2645-22-9Relevant articles and documents
Cooperative Ligands in Dissolution of Gold
Eronen, Aleksi,Heli?vaara, Eeva,Liljeqvist, Henri,Moslova, Karina,Muuronen, Mikko,Repo, Timo
supporting information, (2021/05/19)
Development of new, environmentally benign dissolution methods for metallic gold is driven by needs in the circular economy. Gold is widely used in consumer electronics, but sustainable and selective dissolution methods for Au are scarce. Herein, we describe a quantitative dissolution of gold in organic solution under mild conditions by using hydrogen peroxide as an oxidant. In the dissolution reaction, two thiol ligands, pyridine-4-thiol and 2-mercaptobenzimidazole, work in a cooperative manner. The mechanistic investigations suggest that two pyridine-4-thiol molecules form a complex with Au0 that can be oxidized, whereas the role of inexpensive 2-mercaptobenzimidazole is to stabilize the formed AuI species through a ligand exchange process. Under optimized conditions, the reaction proceeds vigorously and gold dissolves quantitatively in two hours. The demonstrated ligand-exchange mechanism with two thiols allows to drastically reduce the thiol consumption and may lead to even more effective gold dissolution methods in the future.
Pyridinethiol-Assisted Dissolution of Elemental Gold in Organic Solutions
R?is?nen, Minna,Heli?vaara, Eeva,Al-Qaisi, Feda'a,Muuronen, Mikko,Eronen, Aleksi,Liljeqvist, Henri,Nieger, Martin,Kemell, Marianna,Moslova, Karina,H?m?l?inen, Jani,Lagerblom, Kalle,Repo, Timo
supporting information, p. 17104 - 17109 (2018/12/04)
Dissolution of elemental gold in organic solutions is a contemporary approach to lower the environmental burden associated with gold recycling. Herein, we describe fundamental studies on a highly efficient method for the dissolution of elemental Au that is based on DMF solutions containing pyridine-4-thiol (4-PSH) as a reactive ligand and hydrogen peroxide as an oxidant. Dissolution of Au proceeds through several elementary steps: isomerization of 4-PSH to pyridine-4-thione (4-PS), coordination with Au0, and then oxidation of the Au0 thione species to AuI simultaneously with oxidation of free pyridine thione to elemental sulfur and further to sulfuric acid. The final dissolution product is a AuI complex bearing two 4-PS ligands and SO42? as a counterion. The ligand is crucial as it assists the oxidation process and stabilizes and solubilizes the formed Au cations.
Hypervalent iodine(III)-promoted metal-free S-H activation: An approach for the construction of S-S, S-N, and S-C bonds
Rattanangkool, Eakkaphon,Krailat, Watanya,Vilaivan, Tirayut,Phuwapraisirisan, Preecha,Sukwattanasinitt, Mongkol,Wacharasindhu, Sumrit
, p. 4795 - 4804 (2014/08/05)
The activation of the sulfur atom of thiols with (diacetoxyiodo)benzene (DIB) has been explored in the preparation of symmetrical disulfides and sulfenamides. Disulfides can be produced in excellent yields (75-95%) upon treatment of thiols with DIB. The reaction was complete in less than five minutes at room temperature. Aliphatic, aromatic, and heteroaromatic thiols are compatible with this transformation. Moreover, heteroaromatic disulfides obtained from heteroaromatic thiols further reacted with a nucleophilic amine in the presence of a base to provide the corresponding sulfenamides in fair to good yields (43-90%) in a one-pot fashion. The methodology was successfully extended to indole as a representative electron-rich aromatic compound, which allowed successful construction of a S-C bond in one pot. The key benefits of this reaction include lower toxicity, low cost of DIB reagent, and mild reaction conditions (room temperature, undried solvents and open flask).
