Benzophenone (destillation)

[frogfot]

This came up at xinventions, but more people must see this.
Benzophenone is another ketone which probably can be peroxidised (probably). This would theoretically yield a very stable peroxide, because there would be alot of electron rich benzene rings near peroxide bondings, wich would donate some el dencity to peroxide bondings. But thats just theory.

There are a "simple" way to produce benzophenone, by destillation of calcium benzoate. I have made some experiments on small scale and got nice results. Heating small ammount of calcium benzoate in a quarz pipe (28X1 cm) closed at one end, produced dence heavy orange fumes that fell directly on the ground, it could be easily collected in a beaker, it condensed after a while.
Orange product smelled something between roses and cherry.
Well, benzophenone should smell roses (pdf on web) and cherry smell is probably an impurity of an aldehyde. This is what i got:
<a href="http://www.geocities.com/frogfot/stuff/benzophenone.jpg" target="_blank">www.geocities.com/frogfot/stuff/benzophenone.jpg</a> (50ml baker)

While trying to upscale this procidure it filed in every way. I used an iron pipe (35X4,5cm), clutched in one end and filled with ~10g calcium benzoate. Open end was directed into a baker in icebath. Heated pipe with a torch, fumes filled baker but they condenced at very slow rate.
Another problem was incompleate decomposition. It seems that a more powerfull torch is required, or, something have to be done about chamber/calcium benzoate. To raise efficiency of heat from torch or to lower decomposition temperature.

Can anybody solve those problems or give an addvice, please?
Even if benzophenone cannot be peroxidised, it would be fun to produce some, for use in other experiments.

Heres different physical properties of benzophenone:
MP 49^oC; BP 306^oC; insoluble in water; 13g soluble in alcohol
Have no decomposition temperature of calcium benzoate, it seems that it's much higher than 300^oC.

[Editted to change "&lt;&gt;" to "[]", to make superscripts work]

<small>[ February 25, 2003, 01:09 PM: Message edited by: Mr Cool ]</small>

[IPN]

Sounds like something very interesting to try. Have you tried to make it into peroxide yet?

What king of torch do you have? Because my torch can reach 1500C easily. I have also access to a oxy-acetylene torch reaching temperatures up to 3000C.

I would test this but I don’t have any calcium benzoate.
Or could it be made by mixing solutions of sodium benzoate and calcium chloride?

Btw. that product looks like oily phorone...

Found this with a little search:
<a href="http://www.orgsyn.org/orgsyn/prep.asp?prep=cv1p0095" target="_blank">http://www.orgsyn.org/orgsyn/prep.asp?prep=cv1p0095</a>

<small>[ February 25, 2003, 12:07 PM: Message edited by: IPN ]</small>

[frogfot]

Calcium benzoate can be producet like you said, if hot saturated solutions are mixed and then cooled down. Solubility of Ca benzoate is 2,67g at 0^oC and 8,3g at 80^oC in 100ml water. I never thought of this way, will use it in the future.

I used to make it another way, maybe it's good to post for those that don't have CaCl₂. Make saturated solution of sodium benzoate (found as spice for canning) and add ~20ml 30% HCl for every 22g.
Benzoic acid precipitates, filter and wash with cold water, then add excess of CaCO₃ and leave for a day. It reacts very slowly, then it's just to evaporate.

EDIT: Forgot, havn't tryed to peroxidise it, need bigger ammount and advice. Impurities have to be removed somehow, and because its not soluble in water how could one react it with H₂O₂? Maby dissolving it in alcohol, but maby alcohol will react too?

My torch can probably do 1500^oC too, it's usual propane.

[Editted for same reason as above]

<small>[ February 25, 2003, 01:10 PM: Message edited by: Mr Cool ]</small>

[Mr Cool]

As well as the water solubility problem (which may be overcome with a load of alcohol), OB is really going to suck. It may be possible to nitrate it though, you would get a max of two -NO₂'s per benzene ring I think because -CO-Ph will be meta directing, but also deactivating so nitration might be hard, you could end up with just one -NO₂ per ring.

Edit:

A good rule of thumb for working out directing orientation on aromatics is thus:
If the substituting group contains double bonds, it will be meta directing and deactivating.
If the substituting group contains all single bonds, it will be ortho/para directing and activating.
Halogens are ortho/para directing, but deactivating because of their high electronegativity.
So, -NH₂, -OH, -C_nH_2n+1 etc are all activating o/p- directors, -CHO, -NO₂, -COOH etc are all deactivating m- directors.

<small>[ February 25, 2003, 01:20 PM: Message edited by: Mr Cool ]</small>

[frogfot]

Thanx for adress, IPN. I got those synthesises in organic chem book, but they require some rare chems.
Mr Cool, I don't wanna sound ignorant but what is OB? May i guess, is it mass ratio between peroxide bondings and the rest of molecule?
Maby this peroxide will suck as you said, but it could also be very unsencitive compared to other peroxides, which should proove the theory, that benzene rings can stabilize peroxide bondings. One could take acetophenone, which is smaller than benzophenone and it's prepared nearly same way. (therm. decomp. of Ca benzoate + Ca acetate)

I realised that benzophenone have no problem to condence, it condences directly in contact with surrounding air, but it remains as "fog". I mean, it remains as small drops in air, which take some time to settle down. If one would let this fog go through a thin 10 m long pipe this would settle it down on walls. Gonna by copper pipe and test this. (i planned to by it anyway)

I was a bit late :rolleyes:

<small>[ February 27, 2003, 12:30 PM: Message edited by: frogfot ]</small>

[Stoic]

OB = Oxygen Balance, IIRC.

[megalomania]

If I were doing this I would set the pipe up in such a manner as to direct a gentle flow of air through it while the pipe is being heated. The air flow will push any benzophenone out. You can bubble this exit gas into water in which benzophenone is insoluble. The benzophenone should condense right away and can be collected by filtration. Vaporized calcium benzoate for example will be soluble in water, and hopefully so will any other byproducts.

You may wish to consider laying your reaction pipe in a bed of coals. This is an effective means of directing the heat where you need it. A torch may have a flame of 1500 degrees, but that doesn’t mean your pipe’s core will get that hot considering a torch can only heat a small point at any one time.

[frogfot]

Tested same procidure with 7,6 m copper pipe, it worked ok on small scale, fumes settled down. Actually it took about 15 minutes to fill the pipe. But if one would go bigger, whole device must be closed airtight.

Heres used setup:
<a href="http://www.geocities.com/frogfot/stuff/benz2.png" target="_blank">http://www.geocities.com/frogfot/stuff/benz2.png</a>

This would be perfect setup:
<a href="http://www.geocities.com/frogfot/stuff/benz1.png" target="_blank">http://www.geocities.com/frogfot/stuff/benz1.png</a>

Dropping acetone have 2 reasons. First, wash down product from walls, because it's thick. Second, i beliave benzophenone particles "stick" better to acetone than to any other dry surface.

Bed of coals is nice idea, it would be hard to accomplish at home but one could make it next time i go camping.

Experiments kinda stopped, i'm searching for suitable parts..

EDIT:
Oh, would those peroxides be something possible? (dont laugh.. :rolleyes: )
<a href="http://www.geocities.com/frogfot/stuff/benzophenone.png" target="_blank">http://www.geocities.com/frogfot/stuff/benzophenone.png</a>
Calculated their OB just for fun:
(1)di- -266
(2)di- -234
tri- -234
Yp, thats low, but AP is also a bit low (-151).

<small>[ February 28, 2003, 04:55 PM: Message edited by: frogfot ]</small>

[frogfot]

It was long time, but finally got much better results. I fount suitable reaction chamber
that is nearly airtight. Heres pic on it, ive combined steel body with brass adapter.
http://www.geocities.com/frogfot/stuff/vessel.jpg

Ive tested it in production of acetone with success, heres more details on vessel:
(http://www.geocities.com/frogfot/synthesis.html#aceton)

After some tests i realised that setups from post above totally sucked they cannot settle down the product and passing fumes through water didn't worked eather.
But another way worked great. I let the pipe from reaction chamber into an outlet of filtering
flask that was closed in top with a filter from a vacuumcleaner (the one that suppose to remove really small particles from air). And it worked great! The fumes remained in flask and settled down after a while. There was small ammounts of water too (Probably crystall water).
Decomposing 30 g benzoate (partially) gave 5 ml product and about 2 ml water. Though i will make a bit more precise tests on larger scale.
One good thing to mention is that reaction must be pushed to the end, this will ensure that remaining cake in reaction vessel will be porous and easy to remove (which wasn't in my case).

And another great thing happened some weeks ago in my dream (in case) :) My dad helped to
draw a mass spectra of product, and it showed to be above 80% benzophenone! I should mention that tested sample have been standing for some month and any volatiles would dissapear. This will be tested another time with fresh product. I will also add further results in this
post on yields. And maby write the whole procidure as for acetone destillation on my page.

[John Ashcroft]

Your benzophenone is definitely very impure. Benzophenone is colorless.

Such high temperatures shouldn't be necessary for decomposing calcium benzoate into calcium carbonate and benzophenone. Calcium acetate, for example, begins decomposing around 160C.

How was your calcium benzoate acquired/prepared?

A cyclic peroxide of benzophenone is going to be very weakly explosive. Nitrating the benzophenone prior to peroxidation will result in a dangerous peroxide product. Firstly, the improved oxygen balance will make decomposition more exothermic, meaning that a random decomposition event of a single (or several) molecules (not especially uncommon with organic peroxides) is more likely to propagate into detonation of the entire crystal. Secondly, the nitro groups are electron *withdrawing*, meaning that electrons will be withdrawn from the aromatic ring, thus withdrawing electrons from the oxygens of the peroxide bonds, which will dramatically weaken the peroxide bonds - a dangerous situation indeed.

[frogfot]

Made same experiment on larger scale, 50 g benzoate. This gave totally 20 ml liquid, from which 13-15 ml was red-brown goo and rest was water.
I described this on page too:
http://www.geocities.com/frogfot/synthesis.html#benzophenone

John, it would take alot of time if temperature was near decomposition of salt..
I have tryed the peroxidation and failed, Mr Cool was right about loads of alcohol. I dissolved small sample of ubtained "benzophenone" in 5 times methanole and added one ammount of 30% H₂O₂ after what benzophenone separated.. failure :(
Anyway, some drops of 30% HCl was also added and this stayed over night... nothing happened.

Well, it probably got some other uses (nonexplosive), now its only to purify the product, dunno how...