Copper(I) hydroxide

Copper(I) hydroxide is the hydroxide of the metal copper with the chemical formula of CuOH. It is a mild, highly unstable alkali. The color of pure CuOH is yellow or orange-yellow,[2] but it usually appears rather dark red because of impurities. It is extremely easily oxidized even at room temperature. [3]

Copper(I) hydroxide

Names
Other names Cuprous hydroxide; Copper monohydroxide
Identifiers
3D model (JSmol)	Interactive image
ChemSpider	8031144
InChI InChI=1S/Cu.H2O/h;1H2/q+1;/p-1 Key: ZMHWUUMELDFBCZ-UHFFFAOYSA-M
SMILES [OH-].[Cu+]
Properties
Chemical formula	CuOH
Molar mass	80.55 g/mol
Hazards
NIOSH (US health exposure limits):
PEL (Permissible)	TWA 1 mg/m^3 (as Cu)[1]
REL (Recommended)	TWA 1 mg/m^3 (as Cu)[1]
IDLH (Immediate danger)	TWA 100 mg/m^3 (as Cu)[1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Preparation

Copper(I) hydroxide can be prepared according to the following reaction:

${\displaystyle \overbrace {\ce {32S2O3^{2}-}} ^{\ce {thiosulfate}}+{\ce {{32Cu^{2}+}+16H2O->[\overbrace {\ce {CH3CH2OH}} ^{\ce {ethanol}}]32CuOH(v)}}+\overbrace {\ce {3S8}} ^{\ce {sulfur}}+\overbrace {\ce {8S4O6^{2}-}} ^{\ce {tetrathionate}}+\overbrace {\ce {8SO4^{2}-}} ^{\ce {sulfate}}}$

In this reaction, ethanol serves as a catalyst. It can also be a solvent for the byproduct sulfur and thus get rid of it.

Another method is by the double displacement of CuCl and NaOH：

${\displaystyle {\ce {CuCl + NaOH <=> NaCl + CuOH v}}}$

Notably, this method is rarely used because the CuOH produced will gradually dehydrate and eventually turn into Cu₂O.

Reactions

Similar to iron(II) hydroxide , copper(I) hydroxide can easily oxidise into copper(II) hydroxide:

${\displaystyle {\ce {4CuOH + 2H2O + O2 <=> 4Cu(OH)2}}}$

References

1. NIOSH Pocket Guide to Chemical Hazards. "#0150". National Institute for Occupational Safety and Health (NIOSH).
2. Soroka, Inna L.; Shchukarev, Andrey; Jonsson, Mats; Tarakina, Nadezda V.; Korzhavyi, Pavel A. (2013). "Cuprous hydroxide in a solid form: does it exist?". Dalton Transactions. 42 (26): 9585. doi:10.1039/C3DT50351H.
3. NaOH