!
www.american-buddha.com/addict.war.1.htm