Solvent-free mechanochemical synthesis of dithiophosphonic acids and corresponding nickel(II) complexes. (2nd November 2017)

• Record Type: Journal Article
• Authors: Ajayi, Tomilola J.; Pillay, Michael N.; van Zyl, Werner E.
• Is Part Of: Phosphorus, sulfur, and silicon and the related elements. Volume 192:Number 11(2017)
• Page Start: 1205
• Page End: 1211
• Publication Date: 2017-11-02
• Subjects: Green chemistry -- dithiophosphonic acid -- solvent-free -- nickel(II) complexes -- atom economy -- hydrated; Sulfur compounds -- Periodicals; Organosulfur compounds -- Periodicals; Phosphorus compounds -- Periodicals; Organophosphorus compounds -- Periodicals; Silicon compounds -- Periodicals; Organosilicon compounds -- Periodicals; 546
• DOI: 10.1080/10426507.2017.1358717
• Languages: English
• ISSNs: 1042-6507

Abstract

GRAPHICAL ABSTRACT: ABSTRACT: We report a green chemistry route for dithiophosphonic acids of the type [HS2 P(OR)(4-MeOC6 H4 )] [R = H, (1 ); Me (2 ); Et (3 ); i Pr (4 )]. The different dithiophosphonic acids formed through the stoichiometric addition of water or alcohols to Lawesson's Reagent (molar ratio 2:1), followed by an intimate grinding of the mixture (mechanochemistry). The products formed without the use of solvent or external heat in less than 5 minutes. The acids are formed with 100% atom economy, and because they form in essentially quantitative yield, are also formed with >98% atom efficiency and an E-factor = 0, because no waste is produced. Of importance is that this methodology is different from conventional methods in forming dithiophosphonic acids where the use of organic solvents, added heat, long reaction times and lower yields are commonplace. We further demonstrate that nickel(II) complexes can form directly from the in situ generated acids. Thus, the reaction between1–4 and NiCl2 ‧ 6 H2 O (molar ratio 2:1) lead to complexes of the type [Ni{S2 P(OR)(4-MeOC6 H4 )}2 ] [R = H, (5 ); Me (6 ); Et (7 ); i Pr (8 )] with no use of organic solvent. All compounds were characterized or verified by a combination of 1 H, 31 P NMR, elemental analysis (solids), and FT-IR.