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Halide Free Phosphonium Ionics - Ideal Candidates for Halide Free Applications

Phosphorus solutions for lubrication, reduced corrosion, halide contaminants and more!

Halogen-free phosphonium ionic liquids are of interest in many applications and numerous non-halogen ionic liquids (ILs) were made by reacting a tertiary phosphine with dialkylsulfates, carbonates, trialkylphosphates, methane sulfonates or fluorinated esters, and alkyl tosylates.

Among these ILs, phosphonium tosylates have been successfully employed as solvents in the rhodium catalyzed hydroformylation of olefins [1],  rhodium-catalyzed transfer hydrogenation of ketones [2], Diels-Alder reaction of isoprene with oxygen-containing dienophiles [3], incorporated into liquid polymer systems for catalytic reductions [4], used for removal of sulphur from liquid hydrocarbons [5],  photopolymerization of N-isopropylacrylamide (NIPAM) [6] and flame retardants for polycarbonates [7].

Tributyl(methyl)phosphonium tosylate (CAS# 55767-12-9) (Strem Catalog # 15-7570) is a solid with a melting point of 73 0C [8-9]:


For the convenience of handling, this ionic liquid is currently offered by Solvay as a 50% solution in water under the name CYPHOS® IL120W (Strem Catalog # 15-7570).

CYPHOS® IL 120 (Strem Catalog # 15-7570)  belongs to a powerful class of catanionic hydrotropes with a potential use in the extraction of value-added compounds from biomass [10]. Furthermore, CYPHOS® IL 120 (Strem Catalog # 15-7570) has been investigated with positive results on the reaction of primary aromatic amines with alkylene carbonates [11]. CYPHOS® IL 120 (Strem Catalog # 15-7570) has also been exploited in CdS thin film electrodeposition [12].

As with phosphonium halides, phosphonium tosylates are amenable to chemical modification (anion exchange) too, but producing halide-free ionic liquids suitable for a number of applications [13]:


In a recent study, tributyl(methyl)phosphonium bistriflamide was investigated as an additive (30%) to a safe and efficient hybrid electrolyte for LIB application on two types of cathodes, NCA and LMO. It was shown that the  physicochemical properties of the IL mitigated  flammability and delayed the ignition of the proposed electrolyte, and markedly improved the interfacial resistance of the NCA//Li and LMO//Li half-cells [14].

In another recent publication, the pivotal role of ionic liquids with FSI-anion [including methyltributylphosphonium bis(fluorosulfonylimide] to successfully cycle Li metal in water and air containing organic electrolytes was clearly demonstrated providing “a new avenue for the realization of Li metal in Li−air and other Li metal-based battery systems…capable of delivering the highest theoretical specific energy among rechargeable battery systems” [15].

It is clear from this short overview that the interest in phosphonium halogen-free ionic liquids remains unabated and Solvay and Strem Catalog, part of Ascensus Specialties distribution agreement helps numerous customers “solve technical challenges and unlock new business opportunities” [16]. 



  1. Chem. Commun. 1998, 2341-2342.
  2. Catalysis Lett. 2000, 67, 113-115.
  3. Tetrahedron Lett. 2001, 42, 2011–2014.
  4. Green Chem. 2006, 8, 807–815.
  5. US 8936719 B2, 2015.
  6. Macromol Chem Phys 2013, 214 (7), 787-796.
  7. Polym. Degrad. Stab. 2016,130, 165-172.
  8. WO0187900 A1, 2000.
  9. Aust. J. Chem. 2009, 62, 309–321.
  10. Green Chem. 2015, 17, 3948–3963.
  11. Org. Biomol. Chem. 2010, 8, 5187–5198.
  12. Phys. Chem. Chem. Phys. 2009, 11, 8532-8537.
  13. J. Mater. Chem. 2011, 21, 7640–7650.
  14. Electrochim. Acta 2021, 371,137841.
  15. ACS Appl. Energy Mater. 2019, 2, 8912−8918.
  16. Solvay and Strem Catalog, part of Ascensus Specialties sign phosphorus specialties distribution agreement

Featured Product

15-7570 Tributylmethylphosphoniump-toluenesulfonate, min. 95% (45-55% in water), CYPHOS® IL 120W (55767-12-9)

Related Products

CYPHOS® IL Products
Phosphorus Ligands and Compounds Booklet
All products sold in collaboration with Solvay



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