Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
13V362~
HOECHST A~TIENGESELLSCHAFT HO~ 86/F 281 Dr.~A/mu
Descr;ption:
tMeth)acrylate esters
The invention relates to esters of wholly or partially
deuterated (meth)acrylic acid with alcohols, which have
only a little hydrogen or none at all in the molecule, to
processes for the preparation of these esters and to their
use for the preparation of transparent polymeric materials
for optical fibers. Various esters of perdeuterated meth-
acryLic acid and their use for the preparation of trans-
parent pclymers for optical fibers are known.
Thus, fluoroalkyl esters of deuterated methacrylic acid
of the formula
~ CD3
CD2 = C~ / Rl wherein R1 and R2
COOCH
~ R2
are lower fluoroalkyl radicals or hydrogen atoms, but at
Least one of the two radicals is required to be a lower
fluoroalkyl radical, are known tcf. Japanese Published
Application 61-20,906). 2,2,2-Trifluoroethyl, 2,2,3,3-
tetrafluoro-1-propyl and 1,1,1,3,3,3-he~afluoro-2-prc,pyl
are mentioned by name. On the other hand, these esters
still contain a relatively large number of hydrogen atoms
in the molecule, which have an attenuating effect on the
light transmission of the polymers prepared from these
esters.
Esters of wholly or partially deuterated methacrylic acid
with borneol, isoborneol and fenchyl alcohol are also
known (cf. EP-A 144,712; US Patent 4,575,188). However,
the methyl groups in the alcohol components of these esters
make a considerable contribution to the residual hydrogen
13~?362~;
content of the esters, since their hydrogen atoms are
diff;cult to replace by deuterium.
As is known, one hydrogen atom per mole of monomer in-
S creases the attenuat;on of the light transmission of the
polymer in the wavelength region from 600 to 800 nm due
to absorpt;on by about 11 d~/km. It was then desirable to
find monomers which provide the polymeric transparent
materials prepared from them by polymer;2at;0n with the
lowest possible attenuation. At the same time, the trans-
parent polymeric materials should have a glass point TG
~hich is higher than that of the hitherto mainly used
polymethyl methacrylate (TG = 105C).
It has been found that the object can be achieved when
uholly or partialLy deuterated (meth)acrylic acid is ester-
ified with certain alcohols which contain only a little
hydrogen or none at all in the molecule.
Thus, the invention relates to a compound of the formula
t I )
Rl R3
C = C - COO - R4 ( I )
R2
uherein
R1 and R2 are identical or different and are a hydrogen atom
or deuterium atom,
R3 is H, D, -CH3, -CH2D, -CHD2 or -CD3 and
R4 is one of the groups -C(CH3)2-CN, -C(CD3)z-CN,
(bicyclo-2.2.1-hept-2-yl) or
(tricyclo-2.2.12'6-hept-3-yl),
13~626
-- 3
it being possible for the rings to be deuterated, and,
if R3 ;s -CD3,
R4 can also be -C~CF3)2-CF~CF3)2, -CF~CF3)2 or
-CD~CF3)2-
s
The invention also relates to a process for their preparat-
ion and to their use for the preparat;on of transparent
polymeric materials.
In the formu~a (I), R1 and R2 are preferably a deuterium
atom, R3 is preferably a deuterium atom or one of the groups
-CH3, -CH2D, -CHD2 or -CD3, especially a deuter;um atom
or a perdeuteromethyl group, and R4 is preferably
~ (bicyclo-2.2.1-hept-2-yl, norbornyl) or
~ (tricyclo-2.2.1.02'6-hept-3-yl),
it be;ng possible for the rings to be deuterated, and in
the case of R3 = -CD3 can also be
-C(CF3)2-CF(CF3)2, -CF(CF3)2 or -CD(CF3)2.
; 25
The acid components of the esters according to the inven-
tion are thus preferably deuterated acrylic acid and meth-
acrylic acid. The preparation of the deuterated acids is
known per se, and it can be carried out, for example, in
the follo~ing manner.
Methyl (meth)acrylate, deuterium oxide, a noble metal
salt and a polymerization inhibitor are stirred for several
hours at a temperature of around 100C in a reactor.
It is also possible to obtain perdeuterated acrylic acid
in accordance with the following reaction equation:
13~336~6
-- 4 --
Lindlar
Ca~011)23~ Catalyst>
H-C-C-COOR D-C-C-COOR D2C=CD-COOR
D20 D2 gas
If required, the corresponding acids can be obtained from
the esters.
For the further conversion (ester;fication), the acid of
~0 the formula II
Rl\ R3
/ C=C-C~ -R~ (II)
R2
wherein R~, R2 and R3 are as defined above, is used as
such ~R5 = OH or OD) or in the form of an acid halide (R5 =
Cl or 8r, preferably Cl). The acid halide is prepared by
means of a conventional halogenating agent, for example
oxalyl chloride, phosphorus pentachloride, phosphorus
trichloride, phosphorus oxychloride, benzoyl chloride,
benzotrichloride, phosphorus tribromide and especially
thionyl chloride. The halogenation with thionyl chloride
is preferably carried out in the presence of a catalyst
such as dimethylformamide. The reaction is carried out
in an aromatic hydrocarbon, for example toluene, xylene or
trimethylbenzene, as the solvent and the reaction temper-
ature is in the range from 50 to 100C, preferably 70 to 90C.
The (meth)acrylic acid or the acid halide is then reacted
with a compound of the formula ~III)
HoR4 (III)
wherein
R4 is as defined above.
The acid halide is preferably used for the esterification
of the alcohols HO-C(CH3)-CN, HO-CD(CF3)2, HO-CF(CF3)2
~3~3~Z~
and Ho-c(cF3)2-cFtcF3)2-
The ester;fication is preferably carried out in a sol-
vent, and the reaction temperature is -10 to 50C, prefer-
ably 0 to 25C. The solvent used is a polar organic sol-
vent, especially a symmetrical, asymmetrical or cyclic
ether, for example diethyl ether, dipropyl eeher, diiso-
propyl ether, tert.-butyl methyl ether, tetrahydrofuran
and dioxane, an aliphatic halogenohydrocarbon, preferably
chlorohydrocarbon, for example dichloromethane, trichloro-
methane, tetrachloromethane, 1,1-dichloroethane and 1,2-
dichloroethane, an aromatic halogenohydrocarbon, prefer-
ably chlorohydrocarbon, for example chlorobenzene and 1,2-
or 1,3-dichlorobenzene, or an aliphatic or aromatic nit-
rile, for example acetonitrile and benzonitrile. The sol-
vent can also be a mixture of several polar solvents. It
is e~pedient to carry out the esterification of the acid
halide ~ith the alcohol in the presence of an organic base,
especially a trialkylamine having 1 to 4 carbon atoms in
each of the alkyl groups. The base is employed in a quan-
tity from 0.5 to 2 mole, preferably 0.8 to 1.2 mole (rel-
ative to 1 mole of acid halide). The ester obtained is
isolated from the reaction mixture by distillation, prefer-
ably under a pressure of 1,013 to 200 mbar, or - after
removal of the solvent by distillation - by hot extraction
of the solid residue ~ith a non-polar solvent, preferably
; an aliphatic hydrocarbon such as n-hexane, and subsequent
crystallization. It is appropriate to carry out the dis-
tillation in the presence of a conventional polymeri2ation
inhibitor, for example hydroquinone or hydroquinone mono-
methyl ether; the latter is used in a quantity from 100
to S00 ppm (relative to acid halide). The bottom temper-
ature is in the range from 20 to 100C, preferably 30 to
85C. For further purification, the ester is distilled
again, preferably under a reduced pressure, or recrystallized.
:
The alcohol is employed in a quantity of O.S mole, prefer-
ably 0.8 to 1.2 mole (relative to 1 mole of (meth)acrylic
acid).
,,~
, ~
. .
l;~V~2~
Operation in the presence of a dehydrating agent, for
example oleum, represents a ~urther esterification method.
The (meth)acryl;c acid esters of bicycloheptyl (norbornyl)
and tricycloheptyl alcohol can be prepared according to
known methods by acid-catalysed addition of (meth)acrylic
acid to bicycloheptene or b;cycloheptadiene respectively.
After known free-radical polymerization by themselves, with
one another and/or with other comonomers, for example
methacrylic acid esters of aliphatic or alicyclic alcohols,
the esters according to the invention give transparent
polymeric materials which show low attenuation of incident
light and a high glass temperature TG. The alcohols used
for the preparation of the esters according to the inven-
tion contain either no hydrogen or only a littLe hydrogen
in the molecule.
Compared with borneol and isoborneol, the methacrylates
Z0 of which are known, the cyclic alcohols of the norbornene
type (bicyclo-2.2.1-heptan-2-ol and tricyclo-2.2.1 o2 6-
heptan-3-ol) have the advantage of a more favorable C/H
ratio and offer the possibility of replacing all the hydrogen
atoms by deuterium by means of catalytic H/D exchange with
D20, on the basis of a Wagner-Meerwein rearrangement.
Since a mixture of exo- and endo-norborn-2-yl alcohol or
exo- and endo-tricyclohept-3-yl alcohol is formed in the
addition reaction, the anisotropy of a polymer produced
from the esters is reduced, whereby the transparence is
increased.
The transparent polymeric materials obtained from the
esters are used for the production of optical fibers,
resist material, ienses, optical data storage media and
other transparent articles.
The invention is explained in more detail by the examples
which follow.
13~:~36Z~
-- 7
Example 1
2-Cyano-isopropyl methacrylate
9 ml of 2-cyano-isopropyl alcohol ~0.098 M) were added to
10 ml of methacrylic acid chloride (0.103 M) in S0 ml of
methyL tert.-butyl ether, 15 ml of triethylamine were then
added dropwise with ice-cooling and the mixture was stirred
for 1 hour. The triethylammonium hydrochloride was filtered
off, and the filtrate was freed of solvent and distilled in
vacuo. 7.9 9 of 2-cyano-isopropyl methacrylate were dis-
tilled off at 49 - 50C/1.3 mbar, corresponding to 51.6
yield.
IR(CH2Cl2): C=0 at 1750 cm 1, C-N at 2290 cm 1 (weak)
Molecular massO 15
Example 2
The perdeuterated compound was prepared analogously from
methacrylic acid chloride-D5 and 2-cyano-isopropyl alcohol-
D6. Yield 90 9, boiling point 53C/1.3 mbar.
Molecular mass: 164
Example 3
50 mg of di-lauroyl peroxide were in each case dissolved
in 5 ml of the 2-cyano-isopropyl methacrylate according
to each of Examples 1 and 2, and the solutions were kept
for 20 hours at 50C and then for 2 hours at 90C. This
gave glass-clear polymers of glass temperature 117C and
a decomposition temperature 220C.
Example 4
Norbornyl methacrylate
165 9 of norbornene (= 1.75 M) were dissolved in 100 ml of
methylene chloride, and 1 9 of tert.-butylpyrocatechol was
added as a stabilizer. With stirring and cool;ng, a
;
13~362~
-- 8
mixture of 150 ml of methacryl;c ac;d and 15 ml of ~f3 etherate
was added dropw;se at 30 - 40C in the course of 2 hours.
The mixture was stirred for a further 2 hours, and the
solution was washed with water untiL neutral, dried and
concentrated by dist;llat;on. The v;scous res;due was
distilled in an oil pump vacuum at bD;l;ng po;nt =52C/0.013
mbar. Th;s gave 210 9 of norbornyl methacryLate, corres-
pond;ng to 66~ y;eld. lR(CH2Cl2) C=0 at 1710 cm 1
Molecular mass: 180
The H -NMR spectrum was cons;stent w;th the ind;cated
structure
Example 5
Starting from methacryl;c ac;d-D5 and partially deuterated
norbornene, ;t was possible to prepare the deuterated ester
(partially deuterated in the norbornyl radical) analogously
to Example 4, the yield and boiling point corresponding to
the undeuterated compound.
Example 6
5 ml of each of the pure compGunds from Example 4 and
Example 5 were kept with 50 mg of d;lauroyl peroxide in
each case for 20 hours at 50C and then for 2 hours at 90C.
This gave glass-clear, hard polymers. The d;fferent;al
thermal analysis gave 2 TG values of 120.8C and 172C,
decompos;tion temperature 225C.
Example 7
Perfluoro-dimethylbutyl perdeutero-methacrylate
40 9 of perfluorodimethyl-butan-2-ol were added to 10 ml of
methacrylic acid chloride-D5, dissolved in 50 ml of methyl
tert.-butyl ether. 17 ml of triethylam;ne were added
dropwise with stirr;ng and cool;ng. The temperature was
ma;ntained at Z0C. After 1 hour, the precipitated triethyl-
-
13~36Z6
_ 9 _
ammonium hydrochlor;de was filtered off with suction and
the filtrate was distilled. The perfluorodimethylbutyl
perdeuteromethacryLate boiled at 45C/11 mbar. The yield
was 14 9, corresponding to 28.5% of theory.
The ester was polymerizable with 1% of dilauroyl peroxide
(20 hours at 50C, 1 hour at 90C) and gave a glass-clear
polymer having a glass temperature of 111C.
E~ample 8
Tricyclo-2.2.1.02 6-hept-3-yl acrylate
30 ml of norbornadiene (= 0.32 M) were d;ssolved in 50 ml
of CH2Cl2, and a mixture of 20 ml of acrylic acid (= 0.29 M),
0.5 9 of tert.-butylpyrocatechol and 3 ml of ~F3 etherate
were added dropwise to the solut;on at 20C with stirring.
A slightly exothermic reaction was observed. After 6 hours,
the batch was transferred into a separating funnel and
washed therein with water, and then dried. In the distil-
lation which followed, 12.6 9 of a substance passed over at
60C and 1.7 mbar. The substance had a molar mass of 164,
and the H1- and C13-NMR spectrum showed the structure
of a tricyclo-2.2.1.02 6-hept-3-yl acrylate. Yield 26.5%.
Example 9
Tricyclo-2.2.1.02 6-hept-3-yl methacrylate
Analogously to Example 8, a mixture of 25 ml of methacrylic
acid, 5 ml of BF3 etherate and 1 9 of tert.-butylpyro-
catechol (as stabilizer) was added to 35 ml of norbornadiene
dissolved in 50 ml of CH2Clz. After 6 hours of a slightly
exothermic reaction, the batch was worked up as in Example 8.
Boiling point 75 - 85C at 1.7 mbar, yield 32 9 = 62%
of theory: molecular mass 178.
~3~33~
- 10 -
The H1- and C13-NMR specerum showed the structure of a
tricyclo-2.2.1.02~6-hept-3-yl methacrylate.
Example 10
Deuterohexafluoroisopropyl perdeutero-methacrylate
30 ml of perdeuterated methacrylic acid and 45 ml of per-
deuterated hexafluoroisopropanol (prepared by catalytic
hydrogenation of hexafluoroacetone with D2 on a Pd/C
catalyst) were mixed with 75 ml of ~6X oleum. During the
reaction, the temperature rose to 40C. After 15 minutes,
the mixture was transferred into a thin-layer evaporator
and distilled at a wall temperature of 130C under a vacuum
of 44 mbar. At a top temperature of 50 to 60C, 60 9 of
crude deuterohexafluoroisopropyl perdeuteromethacrylate
passed over, and this was distilled once more. This gave
50 9 of end product, corresponding to a yield of 60Z of
theory.
The ester was polymerizable by means of 0.1% by weight of
dilauroyl peroxide and gave a polymer having a TG value
of 74C and a decomposition temperature h;gher than 200C.
Example 11
Perfluoroisopropyl perdeutero-methacrylate
12.9 g (0.222 M) of potassium fluoride were suspended in
80 ml of diglyrol d;methyl ether. 33 9 (0.198 M) of hexa-
fluoroacetone were passed ;nto this suspens;on at room
temperature. The batch was then stirred for a further 2
hours and the und;ssolved potass;um fluoride was then sep-
arated off. 22 9 (0.2 M) of methacryl;c ac;d chloride-Ds
were added dropw;se to the filtrate at room temperature
and the react;on m;xture was stirred for a further hour.
After the sol;d formed had been separated off, the fil-
trate was distilled.
~3~362~i
- 11 -
Colorless liquid, bo;ling point 45.2 - 45.4 C/80 mbar.
Yield 32 9 = 64X of theory.
The ester was polymerizable by means of 0.5% by weight of
dilauroyl pero~ide for 24 hours at 50C, to give a gLass-
clear polymer having a TG value of 76C.
