CH635583A5 - METHOD FOR PRODUCING OPTIONALLY SUBSTITUTED THIOXANTHONES. - Google Patents

Description

The present invention relates to a process for the preparation of optionally substituted thiaxanthones, which is characterized in that the corresponding o, o'-dihalobenzophenone is reacted in an alkaline medium in the presence of sulfur.

The invention also relates to the thio-xanthones produced in this way. In particular, the invention relates to a process for the preparation of compounds of the formula

10th

15

(I),

20th

25th

wherein

Rj and R2 independently of one another are hydrogen, alkyl (CVC4), alkoxy (C1-Q2) or halogen,

R3 independently of one another alkyl (C1-C4), R4 independently of one another alkyl (CVC4) and n and m independently of one another represent zero, 1, 2 or 3, which is characterized in that a compound of the formula

R,

("«)

Shark shark

R.

(II),

R "

(R3) n

30th

4Jm V "3

wherein

Ri, R2, R3, R4, n and m have the above meaning and Hai means halogen, reacted in an alkaline medium in the presence of sulfur.

3. The method according to claims 1 and 2, characterized in that 2-chlorothioxanthone is produced.

4. The method according to claims 1-3, characterized in that in the presence of alkali metal hydroxide, Al-potassium carbonate and / or ammonia and sulfur, preferably in the presence of an alkali metal hydroxide and sulfur.

5. The thioxanthone compounds obtained by the process according to claim 1.

6. Use of the compounds of the formula (I) prepared by the process according to claim 1 for the photopolymerization of photopolimerizable systems.

7. Use according to claim 6 in the presence of derivatives of ß-aminopropionic acid, preferably of compounds of the formula

(R4j o

II

c

Shark shark

(II),

m

(R3jn

35 where

Rx, R2, R3, R4, n and m have the meaning given above and shark halogen means reacted in an alkaline medium in the presence of sulfur.

The process according to the invention is preferably used to prepare compounds of the formula

R2

45

50

O

11

c

Ri

(la),

(R0m '

(Ra) n

R

5 \

N - CH2 - CH2 Z (IV),

O

where Z is -CN or -C-NH2,

R5 and R6 independently of one another are an alkyl radical having 1-14 C atoms, β, or 5-hydroxyalkyl (C2-C4), or Rs and R6 together with the common nitrogen atom represent a radical of the piperazine, the N-alkyl (C1-C4) -Piperazine, morpholine or

^ Œ-CH-

ZCH_CH "-N

CH_-CH0-

mean. ^

60

65

wherein

Rx 'alkyl (Q-C4), alkoxy (Cx-C8) or halogen R2' hydrogen or halogen n 'zero, 1 or 2, and m' zero or 1 and R3 and R4 have the above meaning by using a compound of the formula

O

n c

R!

m

"1

(Ha),

Shark

Shark (BJ)

n '

where Rx ', R2', R3 ', R4', m ', n' and shark have the meaning given above, in an alkaline medium in the presence of sulfur.

Compounds of the formula according to the invention are preferably prepared

II

C.

S

R / 'halogen,

R3 'is methyl or ethyl and n "is zero or 1 by using a compound of the formula oc1 ^ -

Shark Hai (Ri)

\ Y n "

where R / ', R3', n "and shark have the above meaning, in an alkaline medium in the presence of sulfur.

In the above formulas, halogen is preferably chlorine or bromine, preferably chlorine.

Ri is preferably R /, preferably alkoxy or halogen, preferably R / ', preferably chlorine.

R2 is preferably hydrogen, alkyl or halogen, preferably R2 ', preferably hydrogen.

R3 is preferably R3 ', preferably methyl, preferably in the 1- and / or 4-position.

R4 is preferably methyl or ethyl, preferably methyl, preferably in the 5- and / or 8-position.

n is preferably n ', preferably n ", preferably zero.

m is preferably zero, 1 or 2, preferably m ", preferably zero.

Ri as alkyl preferably has 1 or 4 carbon atoms, and is preferably methyl.

R2 as alkyl preferably has 1 or 4 carbon atoms.

R2 as alkoxy preferably has 1-8, preferably 1-4, preferably 1 or 4 carbon atoms, preferably 1 carbon atom.

The reaction according to the invention is preferably carried out in a solvent, but the addition is not absolutely necessary. The less aggressive carbonates are advantageously used in the melt.

The amount and type of solvent are not critical. Non-polar solvents are also suitable in this sense, but preference is given to using those which have polar groups, such as ether, carbonyl, hydroxyl, cyanide, SO 2, SO groups, preferably with ether, carbonyl, hydroxyl and / or SO groups. Alcohols, alkoxy alcohols, ethers, polyethers or aprotic solvents can be used in the same way.

A mixture of different solvents, e.g. a mixture of polar and non-polar compounds. The amount of solvent used is not critical; nor does it need to be in a pure form. For example, the reaction mixture can form a paste which contains about 50-100 ml of solvent, more or less, per mole of benzophenone used. Examples of suitable solvents are methanol, ethanol, propanol, betanol and higher alcohols, glycols, polyglycols, 2-methoxyethanol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol and related compounds, dimethyl

635 583

sulfoxide, N, N-dimethylacetamide, N-methylpyrrolidene, hexamethylphosphoric triamide or sulfolane.

The amount and composition of the solvent also depend on the reaction temperature and the melting point of the reaction mixture. The reaction mixture is preferably readily stirrable. It is preferably carried out at temperatures of 50-200 ° C., preferably at temperatures of 60-160 ° C., preferably at 70-140 ° C., preferably at 75-120 ° C., but the temperature range is not critical and, if appropriate, higher or lower temperatures are used.

Suitable alkaline compounds are, for example, hydroxides, carbonates, hydrocarbonates or alcoholates. Alkali or alkaline earth metal compounds in aqueous 30-50% solution and / or ammonia, preferably alkali hydroxides, alkali carbonates and / or ammonia, are preferably used. Preferably sodium or potassium compounds, preferably sodium or potassium hydroxide. At least as much sulfur and cation equivalents of the alkaline compound are used as are necessary for the ring formation for the thioxanthone compound or for binding the released halogen of the compound of formula (II). The compound of the formula (II) is prepared in a manner known per se by means of Friedel-Craft's reaction.

The use of the thioxanthones produced according to the invention is versatile. In particular, the invention also relates to the use of the thioxanthone compounds produced according to the invention as photoinitiators and also to photopolymerizable systems consisting of a photopolymerizable composition which contains a thioxanthone compound prepared according to the invention. Such compositions are known per se.

The invention also relates to an agent for photopolymerization which contains a compound of the formula (I) prepared according to the invention. Such an agent contains e.g. Polymers, prepolymers such as those described below as polymerizable compounds or e.g. also epoxidized compounds such as epoxidized linseed oil. Such an agent can contain up to 90% of the compound of formula (I).

The present invention also relates to a method for photopolymerizing a photopolymerizable system according to the invention, which is characterized in that ultraviolet light with a wavelength of 250-400 nm is allowed to act on it.

Compounds of the formula (I) prepared according to the invention are preferably used for the photopolymerization of photopolymerizable systems which contain unsaturated compounds.

The expression "photopolymerizing photopolymerizable systems" is to be understood in the broadest sense. This includes z. further polymerizing or cross-linking polymeric materials, e.g. of prepolymers, the homo-, co- and terpolymerization of simple monomers as well as the combination of the mentioned types of reactions under the influence of UV light.

Any of the known UV light sources, the light rays in a wavelength of 250-400 nm such as Providing sunlight or actinic light can be used for photopolymerization, e.g. Sun lamps or mercury arc lamps.

Photopolymerizable compositions for use in the present invention are generally known, e.g. in the UV coating or for UV-polymerizable printing inks. Such compositions preferably polymerize to form free radicals, the molecule to be polymerized generally. is unsaturated. The Together

5

10th

15

20th

25th

30th

35

40

45

50

55

60

65

635 583

4th

Design can only consist of a single component or of several components. The composition preferably contains at least one polyfunctional unsaturated reactive compound which has a crosslinking action. Furthermore, at least one component of the composition is preferably an unsaturated carboxylic acid or its ester, preferably an α, β-unsaturated carboxylic acid or its ester such as e.g. an acrylate or methacrylate or is produced by means of such.

The composition preferably contains several components and preferably contains at least one reactive unsaturated prepolymeric compound and / or at least one relatively long-chain unsaturated monomer and one or more crosslinking monomers. Examples of such reactive prepolymers are acrylic acid or methacrylic acid esters of polyethers, e.g. B. of hydroxyl-containing polyethers, polyesters, polyester-modified urethanes or epoxy resins, these prepolymer compounds contain at least one unsaturated reactive bond. This can be obtained by using monomers for the preparation of the prepolymers which already contain unsaturated bonds and thus e.g. unsaturated reactive polyester or the prepolymer product with an unsaturated compound, e.g. modified with acrylic acid or methacrylic acid. Examples of long chain monomers are acrylic acid derivatives of epoxidized unsaturated fatty acids, e.g. Acrylic acid derivatives of epoxidized linseed oil. Examples of monomers are vinyl and allyl compounds such as e.g. Styrene, trimethylol propanediallyl ether as well as vinyl and allyl esters, e.g. Vinyl acrylate, diallyl maleate, diallyl phthalate, acrylic esters of alcohols, acrylic esters of phenoxyethyl alcohol as well as polyfunctional acrylates such as e.g. the acrylic esters of neopentyl glycol or pentaerythritol.

Other additives such as B. antioxidants, pigments, fillers can be used simultaneously. The exact composition of such systems is not critical and can be varied depending on the intended use.

The compounds of the formula (I) are preferably used in the presence of amines which have at least one a-CH group. Such amines are known.

Derivatives of B-aminopropionic acid, preferably compounds of the formula, are preferably used

Examples of such compounds are (HO-CH2-CH2-) 2N-CH2-CH2-CN (a)

5 (110-CH2-CH2-) 2N-CH2-CH2CONH2 (b)

(c)

Q N-CH ^ -CH ^ -CONH

(<3)

15

H2NCO-CH2-C1I2-Nv_jN-CH2-CH2-CONH2

Compounds (a), (b) and (c) are preferred.

The compounds of formula (IV) are prepared in a manner known per se.

The amount of the photosensitizing compounds of formula-20 mei (I) used according to the invention used will vary depending on the intended use. In general, 0.01-10, preferably 1-8, preferably 2-6 percent by weight, based on the photopolymerizable composition, is sufficient.

If amines are added, the amount of amine used is preferably the same as that of the compound of the formula (I).

The photopolymerizable systems are of particular interest for UV-curable coatings, e.g. B. Lak-ke or printing inks, e.g. Offset, - lithographic printing-30 inks.

In the following examples, degrees mean degrees Celsius.

example 1

12.5 g of 2,2'-dichlorobenzophenone and 4 g of sulfur are initially charged in 40 ml of N-methylpyrrolidone. A solution of 7.0 g of NaOH in 7 g of HzO is added to the suspension at 90-97 ° within one hour with stirring, a brown mixture being formed. The mixture is then stirred at 90 ° C. for 4 hours; the relatively thick mass 40 is then mixed with 20 ml of methanol and 20 ml of water. The precipitate is filtered off at 10 °, washed with water and dried at 90 °. 10.0 g of thioxanthone of mp. 217-218 ° of the formula are obtained

5 \

R.

n - ch2 - ch2 z (iv),

O

45

50

where Z is -CN or -C-NH2,

R5 and R6 independently of one another are an alkyl radical having 1-14 C atoms, ß; y- or 5-hydroxyalkyl (C2-C4), or

R5 and Rö together with the common nitrogen atom represent a residue of piperazine, N-alkyl (Cx-CJ-piperazine, morpholine or

^ ch -ch -

zch ch -n ch2-ch2-

mean.

Z is preferably -CONH2. Rs and R6 preferably independently of one another denote an alkyl radical with 1-4 C atoms, β-hydroxyethyl or together with the common nitrogen atom a radical of the piperazine or morpholine, preferably of the morpholine.

Example 2

14.3 g of 2,2 ', 5-trichlorobenzophenone and 4 g of sulfur are placed in 40 ml of 2-methoxyethanol. A mixture of 7.0 g of NaOH in 7.0 g of H 2 O is added to mixture 55 at 107-113 ° within 45 minutes, the reaction product partially precipitating and 20 ml of methanol and 10 ml of water being added. The precipitate is filtered off, washed with water and dried at 90 °. 60 are obtained 11.6 g of 2-chlorothioxanthone of mp. 154-155 ° of the formula q

5 635 583

This compound is obtained in an analogous manner. If the reaction time is 4 hours, the mixture is mixed with 4 ml instead of 2-methoxyethanol, 40 ml N-methypyrrolidone water and then used for a further 13 hours on and instead of NaOH 15 g Na2C03. Reflux cooked. The precipitate is at

Aspirated 10 °, washed with ethanol, and then

Example 3 5 send the product washed neutral with water and at 80 °

14.3 g of 2,2 ', 5-trichlorobenzophenone and 3.2 g of sulfur dried in a water jet vacuum. 10.2 g of 2-

are in 40 ml of ethanol in a three-necked flask equipped with chlorothioxanthone of mp 154-155 °.

Steady with stirrer and reflux condenser. 20.7 g of K2C03 are added to the mixture at 75 ° in the course of one hour, with stirring, in an analogous manner to that described in Examples 1-3, the mixture turning brown. The connections in Table 1 are established after i0.

Table 1

No connection No connection

O

h c \

• j <

u CH3

'„Ä®-

CH3

O

C ^ Cl

0

fi

: 5§r * ■ (SC

ch3

ch3

Example 4

A mixture consisting of 60 g of a prepolymer of the formula ch2 = ch-coo-ch2-ch (oh) -ch2-0 (ch3) 2-® "0-ch2-ch (oh) - |

lch20 c (ch3) y © -0-ch2-ch (oh) -ch2-ooc-ch = ch2

with a viscosity of approx. 9000 poise (at 77 ° C) (compared to a US Cure device, cured to form a tack-free, glossy film

Patent Specification No. 3,713,864), 35 g of pentaerythritol tetraacrylate tet.

as well as 5 g of 2-chlorothioxanthone, 5 g of dibutylaminoethanol. In a similar manner, the rest are used with a spatula in an amount of 3.5 g / m 2 on some of the compounds mentioned in Table 1.

coated art paper and applied in UV mini

s

Claims (2)

635 583 2 PATENT CLAIMS 1. A process for the preparation of optionally substituted thioxanthones, characterized in that the corresponding o, o'-dihalobenzophenone is reacted in an alkaline medium in the presence of sulfur. 2. The method according to claim 1 for the preparation of compounds of the formula (I), wherein Rj and R2 independently of one another are hydrogen, alkyl (Q-C4), alkoxy (Cx-C12) or halogen, R3 independently of one another alkyl (Ci-C4), R4 independently of one another alkyl (Cx-C4) and n and m independently of one another are zero, 1, 2 or 3, characterized in that a compound of the formula O «I