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1037
(1a) (0.01 mol) and 157 g (1 mol) 4-chloronitrobenzene.
The mixture was heated to 170 8C with stirring for 5 h.
The reaction mixture was cooled to room temperature and
300 ml of water are added. After phase separation 4-fluor-
onitrobenzene was isolated via fractional distillation of the
organic phase. Yield ¼ 135 g liquid (0.96 mol), 96%.
For entries 8 and 9 in Table 1 (Et2N)4PBr and Ph4PBr
were used in the same process with 0.01 mol of each
catalyst. The yield was 93 and 89%, respectively.
and 28 g of sulpholane instead of dichloromethane were
used. The reaction mixture was stirred for 24 h (instead of
32 h) in step (b).
4.6.2. With PPh4Br
Tetraphenylphosphonium bromide of 8.38 g was used.
The reaction mixture was stirred for 28 h (instead of
32 h) in step (b).
4.6.3. With (NEt2)3PNPPh3Br (3a)
(NEt2)3PNPPh3Br of 12.75 g was used in the first step and
16.15 g in the second step, respectively.
4.4. 2,6-Difluorobenzaldehyde (7)
A vessel was charged with 600 g sulpholane and 211 g
KF. Sulpholane of 80 g was removed in vacuum. (N,N-
dimethylimidazolidino)-tetramethylguanidinium chloride
(1a) of 9.7 g and 265 g 2,6-dichlorobenzaldehyde were
added and the mixture was heated to 180 8C for 24 h with
stirring. 2,6-Difluorobenzaldehyde was isolated from the
reaction mixture by fractional distillation under reduced
pressure.
4.7. 1,3,5-Trifluorobenzene (16)
(a) A stainless steel autoclave was charged with 500 g
trichlorobenzene, 3 ml dichloromethane, 2.8 ml nitro-
benzene, 520 g potassium fluoride, 34.72 g 1a and
1100 ml sulpholane. The vessel was pressurised with
1 bar of nitrogen and the mixture was stirred at 230 8C
for 12 h. The vessel was cooled to room temperature
and the crude product mixture was distilled off,
analysed by GC and used in the next step without
further purification.
For entries 1 and 3 in Table 2, (NEt2)3PNPPh3Br (3a) and
Ph4PBr were used in the same process with the same
equimolar ratios of each catalyst compared to CNCþ (1a).
4.5. 2,4-Difluorobenzoyl fluoride (9)
(b) A stainless steel autoclave was charged with the crude
product from step (a), 2 ml dichloromethane, 2.8 ml
nitrobenzene, 292 g potassium fluoride, 34.72 g 1a and
620 ml sulpholane. The vessel was pressurised with
1 bar of nitrogen and the mixture was stirred at 230 8C
for 24 h. The vessel was cooled to room temperature
and the crude product mixture was distilled off and
analysed by GC.
A vessel was charged with 100 g (0.48 mol) 2,4-dichlor-
obenzoyl chloride, 1.78 g 1a, 100 g of dimethylimidazolin-
dione and 94.3 g (1.62 mol) potassium fluoride. The mixture
was stirred under nitrogen at 190 8C for 24 h. The product
was distilled off from the reaction mixture under reduced
pressure. Yield ¼ 75% (0.36 mol). For entry 8 in Table 3
(NEt2)3PNPPh3Br (3a) was used in the same process with
the same equimolar ratio compared to 1a.
4.7.1. With (NMe2)3PNPPh3Br (3b)
(NMe2)3PNPPh3Br (3b) of 35.8 g in each step was used
for the same process with half the amounts of all other
materials.
4.6. 2,3,4,5-Tetrafluorobenzotrifluoride (11) with CNCþ
(1a)
(a) A stainless steel autoclave was charged with 400 g
tetrachlorobenzotrifluoride, 212 g potassium fluoride,
5 g (N,N-dimethylimidazolidino)-tetramethyl-guanidi-
nium chloride (1a) and 2 g dichloromethane was stirred
for 8 h at 200 8C. The vessel was cooled to room
temperature. The solids were removed by filtration. The
product mixture was analysed by GC and used in the
next step without further purification.
(b) A stainless steel autoclave was charged with the crude
product from step (a), 6.3 g (N,N-dimethylimidazolidi-
no)-tetramethylguanidinium chloride (1a) and 193.5 g
potassium fluoride. The mixture was stirred at 200 8C
for 32 h. The vessel is then cooled to room temperature
and the crude product is distilled.
References
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4.6.1. With PNCþ(2a)
6.6 g
N-(N,N-dimethylimidazolidino)-tris-(diethyla-
mino)-phophazenium chloride (2a) instead of CNCþ (1a)
[8] A. Kolomeitsev, S. Pasenok, DE Patent 19 631 854 (1998).