Synthesis of K[4-ROC6F4BF3] from potassium pentafluorophenyltrifluoroborate and O-nucleophiles

Article abstract of DOI:10.1016/j.jfluchem.2013.01.020

A new route to potassium polyfluoroaryltrifluoroborates, K[4-ROC ₆F₄BF₃], consisting in the nucleophilic alkoxydefluorination of K[C₆F₅BF₃] with MOR (M = K, Na) in a polar aprotic solvent is suggested. Reaction of K[C ₆F₅BF₃] with KO-t-Bu proceeds smoothly at 25 °C in DME, but the attempted alkoxydefluorination of K[C₆F ₅BF₃] with other NaOR at 30 °C in DME failed. A series of K[4-ROC₆F₄BF₃] (R = Me, Et, Pr, i-Pr, Bu, PhCH₂) is prepared using the corresponding sodium alkoxides in DMF at 130 °C in 80-90% isolated yield. Salt K[4-CH₂CHCH ₂OC₆F₄BF₃] is prepared at 100 °C whereas at 130 °C formation of 2,3,5,6-C₆F₄HOCH ₂CHCH₂ occurs. Salt K[4-PhOC₆F ₄BF₃] is obtained in 82% yield using KOPh (2 equivalents) in DMSO at 130 °C.

Full text of DOI:10.1016/j.jfluchem.2013.01.020

Journal of Fluorine Chemistry 149 (2013) 82–87
Contents lists available at SciVerse ScienceDirect
Journal of Fluorine Chemistry
journal homepage: www.elsevier.com/locate/fluor
Synthesis of K[4-ROC6F4BF3] from potassium pentafluorophenyltrifluoroborate
and O-nucleophiles
Anton Yu. Shabalin a, Nicolay Yu. Adonin a, , Vadim V. Bardin a,b, Sergey A. Prikhod’ko a,
*
Maria N. Timofeeva a, Maria V. Bykova a, Valentin N. Parmon a
a G.K. Boreskov Institute of Catalysis, SB RAS, Acad. Lavrentjev Avenue 5, 630090 Novosibirsk, Russian Federation
b N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry, SB RAS, Acad. Lavrentjev Avenue 9, 630090 Novosibirsk, Russian Federation
A R T I C L E I N F O
A B S T R A C T
Article history:
A new route to potassium polyfluoroaryltrifluoroborates, K[4-ROC6F4BF3], consisting in the nucleophilic
alkoxydefluorination of K[C6F5BF3] with MOR (M = K, Na) in a polar aprotic solvent is suggested. Reaction
of K[C6F5BF3] with KO-t-Bu proceeds smoothly at 25 8C in DME, but the attempted alkoxydefluorination
of K[C6F5BF3] with other NaOR at 30 8C in DME failed. A series of K[4-ROC6F4BF3] (R = Me, Et, Pr, i-Pr, Bu,
PhCH2) is prepared using the corresponding sodium alkoxides in DMF at 130 8C in 80–90% isolated yield.
Salt K[4-CH255CHCH2OC6F4BF3] is prepared at 100 8C whereas at 130 8C formation of 2,3,5,6-
C6F4HOCH2CH55CH2 occurs. Salt K[4-PhOC6F4BF3] is obtained in 82% yield using KOPh (2 equivalents)
in DMSO at 130 8C.
Received 14 December 2012
Received in revised form 22 January 2013
Accepted 23 January 2013
Available online 10 February 2013
Keywords:
Pentafluorophenyltrifluoroborate
O-nucleophile
ß 2013 Elsevier B.V. All rights reserved.
Nucleophilic substitution
NMR spectroscopy
1. Introduction
[22] and by two transition metal catalyzed reactions. Thus,
potassium azidoaryltrifluoroborates were prepared in 73–98%
Organoboronic acids and potassium organotrifluoroborates are
widely used in organic synthesis [1–4]. A routine way to K[RBF3] is
transformation of the appropriate organoboronic acid or its
derivatives, RB(OAlk)2 or M[RB(OAlk)3], under the action of
K[HF2] [5,6]. An alternative promising approach to K[RBF3] is
modification of the organic moiety bonded to boron [7]. Many non-
fluorinated potassium organotrifluoroborates were prepared by this
route using oxidation [8], reductive amination [9], substitution
[10,11], condensation [12], the 1,3-dipolar cycloaddition [13], cross-
coupling reactions [14,15], and Wittig reactions [16–18]. Treatment
of CF255CF(CF3)2BꢀNMe3 withCF3SiMe3 in the presence of [Me4N]F in
THF gives a mixture of [Me4N][(E)-CF3CF55CF(CF3)2BF], [Me4N][(E)-
CF3CF55CF(CF3)3B], and [Me4N][CF255CF(CF3)2BF] [19]. Recently the
formation of K[RFCFXCF2BF3] from K[RFCF55CFBF3], K[RFCX2CF2BF3]
from K[RFCX55CFBF3] and K[RFCꢁCBF3] (X = Cl, Br) by electrophilic
halofluorination of polyfluoroalkenyltrifluoroborates with NCS or
NBS in aHF was reported [20]. Reaction of K[trans-C4F9CF55CFBF3]
with Cl2 in MeOH resulted in K[C4F9CFClC(O)BF3] [21]. To date, the
modification of aryl moiety in K[ArBF3] via substitution of an
aromatically bonded halogene atom is presented by metalation of
potassium 3- and 4-bromophenyltrifluoroborates with alkyllithium
yields from the corresponding bromo- or iodoaryltrifluoroborates,
NaN3, and CuBr or CuI (10 mol.%) in the presence of secondary amine
in DMSO [23]. Hydrodefluorination of K[C6F5BF3] with Zn in the
presence of NiCl2ꢀ6H2O and bpy in aprotic dipolar solvents (DMF,
DMA or NMP) resulted in K[2,3,4,5-C6HF4BF3] [24].
We elaborated a new convenient synthesis of K[4-ROC6F4BF3]
by reaction of easily available potassium pentafluorophenyltri-
fluoroborate, K[C6F5BF3] [25,26], with nucleophiles MOR
(M = Na, K; R = alkyl, allyl, benzyl and phenyl).
2. Results and discussion
Typical conditions of nucleophilic alkoxydefluorination of
polyfluoroaromatic compounds were heating with NaOAlk in
excess of the corresponding alcohol, THF or dioxan [27,28]. We
found that K[C6F5BF3] (1) does not react with methanol at 22 8C
over a period of 30 h, but at elevated temperature it undergoes
hydrodeboration to yield pentafluorobenzene (heating of 1 in
MeOH at 70 8C for 4 h as well as at 90 8C for 1 h gives C6F5H at 80%
conversion of 1). Complete hydrodeboration of 1 occurred at 90 8C
over 6 h. In all cases, formation of K[BF3OMe] and K[BF2(OMe)2]
was detected by the 19F NMR spectroscopy (Scheme 1).
Unexpectedly, K[C6F5BF3] does not react with NaOMe in MeOH
at 24 8C over a period of 28 h as well as under reflux for 4 h.
* Corresponding author. Tel.: +7 383 326 9674; fax: +7 383 330 8056.
E-mail address: adonin@catalysis.ru (N.Yu. Adonin).
0022-1139/$ – see front matter ß 2013 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.jfluchem.2013.01.020

A.Y. Shabalin et al. / Journal of Fluorine Chemistry 149 (2013) 82–87
83
F
F
F
F
F
F
F
F
F
F
F
F
DMF
130 °C, 4 h
O
70-90 °C
+ K[BFn(OMe)4-n
]
+ MeOH
K
F
BF3
F
F
F
F
F
2
(n = 2,3)
ONa
+
BF3
K
F
1
1. DMF,
F
F
F
F
100 °C, 4 h
Scheme 1.
1
K
O
BF3
2. K[HF2],
DMF,
25 °C, 8 h
F
F
F
F
F
F
F
Scheme 5.
DME
25 °C, 3 h
K
K
t-BuO
F
BF3 + KO-t-Bu
BF3
+ KF
F
F
F
F
F
F
F
F
F
F
F
F
F
DMSO
125 °C, 8 h
K
1
88 %
F
BF3 + KOH
F
+ F
OK +
OK +
F
F
F
F
Scheme 2.
+ K[BF4] + K[BF3OH]
1
Scheme 6.
F
F
F
F
DMSO
130 °C, 4 h
K
F
BF3
K
+ KOPh
PhO
BF3 + KF
M[4-ROC6F4BF3] (M = K, Na) with wet K[HF2] (in excess) led to
desired potassium salt in high yield (Scheme 4).
F
F
F
F
Reaction of K[C6F5BF3] with NaOCH2CH55CH2 under the same
conditions gives 1-allyloxy-2,3,5,6-tetrafluorobenzene (2) besides
minor pentafluorobenzene. Decreasing temperature to 100 8C
allowed to prepare potassium 4-allyloxy-2,3,5,6-tetrafluorophe-
nyltrifluoroborate in 87% isolated yield (Scheme 5).
1
82 %
Scheme 3.
These circumstances promoted us to use aprotic solvents as a
In contrast to alkoxydefluorination, our attempt to prepare K[4-
HOC6F4BF3] from 1 and KOH in DMSO failed. No reaction was
observed after stirring at 80 8C over 4 h. When the temperature
was increased up to 125 8C and the reaction time was prolongated
to 8 h, potassium 2,3,5,6-tetrafluorophenolate (major), and few
pentafluorobenzene and KOC6F5 were formed besides K[BF4] and
K[BF3OH] at 33% conversion of 1 (Scheme 6).
reaction media instead of alcohols. Although K[C6F5BF3] is low
soluble in 1,2-dimethoxyethane (DME) (low-polar aprotic solvent),
it reacts with commercially available KO-t-Bu (3 equivalents) at
room temperature to give K[4-t-BuOC6F4BF3] in high yield (Scheme
2).
Attempted reaction of K[C6F5BF3] with NaO-t-Bu prepared from
t-butanol and NaH in DME (30 8C, 7 h) leads to incomplete
conversion of 1 with formation of M[C6F5BFn(OAlk)3-n], C6F5H,
2,3,5,6-C6F4HOCH3, and 2,3,5,6-C6F4HOCH2CH2OCH3 besides un-
known products. Target borate, K[4-t-BuOC6F4BF3], was not
detected. Similar unsatisfactory results were obtained in reaction
with NaOR (R = Me, Et, Pr, i-Pr, Bu) in DME (30 8C, 4 h) (19F NMR),
but in these cases detailed analysis of products was not performed.
To determine the optimal reaction conditions, we studied
reaction of K[C6F5BF3] with potassium phenoxide in some polar
aprotic solvents. Stirring of 1 with KOPh (1 equivalent) in DMF at
100 8C for 4 h results in 6% conversion of substrate. At 130 8C
conversion of 1 increases to 24%. The related results were obtained
in dimethylacetamide and in N-methylpyrrolidone. When reaction
was performed in DMSO at 130 8C, conversion of 1 became 62%, but
prolongation of reaction time to 10 h was not effective. The
satisfactory result (85% conversion of 1) was achieved using two
equivalents of KOPh.
The obtained results showed the unambiguous substitution of
fluorine atom at position para to BF3 group in K[C6F5BF3]. No
detectable amounts of K[2- and 3-ROC6F4BF3] isomers were found.
Taking into account the strong
s
-electron donor effect and
I = –0.32,
negligible mesomeric influence of [BF3]ꢂgroup
(
s
s
R = ꢂ0.07 [25]), this picture is expected because such combina-
tion of electronic effects of X in C6F5X favors to the formation of 4-
R0C6F4X (detailed discussion of nucleophilic substitution in C6F5X
see reviews [27,28]).
3. Conclusions
The studied O-nucleophiles exclusively attack the carbon atom
of [C6F5BF3] (1) at the para-position to BF3 group. KO-t-Bu reacts
with K[C6F5BF3] in DME at 25 8C to give K[4-t-BuOC6F4BF3] in 88%
preparative yield. Sodium alkoxides (in situ generated from
aliphatic alcohols and NaH) are the less reactive, and for successful
alkoxydefluorination of 1 reaction should be performed at 130 8C
in polar aprotic solvents (DMF etc.). After treatment with K[HF2]
salts K[4-ROC6F4BF3] (R = Me, Et, Pr, i-Pr, Bu and PhCH2) were
obtained in 86–98% yields. Reaction of 1 with sodium allylate at
130 8C gave 1-allyloxy-2,3,5,6-tetrafluobenzene while at lower
temperature (100 8C) the desired salt K[4-AllylOC6F4BF3] was
synthesized in 81% yield.
Reaction in preparative scale gave potassium 4-phenoxy-
2,3,5,6-tetrafluorophenyltrifluoroborate in 82% yield after crystal-
lization from ethanol (Scheme 3).
K[C6F5BF3] smoothly reacts with sodium alkoxides (prepared
from ROH and NaH) in DMF at 130 8C to form the corresponding 4-
alkoxy-2,3,5,6-tetrafluorophenyltrifluoroborates in >92% yield
(
19F NMR) at quantitative conversion of 1. Treatment of crude
4. Experimental part
K[HF2]
F
F
F
F
F
F
F
F
F
F
F
F
(excess)
ROH, NaH
K
K(Na)
K
RO
F
BF3
RO
BF3
BF3
4.1. General
DMF
DMF
130 °C, 4 h
25 °C, 8 h
The NMR spectra were recorded on a Bruker AVANCE 300
spectrometer (1H at 300.13 MHz, 19F at 282.40 MHz, and 11B at
96.29 MHz). The chemical shifts are referenced to TMS (1H), CCl3F
R = Me (88%), Et (81%), Pr (87%), i-Pr (86%), Bu (89%), PhCH2 (80%)
Scheme 4.

84
A.Y. Shabalin et al. / Journal of Fluorine Chemistry 149 (2013) 82–87
(
19F, with C6F6 as secondary reference (ꢂ162.9 ppm)), and
1,3-(CH2 = CHCH2O)2-2,5,6-C6F3H (4) (mixture with 3). 1H NMR
(acetone-d6):
6.84 (ddd, 4J(H4, F2) = 7.5 Hz, 4J(H4, F6) = 7.5 Hz,
3J(H4, F5) = 12.2 Hz, 1H, H4), 6.03 (m, 1H), 5.39 (m, 1H), 5.26 (m,
BF3ꢀOEt2/CDCl3 (15%, v/v) (11B), respectively. IR spectra were
measured on a Shimadzu FTIR-8300 spectrometer. GC–MS analysis
was done on a Hewlett-Packard 1800A (with HP-5MS column)
instrument. High resolution mass spectra were recorded on a
Thermo Scientific DFS spectrometer in EI mode (70 eV). These
analyses as well as elemental analysis were performed in the
Collective Service Center of SB RAS (Novosibirsk).
d
a
b
a
1H), 4.67 (d, 3J(H , H ) = 5.8 Hz, 2H, H ). 19F NMR (acetone-d6):
d
ꢂ142.0 (ddd, 3J(F5, F6) = 22 Hz, 3J(F5, H4) = 12 Hz, 5J(F5, F2) = 10 Hz,
1F, F5), ꢂ153.3 (dd, 4J(F2, H4) = 7 Hz, 5J(F2, F5) = 10 Hz, 1F, F2),
ꢂ161.9 (dd, 3J(F6, F5) = 22 Hz, 4J(F6, H4) = 7 Hz, 1F, F6). HRMS (ESI)
Calcd. for C12H11F3O2: 244,0706, found 244.0708 (isomer mixture).
As a convention for the presentation of the NMR spectral data,
the labeling of the hydrogen atoms in RO groups is presented by
Greek superscripts, e.g., CH3 –CH2 –O.
4.4. Reaction of K[C6F5BF3] with MeOH
b
a
Dimethylformamide was distilled over P4O10 under reduced
pressure. Methanol, ethanol, propanol-1, propanol-2, butanol-1,
and t-butanol were refluxed with CaO and distilled. t-Butanol was
additionally crystallized by freezing. Allyl alcohol was stirred with
K2CO3 and distilled. 1,2-Dimethoxyethane (Acros) was stirred with
CaH2 and distilled. N-Methylpyrrolidone (Acros) and dimethyl
sulfoxide (Panreac) were stirred with CaH2 and distilled. NaH (60%
dispersion in oil) (Sigma–Aldrich), benzyl alcohol (Acros) and KO-
t-Bu (Merck) were used as supplied. Potassium pentafluorophe-
nyltrifluoroborate was prepared as described [26]. Previously
unknown 2,3,5,6-C6F4HOCH2CH55CH2 was prepared from C6F5H
and sodium allyloxide in DMSO.
(1) A solution of K[C6F5BF3] (25 mg, 0.09 mmol) in MeOH (0.8 mL)
was kept at 24 8C for 30 h. The 19F NMR spectrum showed no
reaction.
(2) A solution of K[C6F5BF3] (25 mg, 0.09 mmol) in MeOH (0.8 mL)
was kept at 70 8C for 4 h in a sealed tube. The 19F NMR spectrum
showed resonances of K[C6F5BF3] (80% conversion), C6F5H
(0.07 mmol), K[BF3OMe] (0.05 mmol) and K[BF2(OMe)2]
(0.02 mmol) (C6F6 quantitative internal reference).
(3) A solution of K[C6F5BF3] (31 mg, 0.11 mmol) in MeOH (0.7 mL)
was kept at 90 8C for 1 h in a sealed tube. The 19F NMR spectrum
showed resonances of K[C6F5BF3] (81% conversion), C6F5H
(0.07 mmol), K[BF3OMe] (0.03 mmol) and K[BF2(OMe)2]
(0.04 mmol) (C6F6 quantitative internal reference).
4.2. Preparation of potassium phenoxide
(4) A solution of K[C6F5BF3] (34 mg, 0.12 mmol) in MeOH (0.9 mL)
was kept at 90 8C for 6 h in a sealed tube. The 19F NMR spectrum
showed resonances of C6F5H (0.12 mmol), K[BF3OMe]
(0.06 mmol) and K[BF2(OMe)2] (0.05 mmol) (C6F6 quantitative
internal reference).
A 25 mL flask was charged with freshly distilled phenol (2.9 g,
30 mmol), KOH (1.7 g, 30 mmol) and distilled water (10 mL).
Solution was stirred at 24 8C for 0.5 h and evaporated to dryness
under reduced pressure to yield 3.9 g (98%) of KOPh.
K[BF3OMe]. 19F NMR (MeOH):
d
ꢂ152.7 (q (1:1:1:1), 1J(F,
B) = 12 Hz, 3F) (lit. 19F NMR (MeOH, ꢂ50 8C):
d
ꢂ150.6 (q
(1:1:1:1), 1J(F, B) = 12 Hz, 3F) [29])
4.3. Preparation of 2,3,5,6-C6F4HOCH2CH55CH2
K[BF2(OMe)2]. 19F NMR (MeOH):
d
ꢂ155.1 (q (1:1:1:1), 1J(F,
A 50 mL flask was charged with DMSO (18 mL) and allyl
alcohol (1.48 g, 25 mmol). An addition of the first portions of
NaH caused exothermic reaction with gas evolution and
formation of voluminous foam. The further addition of NaH
(total 1.17 g, 29 mmol) was performed at 80–85 8C (bath) within
20–30 min. The formed solution was stirred at 80 8C for 40 min,
cooled to 60 8C and solution of C6F5H (3.4 g, 20 mmol) in DMSO
(2 mL) was added in portions. Within 10–20 min white
suspension was formed. It was stirred at 60 8C for 3 h, diluted
with water (30 mL), and steam distilled. Bottom phase of
distillate was separated, aqueous one was extracted with CH2Cl2
(2ꢃ 5 mL), combined extract was washed with water and dried
with MgSO4. Solvent was removed under reduced pressure to
give colorless liquid (3.0 g), which consisted of 2,3,5,6-
C6F4HOCH2CH55CH2 (2) (77%), 1,2-diallyloxy-3,4,6-trifluoroben-
zene (3) (5%) and 1,3-diallyloxy-2,5,6-trifluorobenzene (4) (18%)
B) = 23 Hz, 3F) (lit. 19F NMR (MeOH, ꢂ50 8C):
(1:1:1:1), 1J(F, B) = 22 Hz, 3F) [29])
d
ꢂ153.5 (q
4.5. Reaction of K[C6F5BF3] with NaOMe in MeOH
K[C6F5BF3] (305 mg, 1.11 mmol) was dissolved in MeOH
(10 mL) and a solution of NaOMe (1.5 mmol) in MeOH (1.8 mL)
(prepared from sodium and methanol) was added in one portion.
Solution was stirred at 24 8C for 28 h (no reaction) (19F NMR) and
then refluxed with stirring for 4 h. The 19F NMR spectrum showed
resonances of K[C6F5BF3] besides trace of C6F5H.
4.6. Reaction of K[C6F5BF3]) with NaOR (R = Me, Et, Pr, i-Pr, Bu,
PhCH2) in DMF (general procedure)
(
19F NMR). Vacuum distillation gave 2 (2.0 g) (bp. 38–40 8C
A 10 mL flask equipped with a magnetic stir bar was charged
with DMF (2 mL), BuOH (119 mg, 1.6 mmol), and NaH (56 mg,
1.4 mmol) was added in one portion to cause gas evolution and
foaming. Suspension was stirred at 25 8C for 1 h under an
atmosphere of argon, and K[C6F5BF3] (274 mg, 1.0 mmol) was
added in one portion. The flask was immersed into hot (130 8C) oil
bath, and the reaction mixture was stirred for 4 h. After cooling to
(6 Torr)) and isomer mixture 3 and 4 (0.2 g) (bp. 44–48 8C
(1 Torr).
2,3,5,6-C6F4HOCH2CH55CH2 (2). 1H NMR (acetone-d6):
d
7.14
(tt, 3J(H4, F3, 5) = 10.5 Hz, 4J(H4, F2, 6) = 7.2 Hz, 1H, H4), 6.03 (m, 1H),
a
b
a
5.39 (m, 1H), 5.26 (m, 1H), 4.75 (d, 3J(H , H ) = 6 Hz, 2H, H ). 19F
NMR (acetone-d6):
d
ꢂ140.3 (ddd, 3J(F3, F2) = 22 Hz, 3J(F3,
H4) = 10 Hz, 5J(F3, F6) = 10 Hz, 2F, F3, 5), ꢂ156.4 (ddd, 3J(F2,
F3) = 22 Hz, 5J(F2, F5) = 10 Hz, 4J(F2, H4) = 8 Hz, 2F, F2, 6). HRMS
(ESI) Calcd. for C9H6F4O: 206.0349, found 206.0351.
25 8C, C6H5CF3 (10 ml, 0.082 mmol) (quantitative internal stan-
dard) was injected. The 19F NMR spectrum showed the formation
of M[4-BuOC6F4BF3] (M = K, Na) in 97% yield. Water (0.2 mL) and
K[HF2] (780 mg, 10 mmol) were added, and mixture was stirred at
25 8E for 8 h. The mixture was diluted with MeCN (5 mL) and
stirred with K2CO3 (50 mg) for 1–2 h. Suspension was filtered
1,2-(CH255CHCH2O)2-3,4,6-C6F3H (3) (mixture with 4). 1H NMR
(acetone-d6):
d
6.96 (dt, 4J(H4, F6) = 7.3 Hz, 3J(H4, F3, 5) = 10.7 Hz,
a
1H, H4), 6.03 (m, 1H), 5.39 (m, 1H), 5.26 (m, 1H), 4.60 (d, 3J(H ,
b
a
H ) = 6 Hz, 2H, H ). 19F NMR (acetone-d6):
d
ꢂ131.9 (dd, 4J(F3,
through a silica gel (60 mm), which was washed additionally with
H4) = 11 Hz, 5J(F3, F6) = 10 Hz, 1F, F3), ꢂ141.1 (dd, 3J(F5, F6) = 22 Hz,
3J(F5, H4) = 11 Hz, 1F, F5), ꢂ157.4 (ddd, 3J(F6, F5) = 22 Hz, 5J(F6,
F3) = 10 Hz, 4J(F6, H4) = 8 Hz, 1F, F6).
acetonitrile (10 mL) Combined solution was evaporated under
reduced pressure to yield K[4-BuOC6F4BF3] (white solid) (292 mg,
89%). Salts K[4-MeOC6F4BF3], K[4-EtOC6F4BF3], K[4-PrOC6F4BF3],

A.Y. Shabalin et al. / Journal of Fluorine Chemistry 149 (2013) 82–87
85
K[4-i-PrOC6F4BF3], and K[4-PhCH2OC6F4BF3] were prepared in 88,
81, 87, 86 and 80% isolated yield, respectively.
Reaction of K[C6F5BF3] (137 mg, 0.5 mmol) with allyl alcohol
(47 mg, 0.8 mmol) and NaH (28 mg, 0.7 mmol) in DMF (1 mL)
under the same conditions led to formation of 1-allyloxy-2,3,5,6-
ꢂ159.5 (dd, 3J(F3, F2) = 23 Hz, 5J(F3, F6) = 11 Hz, 2F, F3,5). IR (KBr):
2962w (CH), 1657 m, 1508 m, 1390w, 1301w, 1150 m, 841w,
811 m, 759w, 637w cmꢂ1
.
Anal. calcd for C10H9BF7KO (328.03): C, 36.61; H, 2.77; F, 40.54;
found: C, 34.9; H, 2.66; F, 41.5.
tetrafluorobenzene
(2)
(0.36 mmol)
besides
C6F5H
K[4-C6H5CH2OC6F4BF3]. 1H NMR (CH3CN):
d
7.42 (m, 2H, Hortho),
a
(0.06 mmol), M[BF4] (M = K, Na) and minor unknown products
(determined by 19F NMR in mother liquor after cooling of reaction
suspension).
7.34 (m, 3H, Hpara, meta), 5.15 (s, 2H, H ). 1H NMR (acetone):
d
7.64
a
(m, 2H, Hortho), 7.54 (m, 3H, Hpara, meta), 5.36 (s, 2H, H ). 11B NMR
(acetone):
d d
1.90 (q, 1J(B, F) = 44 Hz, BF3). 19F NMR (acetone):
K[4-CH3OC6F4BF3]. 1H NMR (CD3CN):
NMR (acetone):
4.14 (s, 3H, CH3). 11B NMR (acetone):
1J(B, F) = 44 Hz, BF3). 19F NMR (CD3CN): –133.3 (q, 1J(F, B) = 44 Hz,
d
3.96 (s, 3H, CH3). 1H
ꢂ133.6 (q, 1J(F, B) = 44 Hz, 3F, BF3), ꢂ135.3 (ddq, 3J(F2, F3) = 24 Hz,
d
d
1.93 (q,
5J(F2, F5) = 12 Hz, 4J(F2, BF3) = 12 Hz, 2F, F2, 6), ꢂ158.9 (dd, 3J(F3,
d
F2) = 24 Hz, 5J(F3, F6) = 11 Hz, 2F, F3, 5). 19F NMR (CD3CN):
d
ꢂ133.4
3F, BF3),–136.5 (ddq, 3J(F2, F3) = 23 Hz, 5J(F2, F5) = 11 Hz, 4J(F2,
BF3) = 11 Hz, 2F, F2, 6), ꢂ160.1 (dd, 3J(F3, F2) = 23 Hz, 5J(F3,
(q, 1J(F, B) = 43 Hz, 3F, BF3), ꢂ135.3 (ddq, 3J(F2, F3) = 24 Hz, 5J(F2,
F5) = 11 Hz, 4J(F2, BF3) = 12 Hz, 2F, F2, 6), ꢂ158.8 (dd, 3J(F3,
F6) = 11 Hz, 2F, F3, 5). 19F NMR (DMF):
d
–132.9 (q, 1J(F,
F2) = 24 Hz, 5J(F3, F6) = 11 Hz, 2F, F3, 5). 19F NMR (DMF):
d–132.9
B) = 44 Hz, 3F, BF3), ꢂ135.3 (ddq, 3J(F2, F3) = 23 Hz, 5J(F2,
F5) = 12 Hz, 4J(F2, BF3) = 12 Hz, 2F, F2, 6), ꢂ160.2 (dd, 3J(F3,
F2) = 24 Hz, 5J(F3, F6) = 11 Hz, 2F, F3, 5). IR (KBr): 2958w, 2926w
(CH), 1654 m, 1508 m, 1459vs, 1409w, 1384w, 1301 m, 1195 m,
1140s, 1041 m, 1003s, 952vs, 810 m, 759w, 636 m, 581w,
(q, 1J(F, B) = 47 Hz, 3F, BF3), ꢂ135.3 (ddq, 3J(F2, F3) = 24 Hz, 5J(F2,
F5) = 11 Hz, 4J(F2, BF3) = 12 Hz, 2F, F2, 6), ꢂ158.8 (dd, 3J(F3,
F2) = 24 Hz, 5J(F3, F6) = 11 Hz, 2F, F3, 5). IR (KBr): 3065w, 3035w
(CAr–H), 2928w (C–H), 1654 m, 1506 m, 1458vs, 1382 m, 1300 m,
1217w, 1148vs, 1086 m, 1003s, 953vs, 908 m, 841w, 812 m,
489w cmꢂ1
.
741 m, 697 m, 634w, 475w cmꢂ1
.
Anal. calcd for C7H3BF7KO (286.00): C, 29.40; H, 1.06; F, 46.50.
Anal. calcd for C13H7BF7KO (362.08): C, 43.12; H, 1.95; F, 36.73;
found: C, 43.0; H, 1.84; F, 36.7.
Found: C, 29.5; H, 1.21; F, 46.4.
a
K[4-C2H5OC6F4BF3]. 1H NMR (CD3CN):
d
4.29 (q, 3J(H ,
To get correct analytical data, salts K[4-C2H5OC6F4BF3], K[4-
C3H7OC6F4BF3], and K[4-(CH3)2CHOC6F4BF3] were converted to the
corresponding tetrabutylammonium salts by metathesis with
[Bu4N]Br (0.92 equivalent) in MeCN (10–12 mL per mmol of
borate) at 25 8C for 1 h. After centrifugation, the mother liquor was
decanted, and evaporated to dryness on evaporator to give viscous
oil which solidified within days. Yield was 95–100%.
[Bu4N][4-C2H5OC6F4BF3]. Anal. calcd for C24H41BF7NO (503.39):
C, 57.26; H, 8.21; F, 26.42; N, 2.78; found: C, 57.6; H, 8.44; F, 25.6;
N, 3.25.
[Bu4N][4-C3H7OC6F4BF3]. Anal. calcd for C25H43BF7NO (517.42):
C, 58.03; H, 8.38; F, 25.70; N, 2.71; found: C, 57.8; H, 8.34; F, 24.4;
N, 2.35.
[Bu4N][4-(CH3)2CHOC6F4BF3]. Anal. calcd for C25H43BF7NO
(517.42): C, 58.03; H, 8.38; F, 25.70; N, 2.71; found: C, 58.1; H,
9.24; F, 25.0; N, 2.86.
b
a
b
a
b
H ) = 7.0 Hz, 2H, H ), 1.36 (t, 3J(H , H ) = 7.0 Hz, 3H, H ). 19F
NMR (CD3CN):
d
ꢂ133.3 (q, 1J(F, B) = 43 Hz, 3F, BF3), ꢂ134.9 (ddq,
3J(F2, F3) = 29 Hz, 5J(F2, F5) = 9 Hz, 4J(F2, BF3) = 9 Hz, 2F, F2, 6),
ꢂ157.2 (dd, 3J(F3, F2) = 29 Hz, 5J(F3, F6) = 9 Hz, 2F, F3, 5). 19F NMR
(DMF):
d
ꢂ132.9 (q, 1J(F, B) = 46 Hz, 3F, BF3), ꢂ135.3 (ddq, 3J(F2,
F3) = 24 Hz, 5J(F2, F5) = 12 Hz, 4J(F2, BF3) = 12 Hz, 2F, F2, 6), ꢂ159.6
(dd, 3J(F3, F2) = 24 Hz, 5J(F3, F6) = 12 Hz, 2F, F3, 5). IR (KBr): 2999w
(CH), 1652w, 1503 m, 1461vs, 1396w, 1300 m, 1152s, 1103 m,
1003 m, 955vs, 866w, 813 m, 758w, 640w cmꢂ1
K[4-C3H7OC6F4BF3]. 1H NMR (CD3CN):
.
a
d
4.10 (t, 3J(H ,
b
a
b
a
b
H ) = 6.6 Hz, 2H, H ), 1.73 (tq, 3J(H , H ) = 6.6 Hz, 3J(H ,
g
b
g
b
g
H ) = 7.4 Hz, 2H, H ), 1.00 (t, 3J(H , H ) = 7.4 Hz, 3H, H ). 19F
NMR (CD3CN):
d
ꢂ133.4 (q, 1J(F, B) = 44 Hz, 3F, BF3), ꢂ136.7 (ddq,
3J(F2, F3) = 23 Hz, 5J(F2, F5) = 11 Hz, 4J(F2, BF3) = 11 Hz, 2F, F2, 6),
ꢂ159.4 (dd, 3J(F3, F2) = 23 Hz, 5J(F3, F6) = 11 Hz, 2F, F3, 5). 19F NMR
(DMF):
d
ꢂ132.9 (q, 1J(F, B) = 46 Hz, 3F, BF3), ꢂ135.3 (ddq, 3J(F2,
F3) = 24 Hz, 5J(F2, F5) = 12 Hz, 4J(F2, BF3) = 12 Hz, 2F, F2, 6), ꢂ159.7
(dd, 3J(F3, F2) = 24 Hz, 5J(F3, F6) = 12 Hz, 2F, F3, 5). IR (KBr): 2968 m
(CH), 1655 m, 1507 m, 1456vs, 1396w, 1300w, 1140s, 1005 m,
4.7. Preparation of K[4-CH255CHCH2OC6F4BF3]
A 10 mL flask was charged with NaH (112 mg, 2.8 mmol), DMF
(4 mL) and allyl alcohol (186 mg, 3.2 mmol). Suspension was
stirred at 25 8C for 1 h under an atmosphere of argon and
K[C6F5BF3] (548 mg, 2.0 mmol) was added in one portion. The flask
was immersed into hot (100 8C) oil bath, and the reaction mixture
was stirred for 4 h. The reaction mixture was cooled and treated as
described above (3.6) to give K[4-CH255CHCH2OC6F4BF3] (542 mg,
87%).
957vs, 814 m, 758w, 637w cmꢂ1
K[4-(CH3)2CHOC6F4BF3]. 1H NMR (CD3CN):
H ) = 6.1 Hz, 1H, H ), 1.30 (d, 3J(H , H ) = 6.1 Hz, 6H, H ). 1H NMR
.
a
d
4.43 (sept, 3J(H ,
b
a
b
a
b
a
b
a
b
(acetone):
d
4.33 (sept, 3J(H , H ) = 6.0 Hz, 1H, H ), 1.21 (d, 3J(H ,
a
b
H ) = 6.0 Hz, 6H, H ). 11B NMR (acetone):
d
1.77 (q, 1J(B, F) = 44 Hz,
BF3). 19F NMR (acetone):
d
ꢂ133.5 (q, 1J(F, B) = 43 Hz, 3F, BF3),
ꢂ135.5 (ddq, 3J(F2, F3) = 24 Hz, 5J(F2, F5) = 12 Hz, 4J(F2, BF3) = 12 Hz,
2F, F2, 6), ꢂ158.8 (dd, 3J(F3, F2) = 24 Hz, 5J(F3, F6) = 12 Hz, 2F, F3, 5).
K[4-CH255CHCH2OC6F4BF3]. 1H NMR (CH3CN):
d 6.05 (ddt,
b
g
b
g
b
19F NMR (CD3CN):
d
ꢂ133.2 (q, 1J(F, B) = 43 Hz, 3F, BF3),–136.5
3J(H ,
H
cis) = 10.4 Hz; 3J(H ,
H
trans) = 17.2 Hz, 3J(H ,
a
b
g
b
g
(ddq, 3J(F2, F3) = 23 Hz, 5J(F2, F5) = 11 Hz, 4J(F2, BF3) = 12 Hz, 2F, F2,
6), ꢂ158.6 (dd, 3J(F3, F2) = 23 Hz, 5J(F3, F6) = 11 Hz, 2F, F3, 5). 19F
H ) = 6.1 Hz; 1H, H ), 5.36 (d, 3J(H trans, H ) = 17.2 Hz, 1H, H
g
b
g
a
trans), 5.26 (d, 3J(H cis, H ) = 10.4 Hz, 1H cis), 4.63 (d, 3J(H ,
b
a
b
g
NMR (DMF):
d
ꢂ132.9 (q, 1J(F, B) = 47 Hz, 3F, BF3), ꢂ135.4 (ddq,
H ) = 6.1 Hz, 2H, H ). 1H NMR (acetone):
d
6.20 (ddt, 3J(H , H
b
g
b
a
b
3J(F2, F3) = 24 Hz, 5J(F2, F5) = 12 Hz, 4J(F2, BF3) = 12 Hz, 2F, F2, 6),
ꢂ158.6 (dd, 3J(F3, F2) = 24 Hz, 5J(F3, F6) = 12 Hz, 2F, F3, 5). IR (KBr):
2975 m (CH), 2934w, 1653 m, 1501 m, 1455vs, 1386 m, 1356w,
1300 m, 1154vs, 1108 m, 1032 m, 1005s, 952vs, 910 m, 831 m,
cis) = 11 Hz; 3J(H , H trans) = 17 Hz, 3J(H , H ) = 6 Hz; 1H, H ), 5.53
g
b
g
g
cis
(d, 3J(H
,
H ) = 17 Hz, 1H,
H
trans), 5.40 (d, 3J(H
,
trans
b
g
a
b
b
H ) = 11 Hz, 1H cis), 4.80 (d, 3J(H , H ) = 6 Hz, 2H, H ). 11B NMR
(acetone):
d d
1.92 (q, 1J(B, F) = 44 Hz, BF3). 19F NMR (acetone):
808 m, 757w, 669w, 636 m, 502w cmꢂ1
K[4-C4H9OC6F4BF3]. 1H NMR (CD3CN):
.
ꢂ133.6 (qt, 1J(F, B) = 44 Hz, 4J(F, F2, 6) = 11 Hz, 3F, BF3), ꢂ135.5
(ddq, 3J(F2, F3) = 23 Hz, 5J(F2, F5) = 12 Hz, 4J(F2, BF3) = 12 Hz, 2F, F2,
6), ꢂ159.1 (dd, 3J(F3, F2) = 23 Hz, 5J(F3, F6) = 12 Hz, 2F, F3, 5). 19F
a
d
4.13 (t, 3J(H ,
b
a
b
a
b
H ) = 6.4 Hz, 2H, H ), 1.72 (tt, 3J(H , H ) = 6.6 Hz, 3J(H ,
g
b
g
b
g
H ) = 7.4 Hz, 2H, H ), 1.49 (tq, 3J(H , H ) = 7.4 Hz, 3J(H ,
NMR (CD3CN):
d
ꢂ133.3 (q, 1J(F, B) = 45 Hz, 3F, BF3), ꢂ136.4 (ddq,
d
g
d
g
d
H ) = 7.4 Hz, 2H, H ), 0.97 (t, 3J(H , H ) = 7.4 Hz, 3H, H ). 19F
3J(F2, F3) = 23 Hz, 5J(F2, F5) = 11 Hz, 4J(F2, BF3) = 11 Hz, 2F, F2, 6),
ꢂ158.9 (dd, 3J(F3, F2) = 24 Hz, 5J(F3, F6) = 11 Hz, 2F, F3, 5). 19F NMR
NMR (CD3CN):
d
ꢂ133.2 (q, 1J(F, B) = 45 Hz, 3F, BF3), ꢂ136.6 (ddq,
3J(F2, F3) = 23 Hz, 5J(F2, F5) = 11 Hz, 4J(F2, BF3) = 11 Hz, 2F, F2,6),
(DMF):
d
–132.9 (q, 1J(F, B) = 46 Hz, 3F, BF3), ꢂ135.3 (ddq, 3J(F2,

86
A.Y. Shabalin et al. / Journal of Fluorine Chemistry 149 (2013) 82–87
F3) = 22 Hz, 5J(F2, F5) = 10 Hz, 4J(F2, BF3) = 10 Hz, 2F, F2, 6), ꢂ159.0
(dd, 3J(F3, F2) = 22 Hz, 5J(F3, F6) = 10 Hz, 2F, F3, 5). IR (KBr): 2928w
(C–H), 1653 m, 1504 m, 1459vs, 1385 m, 1301 m, 1250 m, 1149vs,
Anal. calcd for C10H9BF7KO (328.08): C, 36.61; H, 2.77; F, 40.54;
found: C, 36.2; H, 2.58; F, 40.6.
1003s, 1008s, 956vs, 812 m, 760w, 635w, 577w cmꢂ1
.
4.11. Reaction of K[C6F5BF3] with NaO-t-Bu in DME
Anal. calcd for C9H5BF7KO (312.03): C, 36.64; H, 1.62; F, 42.62;
found: C, 36.2; H, 1.41; F, 42.8.
A 10 mL flask was charged with DME (2 mL), t-BuOH (105 mg,
1.4 mmol), and NaH (57 mg, 1.4 mmol). The reaction mixture was
stirring at 25 8E for 1 h. K[C6F5BF3] (129 mg, 0.47 mmol) was
added, and suspension was stirred at 30 8E for 7 h. After cooling to
20 8C, conc. HCl (0.15 mL) was added, and mixture was evaporated
to dryness. Residue was extracted with acetonitrile (5 mL) and
acetone (5 mL), extract was dried with MgSO4, filtered, and solvent
was evaporated under reduced pressure to leave brownish oil
(190 mg). It was dissolved in acetone. The 19F NMR spectrum
4.8. Reaction of K[C6F5BF3] with KOPh (optimization)
A 10 mL flask was charged with KOPh (79 mg, 0.6 mmol),
K[C6F5BF3] (137 mg, 0.5 mmol) and appropriate solvent (1 mL).
The flask was closed with stopper and reaction mixture was stirred
under corresponding conditions. Conversion of K[C6F5BF3] and
yield of K[4-PhOC6F4BF3] were determined from 19F NMR spectra
with a quantitative internal standard C6H5CF3 (10
after cooling to 25 8C.
m
l, 0.082 mmol)
showed signals of M[C6F5BF3], M[C6F5BFn(OR)3ꢂn] (
d
= ꢂ134.2,
ꢂ157.9, and ꢂ164.5 ppm) (100:70) besides minor C6F5H and
2,3,5,6-C6F4HOR. Acetone was evaporated and residue was
extracted with CH2Cl2 (2ꢃ 2 mL). The 19F NMR spectrum and
GC-MS analysis showed presence of C6F5H, 2,3,5,6-C6F4HOCH3, and
2,3,5,6-C6F4HOCH2CH2OCH3 (21:100:64) besides unknown pro-
ducts.
4.9. Preparation of K[4-PhOC6F4BF3]
A 10 mL flask was charged with KOPh (635 mg, 4.8 mmol),
DMSO (4 mL) and K[C6F5BF3] (548 mg, 2.0 mmol). The flask was
closed with stopper and reaction mixture was magnetically stirred
at 130 8C for 4 h. After cooling to 25 8C, solvent was evaporated
under reduced pressure, and residue was washed with water.
Recrystallization from ethanol gave K[4-PhOC6F4BF3] (white solid)
(570 mg, 1.64 mmol, 82%).
4.12. Reaction of K[C6F5BF3] with KOH in DMSO
A 10 mL flask was charged with DMSO (1.5 mL), finely grounded
KOH (24 mg, 0.42 mmol), and suspension was stirred at 25 8E for
10 min K[C6F5BF3] (110 mg, 0.40 mmol) was added, and suspen-
sion was stirred at 80 8E for 4 h. The 19F NMR spectrum showed
signals of borate 1 only. Stirring was continued at 125 8C over a
period of 8 h. The 19F NMR spectrum showed signals of [C6F5BF3]ꢂ,
K[4-PhOC6F4BF3]. 1H NMR (CH3CN):
(tt, 3J(Hpara, Hmeta) = 7.4 Hz, 4J(Hpara, Hortho) = 1.0 Hz, 1H, Hpara), 7.00
(d, 3J(Hmeta, Hortho) = 8.6 Hz, 2H, Hmeta). 1H NMR (acetone):
7.51
(m, 2H, Hortho), 7.24 (m, 1H, Hpara), 7.14 (m, 2H, Hmeta). 11B NMR
d
7.36 (m, 2H, Hortho), 7.10
d
(acetone):
d
1.88 (q, 1J(B, F) = 44 Hz, BF3). 19F NMR (acetone):
d
[2,3,5,6-C6F4HO]ꢂ[
[Et2NH2][2,3,5,6-C6F4HO] (in acetone),
ꢂ171.0 (m, 2F, F2, 6) [30]) besides minor C6F5H, [C6F5O]ꢂ,
[BF3(OH)]ꢂ and [BF4]ꢂ. Acidification with CF3COOH led to
conversion of fluorinated phenolates, [2,3,5,6-C6F4HO]–and
[C6F5O]ꢂ, to 2,3,5,6-C6F4HOH and C6F5OH, respectively. The 19F
NMR spectrum contained signals of [C6F5BF3]ꢂ, 2,3,5,6-C6F4HOH
d
= ꢂ147.3 (m, 2F, F3, 5), ꢂ169.0 (m, 2F, F2, 6) (cf.
ꢂ133.6 (q, 1J(F, B) = 43 Hz, 3F, BF3), ꢂ134.2 (ddq, 3J(F2, F3) = 24 Hz,
d
= ꢂ146.5 (m, 2F, F3, 5),
5J(F2, F5) = 11 Hz, 4J(F2, BF3) = 12 Hz, 2F, F2, 6), ꢂ157.9 (dd, 3J(F3,
F2) = 24 Hz, 5J(F3, F6) = 11 Hz, 2F, F3, 5). 19F NMR (CD3CN):
d
ꢂ133.4
(q, 1J(F, B) = 44 Hz, 3F, BF3), ꢂ135.1 (ddq, 3J(F2, F3) = 23 Hz, 5J(F2,
F5) = 11 Hz, 4J(F2, BF3) = 11 Hz, 2F, F2, 6), ꢂ157.9 (dd, 3J(F3,
F2) = 23 Hz, 5J(F3, F6) = 11 Hz, 2F, F3, 5). 19F NMR (DMSO):
d
ꢂ130.2 (q, 1J(F, B) = 45 Hz, 3F, BF3), ꢂ132.4 (ddq, 3J(F2, F3) = 25 Hz,
5J(F2, F5) = 12 Hz, 4J(F2, BF3) = 12 Hz, 2F, F2, 6),–155.6 (dd, 3J(F3,
F2) = 25 Hz, 5J(F3, F6) = 11 Hz, 2F, F3, 5). IR (KBr): 3065w, 3044w
(CH), 1928w, 1653 m, 1595s, 1504vs, 1493vs, 1455vs, 1403w,
1389 m, 1305s, 1214vs, 1169 m, 1128vs, 1075w, 1020s, 1007vs,
950vs, 889w, 830s, 820 m, 807 m, 747s, 687 m, 637 m, 555w,
[
d
d
= ꢂ141.7 (m, 2F, F3, 5), ꢂ161.4 (m, 2F, F2, 6) ppm; cf. with
= ꢂ141.6 (m, 2F, F3, 5) and ꢂ164.2 (m, 2F, F2, 6) [31]), C6F5H,
C6F5OH (100:50:6:8) besides [BF4]ꢂ.
Acknowledgements
495w, 415w cmꢂ1
.
The study was supported by The Ministry of Education and
Science of Russian Federation, project 2012-1.2.1-12-000-1004-
038.
Anal. calcd for C12H5BF7KO (348.07): C, 41.41; H, 1.45; F, 38.21;
found: C, 41.5; H, 1.60; F, 38.4.
4.10. Preparation of K[4-t-BuOC6F4BF3]
References
A 25 mL flask was charged with KO-t-Bu (673 mg, 6.0 mmol),
DME (8 mL) and K[C6F5BF3] (548 mg, 2.0 mmol). The reaction
mixture was stirring at 25 8E for 3 h. Water (108 mg, 6 mmol) was
added and solvent was evaporated on air overnight. Residue was
extracted with acetonitrile, extract was dried with MgSO4, filtered,
and solvent was evaporated under reduced pressure to leave K[4-t-
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BuOC6F4BF3] (white solid) (578 mg, 88%).
b
K[4-t-BuOC6F4BF3]. 1H NMR (CD3CN):
d
1.35 (s, 9H, H ). 19F
NMR (CD3CN):
d
ꢂ133.4 (q, 1J(F, B) = 44 Hz, 3F, BF3), ꢂ136.7 (ddq,
3J(F2, F3) = 24 Hz, 5J(F2, F5) = 12 Hz, 4J(F2, BF3) = 12 Hz, 2F, F2, 6),
ꢂ154.2 (dd, 3J(F3, F2) = 24 Hz, 5J(F3, F6) = 12 Hz, 2F, F3, 5). 19F NMR
(DME):
d
ꢂ133.0 (q, 1J(F, B) = 45 Hz, 3F, BF3), ꢂ136.5 (ddq, 3J(F2,
F3) = 24 Hz, 5J(F2, F5) = 12 Hz, 4J(F2, BF3) = 12 Hz, 2F, F2, 6), ꢂ154.3
(dd, 3J(F3, F2) = 24 Hz, 5J(F3, F6) = 12 Hz, 2F, F3, 5). IR (KBr): 2984 m,
2937w (CH), 1648 m, 1492 m, 1456vs, 1386 m, 1371 m, 1298s,
1263w, 1199w, 1140vs, 1005s, 951vs, 853 m, 814s, 756w, 730w,
636 m cmꢂ1
.

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