2645-22-9Relevant academic research and scientific papers
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.
Synthesis and characterization of oxo-vanadium complex anchored onto SBA-15 as a green, novel and reusable nanocatalyst for the oxidation of sulfides and oxidative coupling of thiols
Tamoradi, Taiebeh,Ghadermazi, Mohammad,Ghorbani-Choghamarani, Arash,Molaei, Somayeh
, p. 4259 - 4276 (2018/03/21)
Abstract: The present work describes the synthesis of a new oxo-vanadium complex immobilized on SBA-15 nanostructure as an efficient catalyst for oxidation of sulfides and oxidative coupling of thiols. Characterization of the resultant AMPD@SBA-15 nanostructure was performed by various physico-chemical techniques such as Fourier transform infrared spectroscopy, transmission and scanning electron microscopies, energy-dispersive X-ray spectroscopy, inductively coupled plasma optical emission spectroscopy, X-ray diffraction, thermal gravimetric analysis, and N2 adsorption and desorption. The results of the developed procedure bring several benefits such as the use of commercially available, ecologically benign, operational simplicity, and cheap and chemically inert reagents. It shows good reaction times, practicability and high efficiency, and is easily recovered from the reaction mixture by simple filtration and reused for several consecutive cycles without noticeable change in its catalytic activity. More importantly, high efficiency, simple and an inexpensive procedure, commercially available materials, easy separation, and an eco-friendly procedure are the several advantages of the currently employed heterogeneous catalytic system.
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.
Importance of a Fluorine Substituent for the Preparation of meta- and para-Pentafluoro-λ6-sulfanyl-Substituted Pyridines
Kosobokov, Mikhail,Cui, Benqiang,Balia, Andrii,Matsuzaki, Kohei,Tokunaga, Etsuko,Saito, Norimichi,Shibata, Norio
supporting information, p. 10781 - 10785 (2016/09/03)
Although there are ways to synthesize ortho-pentafluoro-λ6-sulfanyl (SF5) pyridines, meta- and para-SF5-substituted pyridines are rare. We disclose herein a general route for their synthesis. The fundamental synthetic approach is the same as reported methods for ortho-SF5-substituted pyridines and SF5-substituted arenes, that is, oxidative chlorotetrafluorination of the corresponding disulfides to give pyridylsulfur chlorotetrafluorides (SF4Cl-pyridines), followed by chloride/fluoride exchange with fluorides. However, the trick in this case is the presence on the pyridine ring of at least one fluorine atom, which is essential for the successful transformation of the disulfides into m-and p-SF5-pyridines. After enabling the synthesis of an SF5-substituted pyridine, ortho-F groups can be efficiently substituted by C, N, S, and O nucleophiles through an SNAr pathway. This methodology provides access to a variety of previously unavailable SF5-substituted pyridine building blocks.
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).
Amino acid and water-driven tunable green protocol to access S-S/C-S bonds via aerobic oxidative coupling and hydrothiolation
Shard, Amit,Kumar, Rajesh,Saima,Sharma, Nidhi,Sinha, Arun K.
, p. 33399 - 33407 (2014/08/18)
A green methodology utilizing a natural supplement such as l-arginine in conjunction with water and oxygen led to oxidative coupling of thiols into disulfides (S-S bond) whereas thiol-yne coupling to access vinyl sulfides (C-S bond) was facilitated in a nitrogen atmosphere. The tunable protocol offers several advantages such as low catalyst loading, high yields, clean reaction, no over-oxidation of the S-S bond besides being metal/base/waste-free. The synthesis of ubiquitous cystine and glutathione disulfide in the same catalytic system is an added advantage and the catalytic system has been recycled up to seven times. the Partner Organisations 2014.
Selective oxidation of thiols and alcohols by physically encapsulated nickel schiff-base complex prepared via sol-gel method as nano-catalyst
Eshtiagh-Hosseini, Hossein,Tabari, Taymaz,Takjoo, Reza,Eshghi, Hossein
, p. 264 - 272 (2013/04/10)
A heterogeneous catalyst was prepared by direct physical encapsulation of nickel Schiff-base complex into the silicon dioxide matrix via sol-gel method. The compounds were characterized by FT-IR, SEM, TEM, XRD, CHNS, and AAS. The catalytic performance in the alcohols and thiols oxidation was investigated in the presence of H2O2 (10 mmol, 30%) as oxidant. After five recycle runs, the catalyst showed 13% reduction in activity with slightly Ni(II)-complex leached to the solvent. Varieties of primary and secondary alcohols were efficiently oxidized to the corresponding ketones. Thiols were oxidized in coupling reaction to disulfides in excellent yields using nano-catalyst with H2O2.
Iodine-catalyzed addition of aromatic mercaptans to indene
Pudukulathan, Zubaidha K.,Kasa, Anjaneyulu
experimental part, p. 187 - 195 (2012/06/01)
Molecular iodine catalysis of additions of various substituted thiophenols to indene to afford the corresponding sulfides in good yields under mild conditions is reported. The regioselectivity of addition can be fine-tuned by modifying the reaction condit
A new method for synthesis of nolatrexed dihydrochloride
Xue, Xiaowen,Zhao, Xueqing,Li, Fei,Zhuang, Weiping,Lian, Yuanyang,Fan, Jianhui,Fang, Dongsheng
experimental part, p. 346 - 350 (2011/03/21)
A new synthetic method for nolatrexed dihydrochloride (thymitaq) has been developed. The synthesis was accomplished in three steps featuring the direct conversion of the starting 4-bromo-5-methylisatin into the methyl anthranilate by potassium peroxydisul
Oxidation of thiols using K2S2O8 in ionic liquid
Hajipour, Abdol R.,Mostafavi, Majid,Ruoho, Arnold E.
experimental part, p. 1920 - 1923 (2010/02/28)
A green, straightforward, and novel method for oxidation of thiols to the corresponding disulfides is reported using K2S2O8 in the ionic liquid 1-butyl-3-methylimidazolium bromide [(bmim)Br] at 65-70C. The corresponding disulfides were obtained in excellent yield and short reaction time.
