α-Substituted boron difluoride acetylacetonates

Article abstract of DOI:10.1134/S1070363208080094

By treatment of α-substituted acetylacetone derivatives with boron trifluoride etherate a series of earlier unknown boron difluoride complexes is obtained. The series includes binuclear complexes containing boron in the chelate fragment connected via sulfur or selenium atom. Gas chromatographic and spectral characteristics of the obtained compounds were investigated. By means of chromato-mass spectrometry their reaction with hydrazine in acidic and alkaline media was studied.

Full text of DOI:10.1134/S1070363208080094

ISSN 1070-3632, Russian Journal of General Chemistry, 2008, Vol. 78, No. 8, pp. 1515–1523. © Pleiades Publishing, Ltd., 2008.
Original Russian Text © I.V. Svistunova, E.V. Fedorenko, 2008, published in Zhurnal Obshchei Khimii, 2008, Vol. 78, No. 8, pp. 1280–1288.
α-Substituted Boron Difluoride Acetylacetonates
I. V. Svistunovaa and E. V. Fedorenkob
a Far East State University,
Oktyabr’skaya ul. 27, Vladivostok, 690950 Russia
e-mail: irasvist@gmail.com
bInstitute of Chemistry, Russian Academy of Sciences, Far East Division, Vladivostok, Russia
Received March 3, 2008
Abstract—By treatment of α-substituted acetylacetone derivatives with boron trifluoride etherate a series of
earlier unknown boron difluoride complexes is obtained. The series includes binuclear complexes containing
boron in the chelate fragment connected via sulfur or selenium atom. Gas chromatographic and spectral
characteristics of the obtained compounds were investigated. By means of chromato-mass spectrometry their
reaction with hydrazine in acidic and alkaline media was studied.
DOI: 10.1134/S1070363208080094
Boron difluoride acetylacetonates possessing a
O
O
O
O
substituent at the central carbon atom of the chelate
ring were poorly studied so far. The data were pub-
lished on complexes containing α-substituent in the
acetylacetone fragment: chlorine or bromine [1], alkyl
or aryl groups [2]. This situation partly originated from
the impossibility to employ the reactions of
electrophilic substitution that are widely used for the
synthesis of substituted metal diketonates [3] to the
preparation of substituted boron difluoride complexes.
The preparation of substituted boron difluoride acetyl-
acetonates by template synthesis from acetic
anhydride, α-substituted ketone, and boron trifluoride
seems hardly feasible due to the possibility of various
side processes [2]. Therefore we applied to the
preparation of new boron difluoride acetylacetonates
chelating with the acetylacetone α-substituted de-
rivatives.
BF3 + B(OBu)3 + H
R
F2B
R
(1)
I−XV
XVI−XXX
R = Cl (I, XVI); Br (II, XVII); I (III, XVIII); NO2 (IV,
XIX); OMe (V, XX); OC(O)CH3 (VI, XXI); OC(O)H
(VII, XXII); OS(O)2Ph (VIII, XXIII); SCN (IX, XXIV);
SEt (X, XXV); SPh (XI, XXVI); SCH2Ph (XII, XXVII); –S–
(XIII, XXVIII); –SS– (XIV, XXIX); –SeSe– (XV, XXX).
formyloxy group. This compound we obtained in a low
yield and only in a process without solvent. The
nearest analog of the formyloxyacetylacetone, the
acetoxyacetone, forms borofluoride chelate in high
yield in any conditions applied. Earlier we have noted
that formyloxy-substituted metal acetylacetonates
could not be obtained in reaction of diketone Х with
copper(II), aluminum(III), and chromium(III) ions [4].
One of the reasons probably preventing formation of
formyloxy-substituted acetylacetonates was their low
stability, as we demonstrated by an example of
complex XXII that differed from the other boron
difluoride complexes we synthesized by its extremely
low stability.
By treatment of diketones I–ХV with the mixture
of boron trifluoride etherate and butyl borate we
prepared in good yield complexes ХVI–ХXХ.
It is opportune to carry out reaction (1) in ether,
although with liquid diketones it can be performed
without a solvent. In most cases this reaction proceeds
with heat evolution. With large amounts of reagents a
self-heating can lead to tarring of the reaction mixture.
Yields of the formed complexes little depend on the
presence of solvent (Table 1). The only exclusion is
the synthesis of complex ХХII that contains
We succeeded in detection by means of gas
chromatography of an intermediate compound formed
in the reaction of boron trifluoride with disulfide
1515

1516
SVISTUNOVA, FEDORENKO
Table 1. Method of preparation, yield, physical and analytical characteristics of F2B(acacR), compounds XVI–XXX
Comp.
no.
Preparation Yield,
Found C,
%
Calculated
C, %
R
mp, °Сa
Color
Formula
method
%
Cl
Cl
а
b
b
а
b
а
b
а
а
b
а
b
а
а
а
а
а
а
а
а
25
78
95
28
26
60
45
60
89
61
–
73.5–75 (hexane)
73.5–75 (hexane)
109–110b (hexane)
151–153 (ether)
colorless
colorless
colorless
yellow
32.80 C5H6BClF2O2
32.93
XVI
XVI
Br
26.55 C5H6BBrF2O2
22.21 C5H6BF2IO2
26.48
21.93
XVII
XVIII
XVIII
XIX
I
I
151–153 (ether)
yellow
NO2
NO2
OMe
OAc
OAc
OFr
OFr
OS(O)2Ph
SCN
SEt
SPh
SBz
S
62–65 (ether–hexane)
59–63.5 (ether–hexane)
64.5–65.5 (ether–hexane)
113–115 (ether)
colorless
colorless
colorless
colorless
colorless
–
31.27 C5H6BF2NO4
31.13
XIX
40.56 C6H9BF2O3
40.94 C7H9BF2O4
40.50
40.82
XX
XXI
112.5–114 (ether)
–
XXI
XXII
XXII
XXIII
XXIV
XXV
XXVI
XXVII
XXVIII
XXIX
XXX
4
–
colorless
colorless
yellow-brown
colorless
light yellow
colorless
colorless
colorless
grey-green
64
78
80
74
75
92
93
71
125–127 (benzene–hexane)
133–142, decomp. (3×ether)
12–13 (hexane)
43.55 C11H11BF2O5S
35.28 C6H6BF2NO2S
40.33 C7H11BF2O2S
51.71 C11H11BF2O2S
53.52 C12H13BF2O2S
37.21 C10H12B2F4O4S
33.62 C10H12B2F4O4S2
27.02 C10H12B2F4O4Se2
43.45
35.16
40.42
51.59
53.36
36.86
33.56
26.59
72–73 (hexane)
92–93.5 (hexane)
174–176 (benzene)
198–210 (benzene)
198–205, decomp. (benzene)
S2
Se2
a Solvent in recrystallization. b Published 108°С [1].
tetraketone ХIV. In the reaction mixture appeared and
later disappeared a volatile compound whose mass
spectrum corresponded to a formula F2B(acacSSacacH).
cooling for 2–3 weeks. Acetoxy-substituted complex
ХХI decomposes partially within one year storage.
Other chelates do not decompose noticeably at
prolonged keeping.
Complexes
ХVI–ХХVII
are
low-melting
crystalline substances well soluble in chloroform,
benzene, THF and moderately soluble in hexane. The
binuclear complxes ХХVIII–ХХX demonstrated a
lower solubility. In contrast to mononuclear
complexes, they are sparingly soluble in benzene and
ether and possess higher melting points. The ethylthio-
substituted complex ХХV under normal conditions is
colorless liquid readily crystallizing at cooling.
Mononuclear chelates (compounds ХVI–ХХII and
ХХIV–ХХVII) are volatile enough for studying them
by gas chromatography. Chromatograms of these
compounds besides the peak of main substance contain
one-two peaks of diketone forming the complex.
Hence, in the evaporator of the chromatograph the
complexes suffer partial decomposition. The relative
intensity of the diketone peak depends on the solvent
used, the injector temperature, and the purity of the
complex. Under the conditions that we commonly used
(solution in chloroform, injector temperature 280°С)
the intensity of the diketone peak is 5–7% of that of
the main peak. With solutions in alcohol the
chromatograms contain only the diketone peaks while
those of chelates are totally absent.
Principal analytical characteristics of compounds
XVI–XXX are listed in Table 1.
Among the compounds we obtained the formyloxy-
substituted complex ХХII is the less stable and
substantially decomposes at low temperature (0°С) in
2-3 days. Nitro-substituted chelate ХIХ can be kept at
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 78 No. 8 2008

α-SUBSTITUTED BORON DIFLUORIDE ACETYLACETONATES
1517
The chromatograms of diketones II, V–VII obtained
on a non-polar phase in capillary column contain two
separate peaks. Mass spectra of these peaks are similar
and correspond to the respective diketone empirical
formula. In the mass spectra of components with large
retention time the peaks of molecular ions are stronger.
It may be assumed that appearance of two separate
peaks reflects separation of ketone and enol tautomers.
region of 1600–1450 cm–1 belonging to vibrations of
the bonds С=О (chelate) and С=С. Intensity of these
bands decreases when frequency increases. In the most
of studied spectra two main bands are 70–80 cm–1
distant. One exclusion is nitro-substituted chelate
displaying the bands of С=О and С=С vibrations
almost as close as in the unsubstituted acetylacetonate.
Alongside the adsorption bands due to vibrations of
F2B(acac) fragment the spectra contain characteristic
bands of respective substituents (Table 2).
Complex ХХIII that contains phenylsulfonate
group decomposes considerably when subjected to
chromatography. The chromatogram of this compound
contains a strong “hump” corresponding to the
decomposition products. The diketone and boron
chelate peaks are of low intensity and partially are
overlapped by the peaks of the decomposition
products. The unambiguous identification of the latter
can be achieved only by application of mass
spectrometry.
1H NMR spectra of compounds ХVI-ХХX are
consistent with the expected structures (Table 2). The
complex formation with boron fluoride group shifts
signals of β-methyl groups of the parent acetylacetones
by 0.2–0.3 ppm downfield, in agreement with the data
of [6]. In all the complexes including dimeric chelates
XXVIII–XXX the methyl groups are equivalent and
resonate as one peak.
Binuclear complexes cannot be studied by GLC,
probably due to low volatility.
Mass spectra of complexes ХVI–ХХVII contain
peaks of molecular ions with isotopic composition
corresponding to calculated ones. The most common
direction of their fragmentation is ejecting fluorine
atom and methyl group. Spectra of halo-substituted
acetylacetonates ХVI–ХVIII show that this route of
fragmentation for these compounds predominates. For
the complexes with more complicated substituents
these reactions become less significant, and
fragmentation route depends on the substituent nature
(Table 2).
IR spectra of the obtained compounds are typical of
boron difluoride acetylacetonates (Table 2). It is
commonly suggested that boron fluoride chelates ex-
hibit two strong bands in the region of 1600–1450 cm–1
due to vibration of С=О and С=С bonds in the chelate
ring [5]. For sulfur-containing complexes XXVI-
XXVIII we observed in the region of 1600–1450 cm–1
three bands: In spectra of these compounds
additionally appears a high-frequency band of low
intensity. In the spectra of other complexes it can be
seen as a bend. Hence, the spectra of boron difluoride
substituted acetylacetonates contain three bands in the
The main band in UV spectra of boron difluoride
substituted acetylacetonates is that corresponding to π3–
π4 transition (Table 3). The introduction of oxygen-
Table 2. Data on IR, 1H NMR, and mass spectra of boron difluoride β-diketonates F2B(acac-R)
ν, cm–1
δ, ppm
R
m/z (intensity, %, [ion]+)
C=O
C=C
B–F
B–O
CH3
other bands
R
(chelate)
H
(1574) 1150 812 – Cα-H
2.21а s (6H)
1556
1088
Cl
1568
1495
1175
1109
2.51b s (6H)
184, 183, 182 (22%, 10%, 65%, [M]+), 169,
168, 167 (22%, 14%, 100%, [M–CH3]+), 165,
164, 163 (24%, 21%, 53%, [M–F]+), 55
(87%)
Br
1560
1491
1172
1081
2.56c s (6H)
228, 227, 226 (71%, 25%, 74%, [M]+), 213,
212, 211 (89%, 30%, 95%, [M–CH3]+), 209,
208, 207 (38%, 34%, 44%, [M–F]+), 79
(20%), 55 (100%)
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 78 No. 8 2008

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SVISTUNOVA, FEDORENKO
Table 2. (Contd.)
ν, cm–1
δ, ppm
R
m/z (intensity, %, [ion]+)
C=O B–F
CH3
other bands
R
C=C B–O
(chelate)
I
1555 1161
1481 1083
2.67 s (6H)
274 (100%, [M]+), 259 (59%, [M–CH3]+), 255
(18%, [M–F]+), 208 (14%), 127 (26%, [I]+)
NO2
1581 1183 1450, 1481 – N–O 2.71 s (6H)
1545 1065 (NO2),
193 (38%, [M]+), 176 (31%), 174 (46%,
[M–F]+), 127 (100%, [M–COCH3–H]+), 117
(22%), 53 (55%)
841 – Cα–N (NO2)
OMe
OAc
1595 1184 1236 – Cα–O–Me
1511 1060
2.38 s (6H)
178 (100%, [M]+), 163 (21%, [M–CH3]+), 159
(53%, [M–F]+), 135 (49%, [M–COCH3]+), 133
(100%), 120 (31%), 92 (33%)
1598 1189 1786, 1766 – C=O
1529 1067 (OOCCH3), 891
2.29 s (6H) 2.34 s (3H, OOCCH3) 206 (17%, [M]+), 187 (31%, [M–F]+), 164
(35%, [M–OCCH2]+), 149 (148, [M–OCCH2–
CH3]+), 145 (94%, [M–OCCH2–F]+), 144
(100%, [M–OCCH2–HF]+), 115 (36%), 101
(36%), 77 (35%)
OFr
1597 1191 1740 – C=O (OOCH) 2.40 s (6H) 8.02 s (1H, OOCH)
1519
192 (11%, [M]+), 173 (31%, [M–F]+), 164
(67%, [M–CO]+), 149 (97%, [M–CO–CH3]+),
145 (65%, [M–CO–F]+), 144 (100%, [M–CO–
HF]+), 129 (40%), 101 (32%), 93 (33%), 55
(97%)
OS(O)2Ph 1593 1200 824, 781, 760, 651, 2.11 s (6H) 7.66–7.96 m (5H, Ph) 304 (7%, [M]+), 285 (9%, [M–F]+), 163 (41%,
1516 1072 620,
599 – SO3Ph
[M–SO2Ph]+), 144 (53%, [M–SO2Ph–HF]+),
141 (48%, [SO2Ph]+), 125 (56%, [SOPh]+), 77
(100%, [Ph]+)
SCN
SEt
1560 1176 2164 – SCN
1478 1116
2.74 s (6H)
205 (81%, [M]+), 190 (7%, [M–CH3]+), 186
(33%, [M–F]+), 114 (26%), 114 (69%)
1560 1186
1470 1119
2.63 s (6H) 2.60
q
(2H, SCH2, 208 (62%, [M]+), 193 (1%, [M–CH3]+), 189
7.5), 1.24 t (3H, CH3, (20%, [M–F]+), 165 (31%, [M–COCH3]+), 160
7.5)
(10%, [M–Et]+), 137 (26%), 133 (41%), 99
(100%)
SPh
1581 1190 749 – Cα–S
1559 1125
1469
2.56 s (6H) 7.08–7.35 m (5H, Ph) 256 (84%, [M]+), 237 (10%, [M–F]+), 221
(13%), 194 (24%), 169 (20%), 165 (20%), 147
(100%, [M–SPh]+), 121 (23%), 103 (37%),
103 (37%)
SBz
S
1496 – Cα–SBz, 773, 2.22 s (6H) 3.67
709
7.08–7.33 m (5H, Ph) [CH2Ph]+), 65 (17%)
s
(2H, CH2), 270 (2%, [M]+), 251 (1%, [M–F]+) 91 (100%,
1574 1178
1554 1132
1477
2.57 s (12H)
S2
1553 1206
1467 1117
2.60 s (12H)
2.64 s (12H)
Se2
1545 1190
1467 1092
a Published in [6]. b Published 2.50 ppm [7]. c Published 2.57 ppm [6].
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 78 No. 8 2008

α-SUBSTITUTED BORON DIFLUORIDE ACETYLACETONATES
1519
containing groups to the central carbon atom
(compounds XX, XXI and XXIII) and halo-
substitution leads to a red shift of this band and to
decrease in intensity. Therewith the band intensity falls
more when shift to red region is larger. Thus, in the
spectrum of iodo-substituted complex whose π3-π4
transition band is the most shifted (by 43 nm) the band
intensity is approximately a half of that in the spectrum
of F2B(acacH).
bands approximally equal in intensity. Assuming that
spectra of complexes XXVIII and XXIX are
analogous to those of other S-substituted chelates
(XXV, XXVI, and XXVII), it is presumable that the
long-wave band (338 nm for complex XXVIII and
296 nm for complex XXIX) is induced by S–S*
transition and the short-wave one, by π3–π4 transition.
This means that the binuclear complexes are the only
boron difluoride chelates where introducing of an α-
substituent leads to a blue shift of spectral bands.
In the spectra of NO2- and SCN-substituted
complexes the band underwent a red shift only by 1-2
nm, but its intensity falls considerably. This behavior
fits to the same trend already noted for the substituted
acetylacetonates of metals [7]. It is suggested that the
presence of two methyl groups retards conjugation of
unsymmetrical NO2 and SCN groups with electronic
system of acetylacetonate ring leading in the case of
metal acetylacetonates to blue shift of π3–π4 transition.
Electronic spectra of the ethanol solution of the
majority of studied compounds differ considerably
from the spectra of solutions in hexane and
chloroform, and coincide with the spectra of parent
diketones. Consequently, the chelates decomposed at
dissolution in ethanol. An exclusion were S-substituted
acetylacetonates XXV, XXVI, XXVII and F2B
(acacH) whose spectra in ethanol were the same as in
chloroform and hexane.
In the spectra of thio-substituted complexes XXV,
XXVI, and XXVII the band of π3–π4 transition is
shifted by 3–9 nm to red region and its intensity falls.
Besides, in the spectra of these compounds a band of
low intensity is present in the region of 320–400 nm
that probably originates from the electron transitions
on the sulfur atom (S–S* transition). This band occurs
also in the spectra of the corresponding ligands.
Using the obtained compounds we continued a
study of the reaction of substituted acetylacetonates
with hydrazine by chromato-mass spectrometry [8].
We were interested in a possibility of judging from the
structure of the formed pyrazoles on the structure of
the parent complexes. Reactions were carried out in
ethanol with hydrazine hydrochloride (acidic condi-
tions) or hydrazine hydrate (alkaline conditions) as the
reagents. In most cases we observed formation of the
respective 4-R-3,5-dimethylpyrazoles.
The most problematic is the interpretation of the
spectra of binuclear complexes XXVIII and XXIX.
Each spectrum of these compounds contains two basic
O
O
F
F
H2O
2 HClor N2H4
N2H4
N
R
B
R
(2)
HN
Table 3. Electronic spectra of substituted acetylacetone derivatives and boron difluoride acetylacetonates
Solvent
H(acac-R), λmax, nm (log ε)
F2B(acac-R), λmax, nm (log ε)
R
H
Ph–Ph*
π3–π4
S–S*
Ph–Ph*
π3–π4
S–S*
chloroform
hexane
288 (4.22)
288 (–)
ethanol
275 (3.92)
295 (3.80)
291 (3.79)
295 (3.79)
286 (4.15)
317 (4.09)
315 (–)
Cl
Br
chloroform
hexane
ethanol
294 (3.84)
320 (4.05)
317 (–)
chloroform
hexane
ethanol
296 (3.55)
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 78 No. 8 2008

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SVISTUNOVA, FEDORENKO
Table 3. (Contd.)
Раство-
H(acac-R), λmax, нм (lgε)
Ph–Ph* π3–π4
F2B(acac-R), λmax, нм (lgε)
R
I
ритель
S–S*
Ph–Ph*
π3–π4
S–S*
chloroform
hexane
331 (3.20)
328 (–)
ethanol
285 (–)
NO2
chloroform
hexane
289 (3.93)
290 (–)
211 (–)а; 248 (–)а
ethanol
276 (3.82)
314 (4.11)
313 (–)
333 (3.23)
OMe
chloroform
hexane
ethanol
295 (3.93)
304 (4.14)
303 (–)
OOCCH3 chloroform
hexane
285 (3.41)
281 (3.48)
286 (3.43)
281 (3.81)
ethanol
282 (3.81)
300 (4.16)
300 (–)
OS(O)2Ph chloroform 275 (3.82)
hexane 219 (3.94); 274 (3.84) 279 (3.82)
ethanol 220 (3.97); 275 (3.76) 283 (3.75)
221 (–); 275 (–)
236 (3.56)а
[280 (–)]
290 (3.94)
291 (–)
SCN
SEt
chloroform
hexane
ethanol
280 (3.78)
295 (4.01)
293 (–)
chloroform
290 (3.91)
288 (3.85)
290 (3.88)
281 (3.90)
279 (3.81)
281 (3.90)
[320 (3.15)]
335 (3.26)
[325 (–)]
hexane
[315 (3.06)] 235 (–)а
[318 (3.16)] 235 (3.05)а
330 (3.06)
ethanol
293 (3.96)
291 (4.04)
290 (–)
[329 (3.18)]
356 (3.09)
349 (–)
SPh
chloroform 253 (4.11)
hexane 250 (4.07)
ethanol 249 (4.10)
329 (3.00)
328 (3.10)
238 (–); [244 (–)]
238 (4.03); 246 (4.04)
288 (3.97)
339 (3.02)
[329 (3.20)]
SBz
S
chloroform
hexane
291 (3.83)
291 (3.92)
291 (3.88)
292 (3.86)
[320 (3.05)]
[310 (–)]
297 (3.93)
297 (–)
296 (3.90)
269 (4.04)
269 (–)
–
ethanol
[310 (–)]
216 (4.06)
218 (–)а
[325 (–)]
338 (3.88)
338 (–)
chloroform
hexane
338 (3.70)
331 (3.69)
ethanol
278 (4.06)
S2
chloroform
hexane
290 (4.08)
288 (4.10)
289 (4.14)
296 (4.09)
295 (–)
[254 (–)]
[254 (–)]
289 (4.09)
290 (4.03)
–
246 (–)
260 (–)
279 (4.19)
279 (–)
285 (–)
ethanol
287 (4.07)
Se2
chloroform
hexane
ethanol
a Not identified.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 78 No. 8 2008

α-SUBSTITUTED BORON DIFLUORIDE ACETYLACETONATES
1521
The pyrazoles are more volatile than the parent
boron difluorides complexes. Therefore it was possible
to transform non-volatile chelates into the volatile
pyrazoles for studying the latter by gas chromato-
graphy. We used this technique to confirm the
structure of dimeric chelates. At the treatment of
compound XXVIII with hydrazine hydrochloride we
obtained bis-(3,5-dimethylpyrazolyl-4)sulfide, and
from compound XXIX, bis-(3,5-dimethylpyrazolyl-4)
disulfide.
250 MHz from solutions in deuterochloroform with
TMS as a reference. Mass spectra were obtained on a
gas chromatograph with mass-selective detector. The
gas chromatographic study was carried out on the
instruments HP 5890 (series II) with flame ionization
detector and HP 5890 (series II) with mass-selective
detector HP 5971. The chromatographic analysis
conditions were as follows: column HP-5MS (HP-5)
30 m × 0.250 mm × 0.25 μ; carrier gas helium (for
GS–MS) or argon (for GS-FID); regime of continuous
flow; flow rate in the column 0.7 ml min–1. Injector:
temperature 280°С; flow distribution 1:20. Tempera-
ture program: 1 min at 50°С, temperature raised at a
rate 10 deg min–1 to 280°С, 20 min at 280°С. Regime
of flame ionization detector: temperature 290°С,
hydrogen 40 ml min–1, air 300 ml min–1, blowing gas
argon, 30 ml min–1. Regime of mass-selective detector:
temperature of the conjugation node 280°С, ionization
energy 70 eV, total scan in the m/z range from 50 to
450, detection delay 2 min.
However, in some cases we observed side
processes.
At performing the process under acidic conditions,
chlorine substitution for R group occurs in some cases.
Actually, at the treatment with hydrazine
hydrochloride of Br-substituted complex XVII, in the
reaction mixture were detected 4-chloro- and 4-bromo-
3,5-dimethylpyrazoles in ca. 2:1 ratio. Formation in
small amount of 4-chloro-3,5-dimethylpyrazole was
also detected in the case of the phenylsulfo-substituted
coomplex XXIII. The reactions with complexes XVIII
and XXX were unsuccessful: the liberation of iodine
and red selenium ocurred, and the reaction mixture
contained in minor amount a volatile substance while
4-iodo-3,5-dimethylpyrazole and bis-(3,5-dimethyl-
pyrazolyl-4)diselenide were not found (similar result
was obtained in the reaction under alkaline conditions).
From complex XIX, 4-nitro-3,5-dimethylpyrazole was
formed, but in a very small amount. Reaction of
hydrazine hydrochloride with SCN-substituted com-
plex XXIV was extremely complex. Depending on the
reagents ratio and reaction duration the formation of 3
to 6 substances occurred, among which bis-(3,5-
dimethylpyrazole-4)disulfide was identified by mass-
spectrometry. We failed to establish the structure of
remaining substances. 4-Thiocyano-3,5-dimethylpyra-
zole was not found among the products.
The diketones used in the work were obtained
along the following methods: HacacOMe [9],
HacacOOCCH3 [10], HacacSEt, HacacEPh [11],
(Hacac)2S, (HacacS)2 [12], (HacacSe)2 [13].
HacacCl is obtained by passing chlorine to the
stirred mixture of HacacH with water (1:3 by volume)
at 0°С to achieve the calculated weight gain. The
organic layer was many times washed with water,
dried over Na2SO4 and several times distilled
monitoring the product purity by gas chromatography.
Yield 50–58%, bp 57–60°С (28–30 mm Hg)
(published data: mp 41-44.5°С at14 mm Hg [14]).
HacacBr is obtained similarly by adding bromine
in 10% excess. The product was used without
additional purification. Yield 65–70%. The product
contained acacBr2 (8–10%, by GLC).
HacacI. To a solution of 15 g of HacacH in 100 ml
of CCl4 (anhydrous) at stirring and cooling to –20°С
was added dropwise a solution of 13.67 g of ICl in
20 ml of CCl4. After 10 min stirring, the reaction
mixture was washed with water and dried over
MgSO4. Solvent was then removed in a vacuum and
the residue was kept at 40–50°С and under a vacuum
1–2 mm Hg to remove completely HacacH and
HacacCl (GLC monitoring), and the product was used
without further purification.
In this reaction under alkaline conditions re-
placement of R by hydrogen atom can occur due to
reducing action of hydrazine. At the treatment of
chloro-, bromo- and sulfo-substituted complexes was
registered the formation, besides 4-R-3,5-dimethyl-
pyrazols, of dimethylpyrazole in a substantial amount.
EXPERIMENTAL
IR spectra in the region of 4000–400 cm–1 were
registered on a Spectrum 100 BX-II instrument from
1
KBr pellets. The H NMR spectra were obtained on a
HacacNO2. A mixture of 3.52 g of Cu(acacNO2)2,
Bruker WH 250 instrument with operating frequency
50 ml of chloroform and 50 ml of 1N sulfuric acid was
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 78 No. 8 2008

1522
SVISTUNOVA, FEDORENKO
shaken to complete dissolution of the chelate. Organic
layer was then washed with a fresh portion of acid and
afterwards several times with water. After drying the
mixture over MgSO4 the solvent was removed in a
vacuum at 30–40°С. Residual viscous oil was used
without further purification.
stirred at heating for 3 h and then the reaction mixture
was left overnight at 0°С. The crystals settled were
filtered off, washed with ether cooled to –20°С, and
dried in air. The filtrate was evaporated by half and left
standing again for crystallization. The crystals were
combined and recrystallized from a solvent indicated
in Table 1.
HacacOOCH. To a mixture of 18 g of HacacCl,
7.36 g of HOOCH and 75 ml of DMFA (anhydrous) at
stirring was slowly added 17 g of NEt3. After 1 h of
stirring the reaction mixture was poured to water and
then the product was extracted with chloroform. After
drying over MgSO4 and removing the solvent, the
residue was several times distilled in a vacuum. Finally
5.0 g of colorless liquid with bp 75–77°С (3 mm Hg)
was obtained, yield 26%. Chromatogram of the
product contains two peaks with the same mass
spectra: 144 [М]+, 116 [HacacOH]+, 102 [CH3C=CHO·
In the syntheses of compounds XXVIII–XXX
0.005 mol of respective diketone was used; repeated
recrystallization was not applied.
General procedure for the prepatation of boron
difluoride acetylacetonates. b. A mixture of diketone
(0.01 mol), boron trifluoride etherate (0.01 mol),
and tributyl borate (0.01 mol) was left for 24 h at room
temperature and then was placed into a freezer (–10°С)
for 5–6 days. The crystals formed were filtered off,
washed with the ether cooled to –20°С, dried in air and
then recrystallized from an appropriate solvent, as
shown in Table 1.
1
(O)CH]+, 74 [CH3COCH2OH]+. H NMR spectrum:
2.23 s (6H, CH3); 5.80 s (1H, CH(Ac)2); 8.42 s (1H,
HCOO).
General procedure of reaction with hydrazine. A
mixture of 20 mg of a complex, 50 mg of N2H4·2HCl,
and 2 ml of ethanol was refluxed for 40 min and then
poured to water, alkalinized with ammonia to рН =
11–12 and then extracted with 5 ml of chloroform. The
chloroform extract was investigated using GLC–MS.
HacacOS(O)2Ph is obtained similarly to HacacOS·
(O)2Me [9] (without chromatographic purification).
PhI was removed by heating to 100°С under a vacuum
of 1–2 mm Hg the residue obtained after distilling off
the solvent (GLC monitoring). Mass spectrum: 256
[M]+, 214 [CH3COCH2OS(O)2Ph]+, 143 [(OH)2SPh]+,
142 [(HO)(O)SPh]+, 141 [SO2Ph]+, 125 [SOPh]+, 77
Reaction with hydrazine hydrate was carried out
similarly.
1
[Ph]+. H NMR spectrum: 1.96 s (6H, CH3); 4.53 (1H,
CH(Ac)2); 7.55–8.0 m (5H, Ph).
REFERENCES
HacacSCN. To a solution of 12.5 g of HacacH in
100 ml of CHCl3 (anhydrous) at cooling to –10°С and
stirring was added 150 ml of a solution of (SCN)2 in
CHCl3 (prepared from 38.6 g of Pb(SCN)2 and 5.9 ml
of Br2). After stirring the reaction mixture for 1.5 h it
was washed with water and dried over Na2SO4. After
removing the solvent in a vacuum, the residue was
washed with hexane and recrystallized from a
benzene–hexane mixture. 11.56 g of beige crystals
were obtained (yield 65%). Mass spectrum: 157 [M]+,
142 [COCH(SCN)COCH3]+, 88 [CH3COCHS]+.
1. Shapkin, N.P., Korotkikh, O.A., and Karasev, V.E., Zh.
Neorg. Khim., 1985, vol. 30, no. 7, p. 1882.
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HacacSCH2Ph.is obtained by analogy to
HacacSPh [11]. Purified by recrystallization from
hexane. Yield 70%, mp 52–54°С (published data: mp
55–56°С [15]). Mass spectrum: 222 [M]+, 91 [PhCH2]+.
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General procedure for the prepatation of boron
difluoride acetylacetonates. a. A mixture of diketone
(0.01 mol), boron trifluoride etherate (0.01 mol), tributyl
borate (0.01 mol) and 20 ml of anhydrous ether was
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Zh. Obshch. Khim., 2002, vol. 72, no. 6, p. 962.
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α-SUBSTITUTED BORON DIFLUORIDE ACETYLACETONATES
1523
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Tetrahedron, 2006, vol. 62, p. 4800.
13. Morgan, G.T., Drew, H.D.K., and Bakker, T.V., J. Chem.
Soc., 1922, Vol. 121, p. 2432.
14. Burdett, J.L. and Rogers, M.T., J. Am. Chem. Soc.,
1964, vol. 86, no. 6, p. 2105.
15. Hayashi, S., Furukawa, M., Yamamoto, J., and Niigata, K.,
11. Yoshida, Z., Ogoshi, H., and Tokumitsu, T., Tetra-
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Chem. Pharm. Bull., 1967, vol. 15, no. 8, p. 1188.
12. Jones, R.D.G. and Power, L.F., Aust. J. Chem., 1971,
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