Sciencemadness Discussion Board

Synthesising Copper Hypophosphite

top204 - 10-7-2013 at 05:21

Hello

I'm needing some advice from people who have more chemistry knowledge than myself.

For my experiments in making non electrically conductive surfaces electrically conducting. i.e. through holes on a PCB, I have a need for copper hypophosphite. My current synthesises method for creating this chemical is to mix Copper(II) Sulphate with Calcium Hypophosphite. The liquid produced is Copper Hypophosphite and the precipitate is Calcium Sulphate.

This method works well, however, Calcium Hypophosphite is both expensive and on the restricted list of chemicals.

Sodium Hypophosphite is both inexpensive and readily available here in the UK, therefore, my question is... How (if possible) can I create Copper Hypophosphite from Sodium Hypophosphite?

I do have a method that seems to work somewhat, but does not produce satisfactory results. My method is.. Dissolve Sodium Hypophosphite in alcohol, dissolve Calcium Chloride in alcohol. Mix together and filter. The precipitate seems to be an impure Calcium Hypophosphite. Use this in the above method to extract Copper Hypophosphite.

Is there a way to directly replace the Sodium with Copper using the Sodium Hypophosphite and a copper salt, or alternatively, is there a better way to produce Calcium Hypophosphite from Sodium Hypophosphite.

By the way. The process for metalising the surface is. Mix Copper Hypophosphite with Ammonium Hydroxide. Dip the board into the solution, remove, then heat the board at 150 degrees C. Clean the board then plate with copper, either electro or electrolessly.

Thanks you in advance, and sorry for the size of the post.

Les

woelen - 10-7-2013 at 05:46

One way might be to mix a highly concentrated solution of NaH2PO2 with a stoichiometric amount of e.g. 70% H2SO4 (diluted just enough, such that it does not produce a lot of heat on mixing with an aqueous solution). For each molecule of NaH2PO2 you need half a molecule of H2SO4. As H3PO2 is a weak acid (much weaker than H2SO4 and also much weaker than HSO4(-)), I expect nearly all H2SO4 to react to H3PO2 and SO4(2-) ions. I expect the sodium sulfate to form crystals, it is not that soluble. What remains is a solution of H3PO2 with of course also some Na2SO4 left in this solution. To this you can add very finely powdered CuO or copper carbonate. Most likely the small amount of left over Na2SO4 does not do real harm.

ScienceSquirrel - 10-7-2013 at 05:47

Can you buy hypophosphorous acid?
You could dissolve copper carbonate in the acid and bob's your uncle.

woelen - 10-7-2013 at 07:10

I wish I could obtain that chemical. Indeed, like top204 says, sodium hypophosphite is easy to obtain (the potassium salts also can be had sometimes), but the free acid and the calcium salt are very hard to obtain if you do not have an affiliation with a chemical company or a suitable research institue. I think it is due to the fact that the free acid is easily used in meth-synthesis as a replacement for the red P/I2 reduction method. Calcium hypophosphite of course also very easily can be converted to the free acid, while the sodium salt is much more difficult to convert to acid of good purity.

AndersHoveland - 10-7-2013 at 18:41

Quote:

"...it is known that phosphorous acid, reduced with nascent hydrogen, yields phosphine and hypophosphorous acid

For the formation of phosphine from phosphorous and sodium hydroxide, heated together, the following equation is usually given:
(4)P + (3)NaOH + (3)H2O --> PH3 + (3)NaH2PO2

Without a doubt the reaction is far more complicated.
...what has not been shown, that hydrogen and at least two acids of phosphorous are formed when phosphine is generated in the usual way. ...When phosphine was obtained, by heating an aqueous solution of potassium hydroxide with phosphorous, only from 10 to 40 percent of the gas obtained was phosphine [the remainder being hydrogen]. The decomposition of phosphonium iodide, PH4I, is the only method of obtaining pure phosphine."

"investigation of sodamide and of its reaction-products with phosphorus" William Phillips Winter p42-43

The article goes on to say that the reaction of sodium phosphide with water generates small portions of phosphites and hydrogen gas, in addition to the main products of sodium hydroxide and phosphine.
Quote:
Precipitated cuprous oxide [Cu2O] is acted on rapidly by phosphine at ordinary temperature, forming a grey white mass and water, the grey substance is quite insoluble in water, if air be excluded; it is [PCu3]. It melts at a red heat, is rapidly dissolved by nitric acid or bromine water, and is attacked by hot sulfuric acid, with the formation of sulfur dioxide and phosphine. It does not reduce potassium permanganate.

While phosphine acts differently on the aqueous solutions of different cupric salts, its action of the ammoniacal solutions of all of them (chloride, sulfate, nitrate, acetate, formate, hydroxide) is the same. Copper phosphide is formed in amount corresponding to two-thirds of the phosphine which disappears, while the phosphorous of the other third is found in the liquid, as phosphoric and hypophosphorous acids in molecular proportions-

(6)PH3 + (12)CuCl2 + (6)H2O + (x)NH3 --> (4)PCu3 + PO4H3 + PO2H3 + (24)HCl + (x)NH3

If, after the absorption of the phosphine, oxygen be admitted, the precipitate redissolves completely, using up a volume of oxygen double that of the phosphine absorbed in the first place.

Journal of the Society of Chemical Industry, Volume 18, p716


[Edited on 11-7-2013 by AndersHoveland]

top204 - 11-7-2013 at 00:30

Thanks for the replies

Woelen, your idea is very interesting and something I had not contemplated, but seems to be fraught with peril, and also seems to inherently leaves an impure substance that has to be further purified. Too little of the additive chemical and impurities are left behind, too much and impurities are also left behind. Also, my poor knowledge on the subject of chemistry would certainly lead to disaster.

AndersHoveland. I have to admit to not understanding most of what was said. I have read that Hypophophites are derived from phosphorous, but this is not an avenue that I am capable of going down, for two main reasons; availability of certain chemicals, and my knowledge of chemistry is not sufficient yet.

I've been reading a patent from 1960 (US2938770) that uses an ion exchange resin (sulphated phenol formaldehyde resin) to produce calcium hypophosphite from calcium chloride and sodium hypophosphite. But again, my lack of understanding at this point in time leaves me with more questions than answers.

While I understand the principles of ion exchange resins, I don't understand the details too clearly (yet).

My understanding is that a water softener ion exchange resin will remove calcium and replace it with sodium, leaving the calcium attached to the resin. So my question is.. If I then poured sodium hypophosphite into the resin, would it produce calcium hypophosphite, which would then be used to synthesise copper hypophosphite?

Or, better still. If I charged the resin with copper chloride first, then with sodium hypophosphite, would the resin initially hold the copper, then on the second charge, produce copper hypophosphite?

Regards
Les




[Edited on 11-7-2013 by top204]

[Edited on 11-7-2013 by top204]

[Edited on 11-7-2013 by top204]

sodium hypophosphite and calcium chloride.

rtrombetta - 18-7-2013 at 16:57

Dilute sodium hypophosphite with 95% methanol and reserve.
Dilute calcium chloride in 100% methanol.
Mix both solutions stirring it. Sodium chloride and calcium hypophosphite will precipitate.
Wash the precipitate with 95% methanol.
Let it dry.

top204 - 19-7-2013 at 05:10

Thanks for the reply rtombetta, however, that's already the method I use for synthesising an impure calcium hypophosphite.

From original post.
"Dissolve Sodium Hypophosphite in alcohol, dissolve Calcium Chloride in alcohol. Mix together and filter. "

I've been doing some experiments with ion exchange resins with very positive results.

rtrombetta - 19-7-2013 at 14:56

Today I'm trying to do this method (Electroless Deposition of Copper on Organic and Inorganic Substrates Using a Sn/Ag Catalyst). I already synthesized the stannous chloride II, the silver nitrate and all PCBs holes are silver coated.
I'm going to do the autocatalytic electroless copper plating using sodium hypophosphite with nickel sulphate instead of using formaldehyde. There's a good book. Seach for "mems materials and processes pdf" and you will see a website with the address "gendocs.ru" that have the complete book in PDF format with all formulations.
I hope that this helps you!

top204 - 22-7-2013 at 02:55

I've gone down the path of using silver, tin and paladium as the metalisation process, but they all suffer from the same big problem. That of price. Silver has shot up in price so much that it is not now viable to synthesise silver nitrate, and buying it is horrendously expensive. And paladium is much, much more expensive.

Instead I use a copper seeding technique based upon sodium hypophosphite that is inexpensive and reliable.

I also went down the route of using an acidic copper/nickel plating bath. i.e. without formaldehyde, but found the deposition rate too slow, and it required higher operating temperatures. I now exclusively use an alkeline copper electroless plating bath using formaldehyde. But please let me know if you have better success.

[Edited on 22-7-2013 by top204]

[Edited on 22-7-2013 by top204]

madisoz - 22-7-2013 at 07:27

Quote: Originally posted by rtrombetta  
Dilute sodium hypophosphite with 95% methanol and reserve.
Dilute calcium chloride in 100% methanol.
Mix both solutions stirring it. Sodium chloride and calcium hypophosphite will precipitate.
Wash the precipitate with 95% methanol.
Let it dry.


I´m not chemist too. Still rtrombetta is probably right. Precipitate should be washed to remove NaCl.

I´m going to try to synthesize Ca(PH2O2)2 myself. My ideas to use glycerol in the process are here

http://www.instructables.com/id/Inexpensive-method-of-indust...


ElectroWin - 22-7-2013 at 11:10

Quote: Originally posted by top204  
Woelen, your idea is very interesting and something I had not contemplated, but seems to be fraught with peril, and also seems to inherently leaves an impure substance that has to be further purified. Too little of the additive chemical and impurities are left behind, too much and impurities are also left behind. Also, my poor knowledge on the subject of chemistry would certainly lead to disaster.


you should also note:
"Sodium sulfate displays a moderate tendency to form double salts." -- https://en.wikipedia.org/wiki/Sodium_sulfate

this will reduce yield of your wanted product

madisoz - 22-7-2013 at 11:38

About double salts - also sodium and calcium hypophosphite tend to form double salt in presence of water

jonco - 2-10-2013 at 04:05

top24 (or anyone),

Can you post details and results of your experiments with ion exchange resins and suppliers in UK?
Quote: Originally posted by top204  
Thanks for the reply rtombetta, however, that's already the method I use for synthesising an impure calcium hypophosphite.

From original post.
"Dissolve Sodium Hypophosphite in alcohol, dissolve Calcium Chloride in alcohol. Mix together and filter. "

I've been doing some experiments with ion exchange resins with very positive results.