Note: Descriptions are shown in the official language in which they were submitted.
This application is a divisional from application 370,083
filed February 4, 1981.
The invention relates to novel polymers having thioxanthone
radicals as side chains and to processes for their preparation.
The polymers according to the invention can be used as sensitisers
for photocrosslinkable polymers or as initiators, if desired in
a mixture with amines, for the pho*opolymerisation of ethylenically
unsaturated compounds or for photochemical crosslinking of polyolefins.
It is known that unsubstituted or halogenated, especially
chlorinated, thioxanthones are suitable as sensitisers for photo-
induced crosslinking reactions. The prerequisite for a successful
application of this type is good compatibility of the sensitiser
in the polymer, i.e. miscibility of the sensitiser with the polymer
must be such that elevated concentrations can be obtained. Furthermore,
the sensitisers must be readily soluble in the solvents used when
processing the polymers. The abovementioned known thioxanthones do
not meet these requirements itl every respect; in particular they
easily separate out from the mixture in the polymer, as a result
of which the sensitiser effect of the polymer is severely impaired.
Novel thioxanthone derivatives with reactive functional
groups have now been found which are outstandingly suitable for use
as sensitisers for photocrosslinkable polymers and in particular
for the preparation of polymers which have thioxanthone radicals
in side chains and which, in turn, are used as sensitisers for photo-
crosslinkable systems. The polymers according to the invention have,
b~
in particular, the advantage of a substantially lower
tendency to separate out from mixtures with the photocross-
linkable systems to be sensitised tlowex tendency to
migration). Moreover, using the novel polymers, it is
possible, surprisingly, so to influence UV absorption that
these substances exert a sensitising effect even on irrad-
iation with long-wave UV light (up to 450 nm) and thus
effect crosslinking of the photosensitive polymers.
It is also known that the photopolymerisation of
ethylenically unsaturated compounds can be initiated by
aromatic ketones of the benzophenone, anthraquinone, xan-
thone and thioxanthone type. It has also been dis-
closed in US Patent Specification 3,759,807 that the init-
iator effect of such aromatic ketones can be accelerated
by the addition of organic amines. Since th~se amines
on their own usually possess no initiator effect, they act
in combination with aromatic ketones as activators or
accelerators. Industrially, this is of great import-
ance since the production rate of photochemically cure~
coatings or printing inks is primarily dependent on the
rate of polymerisation of the unsaturated compound.
Mixtures of the polymers according to the
invention with organic amines as initiators for the
photopolymerisation o* ethylenically unsaturated compounds
or ~or the photochemica] crosslinking of polyolefines are
distinguished by a high rate of polymerisation, a low ten-
dency to yellowing in the case of coatings containing
white pigments, and in some cases by good solubility in
the substrate and/or high storage stability.
The invention thus relates to polymers which have a
mean molecular weight of not less than 1,000 and carry, in
side chains, thio~anthone groupings of the formula I'
8~
7~ \./ \ / ~r2 (I')
~ S 1'
Z 5 4
in which n is the number 1 or 2, X is hydrogen, halogen,
~CN, -OH, -SH, -NH2, -N02, phenylsulfonyl or alkylsulfonyl?
alkyl, alkoxy, alkylthio, N,N-dialkylamino or -CO-alkyl
having, in each case, 1-4 C atoms in the alkyl moieties, Z
is hydrogen, halogen, -0~l, -SH or alkyl, alkoxy~ alkylthio
or N,N-dialkylamino having9 in each case, 1-4 C atoms in
the alkyl mc,ieties, Y is -0~ SRl~ or -N(R2)Rl-, Rl is
straight chain or branched alkylene having a total of 2-23
C atoms and 2-13 C atoms in the rnain chain, cyclop~ntylene,
cyclohexylenel phenylene,
~ -G~ -G--\ /~
or -(CH2CH20)x-CH2CH2-, R2 is hydrogen or straight-chain or
branched alkyl having a total of 1-23 C atoms and 1-13 C
atoms in the main cha.in, G is -CH2-, -CH2CH2-, ~C(CH3)2-,
-O-, -S02~ or -NH- and x is an integer from 1 to 5, the
prpportion of groupings of the formula I' being not le~
than 2 per cent, preferably 2-100 and in particular 20-100
per cent, preferably 2-100 and in particular 20-100 per cent
based on the number of recurring structural elements of the
polymer.
The polymers accorciing to the invention advantage-
ously have a mean molecular weight of not less than 1,000
to 500,000, and in particular a mean molecular weight of
about 1,000 to 100,000.
The mean molecular weigh-t is determined by methods
known per se, for example by determining the light scatter
or by gel permeation chromatography.
The polymers according to the invention are, for ex-
ample, polyethers, polyamines, polyimines, polycondensa-tion
products based on phenol~formaldehydes, polysaccharides,
gelatines and, in particular, polymers which are obtained
by homopolymerisation or copolymerisation of monomers con-
taining C=C double bonds.
The polymers according to the invention can be pre-
pared by synthesis methods known per se for the preparation
of macromolecules with side groups. In principle, the
following routes can be used:
1. Incorporation of the thioxanthone radicals of the form-
ula I' into an existing polymer chain;
2. Build--up of the polymer chain from monomers which al-
ready contain the thioxanthone grouping of the formula I',
in which case the polymer chain can be built up by poly-
merisation or polyaddition.
In some cases, identical products can be obtained by
method 1 and method 2, so that, depending on the nature of
the functional groups, it is possible to use method 1 or
method 2 as desired. If the thioxanthone radicals are
incorporated into an already existing polymer chain, this
incorporation is effected either by a condensation reaction
or by an addition reaction with simultaneous opening of a
ring system, for example of a dicarboxylic acid anhydride
group or of an epoxide group.
In accordance with the abovementioned build-up
method, polymers according to the invention can be prepared
by reacting a compound of the -formula Ia
7~ 2 (Ia)
in which Q~ is -OCH=CH2, -OCH2CH=CH2, -SCH2CH=CH2 or
-NHCH2CH=CH2 if n is 1, and is -OCO-C(R")=CH2, CO
-SCO-C(R~ CH2, -NHCO-C(R~)=CH2, -OCH=CH2 or ~ ll if
CO
n is 2, or is also -CI~=CH2 if R1 is alkylene or phenylene,
and X, Y, Z, and n are as defined under formula I' and R"
is hydrogen or meihyl, if desired ln the presence of
comonomers, the molar ratio of the compound of the formula
Ia to the comonomers being 1:49 to 1:0.
/co
Q~ is preferably ~ OCH=CH2 or
-OCO-C(R")=CH2- CO
In accordance with the abovementioned incorporation
method, polymers according to the invention can be prepared,
for example, by reacting a compound of the formula Ib
CQ~' ]~ (Y~Q2
~ \S/ \.~
Zl 5 4
in which X' is hydrogen, halogen~ -CN,-N02, phenylsulfonyl
or alkylsulfonyl, alkyl~ alkoxy, alkylthio, N,N-dialkylamino
or -CO-alkyl having, in each case~ 1-4 C atoms in the
alkyl moieties, Zl is hydrogen, halogen or alkyl, alkoxy,
alkylthio or N,N-dialkylamino having, in each case, 1-4 C
atoms in the alkyl moieties, and Q2 is -OCH2CH -/CH2 or
-OCH2-COOH if n is 1, and is -OH, -SH, -NH2, -NHR', -S03H,
-COOH, -COCl, -NCO or -OCH2CH /CH2 if n is 2, Y and n
are as defined under formula Il and R' is alkyl having 1~5
C atoms, or salts of compounds of the formula Ib, in which
Q2 is -NH2 or -NHR', with a polymer containing correspond-
ing functional groups, in a ratio of 1:50 to 1:1, based on
the number of recurring structural elements in the polymer.
36
Compounds of the formula Ib in which Q2 is ~COOH,
-COCl, -SO3H or -OCH2COOH can, for example, be reacted with
polymers which contain free OH, NH2, NH-alkyl or SH groups.
Compounds of the formula Ib in which Q2 is -OH, ~-SH, -NH2,
-NHR', -NCO or -OCH2CH~o,CH2 are suitable, for example,
for reaction with polymers which contain anhydride or
-COOH groups. Finally, compounds of the formula Ib in
which Q2 is -OH9 -SH, -NH2, -NHR' or COOH can also be re-
acted with polymers which contain -CH2CH\ ~ H2 groups.
o
Alkyl, alkoxy or alkylthio groups X, X', Z~ Zl~ R'
and R2 and alkyl moieties in radicals X, X', Z and Zl can
be straight-chain or branched. Alkylene groups Rl and alkyl
groups R2 preferably have a total of not more than 18 and in
particulax not more than 12 C atoms.
Examples of alkyl, alkoxy, alkylthio, alkylsulfonyl,
N,N-dialkylamino and -CO-alkyl groups X, X', Z~ Zl' R' or R2
accordingto the definition areo the methyl,ethyl r n-propyl,
isopropyl, n-butyl, sec.-butyl, n-pentyl, 2- or 3-pentyl, n-
hexyl, n-heptyl, 2- or 3-heptyl, n-octyl, n-nonyl, n-decyl,
2-decyl, n~dodecyl, n-tridecyl, tridec-7-yl, heptadec-9-yl,
2,6,10-trimethyldodecyl and 2,6,10,14-tetramethylhexadecyl
groups; the methoxy, ethoxy, n-propoxy, isopropoxy and n--
butoxy groups; the methylthio, ethylthio and n-propylthio
groups; the methylsulfonyl and ethylsulfonyl groups; the
N,N-dimethylamino, N,N-diethylamino, N-methyl-N-ethylamino
and N,N-di-n-propylamino groups; and the acetyl, propionyl
and butyryl groups.
Alkyl groups R', X, X', Z-, and Zl are preferably straight-
chain and in particular have 1 or 2 C atoms.
Examples of alkylene groups Rl according to the def-
inition are: the 1,2-ethylene, propylene, tetramethylene,
isobutylene, pentamethylene, iso- and neo-pentylene, hexa-
methylene, heptamethylene,2- ~ 3~methylhexy1e~e, oct~qethylene,
n~lamethylene, decameth~lene, 2 methyl-nonylene, dodecamethylene,
tridecamethylene, hexylheptylene, oc~ylnonylene, 2,6 9 10-
trimethyldecylene and 2,6,10,14-tetramethyl-dodecylene
groups.
A cyclopentylene, cyclohexylene or phenylene group
R1 is, for example, the 1,3-cyclopentylene group, the 1,3
or in particular 1,4-cyclohexylene group or the 1,3- or
1,4-phenylene group. Preferred bicyclic radioals R
are those of the formulae
~ -G-~ G~
=0 0--,, 0--.
in which G is -CH2-, -O- or -S02-.
Rl is preferably alkylene having a total of 2-18
and in particular 2-12 C atoms, 1,3-cyclopentylene, 1,4-
cyclohexylenel -CH2CH20CH2CH2- or -(CH2C 2 )2 2 2
R2 is preferably hydrogen.
Preferred polymers are, on the one hand, those in
which Z is hydrogen and X, Y and n are as defined under
formula I'. The grouping -CO-(Y ~ 1 is preferably bonded in
the 1- or 3-position.
A further ca-tegory of preferred polymers comprises
those in which X is bonded in the 6-position
and i.s -N02, alkylsulfonyl having 1-4 and in
particular 1 or 2 C atoms or phenylsulfonyl, Z is bonded
in the 7-posi-tion and is alkyl, alkoxy, a]kylthio or N 9 N-
dialkylamino having, in each case~1-4 and in particular
1 or 2 C atoms in the alkyl moieties, and the grouping
~CO-(Y ~ is in the l-position or 3-position.
According to a further preference, Z is hydrogen
and X is bonded in the 6-position and is -N02, alkylsul-
fonyl having 1-4 and in particular 1 or 2 C atoms or
phenylsulfonyl. In this case the groupin~ -Co-tY- ~ 1 is
likewise prefe~ably bonded i.n the 1- or 3-position.
Very particularly preferred polymers are
those in which X is hydrogen and Z is hydrogen or
me-thyl or methoxy bonded in the 7-position, and the group
-CO-(Y ~ is in the 1- or 3-position, and in particular
those in which n is 1 or 2, Y i~ -~1- ~ -NE~ 1 is
alkylene having 2-6 C atoms, -CH2CH20CH2CH2- or
- (cH2cH2~cH2cH2
Compounds of the formula Ia are suitable ~or homo-
polymerisation or for copolymerisation with other ethylen-
ically unsaturated comonomers, especially those of the
type indicated further below.
Examples of starting polymers which can be reacted
with compounds of the formulaIb are: polyacrylic acid,
polymethacrylic acid, copolymers of these acids and other
ethylenically unsaturated monomers, copolymers built up
from maleic anhydride and ethylenically unsaturated mono-
mers, such as methyl vinyl ether, ethylene, styrene, hex-
l-ene, dec-l-ene, tetradec-l-ene and octadec-l-ene, poly-
mers having free hydroxyl groups, such as homopoly~ers and
copolymers of hydroxyalkyl acrylates and hydroxyalkyl
methacrylates, polyvinyl alcohols, natural or regenerated
cell.ulose, cellulose derivatives, hydroxyalkylcellulose,
polyethers having free -OH groups, phenol-formaldehyde
polycondensation products, polymers having free glycidyl
groups, such as copolymers based on glycidyl acrylates and
glycidyl methacrylates, polyethyleneimines and polymers
with free amino groups in side chains, for example poly-p-
aminostyrene.
Preferred polymers acccrding to the invention are
those which have a mean molecular weight of about 1,000 to
100,000 and contain recurring structural elements of the
formula XI to XX
C~2
-C-C0-Q3-Y-CO-Th (XI),
,C~2
C8-Y -CO-~h (XII),
CO
~N_y-CO-~h (XIII),
CH-CO
CH2
, ~H-O-(Y~ lC0_Th (XIV),
i ~
R"-C-OCO-Y-CO--Ih (XV)
~H2
ca2
N-CO-Y-CO~Thl (XVI),
~H-COOH CH-CO
~H C0 Q4 1 (XVII), I o~N 1 (.~VIIa),
CH2 ~~[
R" c-COO(C~2~CX~C'l2 ~5 (Y'n-l 1 (XVIII)
-- 10 --
CH2
. OH
. O(C~ p ~d~C-d2~Q5~(~ ~ CO-T~1 tXIX)
.
or
C~2 OH
R" C-COOCH2-C~-C~2-o-(y~ X)
in which "Th" is a radical of the formula I"
~ /CO\ ~o,~
i1 i1
z ~ S ~ (I")
and
"Thl" is a radical of the formula I"'
~\ ~CO\ ~.~ (I"')
i~\s/'\ ~
Zl
X, Y, Z~ R" and n are as defined a~ov~ and X' and
Zl are as defined under formula Ib, Q3 is -O-, -S- or -NH-,
Q4 is -O-, -S-, -NH- or -NR'-, Q5 is -OCO-, -O-, -S-, -NH-
or -NR1-, R' is alkyl having 1-5 C atoms, p is the number 1
or 2, Yl is -ORl-, -SRl- or -NHRl- and Rl is straight-chain
or branched alkylene having a -total of 2-23 C atoms and
2-13 C atoms in the main chain, or phenylene.
If the polymers according to the invention are co-
polymers, these preferably consist of recurring structural
elements of the formulae XI to XX and of identical or diff-
erent recurring structural elements of the formula XXI
x
14
_ ~-~H---C - - (XXI)
X5 X6
in which X5 is hydrogen, X4 is hydrogen, chlorine or methyl,
~6 is hydrogen, methyl, chlorine, CN, -COOH, -CONH2, phen~
yl, methylphenyl, methoxyphenyl, cyclohexyl, pyridyl, imi-
daæolyl, pyrrolidyl, -COO-alkyl having 1-12 C atoms in the
alkyl moietY, -COO-phenyl, -COOCH2CH\ / H2,
having 1-3 C atoms in the alkyl moiety, -OCO-allcyl having
1-4 C atoms in the alkyl moiety, -OCO-phenyl, -CO-alkyl
having 1~3 C atoms in the alkyl, alkoxy having 1-20 C
atoms or phenoxy, or X~ is hydrogen and X5 and X6 together
are the grouping -CO-O-CO~ or are each -COOH or -COO-alkyl
having 1-~ C atoms in the alkyl. Preferably, X5 is
hydrogen, X4 is hydrogen or methyl and X6 is hydrogen,
-OCOCH3, -COOH or -COO-alkyl having 1-8 C atoms in the
alkyl, or X4 and X5 are each hydrogen and X6 is -CN, chlor-
ine, phenyl or alkoxy having 1-6 C atoms, especially meth-
oxy, or X~ is hydrogen and X5 and X6 together form the
grouping -CO-O-CO-.
In the above formulae I', I", Ia, Ib and XI to XX,
X and X', Z and Zl ,n, Y and Q1 and Q2 have the corres-
ponding preferred meanings defined above, and the group-
ings -CO-(Y ~ , or -CO-(Y- ~ -Q1 and -CO-(Y ~ Q2 are
preferably bonded to the benzene ring in the 1-position or
3-position. Particularly preferred polymers are those
having recurring structural elements of the formulae XI,
XIII to XV or XVII to XX and in particular polymers which
have recurring structural elements of the formulae XI, XIV
or XVII and, if desired, identical or different recurring
structural elements of the formula XXI 7 in which formulae
- 12 ~
R" is hydrogen or methyl,Q3 is -O-, Q~ and Q5 independently
of one another are -O- or -NH-, p is the number l, n is
the number l or 2, Y is -ORl- or -NHRl-, Rl is alkylene
having 2-6 C atoms or, if Q4 is -O-, also -CH2CH20CH2CH2-
or -(CH2CH20)2-CH2CH2-, X and X' are hydrogen, Z and Zl
are hydrogen or methyl or methoxy bonded in the 7-position,
X5 is hydrogen, X4 is hydrogen or methyl and X6 is hydro-
gen, -OCOCH3, -COOH or -COO-alkyl having 1-8 C atoms in
the al~yl, or X4 and X5 are each hydrogen and X6 is -CN,
chlorine, phenyl or alkoxy having 1-6 C atoms, especially
methoxy, or, if X4 is hydrogen, X5 and X6 together are also
-CO-O-CO-, and the groupings -CO-(Y ~ are bonded in the
1-position or 3-position to the benzene ring of the
radical "Th" or "Th1". Of the radicals X4 to X6, X4
and X5 are particularly preferentially hydrogen and X6 is
particularly preferentially hydrogen, -COOH or Cl 6-alkoxy,
especially methoxy, if desired in cornbination with
structural elements of the formula XXI in which X4 is
hydrogen and X5 and X6 together are -GO-O-CO-.
Polymers with recurring structural elements of the
formulae XI to XIV can be obtained by polymerising a com-
pound of the formula Ia, in which X~ Y~ Z~ Ql and n are
as defined above, if desired in the presence of ethylen-
ically unsaturated comonorners, especially those of the
formula XXIa
X4
~IC = C
I I (XXIa)
X5 X6
in which X4 ? X~ and X6 ar~ as defined under formula XXI,
the molar ratio of compounds of the formula Ie to comono-
mers being 1:49 to l:O and in particular 1:4 to l:O.
Particularly preferentially, acrylic acid is used as the
comonomer.
Polymers with recurring structural elements of
.
- 13 -
the formulae XV to XX can be obtained by
i) reacting a compound of the formula Ib, in which X',
Zl and Y are as defined9 Q2 is -COOH or -COC1 and n is
the number 2, with a polymer containing recurring struct-
ural elements of the formulae XVa or XVIa
C~ . or ! CH2
R"-C-OH (XVa) CIH2 (2VIa~,
NEI
ii) reacting a compound of the formula Ib, in which X',
Zl and Y are as defined, Q2 is -OH, -SH, -NH2 , -NHR' or
-NCO and n is the number 2, with a polymer containing re-
curring structural elements of the formula XVIIa
1CH-CO~
CH~CO (XVIIa)
iii) reacting a compound of the formula Ib, in which X',
Zl and Y are as defined, and Q2 is -OH, -SH, -NH2 , -NHR'
or -COOH and n is the number 2, with a polymer containing
recurring structural elements of the formula XVIIIa or
XIX a
I
CH
R"-C-COO(CH7) -C~- CH (XVIIIa)
I _ p 2
or
X~o O
~.~ O(CH2) C~-\C~2 (XIXa)
in which p and R" are as defined under the formulae XVIII
and XIX, or
iv) reacting a compound of the formula Ib, in which X',
- 14 -
Zl and Y are as defined, n is the number 1 or 2 and Q2 is
-()CH2CH 7 CH2 , with a polymer containing recurring
o
structural elemen-ts of the formula X~a
,H2 (XXa)
R" C~COOH
in which R" is as defined above, the ratio of the poly-
mer:compound of the formula Ib being 1:50 to 1:1, es-
pecially 1:5 to 1:1, based on the number of recurring
structural elements in the polymer. Particularly pre-
ferred polymers are polyacrylic acid and maleic anhydride/
ethylene and maleic anhydride/me-Whyl vinyl ether copol.ymers.
rrhe incorporation of thioxanthone derivatives accor-
ding to the invention into existing polymer chains by means
of a condensation reaction or addi.tion reaction can be
effected in a manner known per se, advantageously at tem-
peratures of about -50C to ~150C and if desired in the
presence of an acid-binding agent, if salts, according to
the definition, of compounds of the formula I are employed.
The reaction is preferably carried out in an inert organic
solvent or a solvent mixture 7 and in the case o~ condensa-
tion reactions is preferably carried out at temperatures of
about -20C to -~100C. Addition reactions are advantage-
ously carried out at elevated temperature, in general at
temperatures between about 80 and 120C or at the reflux
temperature.
Suitable solvents for carrying out the condensation
reactions and addition reactions are, for example: ali-
phatic or cyclic ketones, such as acetone, methyl ethyl
ketone, isopropyl methyl ketone, cyclohexanone, cyclopenta
none and ~-butyrolactone; cyclic ethers, such as tetra-
hydrofuran, tetrahydropyran or dioxan; cyclic amides, such
as N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone or N-
methyl-~-caprolacta.m; N,N-dialkylamides of aliphatic mono-
-- 15 --
carboxylic acids having l-3 C atoms in the acid moiety,
such as N,N-dimethylformamide, N,N-dimethylacetami~e, N,N-
diethylacetamide or N,N-dimethylmethoxyacetarnide; pyridine
and pyridine bases or tertiary amines, in particular tri-
alkylamines ~nd dialkylbenzylamines having, pre~`erably, 1-4
C atoms in the alkyl moieties, for example triethylamine
and diethylbenzylamine; and dialkylsulfoxides, such as
dimethylsulfoxide and diethylsulfoxide.
Preferred solvents for condensation reactions are
cyclic amides and N,N-dialkylamides of -the abovementioned
type, especially N-methyl-2-pyrrolidone, N,N-dimethylform-
amide and N,~-dimethylacetamide. For addition reactions,
cyclic ethers and cyclic ketones, in particular tetrahydro-
furan and cyclohexanone, and also pyridine are preferred.
The homopolymerisation of compounds of the formula
Ie, and also the copolymerisation of these compounds with
other ethylenically unsaturated monomers, for example of
the formula XXIa, can likewise be carried out in a manner
known per se, for example in the presence of conventional
cationic and anionic initiators. Free radical polymeri-
sation is preferred. Advantageously, free radical initi-
ators known per se, such as inorganic or organic peroxides
or azo compounds, for example hydrogen peroxide, potassium
peroxydisulfate, tert.-butyl hydroperoxide, di-tert.-butyl
peroxide, peracetic acid, benzoyl peroxide, diacyl perox-
ide, cumene hydroperoxide, tert.-butyl perbenzoate, tert.-
alkyl peroxycarbonates and ~,~'-azoisobutyronitrile, are
used in amounts of about 0.01 to 5% by weight and prefer-
ably 0.01 to 1.5% by weight, based on the total weight of
monomers. The reaction temperatures for free radical
polymerisation are in general between about 30 and 100C.
However, free radical polymerisation can also be carried
out in the cold, and redox systems in the abovementioned
concentrations can also be used for this purpose, for ex-
ample mixtures of peroxides, such as hydrogen peroxide, and
a reducing agent, such as divalent iron ions.
- 16 -
The polymerisation can be carried out in homogeneous
phase, for example in bulk (block polymerisation) or in
solution, or in heterogeneous phase, i.e. as precipitation
polymerisation, emulsion polymerisation or suspension poly-
merisation. Polymerlsation in solution is preferred.
Suitable solvents are those of the type mentioned
for the condensation reaction or addition reaction and also:
halogenated aliphatic hydrocarbons, such as methylene
chloride, chloroform, tetrachloroethane and tetrachloro-
ethylene; alkyl esters of aliphatic monocarboxylic acids
having a total of 2-6 C atoms, such as methyl formate,
ethyl formate and n-butyl formate or methyl acetate, ethyl
acetate and n-butyl acetate; and ethylene glycol dialkyl
ethers having 1-4 C atoms in the alkyl moieties, such as
ethylene glycol dimethyl ether 9 ethylene glycol diet;hyl
ether and ethylene glycol di n-butyl ether.
The thioxanthone startin~ materials are new. They
may be summarized by formula I
~, \ / \ / ~
~ / \S/ \ ~ (I)
where X, Z, Y and n have the above meaning and Q is
-OCH2C~ -~CH2, ~0CH2~COOH, -~OCM=CEI2, -0CH2CH`-CH2,
-SCH2CH=CH2 or -NHCH2CH=CH2 if n is 1, and is -OH, -SH,
~NH2, -NHR', -SO3H, -COOH, -COCl, -NCO, -OCO-C(R")=CH2,
-SCO-C(R")-CH2, -NHCO-C(R")=CH2, -OCH=CH2, -OCH2CH - CH2
;~CO~
or Co ,if n is 2, or is also -CH=CH2 if Rl is alkylene
or phenylene, and R' is alkyl having 1-5 C atoms and R" is
hydrogen or methyl. Compounds of the formula I in
which Q is -NH2 or -NHR' can also be in the form of salts~
especially salts with inorganic acids, such as H2SO~ or
nitric acid and in particular HCl.
8~
- 17 -
The compounds of the formula I and their salts
accordin~ to the de~inition can be prepared by
a) reacting a compound of the formula II
o\ ~ ~ COOH
i ll il I (IIJ,
S
Z
a Cl 6-alkyl ester of a compound of the formula II or an
acid chloride of a compound of the formula II, in which Z
and Xl are not -SH or -OH, with a compound of the formula
IIIa
H(Y ~ Q' (IIIa)
or, if Q' is -NH2 or -NHR', with a salt of a compound oE
the formula IIIa, to give a compound of the formula Ic
X ~ ~ CO-~Y ~ Q'
! '! I! I (Ic)
i~ \S/ \.~
z
or corresponding sal-ts,
b) r~acting a compound of the formula II or a Cl 6-alkyl
ester of a compound of the forrnula II with a compound of
the formula IIIb
C~i2=CH-OCO-~' (IIIb)
to give a compound of the formula Id
CO-OC~2C~2
I ll ll i (Id;
S /~ ~'
- 18 -
or
c) first reacting an acid chloride of a compound of the
formula II wi.th a salt of a compound of the formula IIIc
H-Y-NH2 (IIIc)
to give the corresponding salt of a compound of the form-
ula IV
C~-Y-N~
1~\ /CO\ ~ (IV)
3~o/ \ S
and reacting the salt of a compound of the formula IV, in
the presence of an inert organic solvent, with phosgene to
give a compound of the formula Ie
ca~ CO-Y-~CO
!, i! il ! (Ie)
~ / \ 5 / \ ~
in which formulae Y, Z, R' and n are as defined under
formula I',Xl is hydrogen, halogen, -CN, -OH, -SH, -NO2,
phenylsulfonyl or alkylsulfonyl, alkyl, alkoxy, alkylthio,
N,N-dialkylamino or -CO-alkyl having,in each case1-4 C atoms
in the alkyl moieties, Q' is -OCH2CH - CH2, -OCH2-COOH,
-OCH2CH=CH2, -SCH2CH=CH2 or -NHCH2CH=CH2 if n is 1, and is
-OH, -SH, -NH2, -NHR', -SO3H, ~COOH, -OCO-C(R")=CH2,
-SCO-C(R")=CH2, -NHCO-C(R")=CH2, -OCH2CH CH2 or ~C~
if n is 2, or is also -CH=CH2 if Rl is alkylene or
phenylene, and R" is hydrogen or methyl, and, if desired,
subsequently converting the group Xl in the compounds of
the formulae Ic, Id or Ie into a group X which differs
-- 19 --
from Xl, and/or converting the group Q' = -COOH in formula
Ic into the group -COCl by treatment with suitable chlor-
inating agents. Salts of compounds of the formulae
IIIa, IIIc, Ic (Q' = -NH2 or -NHR') and IV are, in parti-
cular, salts wivh inorganic acids such as H2SQ4 or nitric
acid and in particular HCl. Salts of compounds of the
formula Ia in which Q' is -NH2 or -NHR' can, if desired,
be converted into the corresponding amines in a manner
known per se, by the addition of suitable bases.
Only compounds of the formula II in which Xl and Z
are not -OH or -SH are suitable for conversion to the acid
chlorides if desired. Examples of chlorinating agents
which can be used are thionyl chloride, PC15 or oxalyl
chloride. Alkyl esters, according to the definition,
of compounds of the formula II are advantageously prepared
from the corresponding acid chlorides.
The above reactions can be carried out in a manner
known per se and, dependingon the nature of the reactants,
with or without the addition of inert organic solvents such
as dioxan, benzene, toluene, methylene chloride or chloro-
form. Acid chlorides of compounds of the formula II are
in general reacted with alcohols or thiols of the formula
IIIa at temperatures between about 25 and 80C. Advan-
tageously, an excess of the corresponding alcohol or thiol
is used as the solvent. The reaction of the acid chlor-
ides of compounds of the formula II with amines of the
formula IIIa is advantageously effected at temperatures
between about Q and 40C. The reaction of the free
acids of the formula II with alcohols of the formula IIIa
is advantageously carried out with removal of the water by
separatior. as an azeotrope and with the addition of cata-
lytic amounts of an acid, such as H2S04 or p-toluene-
sulfonic acid, or in the presence of dehydrating agents,
such as HCl gas or concentrated sulfuric acid. The en-
training agent used is preferably benzeneg toluene or
- 20 -
chloroform. The transesterification of alkyl esters of`
compounds of the formula II is advantageously effected
with the addition of acids, such as HCl or H2S04, aluminium
alcoholates or basic or acid ion exchangers. The re-
action of compounds of the formula II, or their alkyl
esters 9 with compounds of the formula IIIb is advantageous-
ly carried out in the presence of catalysts, such as HgC12,
Li2(PdC14) or PdC12.
The compounds of the formulae IIIa, IIIb
and IIIc are known or can be prepared by methods known per
se. Some of the compounds of the formula II are also
known. They can be prepared in a manner known per se
(cf. German Offenlegungsschrift 2,3~4,799 and US Patent
Specification 4,101,558), for example by cyclising a com-
pound of the formula VIIa or VI:[b
~R COR Xl ~ ~COR"'
S~ or ~ ~--S~
(VIIa) (VIIb)
in which Xl and Z are as defined above and R and R"' are
-OH or, if Z and X1 are not -OH or -SH, also chlorine, or,
if the -COR groups are in the ortho-position relative to
one another, the two Rs together can be -O-, with simul-
taneous hydrolysis of chlorine atoms R or R"'.
The compoun~s of the formulae VIIa and VIIb
can, for example, be prepared analogously to the proced-
ures ctescribed in German Offenlegungsschrift 2,344,799, by
reacting suitably substi-tuted thiophenols or derivatives
thereof, such as alkali metal salts or alkaline earth
metal salts, with nitrobenzenes or halogenobenzenes. For
this reaction, the thiophenol and the nitro- or halogeno-
benzene together must have at least two -COR or ~OR"'
groups, or two groups which can be converted to -COR or
-
~COR"' groups, such as nitrile groups, and one of these
groups must be in the ortho--position relative to the SH
group or to the nitro group or to a halogen ato~.
The conversion of groups Xl, X2 or X3 to groups X
can be carried out in a manner known per se. Thus, for
example, nitro groups Xl, X2 or X3 can be reduced, by
methods known per se, to amino groups, which, in turn, can
be converted to halogen a-toms or -OH, SH, -CN, alkoxy or
N,N-dialkylamino groups. Cyano groups Xl or X2 can be
conver-ted to -CO-alkyl groups X. Thioxanthones of the
formula I which are substituted by alkylsulfonyl or phenyl-
sulfonyl groups can be prepared, for example, by reacting
the corresponding nitro compounds with alkali metal alkyl
sulfinates or alkali metal phenyl sulfinates.
The ~olymers according to the invention,
can also be used as such as sensitisers for
photocrosslinkable polymers of the most diverse types.
Such polymers are used, for example, for the pro-
duction of printing plates for the offset printing process
and for the preparation of photo~offset lacquers, for un-
conventional photography, for example for the production of
photographic images by means of photopolymerisation or
photocrosslinking. Such polymers are used, in particular,
as so-called photoresists for the production of printed cir-
cuits by methods known per se. For this purpose, that
side of the printed board assembly which is provided with
the light-sensitive coating is exposed through a slide neg-
ative carrying the conductive pattern and then developed,
after which the unexposed areas of the coating are removed
using developer fluid.
- 22 -
The polymers which can be used are, in themselves,
any desired ~aterials for which the sensiti.vity to light
(sensltivity to actinic radiation) can be increased by the
of the sensit.isers according to the invention. The
po].ymers accordins to the invention are very particular-
ly suitable as sensitisers for polymers of the type
described in German Offenlegungsschrift No. 2,626,769,
i.e. polymers which contain, as light-sensitive groups,
groups of the formula XXII
o
~\ ~Gl
-N ll (XXII)
o
in which Gl and G2 independently of one another are alkyl
having 1-4 C atoms, especially methyl, or Gl and G2 to-
gether are the members required to comp].ete a five-mem-
bered to six-membered carbocyclic ring.
~ he polymers of the invention can be incorporated
into the photocrosslinkable polymers in a manner known per se.
The sensitiser content in the polymer can vary greatly,
depending on the intended use and the number of photo-
crosslinkable groups present in the polymer, but in general
i; between between about 0.1 and 20%, based on the weight
of the polymer.
Finally, -the polymers according to the invention,
are also used as photoinitiators. The invention therefore
also relates to the use of said polymers, as initiators
for the photopolymerisation of ethylenically unsaturated
compounds or for the photochemical crosslinking of poly-
olefines~ and also mixtures of A) polymer with side group~
ings of the formula I' and B) an organic amine, as initia~
tors for the photopolymerisation of ethylenically unsatu-
rated compounds or fo.r the photochemical crosslinking of
- 23 -
polyolefines.
The organic amines used can be aliphatic, aromatic,
araliphatic, cycloaliphatic or heterocyclic amines. They
can be primary, secondary or tertiary amines. Examples
are: butylamine, dibutylamine, tributylamine, cyclohexyl-
amine, benzyldimethylamine, di-cyc].ohexylamine, triethyl-
amine, phenyl-diethanolamine, piperidine, piperazine,
morpholine, pyridine, quinoline, ethyl p-dimethylamino-
ben~oate or Michler's ketone (4,4'-bis-dimethylamino-
benzophenone).
Photopolymerisable compounds a.re, for example, un-
saturated monomers, such as esters of acrylic acid or
methacrylic acid, for example methyl acrylate, ethyl acry-
late, n- or tert.-butyl acrylate, isooctyl acrylate or
hydroxyethyl acrylate, methyl methacrylate or ethyl meth-
acrylate, ethylene diacrylate, butanediol diacrylate,
hexanediol diacrylate, neopentyl diacrylate, trimethylpro-
pane trisacrylate, pentaerythritol tetraacrylate or pen-
taerythritol tris-acrylate; acrylonitrile, methacrylo-
nitrile, acrylamide, methacrylamide and N-substituted
(meth)-acrylamides; vinyl esters, for example vinyl ace-
tate, vinyl propionate, vinyl acrylate or vinyl succinate;
other vinyl compounds, such as vinyl ethers, vinyl ketones
vinyl sulf'ones, styrene, alkylstyrenes, halogenostyrenes,
divinylbenzene, N,N'-divinylurea, vinylnaphthalene, N-
vinylpyrrolidone, vinyl chloride or vinylidene chloride;
allyl compounds, such as diallyl phthalate, diallyl male-
ate, tri.allyl isocyanurate, triallyl phosphate or ethy-
lene glycol diallyl e-ther and the mixtures of such unsatu-
rated monomers.
rrhe mixtures according to the invention are partic-
ularly suitable for the photopolymerisation of acrylic
acid esters and mixtures thereof.
- 24 ~
Further examples areunsaturated acrylic resins.
These include, for example, reaction products of poly-
epoxides (epoxide resins) with acrylic acid or methacrylic
acid or reaction products of polyisocyanates with hydroxy-
al~yl acrylates, and also the reaction products of hydrox-
yl group-containing polyesters or polyethers with acrylic
acid or methacrylic acid. These unsaturated acrylic
resins are in most cases used in a mixture with one or
more acrylates of a mono-, di- or poly-alcohol, for ex-
ample, ethyl acrylate, butyl acrylate, benzyl acrylate, 2-
ethylhexyl acrylate or 2-hydroxypropyl acrylate, ethylene
glycol diacrylateg propylene glycol diacrylate, butanediol
diacrylate, hexamethylene diacrylate, trimethylolpropane
tris-acrylate or pentaerythritol tetraacrylate~
The invention also relates to photopolymerisable
systems consisting of a) at least one ethylenically un-
saturated compound, b) a mixture, according to the defini-
tion, of A) and B) and, if desired, c) other additives,
such as inhibitors, stabilisers, UV-absorbers, fillers,
pigments, dyes, thixotropic agents and levelling assist-
ants, for example silicone oil.
The inhibitors, which are intended to provide pro-
tection against premature polymerisation, in particular
during the preparation of the system by mixing the compon-
ents, are, for example, hydroquinone, hydroquinone deriva-
tives, p-methoxyphenol or ~-naphthol. UV-absorbers
which can be used are, for example, those of the benz-
triazole or benzophenone type. Suitable fillers are,
for example, silica, talc or gypsum.
Preferred photopolymerisable systems of this type
are those in which a) and c) are present in proportions of
99.5-80% by weight and b) is present in a proportion of
~.5-20% by weight.
3V ~8~ii
- 25 -
A~n acrylic acid ester or amix~ture of several acrylic
acid esters is preferably used as component a).
It is also possible to use combinations with known
photoinitiators which forrn free radicals by photofragmen-
tation, for example benzoin ethers, dialkoxyacetophenones
or benzil ketals.
The initiator mixtures according to the invention
are of great importance for the photocuring of printing
inks and white-pigmented coatings, since the drying time
of the binder is a decisive factor for the production rate
of graphic products and should be of the order of ma~ni-
tude of fractions of a second. The initiators according
to the invention are also very suitable for photocurable
systems for the production of printing plates.
A further field of application is the UV-curing of
metal coatings, for example in -the lacquer-coating of
sheet metal for tubes, cans or bottle tops, and also
the UV-curing of plastic coatings, for example floor
coverings or wall coverings based on PVC.
Examples of the UV-curing of paper coatings are the
colourless lacquer-coating of labels, gramophone record
slee~es or book jackets.
The mixtures according to the invention can also be
used as initiators for photochemical crosslinking of poly-
olefines. Polyolefines which can be used are, for
example, polypropylene, polybutylene, polyisobutylene and
copolymers, for example ethylene/propylene copolyrners, but
preferably polyethylene of low, moderate or high density.
The addition of the preferred photoinitiators to
the photopolymerisable systems is generally effected by
simple stirring-in, since most of these systems are liquid
or readily soluble. Usually, a solution of the initia-
tors is obtained and this ensures uniform distribution of
the initiators and also transparency of the polymers.
- 26 -
The polymerisation is effected by the known methods
for photopolymerisation ~y irradiation with light which is
rich in short-wave radiation. Suitable light sources
are, for example, medium pressure, high pressure and low
pressure mercury radiant lamps and also superactinic
fluorescent tubes which have their emission maxima in the
range between 250 and 450 nm.
For the photochemical crosslinking of polyolefines,
the photoinitiator is added to the polyolefine before or
during processing for shaping 9 for example by mixing in
powder form or by mixing with the plasticised polyolefine.
Crosslinking is effected by irradiating the shaped article
in solid form, for example in the form of filrns or fibres.
Example I:
2 g (0.007 mol) of vinyl thioxanthone-l-carboxylate
are dissolved in 49 ml of N,N-dimethylformamide, under
nitrogen, in a 100 ml three-necked flask. 0.02 g
(0.00012 mol) of azoisobutyronitrile, dissolved in 1 ml of
N,N-dimethylformamide, is added at 70C, and the mixture
is polymerised under a nitrogen atmosphere for 24 hours.
The solution is precipitated in 250 ml of methanol and the
resulting polymer is dried in vacuo at 40C (polymer No.l).
465.5 g (1.963 mol) of the ~-(methacryloyloxy)-
ethyl ester of dimethylmaleimide (prepared in accordance
with German Offenlegungsschrift 2,626,769) are dissolved
together with 49.15 g (0.49 mol)ofethyl acrylate in 960 ml
of l-acetoxy-2-ethoxyethane, under nitrogen. A solution
of 3.86 g of azoisobutyronitrile in 25 ml of 1-acetoxy-2-
ethoxyethane is allowed to run in at 80C, under a nitro-
gen atmosphere, and the mixture is then polymerised for 6
hours. The solution is stabilised, whilst s-till hot,
with 2.57 ~ of 2,6-di-tert.-butyl-p-cresol. Viscosity
of the solution, measured with a Hoppler falling ~all vis-
cometer in accordance with DIN 53,015 = 829 . 103 Pa s
- 27 -
(polymer No 2); mean molecular weight (measured by light
scattering in chloroform) = 1,000,000. 2.7% by weight
of polymer No. 1) are added, as the sensitiser, to this
polymer solution. Using the polymer solution, which
has been diluted to a solids content of 1S% by weight,
copper sheets are so coated, by whirler-coating (500 revo
lutions/minute for 1 minute), that, after drying, a 1-3 ~
thick coating of polymer is formed on the copper. The
coated sheets are exposed through a negative original
(step wedge, Stauffer 21-step sensitivity guide) using a
high-pressure mercury discharge lamp 400 at a distance of
60 cm from the vacuum table. After exposure, the image
is developed for 2 minutes in a l,l,l~-trichloroethane bath
by which means the portions which have not been cross-
linked are dissolved out. The resulting relief image
of the recorded step wedge is rendered visible by etching
the exposed parts of the copper with a 50% FeC13 solution.
Last step recorded (slightly etched) after an exposure
time of:
1 minute step 1
3 minutes step 4
6 minutes step 6
]2 minutes step 7.
Example II:
0.64 g of a commercially available copolymer of
ethylene and maleic anhydride (1:1) with a mean molecular
weight of 20,000, 1 g (0.0035 mol) of ~-hydroxyethyl thio-
xanthone-l-carboxylate and 15 ml of tetrahydrofuran are
stirred for 72 hours at 66C in a 100 ml three-necked
flask. 1.2 g of polymer (polymer No. 3) are obtair,ed.
- 28 -
Example III:
2 5 g (0.008 mol) of thioxanthone-l-carboxylic acid
~-ethylvinyl ether, dissolved in 70 ml of toluene 9 are
initially introduced into a 100 ml three-necked flask.
44 ml of toluene are distilled off under nitrogen, through
a descending condenser. The resulting yellow solution
is cooled to -15C. At this temperature 0005 g of
freshly distilled boron trifluoroethyl etherate are added.
The solution is stirred at -15 to -10C for 3 hours.
75 ml of methanol are added to the yellow suspension, the
suspension is then filtered with suction and the product
is dried in vacuo at 40C. This yields 2.2 g (88% of
theory) of polythioxanthone-l-carboxylic acid ~-ethylvinyl
ether (polymer No. 4). 2.7% by weight of this polymer
are added, as -the sensitiser, to the polymer solution des-
cribed in Example I, paragraph 2. Using the polymer
solution, which has been diluted to a solids content of
15% by weight, copper sheets are then coated, and sub-
sequently exposed, in the manner described in Example I.
Last step recorded after an exposure time of:
3 minutes step 1
6 minutes step 3
12 minutes step 5.
Ex_mple IV:
0.744 g of a copolymer of ethylene and maleic anhy-
dride (1:1, with a mean molecular weight of 20,000), 0.8 g
(0.0024 mol) of the hydrochloride of ~aminoethyl thio-
xanthone~ carboxylic acid and 1.5 ml of pyridine are
stirred for 24 hours at 24C in a 10 ml three-necked
flask. The reaction mixture is then diluted with 5ml
o~ pyridine and- precipitated in 300 ml of 1 N HCl. The
resulting suspension is filtered with suction and the re-
action product is dried in vacuo at 40C. This yields
1.3 g of polymer with an intrinsic viscosity of 0.18 dl/g
in chloroform (polymer No. 5).
- 29 -
Examp]e V
7.2 g of a polyacrylic acid with a mean molecular
weight of 30,000 and 21.86 g (0.07 mol) of glycidyl thio-
xanthone-l-carboxylate are dissolved in 260 ml of cyclo-
hexanone with the addition of 0.3 g of tetramethylammonium
bromide and the solution is stirred for 6 hours at 120C
under nitrogen. The viscous, slightly yellow solution
is precipitated in 3 litres of diethyl ether. This
yields 23.8 g (82% of theory) of a polymer which has an
elementary analysis of:
calculated: C 61.56% H 4.3% 0 26.42% S 7.72%
found: C 61.43% H 4.27% 0 26.43% S 7.87%.
Intrinsic viscosity of the polymer in chloroform:0.28 dl/g
Example VI:
20 g (0.054 mol) of ~-(methacryloyloxy)-ethyl -thio-
xanthone-l-carboxylate and 0.2 g (0.0012 mol) of azoiso-
butyronitrile are dissolved in 80 ml of tetrahydrofuran,
under nitrogen, and the solution is refluxed for 8 hours.
The slightly viscous solution is precipitated in 1 litre
of diethyl ether and the resulting white polymer is dried
for 12 hours at 40DC in vacuo. 16.35 g (82% of ~heory)
of a white polymer are obtained; intrinsic viscosity in
chloroform: 0.18 dl/g.
Example VII:
38.055 g (0.103 mol) of ~-(methacryloyloxy)-ethyl
thioxanthone-l-carboxylate, 7.445 g (0.103 mol) of acrylic
acid and 0.455 g (0.003 mol) of azoisobutyronitrile are
dissolved in 205 ml of tetrahydrofuran, under nitrogen,
and the solution is refluxed for 8 hours. The colourless
solution is precipitated in 2.5 litres of diethyl ether
and the resulting powder is drie~ in vacuo at 20-25C.
34.4 g (75.6% of theory) of a white polymer are obtained;
intrinsic viscosity in chloroform: 0.25 dl/g.
3'~
- 30 -
Example VIII:
12.88 g of the dlethylene glycol ester of thioxan-
thone-7-methyl-3-carboxylic acid and 5 g of a copolymer of
methyl vinyl ether and maleic anhydride (1:1) are dissolved
in 1&0 ml of tetrahydrofuran with the addition of 1 ml of
pyridine and the solution is stirred for 48 hours at 70C.
The yellow polymer solution is precipitated in 2 litres of
diethyl ether and the resulting polymer powder is dried in
vacuo at 40C. 16.5 g (92.3% of theory) of polymer are
obtained; intrinsic viscosity in chloroform: 0.30 dl/g.
~ he thioxanthone starting materials used in the
above examples I through VIII can be prepared as ~ollows:
Example 1 Dry sodium thiophenolate prepared from 7.5 g
(0.33 gram equivalent) of sodium, 300 ml of methanol and
36 ml (0.33 mol) of thiophenol is dissolved in 300 ml of
dimethylsulfoxide, and 80.4 g (0.3 mol) of 3-nitrophthalic
acid N-phenylimide are added. The reac~ion mixture is heated
at 50 C for 90 minutes andthen poured into a mixture of
300 ml of water and 300 ml of anhydrous acetic acid. The
resulting suspension is filtered with suction and the
product is dried at 80C/13,000 Pa. 100 g (100% of
theory) of 3-phenylthiophthalic acid N-phenylimide are ob-
tained.
99.4 g (0.3 mol) of 3-phenylthiophthalic acid N-
phenylimide are suspended in 1,326 ml of a 20% sodium
hydroxide solution and the suspension is heated at 100C
for 30 minutes, with stirring. After cooling, the alk-
aline suspension is acidified with 672 ml of 37% hydro-
chloric acid, with stirring. After one hour the fine
suspension is filtered with suction 9 the material on the
suction filter is suspended, whilst till wet, in 882 ml of
37% hydrochloric acid and the suspension is refluxed ~or
- 31 -
one hour. The reaction mixture is cooled, the result-
ing fine suspension is filtered with suction and the pro-
duct is dried at 80C/13,000 Pa. 69.4 g (85 of theory)
of 3-phenylthiophthalic acid are obtained.
69 g (0.25 mol) of 3-phenylthiophthalic acid and
700 ml of polyphosphoric acid are heated at 200C for 90
minutes9 with stirring, then cooled and stirred into 3,000
ml of water. After one hour the resulting suspension
is filtered wi-th suction and the material on the suction
filter is washed with water and dried at 80C. The re-
sulting crude product is dissolved in 350 ml of hot N,N-
dimethylformamide, animal charcoal is added and the mix-
ture is filtered. The filtrate is diluted with five
times the amount of water, the resulting suspension is fil-
tered and the product is washed with water and dried. 63 g
(98% of theory) of thioxanthone-l-carboxylic acid are ob-
tained; melting point 259C. The acid obtained in this
way can be further used direct.
82 g (0.32 mol) of thioxanthone-l-carboxylic acid
in 460 ml of thionyl chloride are refluxed for 5 hours.
The resulting dark, clear solution is evaporated to dry-
ness. 87.5 g (100% of theory) of thioxanthone-l-car-
boxylic acid chloride are obtained.
11 g (0.04 mol) of thioxanthone-l-carboxylic acid
chloride and 10.4 g (0.08 mol) of 2-hydroxyethyl meth--
acrylate in 170 ml of dioxan are heated at 80C for 3hours and the mixture is then evaporated to dryness. The
solid residue is stirred with 100 ml of water and the pH
of the resulting suspension is adjusted to 8 with a 3%
sodium bicarbonate solution. The crude product is
then extracted with 200 ml of methylene chloride, the ex-
tract is dried over solid sodium sulfate and the methy-
lene chloride is evaporated. The residue is dissolved
in 100 ml of methanol and the solution is filtered with
- 32 -
4 g of animal charcoal. The product which has crystal-
lised out is dissolved in 1,200 ml of die-thyl ether and
extracted with 50 ml of 1% sodium hydroxide solution.
The ether phase is washed with wa-ter and dried over sodium
sulfate. The ethereal solution is then stabilised with
0.05% by weight of 2,6-di-tert.-butyl cresol and concen-
trated. 7.7 g (52% of theory) of ~-(methacryloyloxy)-
ethyl thioxanthone-l-carboxylate are obtained; melting
point 112-113C.
IR spectrum (chloroform): 1740 cm 1 (-COOR); 1660 cm 1 (-CO-)~
Analysis for C20H1605S (molecular weight 368.34):
calculated: C 65.22% H 4.37% S 8.68%
found: C 63.8% H.-4.10% S.8.41%.
Example 2:
. . ~ . . _
18.4 g (0.06 mol) of the sodium salt of thioxan-
thone-l-carboxylic acid (prepared by reacting thioxanthone-
l-carboxylic acid with NaOH), 14.5 g (0.18 mol) of 2-
chloroethanol and 0.18 g of diethylamine are refluxed at
130C for 4 hours. After cooling the reaction mixture,
this is twice boiled Up with, in each case, 100 ml of dioxan
and f'iltered hot. The dioxan extracts are evaporated to
dryness. The residue is recrystallised from 1,000 ml of
methanol with the addition of animal charcoal. 13.2 g
(73.3% of theory) of ~-hydroxyethyl thioxanthone-l-carboxy-
late are obtained; melting point 169C.
IR spectrum (chloroform):1750 cm 1(-COOR):1660 cm l(-Co-).
Analysis for C16H1204S (molecular weight 300.33):
calculated: C 64.04% H 4.0% S 10.7%
found: C 63.8% H 4.0% S 10.6%.
L~
- 33 -
Example 3:
90.2 g (0.726 mol) of p-thiocresol are dissolved in
600 ml of N,N-dimethylformamide, after which 31.7 g (0.792
mol) of finely powdered sodium hydroxide are added. After
stirring for half an hour at 20-25C, 158.0 g (0.660 mol)
of dimethyl nitroterephthalate are added to the homogene-
ous solution, and the reaction mixture is stirred for 1.5
hours at 70C. After cooling to 20-25C 7 1 ~000 ml of
water are added and -the precipitate which has separated
out is filtered off. 275 g of moist product are obtain-
ed. This is heated in a solution of 89.5 g of KOH in
1,200 ml of methanol for one hour under reflux. The mix-
ture is cooled to 20-25C, 1,000 ml of water and a little
active charcoal are added and the resulting mixture is
filtered after stirring for half an hour. The filtrate
is freed from methanol in a rotary evaporator and the re-
sidual aqueous phase is extracted with three times 200 ml
of methylene chloride. The precipitate formed after
acidifying the aqueous phase with sulfuric acid is fil-
tered off and washed with water. After drying in vacuo
at 80C, 140 g (74% of theory) of 2-(4-methylphenylthio)-
terephthalic acid remain; melting point >250C; IR
spectrum (KBr): 1690 cm 1.
Elementary analysis for C15H12C)4~ (molecular weight 288.32):
calculated: C 62.49% H 4.20%
found: C 62.56% H 4.28%.
The 2-(4-methylphenylthio)-terephthalic acid is
treated with chlorosulfonic acid at between 5 and 10C,
after which the reaction mixture is poured onto ice and the
thioxanthone-7-methyl-3-carboxylic acid which has precip-
itated is filtered off and dried in vacuo at 100C; yield
99% of theory; IR spectrum (KBr): 1640 cm 1; UV spectrum
(N,N-dimethylformamide):~ max = 395 nm, e = 5733-
- 34 -
Example ~:
8.34 g (0.03 mol) of the sodium salt of thioxan-
thone-l-carboxylic acid and 0.1 ml of triethylamine are
heated in 15 ml of epichlorohydrin at 130C until a dark,
homogeneous solution has formed, and the solu-tion is then
kept at this temperature for 3 hours. The reaction
mixture is then diluted with 50 ml of dioxan, heated to
reflux and cooled, and the sodium chloride which has pre-
cipitated out is filtered off with suction. The sol-
vent is evaporated and the residue is stirred with 15 ml
of diethyl ether. The crude product which has crystal-
lised out is filtered off with suction. Both the pro-
duct which has crystallised out and the mother liquor are
purified through a silica gel column (solvent system
chloroform/acetone in a volume ratio of 19:1). The
products obtained after chromatography are recrystallised
from methanol. 7.54 g (80.5% of theory) of glycidyl
thioxanthone-l-carboxylate are obtained; melting point
115-117~C.
IR spectrum (chloroform): 1750 cm l(-COOR); 1660 cm l(_Co-).
UV spectrum:~max = 385 nm, E = 6600.
Elementary analysis for C17H120~S (molecular weight 312.3~)
calculated: C 65.38% H 3.88% S 10.27%
found: C 64.62% H 3.87% S 10.19%.
Example 5:
0.6 g (0.01 mol) of ethanolamine are mixed with 5.6
ml of ethanolic hydrochloric acid (19.5%). The ethanol is
then distilled off, to dryness. 5.5 g (0.02 mol) of
thioxanthone-l-carboxylic acid chloride are dissolved in
550 ml of acetonitrile and the solution is mixed with the
ethanolamine hydrochloride previously prepared. The re-
action mixture is refluxed for 60 hours and then evaporated
to dryness. The residue is stirred with 200 ml of water
- 35 ~
and insoluble constituents are filtered off with suction.
The solution is rendered alkaline with 10% aqueous potas
sium carbonate and immediately extracted by shaking with
twice 200 ml of diethyl ether, after which the diethyl ether
is evaporated. 0.67 g (20% of theory) of the hydro-
chloride of ~aminoethyl thioxanthone-l-carboxylate is ob-
tained; melting point 231~ ~with decomposition).
IR spectrum (KBr): 1755 cm 1(-COOR); 1660 cm (-C0-).
UV spectrum (H20) A max = 390 nm, ~ = 5000.
Elementary analysis for C16H14ClN03S (molecular weight
335.8):
calculated: C 57.23% H 4.20% Cl 10.56% N 4.17% S 9.55%
found: C 57.75% H 4.5% Cl 10.2% N 4.2% S 9.2%.
Example 6:
19 g (0.0683 mol) of the sodium salt of thioxan-
thone-].-carboxylic acid, 190 ml of ~-chloroethyl vinyl
ether and 0.3 g (0.0033 mol) of triethylammonium iodide
are refluxed for 6 hours in a 250 ml three-necked flask.
The reaction solution is cooled and filtered and the fil-
trate is then evaporated. The reaction product is re-
crystallised from ligroin. This yields 21.2 g (95.1% of
theory) of the ~-ethylvinyl ether of thioxanthone-l-car-
boxyli.c acid, which has a melting point of 163-164C and
an elementary analysis of:
calculated: C 66.24% H 4.33% S 9.82%
found: C 65.92% H 4.21% S 9.74%.
UV absorption spectrum: ~max 258, 289, 302 and 384 nm;
~max = 43400' 4700~ 3900 and 7000
xample 7:
20 g (0.078 mol) of thioxanthone-l-carboxyli.c acid
and 0.1 g of Li2(PdC14) in 400 ml of vinyl acetate are re-
fluxed for 21 hours in a 750 ml sulfonation flas~. The
greyish suspension is cooled to 50C and 5 g of active
- 36 -
charcoal are added. After 15 minu-tes, the suspension
is ~iltered with suction and the material on the suction
filter is boiled in 1 litre of methylene chloride for 15
minutes and the mixture is filtered hot. The solution
is evapora~,ed and the resulting yellow powder is recrystal-
lised from 500 ml of toluene, with active charcoal. This
yields 15 g (68.12% of theory) of vinyl thioxanthone-l-
carboxylate with a melting point of 220-222C and an ele-
mentary analysis of:
calculated: C 68.07% H 3.57% 0 17.0% S 11.3~%
found: C 67.75% H 3.56% 0 17.23% S 11.21%.
lH-NMR spectrum (100 MHz, CDC13 ~ DMS0-d6): lH: 8.5 ppm,
7H: 7.4-8.~ ppm, 2H: 4.65-5.0 ppm.
UV spectrum: 386 nm, ~.= 6800.
Example ~:
~ sing the procedure described in Example 3, 5 g
(0.019 mol) of thioxanthone-7-methyl-3-carboxylic acid are
converted to the acid chloride using 50 ml of thionyl
chloride, and the acid chloride is treated with 50 ml of
diethylene glycol. After adding 100 ml of water and
drying the resulting precipit;ate, 5.0 g (73% of theory) of
the yellow diethylene glycol ester of thioxanthone-7-
methyl-3-carboxylic acid are obtained; melting point
lOq-109C.
