helge

I think you could make the following types of copper benzoate:



For type A you can simply add any Copper(II)-salt to the sodium benzoate.
Type B should be harder to prepare since Copper(I) isn't stable in aqueous solution. It will form Cu2+ and Cu. But if copper(I)benzoate is hardly soluble (is it?) the preparation of copper(I)benzoate can be successful.

To get the Cu(I) you have to boil copper in hydrochloric acid. this way CuCl is formed. If you don't boil you'll get CuCl2.
To the freshly prepared Cu(I) solution you can add sodium benzoate and maybe Copper(I)Benzoate is formed.
I have not tried this yet, so i don't now whether it works, but I think Copper(I)benzoate will make an other blue than the easier to make Copper(II)benzoate.

regards, helge