Precious Metal Extraction with Thiol and Dithioether Derivatives of a Trident Molecule

Abstract

Thiol and dithioether derivatives of tripodal extraction reagents have been newly prepared and employed to investigate the extraction behavior of precious metals. Both sulfur-containing compounds did not exhibit a pH dependency for precious metal extraction. The thiol type derivative exhibited a high extraction ability for gold(III), silver and palladium(II), and a 1 : 3 (extractant : metal) stoichiometry for gold(III) and silver.The results showed that the thiol derivative exhibited little structural effect due to the strong functionality of thiol group. The dithioether derivative also extracted gold(III), silver and palladium(II), however the silver extraction is caused by the structural effect of the tripodal framework, while gold(III) and palladium(II) extraction is probably attributed to a partial structural effect. The tripodal derivative possesses a high extraction ability compared with the corresponding monopodal compound. Tripodal and monopodal derivatives showed 1 : 1 and 1 : 2 (extractant : metal) stoichiometry for silver. This means that the tripodal derivative exhibited the structural effect as a size effect, converging effect of the multi functionality, complementary effect. The coordination site of the tripodal derivative was confirmed by 1 H-NMR spectra before and after the silver loading. Stripping of the loaded silver from the tripodal derivative was also investigated. Finally, the stepwise separation of silver and palladium(II) was carried out and roughly achieved by using different eluents.

Comparative Extraction of Aluminum Group Metals Using Acetic Acid Derivatives with Three Different-Sized Frameworks for Coordination

“…Our group has synthesized various extraction reagents based on different framework types, namely calix [4]arenes [15,18,19], "trident" molecules as alkenyltrimethylols [16,[19][20][21][22], and 2,2 ,2 -trihydroxytriphenylmethane [23]. These frameworks provide unique properties for the synthesis of their derivatives and for metal extraction (Table 1).…”

Silicas Chemically Modified with Sulfur-Containing Groups for Separation and Preconcentration of Precious Metals Followed by Spectrometric Determination

“…These functional groups fixed on the silica surface were chosen because thiourea and its derivatives, as well as dithiocarbamates, are widely used in liquid extraction of precious metals [27][28][29][30]. Reagents containing thiol sulfur are more selective than reagents containing thionic or sulfide sulfur [31,32].…”

New Trident Molecule with Phosphoric Acid Functionality for Trivalent Rare Earth Extraction

“…They also provide three-dimensionally arranged coordination site for guest molecules or ions [25][26]. They were employed as extraction reagents and ion-selective electrodes [25][26][27][28][29][30][31][32][33], and we named as "trident" molecules [29]. Their coordination site can be narrower than that of calix [4]arene derivative when functional groups are introduced close to the carbon atom as a junction to tripodal branched groups.…”