U.S. patent application number 09/835751 was filed with the patent office on 2001-11-22 for hydrolysis-stable and polymerizable acrylophosphonic acid monoesters.
This patent application is currently assigned to Ivoclar Vivadent AG. Invention is credited to Moszner, Norbert, Rheinberger, Volker, Zeuner, Frank.
Application Number | 20010044513 09/835751 |
Document ID | / |
Family ID | 27213805 |
Filed Date | 2001-11-22 |
United States Patent
Application |
20010044513 |
Kind Code |
A1 |
Moszner, Norbert ; et
al. |
November 22, 2001 |
Hydrolysis-stable and polymerizable acrylophosphonic acid
monoesters
Abstract
Hydrolysis-stable and polymerizable acrylophosphonic acid
monoesters with the general formula (I) 1 which are particularly
suitable as a component of dental materials.
Inventors: |
Moszner, Norbert; (Eschen,
DE) ; Zeuner, Frank; (Vaduz, DE) ;
Rheinberger, Volker; (Vaduz, DE) |
Correspondence
Address: |
Joseph M. Noto
NIXON PEABODY LLP
Clinton Square
P.O. Box 31051
Rochester
NY
14603
US
|
Assignee: |
Ivoclar Vivadent AG
|
Family ID: |
27213805 |
Appl. No.: |
09/835751 |
Filed: |
April 16, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60250711 |
Dec 1, 2000 |
|
|
|
Current U.S.
Class: |
526/278 ;
526/274; 526/277 |
Current CPC
Class: |
A61K 6/30 20200101; C08L
33/08 20130101; C08L 33/08 20130101; A61K 6/30 20200101; A61K 6/30
20200101 |
Class at
Publication: |
526/278 ;
526/274; 526/277 |
International
Class: |
C08F 230/02 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 17, 2000 |
DE |
100 18 969.5 |
Claims
1. Acrylophosphonic acid monoesters of the general formula (I),
stereoisomers thereof or mixtures of these 12in which R.sup.1,
R.sup.2, R.sup.3, X, Y, m and n have the following meanings:
R.sup.1=a linear or branched C.sub.1 to C.sub.20 alkyl or C.sub.6
to C.sub.14 aryl radical; R.sup.2=a hydrogen, a linear or branched
C.sub.1 to C.sub.5 alkyl or phenyl radical; R.sup.3=a linear or
branched C.sub.1 to C.sub.8 alkylene radical, phenylene or is
absent; Y=oxygen, C.sub.1 to C.sub.8 alkylene or is absent; m=0 or
1; n=1 or 2; provided that Y=0, m=0 and R.sup.3=absent cannot be
true at the same time and further provided that for m =1 and n=1
X=hydrogen or a linear or branched C.sub.1 to C.sub.3 alkyl radical
or a C.sub.6 to C.sub.14 aryl radical; for m=1 and n=2 X=a linear
or branched C.sub.1 to C.sub.10 alkylene, C.sub.6 to C.sub.10
arylene, C.sub.7 to C.sub.20 arylalkylene radical or a chemical
bond which links together two radicals with the structure of
formula (I) in brackets, the individual radicals being able to be
substituted or unsubstituted.
2. Acrylophosphonic acid monoesters according to claim 1,
characterized in that the variables of formula (I) have the
following meanings independently of each other: R.sup.1=a linear or
branched C.sub.1 to C.sub.10 alkyl or phenyl radical;
R.sup.2=hydrogen or a linear or branched C.sub.1 to C.sub.3 alkyl
radical; R.sup.3=a linear or branched C.sub.1 to C.sub.4 alkylene
radical, phenylene or is absent; Y=oxygen or is absent; and
X=hydrogen or a linear or branched C.sub.1 to C.sub.3 alkyl radical
(for m=1 and n=1); or X=a linear or branched C.sub.1 to C.sub.6
alkylene radical, phenylene or a chemical bond which links together
two radicals with the structure of formula (I) in brackets (for m=1
and n=2).
3. Acrylophosphonic acid monoesters according to claim 2,
characterized in that the variables of formula (I) have the
following meanings independently of each other: R.sup.1=a linear or
branched C.sub.1 to C.sub.4 alkyl radical, which can be
unsubstituted or can be substituted by an OH group;
R.sup.2=hydrogen or a linear or branched C.sub.1 to C.sub.3 alkyl
radical; R.sup.3=a linear or branched C.sub.1 to C.sub.4 alkylene
radical, phenylene or is absent; Y=oxygen or is absent.
4. Acrylophosphonic acid monoesters according to one of claims 1 to
3, characterized in that m=0 or for m=1, n=2 and X=phenylene or a
chemical bond which joins together two radicals with the structure
of formula (I) in brackets.
5. Use of an acrylophosphonic acid monoester according to claims 1
to 4 as a component of an adhesive, of a polymer, of a composite,
of a cement, of a molded article and in particular of a dental
material.
6. Use according to claim 5, characterized in that the dental
material is a dental adhesive, a fixing cement or a filling
composite.
7. Use according to claim 5 or 6, characterized in that the
acrylophosphonic acid monoester is present in at least partially
polymerized form.
8. Dental material, characterized in that it contains an
acrylophosphonic acid monoester according to claims 1 to 4.
9. Dental material according to claim 8, characterized in that it
contains the acrylophosphonic acid monoester in at least partially
polymerized form.
10. Polymers and copolymers, characterized in that they can be
obtained by polymerization or copolymerization of an
acrylophosphonic acid monoester according to one of claims 1 to 4.
Description
[0001] The present invention relates to polymerizable
acrylophosphonic acid monoesters which have a high hydrolytic
stability and are suitable in particular for preparing, or as
components of, polymers, adhesives or other materials and mainly
dental materials.
[0002] Polymerizable phosphonic acids are of polymer-chemical
importance mainly as comonomers. They allow the preparation of
organic polymers with high thermal stability, good adhesion
properties, high ignition temperature and good solubility in polar
solvents. For this purpose, numerous monomeric phosphonic acids
with polymerizable vinyl, dienyl, allyl, or styryl groups have been
synthetized and polymerized. An overview of phosphonic acids is
given by Houben-Weyl, Methoden der Organischen Chemie, Vol. E 20
(2.sup.nd part), Georg Thieme Verlag, Stuttgart-New York 1987, p.
1300 et seq). Examples of such conventional polymerizable
phosphonic acids are vinyl phosphonic acid, allylbenzene phosphonic
acid, .alpha.-aminoallyl phosphonic acid, phenylethene phosphonic
acid, 1,3-butadiene or isoprene phosphonic acid, 4-vinylbenzene
phosphonic acid or 2-(4-vinylphenyl)-ethane phosphonic acid.
[0003] Phosphonic acids in which the C.dbd.C group is bound to the
phosphorus atom directly or via an oxygen atom, such as e.g. vinyl
phosphonic acid or ethyl phosphonic acid monovinyl ester, show only
a moderate tendency towards homopolymerization, so that only
homopolymers with a low molecular weight are accessible.
[0004] High-molecular-weight polymerisates can on the other hand be
obtained from (meth)acrylophosphonic acids or esters in which the
(meth)acrylic group is not bound directly to the phosphorus, but
via a hydrolysis-stable spacer group. Such (meth)acrylophosphonic
acid derivatives are described for example in DE-B-27 11 234.
[0005] DE-A-32 10 775 discloses 2-acrylamido-2-methyl-propane
phosphonic acid with the formula
CH.sub.2.dbd.CH--CONH--C(CH.sub.3).sub.2--CH.sub.2--
-P(.dbd.O)(OH).sub.2 as well as its use for preparing
copolymerides.
[0006] DE-A-33 13 819 and JP 62-63314 (Chem. Abstr. 107 (1987),
41318f) disclose methacrylic
acid-(2-phosphono-1,1-dimethylethylamine) of the formula
CH.sub.2.dbd.C(CH.sub.3)--CONH--C(CH.sub.3).sub.2--CH.sub.2--P
(.dbd.O) (OH).sub.2.
[0007] According to EP-B-0 089 654 and U.S. Pat. No. 4,650,591
acrylic acid-(2-phosphono-1,1-dimethylethylamine), also called
2-acrylamido-2-methylpropylphosphonic acid, is suitable as a
corrosion inhibitor in the form of its homo- or copolymers.
[0008] DD-A-273 846 discloses adhesion promoters based on
N-acyl-aminomethan-bisphosphonic acid derivatives.
[0009] These known (meth)acrylophosphonic acid derivatives are not
stable in aqueous solution. Rather, they show a hydrolytic clearage
of the (meth)acrylic group which is even catalyzed by dissociated
protons of the phosphonic acid group and thus accelerated.
[0010] The use of aqueous solutions is however advantageous or
absolutely necessary in a whole series of applications of
polymerizable phosphonic acids. This is the case e.g. in the
preparation of low viscosity adhesives which are free from organic
solvents, or in dental adhesives which lead to an optimal wetting
of the moist dentine surfaces only in aqueous form.
[0011] DE 197 46 708 A1 discloses polymerizable acrylophosphonic
acids which are hydrolysis-stable in an aqueous solution, have good
adhesion properties, can be polymerized with conventional radical
initiators and are therefore suitable as a component in particular
of adhesives, molded articles, cements or composites and in
particular dental materials. The acrylophosphonic acids show a good
solubility, in the form of their carboxylic acid esters, in water
and polar organic solvents, whereas in the form of carboxylic acids
they are easily soluble in water but hardly soluble in organic
solvents. The different dissolving behaviour of ester and acid can
be disadvantageous in the case of aqueous materials. The hydrolysis
of the carboxylic acid esters to produce the free carboxylic acid
and alcohol can significantly change the solubility of the monomers
and thus lead to partial or complete precipitation of the
phosphonic acid component and thus influence the properties of the
material.
[0012] The object of the invention is the preparation of
hydrolysis-stable polymerisable acrylophosphonic acid derivatives
which are easily soluble in water and in polar organic solvents and
the solution behaviour of which is not changed by hydrolysis.
[0013] Surprisingly, this object was achieved by acrylophosphonic
acid esters of the following general formula (I) 2
[0014] in which R.sup.1, R.sup.2, R.sup.3, X, Y, m and n,
independently of each other, have the following meanings:
[0015] R.sup.1=a linear or branched C.sub.1 to C.sub.20 alkyl or
C.sub.6 to C.sub.14 aryl radical;
[0016] R.sup.2=hydrogen, a linear or branched C.sub.1 to C.sub.5
alkyl or phenyl radical;
[0017] R.sup.3=a linear or branched C.sub.1 to C.sub.8 alkylene
radical, phenylene or is absent;
[0018] Y=oxygen, C.sub.1 to C.sub.8 alkylene or is absent;
[0019] m=0 or 1;
[0020] n=1 or 2;
[0021] provided that Y=O, m=0 and R.sup.3=absent cannot be true at
the same time and
[0022] further provided that
[0023] for m=1 and n=1
[0024] X--hydrogen or a linear or branched C.sub.1 to C.sub.5 alkyl
radical or a C.sub.6 to C.sub.14 aryl radical;
[0025] for m=1 and n =2
[0026] X=a linear or branched C.sub.1 to C.sub.1 alkylene, C.sub.6
to C.sub.10 arylene, C.sub.7 to C.sub.20 arylalkylene radical or a
chemical bond which links together two radicals with the structure
of formula (I) in brackets.
[0027] The individual alkyl and alkylene radicals can be linear,
branched or cyclic. In addition, the individual alkyl, aryl,
alkylene, arylene, phenyl, phenylene and arylenealkylene radicals
have one or more, preferably 1 to 2 substituents, such as Cl, Br,
CH.sub.3O, COOH, CN or preferably OH.
[0028] R.sup.1is preferably unsubstituted or substituted by one or
more OH groups, preferably 1 or 2 OH groups. The remaining radicals
are preferably not substituted.
[0029] Further, there are preferred definitions for the
above-mentioned variables of the formula (I) which, unless
otherwise stated, can be chosen independently from each other and
are as follows:
[0030] R.sup.1=a linear or branched C.sub.1 to C.sub.10 alkyl or
phenyl radical; R.sup.2=hydrogen or a linear or branched C.sub.1 to
C.sub.3 alkyl radical;
[0031] R.sup.3=a linear or branched C.sub.1 to C.sub.4 alkylene
radical, phenylene or is absent;
[0032] Y=oxygen or is absent;
[0033] X=hydrogen or a linear or branched C.sub.1 to C.sub.3 alkyl
radical (for m=1 and n=1); or
[0034] X=a linear or branched C.sub.1 to C.sub.6 alkylene radical,
phenylene or a chemical bond which links together two radicals with
the structure of formula (I) in brackets (for m=1 and n=2).
[0035] Meanings which are particularly preferred and likewise
chosen independently of each other are:
[0036] R.sup.1=a linear or branched C.sub.1 to C.sub.4 alkyl
radical which is unsubstituted or can be substituted by an OH
group;
[0037] R.sup.2=hydrogen or a linear or branched C.sub.1 to C.sub.3
alkyl radical;
[0038] R.sup.3=a linear or branched C.sub.1 to C.sub.4 alkylene
radical, phenylene or is absent;
[0039] Y=oxygen or is absent.
[0040] Furthermore, acrylophosphonic acid monoesters are
particularly preferred in which R.sup.1, R.sup.2, R.sup.3, Y and n
have the above mentioned meanings and (i) m=0 or (ii) m=1, n=2
and
[0041] X=phenylene or a chemical bond which links together the two
radicals with the structure of formula (I) in brackets.
[0042] Preferred compounds are those where at least one,
particularly preferably all, of the variables of formula (I) have
the preferred definitions described above, the formula (I)
including all the stereoisomers possible through the named
substituents and their mixtures, such as racemates.
[0043] If m is equal to 0, the radicals X and R.sup.2 are
absent.
[0044] The acrylophosphonic acid monoesters (APME) according to the
invention of the formula (I) can be prepared by partial hydrolysis
of corresponding acrylophosphonic acid esters APE. For this,
diluted caustic soda solution can be used, a silylation for example
with trialkylsilanes is not necessary, so that the acrylophosphonic
acid monoesters are more easily and economically accessible than
comparable phosphonic acids. 3
[0045] Specifically, the reaction of
2-[4-(dimethoxyphosphoryl)-2-oxa-buty- l]-acrylic acid ethyl ester
with caustic soda solution results in the corresponding phosphonic
acid monoester (2-[4-hydroxymethoxyphosphoryl-2--
oxa-butyl)-acrylic acid): 4
[0046] The acrylophosphonic acid esters (APE) used for this can be
obtained for example by reacting .alpha.-halogen methylacrylic acid
esters (HMAE; U=halogen, preferably Cl or Br) with mono- or
difunctional phosphonic acid esters (PE) using methods known from
organic chemistry for preparing C--C--O or C--S bonds (cf. C.
Weygand, G. Hilgetag, Organisch-chemische Experimentierkunst,
Johann Ambrosius Bart Verlag, Leipzig 1970, pp. 963 et seq., 362 et
seq., and 657 et seq; N. Moszner, F. Zeuner, U. K. Fischer, V.
Rheinberger, Macromol. Chem. Phys. 200 (1999) 1062). This reaction
can be illustrated by the following general reaction equation:
5
[0047] Specifically, the reaction of .alpha.-chloromethylacrylic
acid ethyl ester with 2-hydroxyethylphosphonic acid dimethylester
gives 2-[4- (dimethoxyphosphoryl-2-oxa-butyl]-acrylic acid ethyl
ester: 6
[0048] A further preparation possibility is the reaction of
corresponding acrylophosphonic acid (APA) with epoxides accompanied
by formation of OH-substituted acrylophosphonic acid monoesters
OH-APME. The reaction can be carried out analogously to B.
Costisella, H. Gross, J. Prakt. Chem. 317 (1975) 798. 7
[0049] Specifically, the reaction of
2-[4-dihydroxyphosphoryl-2-oxa-butyl]- -acrylic acid with propylene
oxide results in the corresponding phosphonic acid monoester
(2-{4-[hydroxy-(2-hydroxypropoxy)]-phosphoryl-2-oxa-butyl}-
-acrylic acid): 8
[0050] Examples of the acrylophosphonic acids according to the
invention of formula (I) are inter alia: 9
[0051] Compared with the corresponding acrylophosphonic acids, the
acrylophosphonic acid monoesters according to the invention are
much better soluble in mixtures of polar organic solvents, such as
methanol, ethanol, isopropanol, methyl ethyl ketone, acetone, ethyl
acetate, dimethylformamide or dimethyl sulfoxide, and water, but
also have a high solubility in the polar organic solvents
themselves.
[0052] In order to achieve a sufficient adhesion to enamel and
dentine of dental materials, the enamel edges and the dentine are
normally etched with 35 to 40% phosphoric acid for approx 20 to 30
seconds each time after the preparation of for example a cavity.
Surprisingly, the acrylophosphonic acid monoesters according to the
invention have a clearly higher acidity compared with the
corresponding acrylophosphonic acids and thus a greater
self-etching effect on enamel and dentine, so that an additional
etching of enamel and dentine can be avoided.
[0053] Due to the presence of polymerizable groups, the
acrylophosphonic acid esters according to the invention are
suitable as starting materials for the preparation of polymers and
copolymers. They can be homopolymerized with the known methods of
radical polymerisation or copolymerized e.g. with suitable
comonomers.
[0054] To carry out the polymerisation, the known radical
initiators (cf. Encyclopedia of Polymer Science and Engineering,
Vol. 13, Wiley-Interscience Publisher, New York 1988, 754 et seq)
can be used. Azo compounds, such as azobis(isobutyronitrile) (AIBN)
or azobis-(4-cyanovalerianic acid) or peroxides, such as
dibenzoylperoxide, dilauroylperoxide, tert.-butylperoctoate,
tert.-butylperbenzoate or di.-(tert.-butyl)-peroxide are
particularly suitable.
[0055] Benzopinacol and 2,2'-dialkylbenzopinacols are also suitable
as initiators for hot-curing.
[0056] Furthermore, photoinitiators (cf. J. P. Fouassier, J. F.
Rabek (Ed.), Radiation Curing in Polymer Science and Technology,
Vol. II, Elsevier Applied Science, London and New York 1993) can
also be used for polymerisation with UV light or light of visible
wavelengths, such as benzoinethers, dialkylbenzilketals,
dialkoxyacetophenones, acylphosphinic oxides, .alpha.-diketones,
such as 9,10-phenanthrenequinone, diacetyl, furil, anisil,
4,4'-dichlorobenzil and 4,4'-dialkoxybenzil, and
camphorquinone.
[0057] The acrylophosphonic acid monoesters according to the
invention can be used in particular as a component of adhesives,
cements, composites and molded articles as well as, preferably,
dental materials. The acrylophosphonic acid monoesters according to
the invention can also be used in polymerized or partly polymerized
form i.e. in the form of polymers such as homo- or copolymers, for
example as a component of glass ionomer cements.
[0058] The acrylophosphonic acid monoesters according to the
invention can be polymerized alone or in a mixture with
conventional radically polymerizable comonomers, in particular with
difunctional crosslinking monomers. Cross-linking bi- or
multifunctional acrylates or methacrylates, such as e.g.
bisphenol-A-di-(meth)acrylate, bis-GMA (the addition product of
methacrylic acid and bisphenol-A-diglycidyl ether), UDMA (the
addition product of hydroxyethyl methacrylate and
2,2,4-trimethylhexamethylene diisocyanate), di-, tri- or
tetraethylene glycol di(meth)acrylate,
trimethylolpropantri(meth)acrylate and pentaerythritol
tetra(meth)acrylate above all are suitable for the preparation of
adhesives or dental materials. Butane diol di(meth)acrylate,
1,10-decane diol di(meth)acrylate and 1,12-dodecanediol
di(meth)acrylate which are accessible by esterifying (meth)acrylic
acid with the corresponding diols are also suitable.
[0059] The acrylophosphonic acid monoesters according to the
invention can be used in free form or in the form of their salts,
i.e. as phosphonate esters. In the case of the salts alkali- metal
ions, in particular sodium and lithium ions, as well as organic
ammonium ions, in particular those derived from amine accelerators
such as N,N-dihydroxyethyl-p-toluidine,
N,N-bis-(2-hydroxy-3-methacryloxypropyl-3,5-xylidine or
4-(dimethylamino)-benzoic acid-2-ethyl-hexylester are preferably
used as counterions. Amine accelerators are used in the field of
dentistry as a component for example of photoinitiator systems. In
general they are tert. amines which can act as H-donators and thus
accelerate radical generation (cf. L. A. Linden, "Photocuring of
Polymeric Dental Materials and Plastic Composite Resins" in
Radiation Curing in Polymer Science and Technology, Vol. IV, J. P.
Fouassier, J. F. Rabek (Editors), Elsevier Appl.Sci., London, New
York 1993, 396 et seq).
[0060] Moreover, the acrylophosphonic acid monoesters according to
the invention or their mixtures with other radically polymerizable
comonomers can be filled with organic or inorganic particles or
fibers to improve the mechanical properties. Preferred inorganic
particulate fillers are amorphous spherical materials based on
mixed oxides of Sio.sub.2, ZrO.sub.2 and/or TiO.sub.2, microfine
fillers, such as pyrogenic silicic acid or precipitation silicic
acid, as well as macro- or minifillers, such as quartz, glass
ceramic or glass powders with an average particle size of 0.01 to 5
.mu.m. Furthermore, x-ray opaque fillers, such as ytterbium
trifluroide, or glass fibers, polyamide or carbon fibers can also
be used.
[0061] If necessary, further components can be added to the
acrylophosphonic acid monoesters or mixtures thereof, above all
solvents, such as water, methanol, ethanol, isopropanol, methyl
ethyl ketone, acetone, ethyl acetate, dimethylformamide, dimethyl
sulfoxide or mixtures thereof, as well as stabilisers,
UV-absorbers, dyes, pigments or lubricants. Water, ethanol, acetone
and ethyl acetate as well as mixtures thereof are preferred as
solvents for use in dental materials.
[0062] The acrylophosphonic acid monoesters according to the
invention are suitable in particular as a component of dental
materials, such as fixing cements and filler composites and above
all dental adhesives. Such materials are characterized by a very
good adhesion to different substrates, such as hard tooth substance
and metallic substrates, and are hydrolysis-stable under moist
conditions.
[0063] Preferred dental materials according to the invention
contain the following components (a), (b), (c), (d) and/or (e):
[0064] (a) 0.5 to 99 wt. -%, preferably 10 to 80 wt. -% and
particularly preferably 20 to 50 wt. -% of acrylophosphonic acid
monoesters according to the invention,
[0065] (b) 0.01 to 5 wt. -% and preferably 0.1 to 2.0 wt. -% of
radical initiators,
[0066] (c) 0 to 80 wt. -%, preferably 0 to 60 wt. -% and
particularly preferably 0 to 50 wt. -% radically polymerizable
comonomers,
[0067] (d) 0 to 95 wt. -%, preferably 0 to 80 wt. -% and
particularly preferably 0 to 70 wt. -% solvents, in particular
water, ethanol, acetone, ethyl acetate or mixtures thereof as well
as mixtures of water with the named organic solvents,
[0068] (e) 0 to 90 wt. -%, particularly preferably, depending on
the application, 0 to 20 wt. -% (adhesive), 20 to 60 wt. -%
(cement) and 60 to 85 wt. -% (filling composite) filler.
[0069] According to a particularly preferred embodiment, the dental
materials according to the invention are free from acrylophosphonic
acids such as are described by way of e.g. in DE 197 46 708.
[0070] The invention is explained in more detail in the following
examples.
EXAMPLES
Example 1
2-[4-(hydroxymethoxyphosphoryl)-oxa-butyl]-acrylic acid (1)
[0071] 10
[0072] 133 g (0.5 mol)
2-[4-(dimethoxyphosphoryl)-2-oxa-butyl)-acrylic acid ethyl ester
which is accessible by the reaction of 2-hydroxyethylphosphonic
acid diethyl ester with .alpha.-chloromethylacry- lic acid ethyl
ester (N. Moszner, F. Zeuner, U. K. Fischer, V. Rheinberger,
Macromol. Chem. Phys. 200 (1999) 1062), are added dropwise to a
solution of 120 g (3.0 mol) NaOH in 1200 ml water accompanied by
ice-cooling so that the temperature does not exceed 25.degree. C.
Then the reaction mixture is adjusted to a pH of 1 with approx. 260
ml concentrated hydrochloric acid. The product is washed three
times with 500 ml of methylene chloride each time, the remaining
aqueous phase is then saturated with sodium chloride and
subsequently filtered. The filtrate is extracted three times with
500 ml of tetrahydrofuran each time. After the combined extracts
have been dried over anhydrous Na.sub.2SO.sub.4, the product is
concentrated on the rotary evaporator (40 mbar, 50.degree. C.) and
the oily residue dried over phosphorous pentoxide in the desiccator
until its weight is constant. 93.6 g (86% yield) of a colorless
powder remain, which melts in the range between 71-75.degree.
C.
[0073] IR (KBr. cm.sup.-1): 672 (m), 751 (m), 780 (m), 825 (s), 911
(m), 946 (m), 969 (s), 998 (s), 1014 (s), 1027 (s), 1044 (s), 1055
(s), 1063 (s), 1124 (s), 1188 (m), 1210 (m), 1311 (m), 1372 (w),
1393 (m), 1428 (w), 1448 (m), 1456 (m), 1487 (w), 1634 (s), 1678
(s), 2598 (w), 2672 (w), 2870 (m) and 2900-3200 (b).
[0074] .sup.1H-NMR (400 MHz, DMSO-d.sub.6, ppm): 1.95-2.05 (m, 2H,
CH.sub.2P), 3.53-3.65 (m, 5H,OCH.sub.2CH.sub.2), 4.08 (s, 2H,
.dbd.C--CH.sub.20), 5.82 and 6.13 (s, 2.times.1H,CH.sub.2.dbd.C),
10.5 (b, 2H, OH).
[0075] .sup.13C-NMR (100 MHz, DMSO-d.sub.6, ppm ): 26.09 and 27.44
(d; CH.sub.2P), 51.56 (CH.sub.3), 64.76 (OCH.sub.2CH.sub.2), 68.59
(.dbd.C--CH.sub.20), 125.26 (CH.sub.2.dbd.), 138.20 (C=CH.sub.2),
167.11 (C.dbd.O).
[0076] .sup.31P-NMR (161.9 MHz, DMSO-d.sub.6): 26.05.
Example 2
Radical Homopolymerization of Monomer (1)
[0077] 2.24 g (10.0 mmol) monomer 1 and 2.0 mol-%
azobis(isobutyronitrile)- , relative to monomer, were dissolved in
7.7 ml of dimethylformamide in a Schlenk-receptacle. The monomer
solution was degassed by repeated freezing under argon and thawing
under a fine vacuum and subsequently polymerized under argon at
65.degree. C. During the polymerisation, the viscosity of the
starting solution increases perceptibly. After one hour, the
highly-viscous solution is precipitated by pouring into 10 times
the quantity of tetrahydrofuran and, after the colorless polymer
powder is dried until its weight is constant, a monomer conversion
of 40.1% is determined.
Example 3
Investigation of the Hydrolytic Stability of Monomer 1
[0078] Monomer 1 is dissolved in a 1:1 mixture of water and ethanol
and a 20% solution is stored at 37.degree. C. The .sup.1H-NMR
spectrum of the solution is recorded weekly. During the 8-week
investigation period, there was no change in the spectrum of
monomer 1, which shows its hydrolytic stability.
Example 4
Investigation of the Adhesion to Enamel of Monomer 1
[0079] An adhesive of the following composition (amounts in
weight-%) was prepared to investigate the adhesion to enamel on
bovine tooth enamel:
1 Monomer 1: 17.4% Glycerine dimethacrylate: 38.2% 2-hydroxyethyl
methacrylate: 26.3% Water: 17.3% Photoinitiator: 0.8%
[0080] Bovine teeth are embedded in plastic cylinders so that the
enamel zone and the plastic are located on one level. After 15
seconds' of etching with 37% phosphoric acid thorough rinsing is
carried out with water. Then a layer of adhesive of the above
composition is painted on with a microbrush, blown on briefly with
the air blower to remove the solvent and lit for 40 seconds with a
halogen lamp (Astralis 7, Vivadent). A composite cylinder made of
Tetric.RTM. Ceram (Vivadent) is polymerized onto the adhesive layer
in two layers of 1-2 mm each. Subsequently the testpieces are
stored in water for 24 hours at 37.degree. C. and the adhesive
strength is subsequently determined. A value of 14.0 MPa is
recorded.
Example 5
Investigation of the Solubility and Acid Strength of Monomer 1
[0081] The solubility of monomer I in water and ethanol was
determined and the pH value of a 20% solution of the monomer in a
1:1 mixture of ethanol and water measured. The results were
compared with the values of a structurally analogous phosphonic
acid and are listed in Table 1. 11
[0082] The results show that monomer 1 is clearly better soluble in
organic solvents such as ethanol and more strongly acid, than the
comparison monomer.
[0083] The higher acidity of the monomer according to the invention
is also expressed in its etching capacity vis--vis tooth enamel. A
40% aqueous solution of monomer 1 thus produces after only 10
seconds on bovine tooth enamel an etching pattern which is clearly
visible under a scanning electron microscope, whereas in the case
of the corresponding phosphonic acid 30 seconds' exposure time are
required to achieve the same etching effect.
[0084] Such clear differences in the solution behaviour and in the
etching effect were not to be expected given the small structural
difference between monomer 1 and the comparison compound (exchange
of an OCH.sub.3 group for an OH group).
2TABLE 1 Comparison of the properties of phosphonic acid and
phosphonic acid monoester Parameter Comparison monomer Monomer 1
water solubility approx 40 g/dl >50 g/dl solubility in ethanol
practically insoluble >50 g/dl pH value of a 20% aqueous 1.25
0.61 solution
* * * * *