Copper (II) acetate: Difference between revisions
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* '''Does not''' occur naturally. | * '''Does not''' occur naturally. | ||
==Hazards== | ==Hazards== | ||
==Character== | |||
===Hydrates=== | |||
* Copper (II) acetate monohydrate has a molar mass of ~200. 0.36M (for 1L saturated solution) weighs ~71g. | |||
===Thermal decomposition=== | |||
The thermal decomposition of CuAc2·H2O under 500 °C in air included three main steps.<ref>{{cite pub | |||
|title=Study on thermal decomposition of copper(II) acetate monohydrate in air | |||
|last1=Lin, | |||
|first1=Z. | |||
|last2=Han | |||
|first2=D. | |||
|last3=Li | |||
|first3=S | |||
|publication=Journal of Thermal Analysis Calorimitry | |||
|year=2012 | |||
|volume=107 | |||
|pages=471 | |||
|url=https://doi.org/10.1007/s10973-011-1454-4}}</ref> | |||
# Under 168°C the [[copper (II) acetate]] was dehydrated | |||
# Between 168–302°C it began to decompose to volatile compounds, elemental copper, and mixed copper oxides | |||
# Between 302–500 °C the decomposition completes leaving only [[copper (II) oxide]] | |||
==Production== | ==Production== | ||
===Synthesis=== | ===Synthesis=== | ||
;Notes | ;Notes | ||
* The maximum molarity of copper acetate in water is 0.36Mol/L, and this is often a limiting factor in its production. | * The maximum molarity of copper acetate in water is 0.36Mol/L, and this is often a limiting factor in its production. | ||
* Vinegar (5%v/v, 0.874M, acetic acid) is above the (double) molarity which will dissolve the resultant product, so concentrated acetic acid is not necessarily worthwhile, and dilution (to 0.72M) may be worthwhile. | * Vinegar (5%v/v, 0.874M, acetic acid) is above the (double) molarity which will dissolve the resultant product, so concentrated acetic acid is not necessarily worthwhile, and dilution (20% v/v water) (to 0.72M) may be worthwhile. | ||
* Air drying a solution of [[copper (II) acetate]] can result in some decomposition to copper oxide, so instead, use the preferred solvant, dry(er) ethanol. If a black precipitate forms, add distilled water or vinegar and warm with stirring until it dissolves once again. | * Air drying a solution of [[copper (II) acetate]] can result in some decomposition to copper oxide, so instead, use the preferred solvant, dry(er) ethanol. If a black precipitate forms, add distilled water or vinegar and warm with stirring until it dissolves once again. | ||
Line 49: | Line 71: | ||
|url=https://www.researchgate.net/publication/281677446_Synthesis_and_purification_of_copper_catalysts_acetate_CuOOCCH32_acetylacetonate_Cu_acac2_trifluoroacetylacetonate_Cutfacac2_and_hexafluoroacetylacetonate_Cuhfacac2 | |url=https://www.researchgate.net/publication/281677446_Synthesis_and_purification_of_copper_catalysts_acetate_CuOOCCH32_acetylacetonate_Cu_acac2_trifluoroacetylacetonate_Cutfacac2_and_hexafluoroacetylacetonate_Cuhfacac2 | ||
}}</ref> suggests: | }}</ref> suggests: | ||
# | # Dissolve 90g (~0.5mol) of [[copper (II) acetate]] in 1L boiling [[vinegar]] | ||
# Chill to below 0°C | # Chill to below 0°C | ||
# Collect the crystals which form | # Collect the crystals which form |
Latest revision as of 12:26, 5 May 2020
Chemical formula | Cu(CH3COO)2 |
---|---|
OTP appearance | dark green crystals |
Molar Mass(g/mol) | 181.63 |
Density(g/cc) | 1.882 |
Boiling Point(°C) | 240 |
Solubility in water(g/L) | 65.4 (0.36M) @20°C 97.5g (0.537M) @100°C |
Solubility in ethanol(g/L) | 64.4 (0.35M) |
NFPA 704 |
Uses
Other
- organic oxidant
- mordant
- ceramic pigment
- fungicide
- accessible soluble copper (II) salt
Natural occurrence
- Does not occur naturally.
Hazards
Character
Hydrates
- Copper (II) acetate monohydrate has a molar mass of ~200. 0.36M (for 1L saturated solution) weighs ~71g.
Thermal decomposition
The thermal decomposition of CuAc2·H2O under 500 °C in air included three main steps.[1]
- Under 168°C the copper (II) acetate was dehydrated
- Between 168–302°C it began to decompose to volatile compounds, elemental copper, and mixed copper oxides
- Between 302–500 °C the decomposition completes leaving only copper (II) oxide
Production
Synthesis
- Notes
- The maximum molarity of copper acetate in water is 0.36Mol/L, and this is often a limiting factor in its production.
- Vinegar (5%v/v, 0.874M, acetic acid) is above the (double) molarity which will dissolve the resultant product, so concentrated acetic acid is not necessarily worthwhile, and dilution (20% v/v water) (to 0.72M) may be worthwhile.
- Air drying a solution of copper (II) acetate can result in some decomposition to copper oxide, so instead, use the preferred solvant, dry(er) ethanol. If a black precipitate forms, add distilled water or vinegar and warm with stirring until it dissolves once again.
- Procedure
- Reflux/warm any of copper (II) oxide, copper carbonate, malachite or azurite with acetic acid or vinegar.
- CuO(s) + 2 CH3COOH(aq){Cu(CH3COO)2(aq) + H2O40-50°C}→
- CuO(s) + 2 CH3COOH(aq)
- Filter (or decant) the blue solution and retain residue (copper oxides) for next batch
- Extract crystals from concentrated solution
- Repeat
- Combine with 3 volumes of azeotropic ethanol
- Let stand and separate
- Pour off ethanol layer
- Evap, leaving crystals
- Return any condensed alcohol to azeotropic strength, and feed forward.
- Until source is clear
- Repeat
Testing
- Characteristic (different colored) blue-green crystals and blue solutions.
- Chemtest (acetate)
Purification
An unpublished paper[2] suggests:
- Dissolve 90g (~0.5mol) of copper (II) acetate in 1L boiling vinegar
- Chill to below 0°C
- Collect the crystals which form
- Wash them briefly with ice cold distilled water
- Wash in dry ethanol
- Wash in diethyl ether and/or hexane
- Dry using moderate heat (40°-50°C) and drying agents (e.g. calcium chloride), to avoid thermal decomposition to copper (I) acetate
Storage
Store as crystals, not as solution. Aqueous solution degrades (hydrolyzes?) giving a white precipitate which may be copper (I) acetate (Cu(CH3COO)) or basic copper acetate (Cu(OH)(CH3COO) + CH3COOH), or something entirely other.
Disposal
Thermal decomposition to insoluble mineral copper (II) oxide is simple. Mixing with sodium carbonate produces insoluble mineral copper carbonate and sodium acetate.
Vidnotes
- Produce a saturated solution of copper acetate at 20C (65g(anh), 71.44g (hyd) per liter, ~0.36M) to show what the goal looks like
- Show dilution of vinegar before reaction to get to 0.72M solution
- Several days of boiling copper powder in diluted vinegar.
- Show increasing boiling point as copper acetate concentration grows?
- Pre-weigh 0.36M of copper powder
- Cook copper on stove and measure weight before/after to get "degree" of oxidation.
See Also
- Richardson, H. Wayne (1997) "Handbook of Copper Compounds and Applications"
Taylor & Francis
DOI:10.1080/10426919808935268, ISBN: 978-0824789985
link courtesy Google Books.
References
- ↑ Lin,, Z.; Han, D.; Li, S (2012) "Study on thermal decomposition of copper(II) acetate monohydrate in air"
Journal of Thermal Analysis Calorimitry 107; pp471. - ↑ Semenok, Dmitrii (2015) "Synthesis and purification of copper catalysts..."
unpublished
DOI:10.13140/RG.2.1.2479.9204