Copper Benzoate

[californiapyro]

I have been searching online for copper benzoate for quite some time, to no avail. does anyone know a source, or an EASY way to synthesize it? thanks,

 

-Cali

[dave321]

you can make it quite easily from a solution of copper sulphate and a solution of potassium benzoate.

it will precipitate as a turqoise blue volumous precipitate.

 

better to use the potassium salt rather than the sodium salt, since the latter may interfer with any blue flame colour

if not washed properly, due to residual sodium

 

dave

[Seymour]

I've made it before with two routes.

 

Boiling pretty much insoluble Benzoic acid with pretty much insoluble "copper carbonate" (I used basic copper carbonate... which has hydroxide in it too) eventually makes Cu Benz.

 

I prefer adding a soluble copper salt to Sodium benzoate (or ideally Potassium benzoate) solution. Copper benzoate precipitates, and you wash it to get rid of the Na+

[Mumbles]

Skylighter sells it, but appears to be out of stock. Even ifyou get it during one of their big sales, it's still probably much cheaper to buy it. It depends on the price of raw materials of course. Below are some instructions I gave a fellow pyro a few years ago.

 

Mix 320g of K Benzoate with 250g of CuSO4. It will take about 500mL to dissolve the Benzoate, and 800mL for copper sulfate, mix them together and watch the pretty precipitate, let it sit for maybe 10-15 minutes, I hear it changes colors some(probably hydration) get a funnel or something, stick 2-3 coffee filters together, stir the soln up and pour the soln into the filters, it should be coming out relatively clear, add some more water to the jar and swirl it around to get any excess, repeat as necessary, Add 2-3 portions of 300mL of water one at a time and let drain to help wash out residual potassium sulfate, should yield about 300g anhydrous or 360g of the hydrate.

 

One thing I didn't mention to him is to avoid metals like aluminum, iron, or steel. Stick to plastic or glass for mixing, filtering and drying on A vacuum filtration device will really help. See the perchlorate thread for some ideas on those. You could honestly use a t-shirt or cheese cloth to do the filtration, but you may loose some.