Phenols reactions with 1,1-difluorodichloroethene, 1,2-di(fluorochloro) ethene, and trifluorochloroethene

Article abstract of DOI:10.1023/B:RUJO.0000010179.88527.27

Phenols containing in the para-position of the benzene ring substituents of various electronic character add to 1,1-difluorodichloroethene in acetone in the presence of potassium hydroxide. A similar reaction with 1,2-di(fluorochloro)ethene occurs only in

Full text of DOI:10.1023/B:RUJO.0000010179.88527.27

Russian Journal of Organic Chemistry, Vol. 39, No. 8, 2003, pp. 1125 1129. Translated from Zhurnal Organicheskoi Khimii, Vol. 39, No. 8, 2003,
pp. 1196 1200.
Original Russian Text Copyright
2003 by Kremlev, Mushta, Moklyachuk.
Phenols Reactions with 1,1-Difluorodichloroethene,
1,2-Di(fluorochloro)ethene, and Trifluorochloroethene
M. M. Kremlev, A. I. Mushta, and L. I. Moklyarchuk
Institute of Organic Chemistry, National Academy of Sciences of Ukraine, Kiev, 02094 Ukraine
Received May 29, 2002
Abstract Phenols containing in the para-position of the benzene ring substituents of various electronic
character add to 1,1-difluorodichloroethene in acetone in the presence of potassium hydroxide. A similar
reaction with 1,2-di(fluorochloro)ethene occurs only in DMF or N,N-dimethylacetamide and is followed by
hydrogen chloride elimination. Phenols with electron-donor substituents add to trifluorochloroethene in
acetone in the presence of potassium hydroxide, the reaction of phenols with electron-acceptor substituents
requires DMF as solvent.
The products of substituted phenols addition to
fluoroolefins attract lately a growing attention as
initial compounds for preparation of substances with
pesticidal and herbicidal properties. Therefore these
compounds may be interesting as synthons for the
synthesis of physiologically active substances.
At the same time from the reaction mixture were iso-
lated compounds that turned out to be addition
products of substituted phenols to 1,1-difluorodi-
chloroethene Ia e. This selective reaction is apparent-
ly due to a larger positive charge on the carbon atom
of CF2 group in the 1,1-difluorodichloroethene than
on the carbon atoms in the 1,2-di(fluorochloro)ethene.
Reactions of phenol and cresols with trifluoro-
chloroethene were described in [1] where the phenol
was shown to add to trifluorochloroethene in acetone
at 40 C in the presence of potassium hydroxide
affording a single product that did not eliminate
hydrogen fluoride even when heated with powdered
potassium hydroxide to 400 C. A similar 4-nitro-
phenol addition to trifluorochloroethene occurred also
in the presence of potassium hydroxide in DMF
medium. A substituted aniline prepared by reduc-
tion of 4-(1,1,2-trifluoro-2-chloroethoxy)nitrophenol
was used in the synthesis of compounds having a
pesticidal activity [2]. However the physical constants
of this substituted aniline were not mentioned in [2].
The addition of phenol to 1,1-difluorodichloroethene
was also described [1], and the process should be
carried out at temperature below 10 C to avoid the
elimination of hydrogen fluoride and the formation of
phenyl fluorochloroethenyl ether.
R = H (a), CH3 (b), OCH3 (c), Br (d), NO2 (e).
The formation of compounds Ia e in reaction with
1,2-di(fluorochloro)ethene is due to the presence in
the latter of about 5% of 1,1-difluorodichloroethene
arising during the synthesis of the 1,2-di(fluoro-
chloro)ethene from 1,2-difluorotetrachloroethane
(Freon-112) by dechlorination with zinc. We
determined the content of the impurity by means of
19F NMR spectroscopy. The close values of boiling
points of these olefins (21 22 and 15 C respectively
[3]) prevented preparation of pure 1,2-di(fluoro-
chloro)ethene by simple distillation. On the contrary
the treating of crude 1,2-di(fluorochloro)ethene with
phenol in acetone in the presence of a little potassium
hydroxide removes completely the 1,1-difluorodi-
chloroethene impurity. Thus this procedure can be
used for purification of 1,2-di(fluorochloro)ethene.
In contrast to triflurochloroethene, the reactions
between phenol and 1,2-di(fluorochloro)ethene were
not studied.
We obtained compounds Ia e at higher tempera-
ture than indicated in [1]; however we found no
dehydrofluorinated products.
It turned out that substituted phenols both with
electron-donor and electron-acceptor groups in the
para-position of the benzene ring did not react with
the 1,2-di(fluorochloro)ethene in acetone solution in
the presence of potassium hydroxide even at boiling.
Unlike the substituted phenols the 4-methoxycarb-
onylaminothiophenol readily reacted with 1,2-di-
1070-4280/03/3908-1125$25.00 2003 MAIK Nauka/Interperiodica

1126
KREMLEV et al.
(fluorochloro)ethene in acetone in the presence of
potassium hydroxide affording 4-methoxycarbonyl-
aminothiophenyl 1,2-difluoro-2-chloroethenyl sulfide.
The reaction evidently proceeds through two stages.
First 4-methoxycarbonylaminothiophenol adds to
1,2-di(fluorochloro)ethene. and then dehydrochlorina-
tion takes place [4].
The substituted (1,1,2-trifluoro-2-chloroethoxy)-
benzenes (III) obtained are colorless substances,
either crystalline (IIIa c, g) or liquid (IIId, e, h).
However the reaction of 4-methoxyphenol with
1,2-di(fluorochloro)ethene carried out in DMF or
N,N-dimethylacetamide in the presence of potassium
hydroxide at 60 80 C gave rise to 4-(1,2-difluoro-2-
chloroethenyloxy)anisole (II) in a good yield. Like
with the 4-methoxycarbonylaminothiophenol the reac-
tion proceeds through two stages: first the 4-meth-
oxyphenol adds to 1,2-di(fluorochloro)ethene, and
then dehydrochlorination occurs.
R = 2-NHAc (a), 3-NHAc (b), 4-NHAc (c), 4-Br
(d), 4-F (e), 4-COOCH3 (f), 4-CHO (g).
By hydrolysis of compounds IIIa c in a mixture
hydrochloric acid ethanol the corresponding sub-
stituted anilines IVa c were obtained as colorless
fluids, and the hydrolysis of ester IIIf with a water
solution of potassium hydroxide furnished acid V as
colorless crystalline substance.
R = 2-NH2 (a), 3-NH2 (b), 4-NH2 (c).
Compound II is a colorless fluid containing a
mixture of E- and Z-isomers in 1:1 ratio as shows the
1
19F NMR spectrum. Note that in the H NMR spec-
trum of the product no difference appears in the
chemical shifts of aromatic protons from E- and Z-
isomers; apparently the 1,2-difluorochloroethenyloxy
group weakly affects the aromatic ring. The forma-
tion of a mixture of E- and Z-isomers in this reaction
is caused by the presence in the initial 1,2-di(fluoro-
chloro)ethene of E- and Z-isomers in 1:1 ratio [3].
Thus in compound II the configuration of the initial
compound was conserved.
All our previous attempts to prepare organo-
magnesium compound from meta- or para-difluoro-
methoxybromobenzene both by reaction with magnes-
ium turnings or with alkylmagnesium bromides in
ethyl ether or THF resulted only in destruction of the
difluoromethoxy group. In contrast to difluorometh-
oxy moiety the OCF2CFHCl group was stable against
organomagnesium compounds, and 4-(1,1,2-trifluoro-
2-chloroethoxy)bromobenzene (IIId) cleanly afforded
the Grignard reagent with magnesium turnings in
ethyl ether. The carbonization of the organomagnes-
ium compound with carbon dioxide furnished acid V.
We studied addition to trifluorochloroethene of
ortho-, meta- and para-substituted N-acetylamino-
phenols. It turned out that the reaction proceeded in
acetone at room temperature with a slight self-heating.
Under the same conditions 4-bromo- and 4-fluoro-
phenols also easily added to the trifluorochloroethene.
Under similar conditions the trifluorochloroethene
failed to react with phenols having in the para-
position an electron-acceptor substituent (ester or
aldehyde group). Only at the use of DMF or N,N-di-
methylacetamide we obtained the corresponding
products in a good yield. Apparently in these aprotic
solvents the nucleophilicity of phenolate anions is
increased.
In order to extend the set of synthons for produc-
tion of physiologically active compounds we prepared
diazo compounds from substituted anilines IVb and
IVc which were then converted into the correspond-
ing phenols. The latter were treated with chloroacetic
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 39 No. 8 2003

PHENOLS REACTIONS WITH 1,1-DIFLUORODICHLOROETHENE
1H and 19F NMR spectra of compounds I VI
1127
Compd.
no.
1H NMR spectrum (in CDCl3), , ppm, J, Hz
19F NMR spectrum (in CDCl3), , ppm, J, Hz
Ia
Ib
Ic
Id
Ie
II
79.49 d (CF2), JFF 5.1
79.88 d (CF2), JFF 5.1
79.75 d (CF2), JFF 5.1
79.81 d (CF2), JFF 5.1
79.94 d (CF2), JFF 5.1
3.78 s (3H, OCH3), 6.8 d (2H, Harom, JHH 9) 7.0 d (2H, Z-isomer: 143.71 d (1F, F1, JFF 120), 117.57 d
Harom JHH 9)
(1F, F2, JFF 120)
E-isomer: 128.8 d (1F, F1, JFF 36), 102.06 d
(1F, F2, JFF 36)
IIIa 2.2 s (3H, CH3), 6.3 d (1H, CFH, JFH 48), 7.2 s (1H,
83.9 d (2F, CF2, JFF 32), 154.5 d.t (1F, CFH,
NH), 7.5 m (2H, Harom), 7.6 m (1H, Harom), 7.9 m (1H, JFH 48, JFF 12)
Harom
IIIb 2.1 s (3H, CH3), 6.1 d (1H, CFH, JFH 46), 7.2 s (1H,
NH), 6.9 m (1H, Har°m.), 7.3 m (1H, Har°m.), 7.4 m JFH 46, JFF 12)
(2H, Hdarom
IIIc 2.1 s (3H, CH3), 6.1 d (1H, CFH, JFH 48), 7.1 d (1H,
)
84.5 d.d (2F, CF2, JFF 34), 154.6 d.t (1F, CFH,
)
84.0 t (2F, CF2, JFF 9, JFH 13), 154.6 d (1F, CFH,
JFH 49)
Harom, JHH 9), 7.2 s (1H, NH), 7.5 d (2H, Hdarom
,
JHH 9)
IIId 6.2 d (1H, CFH, JHF 49), 7.0 d (2H, Hdarom, JHH 9),
7.5 d (2H, Hdarom, JHH 9)
84.7 s (2F, CF2), 154.1 d.t. (1F, CFH,
JFH 49, JFF 9)
IIIe 6.25 d (1H, CFH, JHF 48), 7.0 m (2H, Hdarom,) 7.15 m
84.5 d (2F, CF2, JFF 15), 116.2 s (1F, Fdarom),
154.1 d (1F, CFH, JFH 48, JFF 12
84.3 d (2F, CF2, JFF 13), 154.5 d (1F, CFH,
JHF 49)
(2H, Hdarom
)
IIIf 2.1 s (3H, CH3), 6.5 d (1H, CFH, JHF 49), 7.3 d
(2H, Hdarom, JHH 6), 7.9 d (2H, Hdarom, JHH 6)
IIIg 6.3 d (1H, CFH, JHF 48), 7.4 d (2H, Hdarom, JHH 9),
7.9 d (2H, Hdarom, JHH 9), 10 s (1H, CHO)
84.5 s (2F, CF2), 154.8 d (1F, CFH, JHF 48)
IVa 3.45 br.s (2H, NH2), 6.2 d.t (1H, CFH, JFH 47), 6.7 m
84.5 d.d (2F, CF2, JFF 81, JFF 12), 154.2 d.t
(2H, Hdarom), 7.0 t (1H, Hdarom), 7.1 d (1H, Hdarom) (1F, CFH, JFH 47, JFF 12)
IVb 3.7 br.s (2H, NH2), 6.2 d.t (1H, CFH, JFH 48), 6.5 m 84.6 t (2F, CF2, JFF 17), 154.0 d.t (1F, CFH,
(3H, Hdarom), 7.1 t (1H, Hdarom
)
JFH 48, JFF 12)
IVc 3.8 br.s (2H, NH2), 5.9 d.t (1H, CFH, JFH 48), 6.9 d
(2H, Hdarom, JHH 8), 7.1 t (1H, Hdarom, JHH 8)
84.4 s (2F, CF2), 154.1 d (1F, CFH, JFH 48)
V
7.3 d.t (1H, CFH, JHF 48, JFF 12), 7.35 d (2H, Hdarom
,
83.8 s (2F, CF2), 155.2 d (1F, CFH, JFH 48)
JHH 9), 8.0 d (2H, Hdarom, JHH 9)
VIa 4.7 s (2H, CH2), 6.13 d (1H, CFH, JFH 48), 6.9 m (3H, 69.8 t (2F, CF2, JFF 12), 139.1 d.t (1F, CFH,
Hdarom), 7.15 m (1H, Hdarom
)
JFH 48, JFF 12)
VIb 4.5 s (2H, CH2), 6.1 d (1H, CFH, JFH 48), 6.8 d (2H,
Hdarom, JHH 8), 7.2 d (2H, Hdarom, JHH 8)
70.1 s (2F, CF2), 139.3 d (1F, CFH, JFH 48)
acid to provide the corresponding phenoxyacetic acids
VIa, b.
The data of 1H and 19F NMR spectra of compounds
I VI are given in table.
EXPERIMENTAL
1H and 19F NMR spectra were recorded on
spectrometer Varian VXR-300 at operating fre-
quencies 299.9 and 282.2 MHz respectively from
solutions in CDCl3 using HMDS and CCl3F as
internal references.
R = 3-OCF2CFHCl (a), 4-OCF2CFHCl (b).
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 39 No. 8 2003

1128
KREMLEV et al.
4-Substituted 1,1-difluoro-2,2-dichloroethoxy-
an appropriate substituted phenol, 0.1 mol of potas-
sium hydroxide, and 40 ml of acetone at stirring was
bubbled at 25 C 0.5 mol of trifluorochloroethene for
5 h. The reaction mixture was poured into water,
extracted with ethyl ether, the ether extract was
washed with water, and dried with MgSO4. The
solvent was distilled off, the residue was recrystalliz-
ed (compounds IIIa c) or distilled in a vacuum
(compounds IIId, e).
benzenes (Ia e). A mixture of 0.2 mmol of an
appropriate substituted phenol, 0.1 mol of potassium
hydroxide, 0.2 mol of 1,2-di(fluorochloro)ethene, and
60 ml of acetone was boiled at stirring for 48 h. The
reaction mixture was then poured into water, extract-
ed with ethyl ether, the ether extract was washed with
water, and dried with MgSO4. The solvent was
distilled off, the residue was distilled in a vacuum.
The yields of compounds obtained were calculated on
the content of 1,1-difluorodichloroethene in 1,2-di-
(fluorochloro)ethene amounting to 5%.
2-(1,1,2-Trifluoro-2-chloroethoxy)acetanilide
(IIIa), yield 51%, mp 81 83 C (benzene). Found,
%: C 44.64; H 3.31; Cl 13.27. C10H9ClF3NO2.
Calculated, %: C 44.94; H 3.37; Cl 13.11.
1,1-Difluoro-2,2-dichloroethoxybenzene (Ia),
yield 64%, bp 91 92 C (20 mm Hg), n2D2 1.4760.
Found, %: C 42.28; H 2.84; Cl 31.11. C8H6Cl2F2O.
Calculated, %: C 42.29; H 2.64; Cl 31.27.
3-(1,1,2-Trifluoro-2-chloroethoxy)acetanilide
(IIIb), yield 63%, mp 75 77 C (benzene). Found, %:
C 44.71; H 3.36; Cl 13.22. C10H9ClF3NO2. Cal-
culated, %: C 44.94; H 3.37; Cl 13.11.
4-(1,1-Difluoro-2,2-dichloroethoxy)toluene (Ib),
yield 72%, bp 110 111 C (20 mm Hg), n2D2 1.5080.
Found,%: C 45.08; H 3.28; Cl 29.39. C9H8Cl2F2O.
Calculated, %: C 44.81; H 3.32; Cl 29.46.
4-(1,1,2-Trifluoro-2-chloroethoxy)acetanilide
(IIIc), yield 57%, mp 117 119 C (benzene). Found,
%: C 44.68; H 3.29; Cl 13.18. C10H9ClF3NO2.
Calculated, %: C 44.94; H 3.37; Cl 13.11.
4-(1,1-Difluoro-2,2-dichloroethoxy)anisole (Ic),
yield 69%, bp 134 135 C (20 mm Hg), n2D2 1.4920.
Found, %: C 42.14; H 3.11; Cl 27.58. C9H8Cl2F2O2.
Calculated, %: C 42.02; H 3.11; Cl 27.63.
4-(1,1,2-Trifluoro-2-chloroethoxy)bromobenz-
ene (IIId), yield 51%, bp 78 80 C (5 mm Hg) nD22
1.4890. Found, %: C 32.91; H 1.69. C8H5BrClF3O.
Calculated, %: C 33.16; H 1.73.
4-(1,1-Difluoro-2,2-dichloroethoxy)bromobenz-
ene (Id), yield 75%, bp 144 145 C (20 mm Hg), nD22
1.5146. Found, %: C 31.20; H 1.85. C8H5BrCl2F2O.
Calculated, %: C 31.37; H 1.63.
4-(1,1,2-Trifluoro-2-chloroethoxy)fluorobenzene
(IIIe), yield 54%, bp 71 73 C (5 mm Hg), nD22
1.4350. Found, %: C 41.84; H 2.15; Cl 15.74.
C8H5ClF4O2. Calculated, %: C 42.01; H 2.19;
Cl 15.54.
4-(1,1-Difluoro-2,2-dichloroethoxy)nitrobenzene
(Ie), yield 70%, bp 164 165 C (20 mm Hg), nD22
1.5168. Found, %: C 35.01; H 1.72; Cl 25.96.
C8H5Cl2F2NO3. Calculated, %: C 35.29; H 1.83;
Cl 26.10.
4-Substituted (1,1,2-trifluoro-2-chloroethoxy)-
benzenes (IIIf, g). Trough a mixture of 0.036 mol of
methyl 4-hydroxybenzoate or 4-hydroxybenzaldehyde,
0.018 mol of potassium hydroxide, and 15 ml of
DMF at stirring was bubbled at 25 C 0.04 mol of
trifluorochloroethene for 3 h. The reaction mixture
was poured into water, extracted with ethyl ether, the
ether extract was washed with water, and dried with
MgSO4. The solvent was distilled off, the residue was
distilled in a vacuum.
4-(1,2-Difluoro-2-chloroethenyloxy)anisole (II).
A mixture of 5 g (0.039 mol) of 4-methoxyphenol,
2.4 g (0.043 mol) of potassium hydroxide, 5.7 g
(0.043 mol) of 1,2-di(fluorochloro)ethene, and 25 ml
of DMF or N,N-dimethylacetamide was stirred for
8 h at 60 C. Then the reaction mixture was poured
into 100 ml of water, organic reaction products were
extracted with ether, the extracts were washed with
2% water solution of sodium hydroxide, with water,
and dried on MgSO4. The solvent was distilled off,
the residue was distilled in a vacuum. Yield of
Methyl 4-(1,1,2-trifluoro-2-chloroethoxy)benzo-
ate (IIIf), yield 55%, bp 85 87 C (0.02 mm Hg).
Found, %: C 44.24; H 3.11; Cl 12.83. C10H8ClF3O3.
Calculated, %: C 44.69; H 2.98; Cl 13.22.
4-(1,2-difluoro-2-chloroethenyloxy)anisole 4.52
g
(56%), bp 40 41 C (0.03 mm Hg), n2D0 1.4950.
Found, %: C 48.80; H 3.23; Cl 16.29. C9H7ClF2O2.
Calculated, %: C 48.98; H 3.20; Cl 16.09.
4-(1,1,2-Trifluoro-2-chloroethoxy)benzaldehyde
(IIIg), yield 53%, bp 68 70 C (0.02 mm Hg).
Found, %: C 44.94; H 2.21; Cl 14.52. C9H6ClF3O2.
Calculated, %: C 45.28; H 2.51; Cl 14.88.
Substituted (1,1,2-trifluoro-2-chloroethoxy)-
benzenes (IIIa e). Through a mixture of 0.2 mol of
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 39 No. 8 2003

PHENOLS REACTIONS WITH 1,1-DIFLUORODICHLOROETHENE
1129
(1, 1,2-Trifluoro-2-chloroethoxy)-substituted
anilines (IVa c). A mixture of 26.75 g (0.1 mol) of
an appropriate substituted acetanilide IIIa c, 65 ml of
ethanol, and 65 ml of concn. hydrochloric acid was
boiled at stirring for 2 h. The reaction mixture was
cooled, poured into water, filtered, and neutralized
with solid sodium hydroxide till pH 8 9. The organic
compounds were extracted with ethyl ether, the
extract was washed with water, and dried with
MgSO4. The solvent was distilled off, the residue was
distilled in a vacuum.
ethyl ether. the ether extract was dried with MgSO4,
the solvent was removed in a vacuum. The residue
was recrystallized from benzene. Yield 5.1 g (67%).
The mixed sample with that prepared by procedure
(a) did not show melting point depression.
3- and 4-(1,1,2-trifluoro-2-chloroethoxy)phen-
oxyacetic acids (VIa, b). To 125 ml of 30% aqueous
sulfuric acid was added at stirring 0.1 mol of an
appropriate amine IVb or IVc. The mixture was
cooled to 5 C, and a solution of 8 g (0.11 mol) of
sodium nitrite in 25 ml of water was added thereto
maintaining the temperature below 2 C. To the
diazo solution obtained 2 g of urea was added, and
the reaction mixture was filtered. The filtrate was
added dropwise at stirring to a solution of 25 g of
CuSO4 9H2O in 200 ml of water and then heated till
the end of nitrogen liberation. The reaction mixture
was cooled, the product was extracted into ethyl
ether. The ether extract was washed with water and
dried on MgSO4. The solvent was distilled off, the
residue was distilled in a vacuum.
2-(1,1,2-Trifluoro-2-chloroethoxy)aniline (IVa),
yield 15.3 g (68%), bp 95 97 C (5 mm Hg), nD22
1.4874. Found, %: C 42.11; H 2.95; Cl 15.84.
C8H7ClF3NO. Calculated, %: C 42.57; H 3.10;
Cl 15.74.
3-(1,1,2-Trifluoro-2-chloroethoxy)aniline (IVb),
yield 14.9 g (66%), bp 96 98 C (5 mm Hg), nD22
1.4926. Found, %: C 42.23; H 3.01; Cl 15.46.
C8H7ClF3NO. Calculated, %: C 42.57; H 3.10;
Cl 15.74.
A mixture of 0.043 mol of p- or m-(1,1,2-tri-
fluoro-2-chloroethoxy)phenol, 0.064 mol of chloro-
acetic acid, 0.11 mol of sodium hydroxide, and 30 ml
of water was stirred at 100 C for 4 h.On cooling the
precipitated sodium salt of the phenoxyacetic acid was
filtered off, the precipitate on the filter was dissolved
in 100 ml of water, acidified with concn. hydro-
chloric acid to pH 3 5. The precipitated phenoxy-
acetic acid was extracted with ethyl ether (3 30 ml),
the combined ether extracts were dried on MgSO4,
and the solvent was distilled off. The residue was
recrystallized from a mixture benzene hexane, 1: 1.
4-(1,1,2-Trifluoro-2-chloroethoxy)aniline (IVc),
yield 16.0 g (71%), bp 125 127 C (15 mm Hg), nD22
1.4899. Found, %: C 42.09; H 2.99; Cl 15.56.
C8H7ClF3NO. Calculated, %: C 42.57; H 3.10;
Cl 15.74.
4-(1,1,2-Trifluoro-2-chloroethoxy)benzoic acid
(V). (a) To 20 ml of 30% water solution of potassium
hydroxide was added dropwise at stirring 2 g
(7 mmol) of ester IIIf, the stirring was continued for
10 min. The precipitated potassium salt of acid V was
filtered off, washed with ethyl ether, and dissolved in
10 ml of water. The water solution was acidified by
concn. hydrochloric acid till pH 5 6, the precipitated
crystals were filtered off, dried, and recrystallized.
Yield 1.64 g (85.5%), mp 167 168 C (benzene).
Found, %: C 42.21; H 2.25; Cl 13.87. C9H6ClF3O3.
Calculated, %: C 42.44; H 2.36; Cl 13.95.
3-(1,1,2-Trifluoro-2-chloroethoxy)phenoxyacetic
acid (VIa), yield 82%, mp 82 84 C. Found, %:
C 42.16; H 2.65; Cl 12.30; F 20.12. C10H8ClF3O4.
Calculated, %: C 42.18; H 2.81; Cl 12.48; F 20.07.
4-(1,1,2-Trifluoro-2-chloroethoxy)phenoxyacetic
acid (VIb), yield 83%, mp 103 105 C. Found, %:
C 41.94; H 3.08; Cl 11.87; F 20.35. C10H8ClF3O4.
Calculated, %: C 42.18; H 2.81; Cl 12.48; F 20.07.
(b) To a mixture of 0.72 g (0.03 mol) of magnes-
ium turnings and 20 ml of ethyl ether was added at
stirring 2 ml of 1,2-dibromoethane, and then a solu-
tion of 8.69 g (0.03 mol) of bromobenzene IIId in
30 ml of ethyl ether. The rate of addition was
controlled so that the reaction mixture moderately
boiled. After all the reagent was added the mixture
was stirred for 1.5 h more and then poured on 50 g
of solid carbon dioxide in 50 ml of ethyl ether. After
warming to the room temperature the ether solution
was washed with water (3 15 ml), the water wash-
ings were extracted with ethyl ether, the extract was
filtered and acidified with concn. hydrochloric acid
till pH 3 5. The precipitated acid was extracted with
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