Stable (CF3)2N— salts and process for preparing them

Details Stable (CF3)2N— salts and process for preparing them Stable (CF3)2N— salts and process for preparing them

2000-09-01

2003-06-24

Ryan, Patrick (Department: 1745)

Chemistry: electrical current producing apparatus, product, and

Current producing cell, elements, subcombinations and...

Include electrolyte chemically specified and method

C252S062200, C361S505000

Reexamination Certificate

active

06582849

ABSTRACT:

The invention relates to stable (CF
3
)
2
N
−
salts, to a process for preparing them and to their use as precursor for organic compounds.
Lithium ion batteries are amongst the most promising systems for mobile applications. The areas of application extend from high-quality electronic appliances (e.g. mobile phones, camcorders) to batteries for electrically driven motor vehicles.
These batteries consist of a cathode, an anode, a separator and a non-aqueous electrolyte. The cathodes used are typically Li(MnMe
z
)
2
O
4
, Li(CoMe
z
)O
2
, Li(CoNi
x
Me
z
)O
2
or other lithium intercalation and insertion compounds. Anodes can consist of lithium metal, carbon materials, graphite, graphitic carbon materials or other lithium intercalation and insertion compounds or alloy compounds. The electrolytes used are solutions containing lithium salts, such as LiPF
6
, LiBF
4
, LiClO
4
, LiAsF
6
, LiCF
3
SO
3
, LiN(CF
3
SO
2
)
2
or LiC(CF
3
SO
2
)
3
and mixtures thereof, in aprotic solvents.
During the search for novel salts for use in batteries, the class of bis(trifluoromethyl)amines was identified as suitable.
One of the first salts described in the literature from the class of bis(trifluoromethyl)amines is caesium bis-(trifluoromethyl)amide. This salt can be prepared by introducing perfluoro(2-azapropane) into a suspension of caesium fluoride and dry acetonitrile. Minkwitz (Inorg. Chem., 28 (1989), 1627-1630) isolates Cs
+−
N(CF
3
)
2
, but neither (C
6
H
5
)
4
As
+
(CF
3
)
2
N
−
nor (C
2
H
5
)
4
N
+
(CF
3
)
2
N
−
.
European application 99101982 describes a new method for preparing the (CF
3
)
2
N
−
anion with an inorganic cation. The salts are stable only in solution and thus have to be used directly.
SUMMARY OF THE INVENTION
The object of the present invention is therefore to provide stable (CF
3
)
2
N
−
salts and a process for preparing them.
The object according to the invention is achieved by compounds of the general formula
[([R
1
(CR
2
R
3
)
k
]
1
A
x
)
y
Kt]
+−
N(CF
3
)
2
  (I)
where
Kt is N, P, As, Sb, S or Se,
A is N, P, P(O), O, S, S(O), SO
2
, As, As(O), Sb or Sb(O),
R
1
, R
2
and R
3
are identical or different
and are each H, halogen, substituted and/or unsubstituted alkyl C
n
H
2n+1
, substituted and/or unsubstituted alkenyl having 1-18 carbon atoms and one or more double bonds, substituted and/or unsubstituted alkynyl having 1-18 carbon atoms and one or more triple bonds, substituted and/or unsubstituted cycloalkyl C
m
H
2m−1
, mono- or polysubstituted and/or unsubstituted phenyl, substituted and/or unsubstituted heteroaryl,
Kt can be included in a cyclic or heterocyclic ring, where the ring may number from 4-8 atoms. A heterocyclic ring may include at least one atom of O, N, P As, Sb, S, Se or combinations thereof. Exemplary rings including Kt are disclosed in U.S. Pat. No. 5,827,602, which is hereby incorporated by reference,
the groups bonded to Kt may be identical or different, where
n is 1-18
m is 3-7
k is 0 or 1-6
l is 1 or 2 in the case where x=1 and 1 in the case where x=0
x is 0 or 1
y is 1-4.
The compounds can be used as reagents for introducing N(CF
3
)
2
groups into organic substances. For instance, it is possible to prepare fluorinated solvents for secondary and primary batteries.
Surprisingly, a further possible application for these salts was found. Owing to their structure, the novel salts are of interest as precursors for the preparation of liquid-crystal compounds.
It has been found that the simple preparation of the complex compounds can be conducted under mild conditions. The salts are isolated in high yields.
Surprisingly, it has been found that the novel salts are stable. They can be isolated and stored at room temperature.
A general example of the invention is explained in greater detail below.
Compounds of the general formula
D
+−
N(CF
3
)
2
  (II)
where D
+
is selected from the group consisting of the metals, preferably alkali metals, are prepared by the process described in European patent application No. 99101982. Preferred alkali metals are Rb, Na, K, and Cs and other metals are Ag, Cu and Ag. A particularly preferred metal is Rb. Further suitable N(CF
3
)
2
-group providers are compounds of the general formula
GN(CF
3
)
2
  (IV)
where G is selected from the group consisting of fluorinated sulfonamides and fluorinated acylamides.
A solution of a compound of the general formula (II) or (IV) in a suitable polar organic solvent selected from the group consisting of acetonitrile, diethoxyethane and dimethylformamide is initially charged. A salt of the general formula
[([R
1
(CR
2
R
3
)
k
]
l
A
x
)
y
Kt]
+−
E  (III)
where
Kt=N, P, As, Sb, S or Se,
A=N, P, P(O), O, S, S(O), SO
2
, As, As(O), Sb or Sb(O),
R
1
, R
2
and R
3
are identical or different
and are each H, halogen, substituted and/or unsubstituted alkyl C
n
H
2n+1
, substituted and/or unsubstituted alkenyl having 1-18 carbon atoms and one or more double bonds, substituted and/or unsubstituted alkynyl having 1-18 carbon atoms and one or more triple bonds, substituted and/or unsubstituted cycloalkyl C
m
H
2m−1
, mono- or polysubstituted and/or unsubstituted phenyl, substituted and/or unsubstituted heteroaryl,
Kt can be included in a cyclic or heterocyclic ring, where the ring may number from 4-8 atoms. A heterocyclic ring may include at least one atom of O, N, P As, Sb, S, Se or combinations thereof. Exemplary rings including Kt are disclosed in U.S. Pat. No. 5,827,602,
the groups bonded to Kt may be identical or different, where
n=1-18
m=3-7
k=0 or 1-6
l=1 or 2 in the case where x=1 and 1 in the case where x=0
x=0 or 1
y=1-4 and
−
E=F
−
, Cl
−
, Br
−
, I
−
, BF
4
−
, ClO
4
−
, AsF
6
−
, SbF
6
−
or PF
6
−
is added in equimolar amounts, at temperatures between −40° C. and 80° C., preferably at room temperature.
Any volatile by-products which may form are removed by applying a reduced pressure. However, the by-products formed are usually salts which are insoluble in these solvents and which are filtered off.
The solvent is removed under reduced pressure. The reaction products can be obtained in yields of more than 80%. Most salts are stable at room temperature and do not decompose on melting.
The novel compounds can be used in electrolytes comprising conventional conductive salts. Examples of suitable electrolytes are those comprising conductive salts selected from the group consisting of LiPF
6
, LiBF
4
, LiClO
4
, LiAsF
6
, LiCF
3
SO
3
, LiN(CF
3
SO
2
)
2
and LiC(CF
3
SO
2
)
3
and mixtures thereof. The electrolytes may further comprise organic isocyanates (DE 199 44 603) to reduce the water content. Likewise, the electrolytes may comprise organic alkali metal salts (DE 199 10 968) as additives. Suitable alkali metal salts are alkali metal borates of the general formula
Li
+
B
−
(OR
1
)
m
(OR
2
)
p
where
m and p are 0, 1, 2, 3 or 4 with m+p=4 and R
1
and R
2
are identical or different,
if desired are joined directly to one another by a single or double bond,
and are, in each case individually or together, an aromatic or aliphatic carboxylic, dicarboxylic or sulfonic acid radical, or
are, in each case individually or together, an aromatic ring selected from the group consisting of phenyl, naphthyl, anthracenyl and phenanthrenyl, which may be unsubstituted or monosubstituted to tetrasubstituted by A or Hal, or
are, in each case individually or together, a heterocyclic aromatic ring selected from the group consisting of pyridyl, pyrazyl and bipyridyl, which may be unsubstituted or monosubstituted to trisubstituted by A or Hal, or
are, in each case individually or together, an aromatic hydroxy acid selected from the group consisting of aromatic hydroxycarboxylic acids and aromatic hydroxysulfonic acids, which may be u

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