copper benzoate

[hashashan]

Hi guys anyone knows how to synthesise copper benzoate from sodium benzoate?

or how to synthesise it at all?

[Mumbles]

I'll start you off, Copper Benzoate is insoluble in water. Work from there.

[pa_pyro]

I won't give the process, but if you have Cu sulphate your set to go, although the small amount of sodium benzoate left might ruin any blue flame color if thats what you are going for.

[FrankRizzo]

You'll want to use *Potassium* benzoate and copper sulfate or benzoic acid and copper carbonate. When I did it, I used the potassium benzoate and copper sulfate (sold as root killer in the plumbing dept of Wal-Mart).

 

The quick and dirty method is to heat some *distilled* water to very near boiling and then dissolve as much copper sulfate as possible, making a beautiful dark blue solution. Then, add potassium benzoate in small amounts until you no longer get a precipitate. You'll also notice that the solution above the precipitate will become clear as the copper ions are used up. Wash your product by letting the solution sit for an hr until the copper benzoate settles, then decant or siphon off the clear solution of dissolved potassium sulfate. You'll then want to add more warm distilled water to your benzoate, mix it up real well and repeat the settling and decanting procedure. Repeat again the washing step a few times with at least one gallon of warm distilled water for each pound of product.

 

I've got a detailed write-up from Tom Pergrin that I'll post later when I get home.

[hashashan]

the problem is that benzoic acid is souluble only in very hot water and i couldnt get the reaction between benzoic acid and copper hydroxide going too well ... all i got is a ton of benzoic acid crystals and some copper benzoate spots

another problem is that i used up all my sodium benzoate so all i got now is benzoic acid

besides another question, anone knows how hot benzoic acid + hexamine + KBrO3/KClO3 burns?

[FrankRizzo]

Note that I said copper *carbonate* not copper hydroxide for reacting with benzoic acid. If you have a pottery supply store within a reasonable distance, they will have the carbonate.

[hashashan]

I have copper carbonate that i once made,

so will copper carbonate react faster with the benzoic acid?

[FrankRizzo]

It sure will. The chemical reaction favors the products because the carbon dioxide leaves the solution. Use an overly tall container and add the benzoic acid slowly to avoid making a mess from the foaming.

 

Edit 12/17/2006

Here's that article I was referring to:

 

 

 

Date: Sun, 30 Apr 2000 14:25:20 -0400

 

Author: Tom Perigrin <tip@pyrosafety.com>

 

Subject: Re: odd reaction

 

Body: >Hi all

>I wanted to make some Copper Benzoate so I dissolved 5 grams of copper

>sulphate in a cup of water and as I did not have any sodium benzoate did

>the same with potassium benzoate. Then I pored one into the other. Instead

>of the pretty blue precipitate I was expecting the whole lot set instantly to

>a yucky blue jelly! Thick enough to stand a spoon in.

 

Copper salts are notorius for changing their morphology tremendously due to

small changes in the conditions of the reaction that produces them. For

example, we had a question a few months about about another unexpected

result from the attempted production of some copper salt under unsually

concentrated conditions...

 

Why did you use 1:1 by weight? You should be using 1 mole of CuSO4 and 2

moles K Benzoate... That would be 249 grams of the blue CuSO4*5 H2O

and 428 grams of KBenzoate... or that proportion.

 

It is almost certain that you did form some copper benzoate, and that it is

perfectly usable. However, it is very difficult to filter gels, and so you

want to pre-treat your mixture before you go any further. Simply boil the

whole mess for 15 to 30 minutes and the gel should be converted to a denser

precipitate which can easily be filtered (the boiling induces many

microscopic dissolution/reprecipitation cycles, thus causing agglomeration

to occur).

 

However, I should mention that the blue gel sounds a bit like Cu(OH)2,

which is often formed as a sky blue gel. Boiling Cu(OH)2 often leads to a

significant darkening, and prolonged boiling leads to the formation of CuO,

which is black. If you sample goes black on boiling, then you formed

Cu(OH)2, and I'd suspect that your KBenzoate had been made with an excess

of KOH compared to benzoic acid.

 

If you have pH paper you should dissolve a bit of the KBenzoate in water

and test the pH. If the pH is notably over 8.7 then that is probably a

contributing factor. In that case, you may have formed some sort of

Cu(benzoate)2*Cu(OH)2 complex.

 

However, the whole experiment is a bit difficult to interperate as you used

the wrong amounts. Try again with the right amounts.

 

(P.S. When I made Cu benzoate, I used MUCH more concentrated solutions...

maybe 10 times more concentrated).

 

 

---

http://www.pyrosafety.com

Paint the sky with flowers of colored fire

[baggs]

Hello,

Here is how I have made it for years, but I am not the creator of the process, just an avid user of it.

You will need the following items:

1) Benxoic Acid

2) Copper Carbonate

3) Adjustable electric heat source

4) Very Large Pot for process, teflon coated or ceramic (No exposed metal)

5) Plastic stirring Spoon

6) Scale (electronic is perfect)

7) Coffee filters

8) Jar that the coffee filters fit in. (I use an older type coffee maker where the filter fits into a removable holder.)

9) Distilled Water

A) Misc other items I forgot to mention.

 

1st) Weigh out by weight 12 parts of Benzoic Acid & 6 Part by weight of Copper Carbonate.

 

2nd) Fill up your Very Large Pot with distilled Water about 50 - 75 parts by weight.

 

3rd) Place pot with water on your adjustable heat source & bring water to just under a boil.

 

4th) Once you have reached almost the water boiling point add in your 12 parts by weight & stir vigorously.

 

5th) Now add in 1/3 of your copper carbonate by weight & stir vigorously. Within a few seconds the reaction starts.

 

6th) The mixture with darken & start releasing small bubbles but lots & lots of them. In fact it will try to overflow you

container which is why it is mixed in small amounts. Anyway as long as you keep stirring the carbon dioxide will

be released from the bubbles & the whole mixture will stop it's growth once all of the copper carbonate has

reacted with the benzoic acid. Now once your mixture has stopped the generation of bubbles (CO2) go on to the

next step.

 

7th) repeat steps 5 & 6 until you have finished off the copper carbonate & there is no more release of CO2.

 

8th) Using the coffee filters, filter the contents of the pot but this will take multiple coffee filters if you used 12oz & 6oz

worth of benzoic acid & copper carbonate. I have used up to 6-10 filters depending on how full I let them get.

 

9th) Allow the water to evaporate naturally or use a vacum system to draw the water out of the coffee filters leaving a

blue powder tha's still a bit wet.

 

10th) Dump all the copper benzoate out of the dried coffee filters onto a non stick cookie sheet & place in your oven

thats pre heated to 225 degree's F. Make sure you have some form of air circilation in the oven as it's needed.

(As a note the oven I use is a temp chamber that goes hot or cold but the real deal is that it has air circilation

which is required & does speed up the process.)

 

11th) Once it has completely dried out take it and run it through a 200-325 mesh screen to break up any of the lumps

that may have, will have formed. Once it's been screened place it in a platic bag then into airtight containers until

you need to use it.

 

Now this method appeared in the American Firework New #119 issue in 1991. Since then I have for many years made 3-5 pounds up & sold it to others for use until this year when I decided to get out of the game & leave it to the younger guys. Hence my reason for selling my last batch to a newbie on Ebay & also having him help me make these past four years, he thought I was training a helper but I trained a replacement. Anyway it is not that hard to make but if care is not taken you will get a @#$#^&*% of blue goo with lots of bubbles rising out of the pot oh so very very fast all over you & your clean work area so do not rush & after you do it enough times you know what quantities you can work with at one time. NEVER MIX IN THE WHOLE 6 PARTS OF THE METALIC CARBONATE AT ONE TIME, UNLESS YOU ARE JUST WORKING IN GRAMS & NOT OUNCES!

 

Chemical sources;

1) Benzoic Acid (Firefox)

2) Copper Carbonate (Skylighter) * (Firefox) * (Ebay) * (Bentspoonmaterials)

3) Distilled Water (Grocery Store) One's outside of a lot of stores are only just filtered tap water which is a NO NO! Use

Distilled water only

4) Copper Benzoate (Skylighter) * (Ebay)

 

Mis equipment sources;

1) Large glass, ceramic, or non stick metal pot (Grocery Store) * (Lab Equipment Supply House) * (Ebay)

2) Heating Element (Grocery Store) * (Ebay) * (Lab Equipment Supply House)

3) Coffee Filters, Large Plastic Spoon, Resealable Jars, Sieve (Local Grocery Store)

4) Electronic Scales, is cheap & perfect for this use. (Ebay) * (Grocery Store) * (Post Office) * (Office Supply Store)

4) Back issue of AFN #119 (American Firework News Website)

 

Good luck & remember that Copper Benzoate is just one of MANY metalic Benzoates you can mnf using this simple process, others include; Calcium Benzoate, Barium Benzoate, & Strontium Benzoate

[AdmiralDonSnider]

I wondered if oven-drying is necessary. Wouldn´t the material dry thoroughly by natural drying?

[andyboy]

In room temperature with low humidity it will dry perfectly alright. Although, there are some pyros that dry everything even though it isn't necessary for the product but it might be an issue when weighing stuff, to much retained water will mess up ratios and the end product could be spoiled. Charcoal is a typical example since it is hygroscopic and retains moisture but this fact is often overlooked when there are other chemicals in the composition that are hygroscopic in a much more visible way, those chemicals will then be blamed.

[tentacles]

I'm not sure you can remove the waters of hydration from copper benzoate using room temperature drying. For certain, the local humidity would have to be very low, probably using a dessicant of some sort. It's pretty easy to dry at elevated temperature, though.

 

I could probably dry the hydration out up here in the winter - I can do it with copper sulfate, very complicated procedure though.. leave it on a shelf for a few weeks..

[Mumbles]

It holds onto 3 waters of hydration after crystallizing. You cannot remove this by atmospheric drying. I kind of wonder about tentacles' drying of copper sulfate too. Then again, copper sulfate is weird stuff, if the water is in the outer shell, it should be able to be removed by a dry atmosphere. I think some of the waters are, and some arn't. Tentacles, you might have the dihydrate by leaving it out.

 

If I remember correctly, all of the waters of hydration are bound in the inner shell of copper benzoate, so yes, you'd need to heat it. It will change color. 120C for a few hours should do the trick.

[AdmiralDonSnider]

Thanks for your responses.

 

How does the benzoate change color? Can it be damaged by overheating or heating for too long?

[tentacles]

Mumbles, that could be - is the dihydrate white? That's what I've got, a ziploc of largish crystals, that were a gorgeous deep blue and a few weeks later were white with a few bluish streaks.

 

Copper benzoate hydrate is baby blue, and the anhydrous is a much deeper blue. I put a picture of my jar on wikipedia a while back, and there's a pic of a pile of the hydrate.

 

http://en.wikipedia.org/wiki/Copper_benzoate

[Mumbles]

Yes, it deepens in color. Short of heating to decomposition, leaving it won't hurt anything. You'd need well over 200C I'd suspect to decompose it. I've seen a variety of colors, probably depending on degree of hydratation. I've seen it go to an almost greenish teal color before. It may have had impurities, or a different crystal structure.

 

I believe the dihydrate is white. Actually simply crushing the crystals turns them quite white in my opinion. Just a tinge of blue. You need well formed crystals to get the intense blue color. You could just have cloudy crystals from excess water evaporating and ruining the lattice. The only real way to tell would be to fully dry and weigh the stuff. I'll admit that I was skeptical that the waters of hydration could evaporate, but weirder things have happened.

[FrankRizzo]

Thanks for your responses.

 

How does the benzoate change color? Can it be damaged by overheating or heating for too long?

 

Yes, it changes to a darker blue, and yes, it will decompose if heated too long. The decomposition will stink your house to high hell if doing it in the kitchen.

[Mumbles]

It will only make your kitchen stink if you dislike the smell of cancer causing benzene.

[AdmiralDonSnider]

Few days ago I attempted to make Cu-benzoate following the instructions given here (using benzoic acid and the carbonate). I used gram quantities and ended up with a mix of beautiful blue crystals (benzoate I assume) and white crystals (of benzoic acid I assume), and it seemed I had a lot of leftover benzoic acid dissolved/precipitating in the water left after filtration. The solid matter in the filter itself seemed to dry well in the sun but while it gave a deep blue at the bottom of the flame, a strong yellow overpowered the rest and rendered the blue useless. (I assume it´s the benzoic acid that colors the flame yellow)

 

So I´m asking myself: what went wrong? Why hasn´t my acid been consumed by the reaction when I added the correct qty. of carbonate? Did I add the carbonate too early (before the acid was dissolved)? How do I know when it´s time? (Please be kind - I´m not really good at chemistry ;-))

 

Thanks!

[Mumbles]

That odd. I went and checked the proceedure, and it's pretty darn close to ideal. If anything, I'd expect there to be some excess carbonate, not acid. It takes a while to convert to the benzoic acid, so it's possible you didn't leave it at boiling temps for long enough. Washing with boiling water a couple times and then alcohol should get out all the extra benzoic acid.

[a_bab]

On a somewhat related note, I explored the possibility of getting copper benzoate out of copper sulfate and sodium benzoate.

After some 10 washes in cold water (in order to save the copper benzoate, which is quite soluble) I made "pellet" stars with NC laquer/AP/Copper benzoate.

 

To the naked eye, indoors, the resulted blue is not convincing at all, it's very washed out. There is no yellow in the flame, nor the flame is greenish (as it perhaps would if Na would be still present in my Cu benzoate).

 

I'll try to shot the flame too see what it looks like "on film". I highly suspec that the blues we see on youtube are in reality much washed, the blue-sensitive sensor adding to the color.

[flamingape]

im supprised noones posted it but heres my writeup

http://pyroguide.com/index.php?title=Copper_benzoate

 

something i didnt add was thet the net reaction is an endothermic process. I started with boiling water and ended up with freezing cold leftovers.

 

the potassium sulphate is force crystallized out meaning the best way is to dissolve both reactants in the minimal ammount of H2O possible and then crash them together , stirr, filter...ASAP

 

using a carbonate will make fizzy bubbles and thats usualy something i try to avoid in any reaction as it can lead to spillovers, blindness,burns etc. etc.

 

and cost aint a problem if you make your benzoate salt from base chems... benzene, NaOH, catylist, Kno3 (you can distill for nitric if you bring a catylist to the party that adds a proton).

 

 

sorry bout the spelling i am buzzed

Edited May 15, 2009 by flamingape

[AdmiralDonSnider]

I rediscovered this thread and wondered if someone could post a description of the synthesis using potassium benzoate and copper sulphate; would be a nice support for a chemisty-bungler like me. Thanks!

[Fred]

Hi Admiral, fortunately you don´t need to acquire chemical skills at all - Copper benzoate can be made easily.

 

Just dissolve 1,28 parts potassium benzoate and 1 part copper sulfate in warm distilled water and slowly pour these solutions together while stirring.

The precipitate of copper benzoate has to be washed several times with distilled water (still more important if you use sodium benzoate!).

The drying time takes days.

Et voila: cheap and easy made Cu(C6H5COO)2

 

A detailed description can be found at http://www.pyroguide.com/index.php?title=Copper_benzoate

 

(Edit:

„1 part potassium benzoate and 1,6 parts copper sulfate“

to

„1,28 parts potassium benzoate and 1 part copper sulfate“)

Edited January 6, 2010 by Fred

[Mumbles]

Well, it looks like there is one more page on pyro guide that needs a MAJOR overhaul. The procedure is fine, but the ratios are way off. You could be precipitating a basic salt with only 1 mole of benzoate since the liquid seems clear(ish).

 

There need to be 2 moles of Potassium Benzoate for every mole of Copper sulfate. The page, and your post even show this in your formulas for copper benzoate (which is also not quite accurate by the way). That will also yeild Copper (II) Benzoate di or trihydrate. Ambient temperature or a desiccator wont be able to remove the crystallized water molecules.

 

It should be 320.4g Potassium Benzoate for every 249.7g CuSO4. It's about 1.28g Potassium Benzoate for every gram of Copper Sulfate.