Copper (II) chloride

 

Copper (II) chloride
aka cupric chloride

Chemical formula	CuCl2
OTP appearance	yellow-brown solid
Molar Mass(g/mol)	134.45
Density(g/cc)	3.386
Melting Point(°C)	498
Boiling Point(°C)	993 (decomp)
Solubility in water(g/L)	757
Solubility in ethanol(g/L)	530
Solubility in methanol(g/L)	680
Solubility in ether(g/L)	1.1
Solubility in acetone(g/L)	30
NFPA 704	0 2 1

Uses

Other

• Precursor for sulfuric acid
• Metal Etchant

Hazards

Soluble copper compounds are toxic to mammals and can be deadly to fish.

Production

Synthesis

The main routes are divided by the source of the chloride ion. The simplest is hydrochloric acid:

via hydrochloric acid

metallic copper

• Bubble air through copper metal immersed in hydrochloric acid. This will not work without the air, and even then it takes days. This may go in two separate steps, first to copper (I) chloride, and thence to copper(II) chloride, shown separately below.

  4 Cu + 4 HCl + O₂ → 4 CuCl + 2 H₂O // from copper(0) to copper (I)

  4 CuCl + 4 HCl + O₂ → 4 CuCl₂ + 2 H₂O // from copper(I) to copper (II)

copper (II) minerals

• Combine malachite and hydrochloric acid

  Cu₂(OH)₂CO₃ + 4 HCl → 2 CuCl₂ + 3 H₂O + CO₂

copper (I) chloride

• Bubble air through copper (I) chloride in hydrochloric acid. This will not work without the air, and even then it takes days.

  4 CuCl + 4 HCl + O₂ → 4 CuCl₂ + 2 H₂O // from (I) to (II)

via sodium chloride

Relative Solubilities

	water		ethanol
	g/L	M	g/L	M
copper chloride	757	5.63	530.00	3.94
sodium chloride	359	6.10	0.65	0.01
copper acetate	65	0.36	71.40	0.39
sodium acetate	1233	15.00	23.00	0.28
copper sulfate	200	1.26	ins	0
sodium sulfate	139	1.02	ins	0

0.035M (100ml) scale

1. Gather 6.7g of copper (II) acetate monohydrate
2. Heat to 160°C (325F) for 10 minutes to drive off the water
3. Measure mass again: should be 6.33g
4. Dissolve in 100ml dried ethanol (saturated limit, 0.35M)
5. Transfer ethanol to separation funnel
6. Prepare saturated saline solution (6M)
7. Repeat
   1. Add 5.7ml of saturated saline solution to ethanol in sep funnel, shaking regularly
   2. Draw off aqueous layer and evaporate

      NB: Should contain mostly sodium acetate, less sodium chloride.

8. Until mostly sodium acetate remains
9. Evap the ethanol layer, leaving mostly copper chloride

When using salt as a source of chlorine, choose an anion whose copper salt that is more soluble in water than ethanol, such as copper (II) acetate or copper sulfate, and preferably an anion for which the sodium salt also prefers water. Mix them in a water/ethanol solution, and allow the copper chloride to dominate the ethanol phase.

Process

1. Combine a water-soluble copper (II) salt (e.g. copper (II) acetate) with sodium chloride in a strong (80%+) ethanol/water mixture. The products are copper (II) acetate, sodium chloride, sodium acetate, and the target copper (II) chloride.
2. Repeat
   1. Decant ethanol layer
   2. Distill to dryness
   3. Return distillate to mother liquor
   4. Filter residue from distillation
   5. Wash with cold dry ethanol
   6. Discard white residue (CuAc, NaAc, NaCl)
   7. Evaporate leaving mostly CuCl2
3. Until the ethanol layer stops containing much

Continuous process

By leveraging the salting-out effect of the water-ethanol mix, it might be possible to create a cycle, where cold CuCl₂-rich ethanol solution is transported by gravity to an evaporation unit which directs the ethanol vapors as they condense back to the source salt mix. This results in the acumulation of copper chloride in the evaporation unit

Ammonium chloride

Heating ammonium chloride and copper (II) oxide or Copper (II) Sulfide

...hydrochlorination of the copper(II) compounds begins at 190ºC to form ammonium chlorocuprates, (NH4)2CuCl4 in with copper (II) oxide and NH4CuCl3 with copper (II) sulfide, which at the temperature higher than 300ºC decompose affording CuCl2

Testing

• There is an exothermic reaction with aluminum and aluminum oxide

Purification

recrystallize from hot dilute aqueous HCl by cooling in a calcium chloride-ice bath

Storage

• Do not store with excess copper. This can result in decomposition to copper (I) chloride:

  Cu + CuCl₂ → 2 CuCl

• Do not store in acidic conditions.

Disposal

• Combining with sodium hydroxide produces insoluble copper hydroxide, which will then absorb carbon dioxide from the air, resulting in nature-safe carbonate/hydroxide compounds equivalent to malachite and azurite
• Combining with sodium bicarbonate or sodium carbonate shortcuts the carbon dioxide absorption and produces the mineral forms of copper directly.

See Also

• US patent 2587579 "Method of production of cuprous oxide and copper chlorides"
  Link courtesy Google
• Borisov, V. A.; D’yachenko, A. N.; Kraidenko, R. I. (2011) "Reaction of ammonium chloride with the copper(II) sulfide and oxide, and identification of the reaction products"
  Russian Journal of General Chemistry 81(7); pp1430-1433. 
  DOI:10.1134/S107036321107005X</ref>