U.S. patent application number 12/285645 was filed with the patent office on 2009-07-02 for method for producing 1,4-bis (dichloromethyl) tetrafluorobenzene.
This patent application is currently assigned to Yuan-Shin Materials Technology Corp.. Invention is credited to Chan-Yuan Ho, Chun-Hsu Lin, Tsair-Feng Lin, Shieh-Jun Wang.
Application Number | 20090171131 12/285645 |
Document ID | / |
Family ID | 40688690 |
Filed Date | 2009-07-02 |
United States Patent
Application |
20090171131 |
Kind Code |
A1 |
Ho; Chan-Yuan ; et
al. |
July 2, 2009 |
METHOD FOR PRODUCING 1,4-BIS (DICHLOROMETHYL)
TETRAFLUOROBENZENE
Abstract
A method for producing 1,4-bis(dichloromethyl)tetrafluorobenzene
is disclosed, which is achieved by reacting
tetrafluoroterephthaldehyde, SOCl.sub.2 and organic solvents. In
the synthesis of 1,4-bis(dichloromethyl)tetrafluorobenzene by
adding formamides as catalyst, there are remarkable advantages
which include shortening the reaction time; simplifying the
synthesizing steps and raising the yield of the product.
Inventors: |
Ho; Chan-Yuan; (Hsinchu
City, TW) ; Lin; Tsair-Feng; (Bade City, TW) ;
Lin; Chun-Hsu; (Taipei City, TW) ; Wang;
Shieh-Jun; (Taipei City, TW) |
Correspondence
Address: |
BACON & THOMAS, PLLC
625 SLATERS LANE, FOURTH FLOOR
ALEXANDRIA
VA
22314-1176
US
|
Assignee: |
Yuan-Shin Materials Technology
Corp.
Taipei City
TW
Chung-shan Institute of Science and Technology. Armaments
Bureau. M.N.D.
Longtan Township
TW
|
Family ID: |
40688690 |
Appl. No.: |
12/285645 |
Filed: |
October 10, 2008 |
Current U.S.
Class: |
570/143 |
Current CPC
Class: |
C07C 17/18 20130101;
C07C 17/392 20130101; C07C 17/38 20130101; C07C 17/18 20130101;
C07C 25/13 20130101 |
Class at
Publication: |
570/143 |
International
Class: |
C07C 17/18 20060101
C07C017/18 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 28, 2007 |
TW |
096150781 |
Claims
1. A method for producing
1,4-bis(dichloromethyl)tetrafluorobenzene, comprising the following
steps: (a) mixing tetrafluoroterephthaldehyde, a catalyst and
SOCl.sub.2 with or without organic solvents to form a mixture,
wherein the catalyst belongs to formamides; (b) heating the
mixture; (c) cooling the mixture, adding the mixture into water
slowly, and letting the mixture separate into two layers; (d)
obtaining an organic layer from the layers of the mixture; and (e)
purifying the organic layer and removing the organic solvents and
the catalyst in the organic layer and affording
1,4-bis(dichloromethyl)tetrafluorobenzene.
2. The method as claimed in claim 1, wherein the molar ratio of
tetrafluoroterephthaldehyde to SOCl.sub.2 is in the range from 2 to
20.
3. The method as claimed in claim 1, wherein the weight ratio of
the catalyst to tetrafluoroterephthaldehyde is in the range from
0.1 to 1.0.
4. The method as claimed in claim 1, wherein the weight ratio of
the organic solvent to tetrafluoroterephthaldehyde is in the range
from 0 to 3.
5. The method as claimed in claim 1, wherein the mixture is
refluxed by heating in the step (b).
6. The method as claimed in claim 1, wherein the mixture in the
step (b) is heated until the temperature thereof rises to the range
from 60 to 130.degree. C.
7. The method as claimed in claim 1, wherein the reaction time of
the step (b) is in the range from 2 to 30 hours.
8. The method as claimed in claim 1, wherein the mixture is cooled
in the range from 0 to 60.degree. C. in the step (c).
9. The method as claimed in claim 1, wherein the mixture is added
to iced water slowly in the step (c).
10. The method as claimed in claim 1, wherein the organic solvent
is at least one selected from the group consisting of toluene,
chloroform, p-xylene, benzene, dioxane, 1,2-dichloroethane,
tetrachloromathane, tetrahydrofuran, nitrobenzene, and
o-dichlorobenzene.
11. The method as claimed in claim 1, wherein the catalyst is
N,N-dialkylformamide, and the alkyl group is a
C.sub.1.about.C.sub.7 alkyl group.
12. The method as claimed in claim 1, wherein the catalyst is
N,N-dimethylformamide (DMF), or N,N-diethylformamide (DEF).
13. The method as claimed in claim 1, wherein the step (e)
comprises the following steps: (e1) adding an organic solvent and
water (H.sub.2O) into the organic layer under stirring; (e2)
neutralizing the mixture; (e3) isolating the organic layer and then
concentrating the organic layer; and (e4) cooling the organic layer
to obtain a solid product.
14. The method as claimed in claim 13, wherein the volume ratio of
the organic solvent to water is in the range from 1 to 10 in the
step (e1).
15. The method as claimed in claim 13, wherein the organic solvent
is dichloromethane in the step (e1).
16. The method as claimed in claim 13, wherein the mixture is
neutralized by concentrated ammonia in the step (e2).
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a method for producing
1,4-bis(dichloromethyl)tetrafluorobenzene (DCMTFB) and, more
particularly, to a method for producing high-yield
1,4-bis(dichloromethyl)tetrafluorobenzene in mass production.
[0003] 2. Description of Related Art
[0004] Parylene polymers possess numerous advantages for
manufacturing purposes. For example, the coating environment is at
room temperature; no residual stress exists after coating; and
precise controls are allowed on the thickness of the deposition
film. Additionally, parylene polymer films have advantages such as
uniformity, excellent acid and alkali resistance, high transparency
and low dielectric constant. Therefore, they have been widely
employed in electric insulation on printing circuit boards,
damp-proofing on sensors or medical instruments, and anti-corrosion
on metal-coating, etc. Presently, the fluoro parylene polymers, for
their low dielectric constant and high melting point, can be
utilized on dielectric coating in the electrical and coating
industries and have become the focus of the attention.
[0005] One of fluoro parylene polymers, for example,
poly(tetrafluoro-p-xylene) has the structure represented by the
following Formula (1).
##STR00001##
Fluoro parylene polymers are generally coated on products by means
of chemical vapor deposition in a vacuum at room temperature.
Products coated with fluoro parylene polymers not only possess
excellent anticorrosive, damp-proofing and insulating
characteristics, but also have the advantages of extra thinness,
transparency and being poreless. By polymerizing active monomers on
the object surfaces, fluoro parylene polymer coatings can be
formed. Unlike the general steps of liquid coating process, there
is another coating process to have the parylene dimers vaporized
first, and as the dimer bonds are cleaved to yield monomer free
radicals at a pyrolysis condition, the monomer free radicals are
polymerized to form parylene polymers.
[0006] Currently, the dimer of fluoro parylene polymers often used
in the industry is octafluoro-2,2-paracyclophane represented by the
following Formula (2).
##STR00002##
[0007] The dielectric constant of fluoro parylene polymers
decreases as the number of fluorine atoms increases within the
polymers. Thus, it can be predicted that the parylene polymers
polymerized from the dimer of fluoro parylene polymers, represented
by the following Formula (3) and containing no hydrogen atoms, can
have a lower dielectric constant.
##STR00003##
[0008] It is important for
1,4-bis(bromodifluoromethyl)tetrafluorobenzene (BFTFB) represented
by the following Formula (4) to be the monomer of the
above-mentioned dimer, to not contain any hydrogen atoms, of
fluoro
##STR00004##
[0009] 1,4-bis(dichloromethyl)tetrafluorobenzene (DCMTFB), as shown
in the following Formula (5), is a critical precursor for synthesis
of the foregoing 1,4-bis(bromodifluoromethyl)tetrafluorobenzene
(BFTFB).
##STR00005##
[0010] Nowadays, 1,4-bis(dichloromethyl)tetrafluorobenzene (DCMTFB)
is synthesized by reacting 1,2,4,5-tetrafluorobenzene (TFB) with
CHCl.sub.3, as shown in the following Reaction (I).
##STR00006##
However, this method is time-consuming and low-yielding, and needs
silica-gel column chromatography to purify the crude product.
Hence, this method is unsuitable for mass production.
[0011] Therefore, it is desirable to provide a prompt and
high-yield method for synthesize
1,4-bis(dichloromethyl)tetrafluorobenzene (DCMTFB), and such method
is appropriate for mass production.
SUMMARY OF THE INVENTION
[0012] The present invention provides a method for producing
1,4-bis(dichloromethyl)tetrafluorobenzene. This method can reduce
the reaction time, simplify the procedures and promote the yield
for producing 1,4-bis(dichloromethyl)tetrafluorobenzene. The
reaction of the method is shown as the following Reaction (II).
##STR00007##
[0013] The present invention provides a method for producing
1,4-bis(dichloromethyl)tetrafluorobenzene, which comprises the
following steps:
[0014] (a) mixing tetrafluoroterephthaldehyde, a catalyst and
SOCl.sub.2 with or without organic solvents to form a mixture,
wherein the catalyst belongs to formamides;
[0015] (b) heating the mixture;
[0016] (c) cooling the mixture, adding the mixture into water
slowly, and letting the mixture separate into two layers;
[0017] (d) obtaining an organic layer from the layers of the
mixture; and
[0018] (e) purifying the organic layer and removing the organic
solvents and the catalyst in the organic layer and affording
1,4-bis(dichloromethyl)tetrafluorobenzene.
[0019] In the method of the present invention, the molar ratio of
tetrafluoroterephthaldehyde to SOCl.sub.2 is at least more than 2.
The molar ratio of tetrafluoroterephthaldehyde to SOCl.sub.2 is
preferably in the range from 2 to 20, and more preferably in the
range from 5 to 8.
[0020] In the method of the present invention, the weight ratio of
the catalyst to tetrafluoroterephthaldehyde is in the range from
0.1 to 1.0, and preferably in the range from 0.2 to 0.4.
[0021] In the method of the present invention, the weight ratio of
the organic solvent to tetrafluoroterephthaldehyde is in the range
from 0 to 3, and preferably in the range from 1 to 2.
[0022] In the method of the present invention, the mixture in the
step (b) is heated until the temperature thereof rises to the range
from 60 to 130.degree. C., and preferably to the range from 85 to
100.degree. C.
[0023] In the method of the present invention, the reaction time of
the step (b) is in the range from 2 to 30 hours, and preferably to
the range from 4 to 6 hours.
[0024] In the method of the present invention, the mixture is
cooled in the range from 0 to 60.degree. C. in the step (c), and
preferably in the range from 25 to 40.degree. C. so as to avoid the
overreaction of hydrolysis.
[0025] In the method of the present invention, the mixture can be
added into water slowly at 0 to 25.degree. C., and preferably into
iced water in the step (c) to avoid the overreaction of
hydrolysis.
[0026] The method of the present invention can be performed without
or with an organic solvent nonreactive to SOCl.sub.2. The organic
solvent is preferably at least one selected from the group
consisting of toluene, chloroform, p-xylene, benzene, dioxane,
1,2-dichloroethane, tetrachloromathane, tetrahydrofuran,
nitrobenzene, and o-dichlorobenzene, and more preferably is toluene
or benzene.
[0027] In the method of the present invention, the catalyst is
N,N-dialkylformamide, wherein the alkyl group is a
C.sub.1.about.C.sub.7 alkyl group. Preferably, the catalyst is
N,N-dimethylformamide (DMF), or N,N-diethylformamide (DEF).
[0028] In the method of the present invention, the purification of
the step (e) preferably comprises the following steps:
[0029] (e1) adding an organic solvent and water (H.sub.2O) into the
organic layer under stirring;
[0030] (e2) neutralizing the mixture;
[0031] (e3) isolating the organic layer and then concentrating the
organic layer; and
[0032] (e4) cooling the organic layer to obtain a solid
product.
[0033] In the above-mentioned step (e), the volume ratio of the
organic solvent to water is in the range from 1 to 10 in the step
(e1), and preferably is 1. The organic solvent can be any organic
solvent which can dissolve
1,4-bis(dichloromethyl)tetrafluorobenzene but is not miscible with
water, and preferably is dichloromethane in the step (e1). The
mixture can be neutralized by any basic solution, and preferably by
concentrated ammonia in the step (e2).
[0034] Other objects, advantages, and novel features of the
invention will become more apparent from the following detailed
description when taken in conjunction with the accompanying
drawings.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Example 1
Preparation of 1,4-bis(dichloromethyl)tetrafluorobenzene (toluene
as the solvent and N,N-dimethylformamide as the catalyst)
[0035] Tetrafluoroterephthaldehyde (TFTPA, 15.45 g),
N,N-dimethylformamide (DMF, 3.01 g), and toluene (15.01 g) were
added into a 250 mL three-necked reactor equipped with a
temperature probe, a condenser and an aeration tube. Under nitrogen
atmosphere, SOCl.sub.2 (63.37 g) was slowly added into the flask
via the channel for the temperature probe by a feed hopper. After
the feed hopper was removed, the flask was reequipped with the
temperature probe. The reaction mixture was heated in an oil bath
under stirring while the aeration of nitrogen was closed, and it
was refluxed at 85.about.95.degree. C. for 2 hours until gas
chromatography (GC) analysis informed that the reaction was
completed. After the reaction mixture was cooled to room
temperature, iced water was slowly introduced thereto to hydrolyze
residual SOCl.sub.2. The reaction mixture was stood for a while and
the aqueous layer was removed. Subsequently, appropriate amounts of
dichloromethane (DCM) and H.sub.2O (the volume ratio of DCM to
H.sub.2O=1/1) were added into the remaining organic layer. The pH
value of the mixture was adjusted to 7.0 by concentrated ammonia
(conc. NH.sub.3(aq)). Then, the organic phase was isolated, washed
by water, dehydrated by anhydrous magnesium sulfate, and
concentrated to remove DCM, toluene, and DMF. Finally, the
resultant was cooled to room temperature so that the crude product
(22.23 g, crude yield: 93.8%) was obtained. The crude product was
recrystallized in n-heptane to afford 13.33 g of the crystal
product. The residual n-heptane solution was evaporated, and then
recrystallized once again to obtain 6.28 g of the crystal product.
The total quantity of recrystallization twice amounted to 19.61 g
of the crystal product (the yield: 82.75%).
Data of chemical analyses:
[0036] (a). Mass spectrum: M.sup.+=316.
[0037] (b). .sup.1H NMR (CDCl.sub.3; external standard: TMS)
chemical shift (.delta.): 6.90 ppm (s, 2H).
[0038] (c). .sup.19F NMR (CDCl.sub.3; external standard:
CFCl.sub.3) chemical shift (.delta.): -139.37 ppm (s, 4F).
[0039] (d). .sup.13C NMR (CDCl.sub.3; external standard: TMS)
chemical shift (.delta.): 143.45 ppm (d, J.sub.C-F=257 Hz, 4
Aromatic C), 120.72 ppm (s, 2 Aromatic C), 58.26 ppm (s, 2
Aliphatic C).
Examples 2 to 16
Preparations of 1,4-bis(dichloromethyl)tetrafluorobenzene
[0040] Examples 2 to 16 were performed in the manner the same as
Example 1. However, the amounts of the reagents and the solvent,
the reaction conditions, and the yields of the products are listed
in Table 1.
[0041] Examples 1 to 16 illustrate that the solvent can be toluene,
chloroform, p-xylene, benzene, dioxane, 1,2-dichloroethane,
tetrachloromathane, tetrahydrofuran, nitrobenzene, or
o-dichlorobenzene, and the catalyst is formamides most
preferably.
Comparative Example
Conventional preparation of
1,4-bis(dichloromethyl)tetrafluorobenzene
[0042] Comparative Example is a conventional method of producing
1,4-bis(dichloromethyl)tetrafluorobenzene, in which
1,2,4,5-tetrafluorobenzene (TFB) is reacted with CHCl.sub.3 to
yield 1,4-bis(dichloromethyl)tetrafluorobenzene. This method is
detailed in the following.
[0043] 1,2,4,5-tetrafluorobenzene (TFB, 3.77 g), anhydrous
AlCl.sub.3 (20.34 g), and CHCl.sub.3 dehydrated by NaH as the
solvent were added into a 100 mL reactor. The mixture was heated in
an oil bath under stirring and refluxed for 24 hours. Subsequently,
the mixture was added into iced water slowly to hydrolyze residual
AlCl.sub.3. The mixture was extracted with chloroform, and then the
organic phase was washed by water, dehydrated by anhydrous
magnesium sulfate, and concentrated to obtain the crude product.
The crude product was purified by silica-gel column chromatography
using n-hexane as the eluent, and recrystallized with n-hexane to
obtain 1,4-bis(dichloromethyl)tetrafluorobenzene (yield:
59.33%).
[0044] Table 2 shows the drawbacks and advantages of the present
Comparative Example compared with Example 1.
[0045] Based on Table 2, the cost of Example 1 is 1.5-fold more
than that of the Comparative Example. However, the method of
Example 1 can reduce the reaction time, simplify the procedures,
have a larger reactor capacity and promote the yield for producing
1,4-bis(dichloromethyl)tetrafluorobenzene. These aspects of Example
1 are better than those of the Comparative Example.
[0046] Although the present invention has been explained in
relation to its preferred embodiment, it is to be understood that
many other possible modifications and variations can be made
without departing from the scope of the invention as hereinafter
claimed.
TABLE-US-00001 TABLE 1 The reaction conditions and the results in
Examples 1 to 16 Reaction Reaction TFTPA SOCl.sub.2 temperature
times DCMTFB Yield Example (g) (g) Catalyst (g) Solvent (g)
(.degree. C.) (hours) (g) (%) Remarks 1 15.45 63.37 DMF 3.01
Toluene 15.01 85-95 2.0 19.61 82.75 2 15.44 55.61 DMF 3.01
Chloroform 25.35 73-79 6.0 16.01 67.59 3 15.46 55.73 DMF 3.02
p-Xylene 14.81 90-104 3.0 14.26 60.13 4 15.46 56.51 DMF 3.00
Benzene 14.97 80-88 4.25 19.24 81.13 5 15.46 55.57 DMF 3.01
Acetonitrile 13.29 77-83 6.0 4.93 20.79 *1 6 15.45 55.45 DMF 3.01
Dioxane 17.55 91-99 4.0 17.49 73.80 7 15.45 58.60 DMF 3.01
1,2-Dichloroethane 21.18 81-87 4.0 17.25 72.79 8 15.45 55.57 DMF
3.01 Tetrachloromathane 27.34 75-81 6.0 16.09 67.89 9 15.45 55.45
DMF 3.03 Tetrahydrofuran 15.29 80-90 3.0 14.47 61.05 10 15.45 55.87
DMF 3.01 Nitrobenzene 20.44 106-108 2.0 13.62 57.47 11 15.45 55.80
DMF 3.01 o-Dichlorobenzene 22.24 94-106 2.0 17.41 73.45 12 15.45
55.52 DMF 3.02 -- -- 85-90 3.0 6.38 26.92 13 15.45 55.93 DMF 3.01
-- -- 85-90 29.0 2.16 9.12 *2 14 15.44 55.71 DMAC 3.00 Toluene
15.00 84-97 6.0 -- -- *3 15 15.44 55.45 NMP 3.00 Toluene 15.00
85-93 5.0 -- -- *4 16 15.44 56.74 DEF 3.01 Toluene 15.01 85-97 4.0
18.75 79.17 DMF: N,N-dimethylformamide DMAC: dimethylacetamide NMP:
N-methylpyrrolidone DEF: N,N-diethylformamide *1: Solution turned
black. *2: TFTPA was of poor purity. *3: Solution turned black and
only little product was obtained. *4: Solution turned black and
only little product was obtained.
TABLE-US-00002 TABLE 2 The drawbacks and advantages of the present
Comparative Example compared with Example 1 Example 1 Comparative
Example Reaction Time 2 hours 24 hours Yield 82.75% 59.33% Reactor
Capacity Large Small Preliminary Process for Simple and Complex
Solvent Convenient Purification of Product Recrystallization Column
Chromatography Cost of Material Expensive (NTD: Cheap (NTD: 51,000)
(For Synthesis of 1 kg 128,000) DCMTFB)
* * * * *