US EPA

7745094 

Journal Article 

A new procedure for the synthesis of lithium hexafluorophosphate 

Naejus, R; Lemordant, D; Coudert, R; Willmann, P 

1998 

Yes 

Journal of Fluorine Chemistry
ISSN: 0022-1139
EISSN: 1873-3328 

Elsevier 

90 

1 

81-85 

French 

10.1016/S0022-1139(98)00161-4 

WOS:000074510800016 

Lithium hexafluorophosphate (LiPF6) has been synthesized using commercial hexafluorophosphoric acid (HPF6) as starting material. The neutralization of this acid monitored by conductimetry by lithium hydroxide in aqueous, alcoholic and acetonitrile media gives LiPF6 with yields of 42, 35 and 61% respectively. This salt may also be prepared by neutralizing similarly lithium hydroxide (LiOH) by pyridinium hexafluorophosphate (C5H5NHPF6) obtained by reaction from equimolar amounts of pyridine and HPF6 in alcoholic media (yield about 90%). From C5H5NHPF6 a new synthesis leads to LiPF6 in two steps. First the reaction of C5H5NHPF6 with ROLi (R = CH3, C2H5) in methyl or ethyl alcohol, acetonitrile and tetrahydrofuran media or with RLi (R =C4H9, tert-bulyl) in pentane or hexane, gives lithium pyridinium hexafluorophosphate Li(C5H5N)PF6 in about 95% yield. Heating this at 30-50°C under vacuum gives LiPF6 with a purity determined by lithium titration of about 99%. 

lithium hexafluorophosphate; hexafluorophosphoric acid; pyridinium hexafluorophosphate; lithium pyridinium hexafluorophosphate