POLYCYCLIC PHOTOINITIATORS

Abstract

Compounds of the formula (I) (I), wherein X is O, S, a direct bond or CR.sub.16R.sub.17; Y is O or S; R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7 and R.sub.8 for example are hydrogen, halogen, C.sub.1-C.sub.4alkyl, or a group of formula (II) or (III) (II) (III) provided that either (i) one of R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7 or R.sub.8 is a group of formula (II) or (III); or (ii) one of R.sub.1, R.sub.2, R.sub.3 Or R.sub.4 is a group of formula (II) or (III) and one of R.sub.5, R.sub.6, R.sub.7 or R.sub.8 is a group of formula (II) or (III); R.sub.9 and R.sub.10 independently of each other are C.sub.1-C.sub.4alkyl or together with the C atom to which they are attached form a 5-membered, 6-membered or 7-membered carbocyclic ring; R.sub.11 is hydrogen, C.sub.1-C.sub.4alkyl, C.sub.5-C.sub.7cycloalkyl, 2-tetrahydropyranyl or Si(C.sub.1-C.sub.4alkyl).sub.3; R.sub.12 and R.sub.13 for example are C.sub.1-C.sub.4alkyl, C.sub.2-C.sub.2alkenyl, phenyl-C.sub.1-C.sub.4alkyl, phenyl-C.sub.1-C.sub.4alkyl which is substituted by C.sub.1-C.sub.4alkyl, R.sub.14 and R.sub.15 independently of each other are C.sub.1-C.sub.4alkyl, C.sub.5-C.sub.7cycloalkyl, or together with the N atom to which they are attached form a 5-membered, 6-membered or 7-membered ring, which may contain additional heteroatoms O, S or N; R.sub.16 and R.sub.17 for example are hydrogen, C.sub.1-C.sub.5alkyl, C.sub.5-C.sub.7cycloalkyl, phenyl-C.sub.1-C.sub.4alkyl, phenyl; are effective photoinitiators.

##STR00001##

Claims

1: A photopolymerizable composition comprising: (A) at least one ethylenically unsaturated photopolymerizable compound and (B) at least one photoinitiator compound of formula (I): ##STR00034## wherein X is O, S, a direct bond or CR.sub.16R.sub.17; Y is O or S; R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7 and R.sub.8 independently of each other are hydrogen, halogen, C.sub.1-C.sub.4alkyl, C.sub.5-C.sub.7cycloalkyl, phenyl, C.sub.1-C.sub.4alkoxy, C.sub.5-C.sub.7cycloalkoxy, phenoxy, C.sub.1-C.sub.4alkylthio, C.sub.5-C.sub.7cycloalkylthio, phenylthio, di(C.sub.1-C.sub.4alkyl)amino, di(C.sub.5-C.sub.7cycloalkyl)amino, N-morpholinyl, N-piperidinyl or a group of formula (II) or (III): ##STR00035## provided that either; (i) one of R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7 or R.sub.8 is a group of formula (II) or (III); or (ii) one of R.sub.1, R.sub.2, R.sub.3 or R.sub.4 is a group of formula (II) or (III) and one of R.sub.5, R.sub.6, R.sub.7 or R.sub.8 is a group of formula (II) or (III); R.sub.9 and R.sub.10 independently of each other are C.sub.1-C.sub.4alkyl or together with the C atom to which they are attached form a 5-membered, 6-membered or 7-membered carbocyclic ring; R.sub.11 is hydrogen, C.sub.1-C.sub.4alkyl, C.sub.5-C.sub.7cycloalkyl, 2-tetrahydropyranyl or Si(C.sub.1-C.sub.4alkyl).sub.3; R.sub.12 and R.sub.13 independently of each other are C.sub.1-C.sub.4alkyl, C.sub.2-C.sub.12alkenyl, phenyl-C.sub.1-C.sub.4alkyl, phenyl-C.sub.1-C.sub.4alkyl which is substituted by C.sub.1-C.sub.4alkyl, or R.sub.12 and R.sub.13 together with the C atom to which they are attached form a 5-membered, 6-membered or 7-membered carbocyclic ring; R.sub.14 and R.sub.15 independently of each other are C.sub.1-C.sub.4alkyl, C.sub.5-C.sub.7cycloalkyl, or together with the N atom to which they are attached form a 5-membered, 6-membered or 7-membered ring, which may contain additional heteroatoms O, S or N; R.sub.16 and R.sub.17 independently of each other are hydrogen, C.sub.1-C.sub.8alkyl, C.sub.5-C.sub.7cycloalkyl, phenyl-C.sub.1-C.sub.4alkyl, phenyl or together with the C atom to which they are attached form a 5-membered, 6-membered or 7-membered ring; provided that; (1) compounds wherein R.sub.2 is a group of formula (III) and R.sub.14 and R.sub.15 together with the N atom to which they are attached form a 6-membered ring, which contains an additional heteroatom O, X is a direct bond and Y is O; and (2) compounds wherein R.sub.2 is a group of formula (III) and R.sub.14 and R.sub.15 together with the N atom to which they are attached form a 6-membered ring, which contains an additional heteroatom O and X and Y are S; and (3) compounds wherein R.sub.7 is a group of formula (III) and R.sub.14 and R.sub.15 together with the N atom to which they are attached form a 6-membered ring, which contains an additional heteroatom O and X and Y are S; are excluded.

2: A photopolymerizable composition according to claim 1, where in the photoinitiator compound of formula (I): one of R.sub.1, R.sub.2, R.sub.3 or R.sub.4 or one of R.sub.5, R.sub.6; R.sub.7 or R.sub.8 is a group of the formula (II) or (III).

3: A photopolymerizable composition according to claim 1, where in the photoinitiator compound of formula (I): one of R.sub.1, R.sub.2, R.sub.3 or R.sub.4 and one of R.sub.5, R.sub.6, R.sub.7 or R.sub.8 is a group of the formula (II) or (III).

4: A photopolymerizable composition according to claim 1, where in the photoinitiator compound of formula (I): one of R.sub.1, R.sub.2, R.sub.3 or R.sub.4 and one of R.sub.5, R.sub.6, R.sub.7 or R.sub.8 is a group of the formula (II); or one of R.sub.1, R.sub.2, R.sub.3 or R.sub.4 and one of R.sub.5, R.sub.6, R.sub.7 or R.sub.8 is a group of the formula (III).

5: A photopolymerizable composition according to claim 1, where in the photoinitiator compound of formula (I): X is S, a direct bond or CR.sub.16R.sub.17; Y is O or S; R.sub.1, R.sub.3, R.sub.4, R.sub.5, R.sub.6 and R.sub.8 are hydrogen; R.sub.2 and R.sub.7 are a group of the formula (II) or (III); R.sub.9 and R.sub.10 are C.sub.1-C.sub.4alkyl; R.sub.11 is hydrogen; R.sub.12 and R.sub.13 are C.sub.1-C.sub.4alkyl; R.sub.14 and R.sub.15 are C.sub.1-C.sub.4alkyl; and R.sub.16 and R.sub.17 are hydrogen or C.sub.1-C.sub.8alkyl.

6: A photopolymerizable composition according to claim 1, which additionally to the component (B) comprises: (x) at least one further photoinitiator (C); (xi) at least one further coinitiator (D); (xii) at least one other additive (D); or (xii) a combination of (x) and (xi) or a combination of (x) and (xii) or a combination of (x) and (xi) and (xii).

7: A photopolymerizable composition according to claim 1, which comprises 0.05 to 15% by weight of the photoinitiator compound of formula (I) based on the total composition.

8-13. (canceled)

14: Compound of the formula (I″): ##STR00036## wherein X is O, S, a direct bond or CR.sub.16R.sub.17; Y is O or S; R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7 and R.sub.8 independently of each other are hydrogen, halogen, C.sub.1-C.sub.4alkyl, C.sub.5-C.sub.7cycloalkyl, phenyl, C.sub.1-C.sub.4alkoxy, C.sub.5-C.sub.7cycloalkoxy, phenoxy, C.sub.1-C.sub.4alkylthio, C.sub.5-C.sub.7cycloalkylthio, phenylthio, di(C.sub.1-C.sub.4alkyl)amino, di(C.sub.5-C.sub.7cycloalkyl)amino, N-morpholinyl, N-piperidinyl or a group of formula (II) ##STR00037## R.sub.9 and R.sub.10 independently of each other are C.sub.1-C.sub.4alkyl or together with the C atom to which they are attached form a 5-membered, 6-membered or 7-membered carbocyclic ring; R.sub.11 is hydrogen, C.sub.1-C.sub.4alkyl, C.sub.5-C.sub.7cycloalkyl, 2-tetrahydropyranyl or Si(C.sub.1-C.sub.4alkyl).sub.3.

15: Process for the preparation of a compound of the formula (I″) by: Friedel-Crafts acylation of a polycyclic aryl compound ##STR00038## wherein; R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7 and R.sub.8 independently of each other are hydrogen, halogen, C.sub.1-C.sub.4alkyl, C.sub.5-C.sub.7cycloalkyl, phenyl, C.sub.1-C.sub.4alkoxy, C.sub.5-C.sub.7cycloalkoxy, phenoxy, C.sub.1-C.sub.4alkylthio, C.sub.5-C.sub.7cycloalkylthio, phenylthio, di(C.sub.1-C.sub.4alkyl)amino, di(C.sub.5-C.sub.7cycloalkyl)amino, N-morpholinyl, N-piperidinyl, provided that at least one of R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7 and R.sub.8 is hydrogen; and X and Y are as defined in claim 14; with a halogenide compound (IIa) or an anhydride compound (IVa): ##STR00039## wherein R.sub.9 and R.sub.10 are as defined in claim 14; and Hal is a halogenide; subsequent halogenation, of the resulting Friedel-Crafts adduct; and hydrolysis of the halogenated intermediate to give the corresponding α-hydroxyketone compound of the formula (I″) as defined in claim 14.

Description

SYNTHESIS EXAMPLES

Example 1: 2-Hydroxy-1-[7-(2-hydroxy-2-methyl-propanoyl)-9H-xanthen-2-yl]-2-methyl-propan-1-one (Cmpd 1)

[0189] ##STR00027##

Intermediate I-1a: 2-methyl-1-[7-(2-methylpropanoyl)-9H-xanthen-2-yl]propan-1-one

[0190] Isobutyroyl chloride (26.64 g, 0.25 mol) and xanthene (18.22 g, 0.1 mol) are dissolved in 100 ml of 1,2-dichloroethane and the solution is cooled to −15° C. To the stirred solution is then added aluminium trichloride (33.3 g, 0.25 mol) within 30 minutes and a temperature between −10 to −15° C. The resulting orange mixture is then stirred 18 h at room temperature and is thereafter slowly poured in a stirred mixture of 600 g of ice, 50 ml of 32% hydrochloric acid and 150 ml of dichloromethane. The organic layer is separated, washed with 50 ml of 5% HCl, 1 M Na.sub.2CO.sub.3 and water, dried over MgSO.sub.4 and evaporated. The residue is recrystallized from dichloromethane-methanol to afford 29.2 g of the title compound as a white solid, mp. 125-131° C.

[0191] .sup.1H-NMR (CDCl.sub.3, 400 MHz, δ ppm): 7.83-7.81 (m, 4ArH), 7.10-7.07 (m, 2 ArH), 4.13 (s, 2H, CH.sub.2), 3.55-3.49 (m, 2H), 1.21 (d, 12H).

Intermediate I-1b: 2-bromo-1-[7-(2-bromo-2-methyl-propanoyl)-9H-xanthen-2-yl]-2-methyl-propan-1-one

[0192] Intermediate I-1a (24.18 g, 0.075 mol) is dissolved in 100 ml of dichloromethane and the solution is cooled to 3° C. To the stirred solution is then added the solution of bromine (24.0 g, 0.15 mol) in 75 ml of dichloromethane at a temperature between 3 to 5° C. within 1 h. The mixture is then stirred for 3 h at room temperature and then diluted with 200 ml of cold water. The organic layer is separated, washed with 100 ml 1 M NaHCO.sub.3 and water, dried over MgSO.sub.4 and evaporated. The residue is recrystallized from dichloromethane-acetonitrile to afford 26.5 g of the title compound as a white solid, mp. 129-138° C.

[0193] .sup.1H-NMR (CDCl.sub.3, 400 MHz, δ ppm): 8.15-8.10 (m, 4ArH), 7.10-7.08 (m, 2 ArH), 4.16 (s, 2H, CH.sub.2), 2.08 (s, 12H).

[0194] Cmpd. 1:

[0195] Intermediate I-1b (8.64 g, 0.018 mol) is dissolved in 35 ml of tetrahydrofurane. To this solution is then added the solution of NaOH (2.88 g, 0.072 mol) in 14 ml of water. The resulting emulsion is vigorously stirred for 26 h at room temperature. Thereafter dichloromethane (60 ml), water (100 ml) and 1M HCl (40 ml) is added. The organic layer is separated, washed with water, dried over MgSO.sub.4 and evaporated. The residue is recrystallized from ethylacetate to afford 5.1 g of the title compound as a white solid, mp. 159-162° C.

[0196] .sup.1H-NMR (CDCl.sub.3, 400 MHz, δ ppm): 7.98-7.94 (m, 4ArH), 7.11-7.08 (m, 2 ArH), 4.14 (s, 2H, CH.sub.2), 4.04 (s, 20H), 1.63 (s, 12H).

Example 2: 2-Hydroxy-1-[7-(2-hydroxy-2-methyl-propanoyl)-9,9-dimethyl-xanthen-2-yl]-2-methyl-propan-1-one (Cmpd 2)

[0197] ##STR00028##

Intermediate I-2a: 1-[9,9-dimethyl-7-(2-methylpropanoyl)xanthen-2-yl]-2-methyl-propan-1-one

[0198] The intermediate I-2a is prepared from 9,9-dimethylxanthene in analogy to intermediate I-1a in 85% yield. White solid, mp. 105-109° C.

[0199] .sup.1H-NMR (CDCl.sub.3, 400 MHz, δ ppm): 8.15-8.14 (d, 2 ArH), 7.88-7.85 (dd, 2 ArH), 7.15-7.13 (d, 2 ArH), 3.61-3.54 (m, 2H), 1.72 (s, 2×CH.sub.3) 1.26-1.24 (d, 12H).

Intermediate I-2b: 2-bromo-1-[7-(2-bromo-2-methyl-propanoyl)-9,9-dimethyl-xanthen-2-yl]-2-methyl-propan-1-one

[0200] The intermediate I-2b is prepared from intermediate I-2a in analogy to intermediate I-1b in 89.3% yield. White solid, mp. 118-130° C.

[0201] .sup.1H-NMR (CDCl.sub.3, 400 MHz, δ ppm): 8.38-8.37 (d, 2ArH), 8.19-8.16 (dd, 2 ArH), 7.14-7.11 (d, 2 ArH), 2.08 (s, 12H), 1.73 (s, 2×CH.sub.3).

[0202] Cmpd. 2:

[0203] Cmpd 2 is prepared from intermediate I-2b in analogy to Cpmd. 1 in 93.2% yield. White solid, mp. 107-119° C.

[0204] .sup.1H-NMR (CDCl.sub.3, 400 MHz, δ ppm): 8.27-8.26 (d, 2 ArH), 8.01-7.99 (dd, 2 ArH), 7.14-7.12 (d, 2 ArH), 4.09 (bs, 2×OH), 1.72 (s, 2×CH.sub.3), 1.66 (s, 12H).

Example 3: 2-Hydroxy-1-[8-(2-hydroxy-2-methyl-propanoyl)phenoxathiin-2-yl]-2-methyl-propan-1-one (Cmpd 3)

[0205] ##STR00029##

Intermediate I-3a: 2-methyl-1-[8-(2-methylpropanoyl)phenoxathiin-2-yl]propan-1-one

[0206] The intermediate I-3a is prepared from phenoxantiin in analogy to intermediate I-1a in 77% yield (after two crystallizations from methanol). Light yellow solid, mp. 82-92° C. According to NMR it consists of two regiosomers in ca 1:1 ratio. The isobutyroyl groups in these regioisomers are presumably in positions 2,7 respectively 2,8 of the phenoxanthiin ring system.

[0207] .sup.1H-NMR (CDCl.sub.3, 400 MHz, δ ppm): 7.74-6.98 (m, 6 ArH), 3.48-3.41 (m, 2H), 1.27-1.17 (m, 12H).

Intermediate I-3b: 2-bromo-1-[8-(2-bromo-2-methyl-propanoyl)phenoxathiin-2-yl]-2-methyl-propan-1-one

[0208] The intermediate I-3b is prepared from intermediate I-3a in analogy to intermediate I-1b in 91.5% yield. Yellow solid, mp. 104-131° C. According to NMR it consists of two regiosomers in ca 1:1 ratio. The isobutyroyl groups in these regioisomers are presumably in positions 2,7 respectively 2,8 of the phenoxanthiin ring system.

[0209] .sup.1H-NMR (CDCl.sub.3, 400 MHz, δ ppm): 8.06-7.0 (m, 6 ArH), 2.04 (s, 6H), 2.03 (s, 6H)

[0210] Cmpd. 3:

[0211] Cmpd 3 is prepared from intermediate I-3b in analogy to Cpmd. 1, Table 1 in 78% yield. Yellow solid, mp. 119-125° C. According to NMR it consists of two regiosomers in ca 1:1 ratio. The isobutyroyl groups in these regioisomers are presumably in positions 2,7 respectively 2,8 of the phenoxanthiin ring system.

[0212] .sup.1H-NMR (CDCl.sub.3, 400 MHz, δ ppm): 7.89-7.0 (m, 6 ArH), 3.81 (s, OH), 3.79 (s, OH), 1.61 (s, 6H), 1.60 (s, 6H).

Example 4: 2-Hydroxy-1-[8-(2-hydroxy-2-methyl-propanoyl)thianthren-2-yl]-2-methyl-propan-1-one (Cmpd 4)

[0213] ##STR00030##

Intermediate I-4a: 2-methyl-1-[8-(2-methylpropanoyl)thianthren-2-yl]propan-1-one

[0214] The intermediate I-4a is prepared from thianthren in analogy to intermediate I-1a in 24.5% yield (after two crystallizations from acetonitril). Light yellow solid, mp. 98-110° C.

[0215] .sup.1H-NMR (CDCl.sub.3, 400 MHz, δ ppm): 8.01-8.00 (d, 2 ArH), 7.83-7.80 (dd, 2 ArH), 7.54-7.52 (d, 2 ArH), 3.53-3.44 (m, 2 CH), 1.21-1.19 (d, 12H).

Intermediate I-4b: 2-bromo-1-[8-(2-bromo-2-methyl-propanoyl)thianthren-2-yl]-2-methyl-propan-1-one

[0216] The intermediate I-4b is prepared from intermediate I-4a in analogy to intermediate I-1b in 95% yield. Yellow solid, mp. 114-118° C.

[0217] .sup.1H-NMR (CDCl.sub.3, 400 MHz, δ ppm): 8.22-8.21 (d, 2 ArH), 8.10-8.07 (dd, 2 ArH), 7.55-7.53 (d, 2 ArH), 2.03 (s, 12H).

[0218] Cmpd. 4:

[0219] Cmpd 4 is prepared from intermediate I-4b in analogy to Cpmd. 1 in 79% yield. Yellow solid, mp. 143-147° C.

[0220] .sup.1H-NMR (CDCl.sub.3, 400 MHz, δ ppm): 7.76-7.75 (d, 2 ArH), 7.59-7.56 (dd, 2 ArH), 7.06-7.04 (d, 2 ArH), 3.31 (s, OH), 1.10 (s, 12H).

Example 5: 2-Hydroxy-1-[8-(2-hydroxy-2-methyl-propanoyl)dibenzofuran-2-yl]-2-methyl-propan-1-one, (Cmpd 5)

[0221] ##STR00031##

Intermediate I-5a: 2-methyl-1-[8-(2-methylpropanoyl)dibenzofuran-2-yl]propan-1-one

[0222] The intermediate I-5a is prepared from dibenzofurane in analogy to intermediate I-1a. The crude product was obtained in 99% yield as a viscous, light yellow oil.

[0223] .sup.1H-NMR (CDCl.sub.3, 400 MHz, δ ppm): 8.65-8.64 (d, 2 ArH), 8.17-8.14 (dd, 2 ArH), 7.66-7.64 (d, 2 ArH), 3.71-3.63 (m, 2 CH), 1.29-1.27 (d, 12H).

Intermediate I-5b: 2-bromo-1-[8-(2-bromo-2-methyl-propanoyl)dibenzofuran-2-yl]-2-methyl-propan-1-one

[0224] The intermediate I-5b is prepared from intermediate I-5a in analogy to intermediate I-1b in 69% yield (after crystallization from methanol). Off white solid, mp. 127-160° C., purity about 95% by .sup.1H-NMR.

[0225] .sup.1H-NMR (CDCl.sub.3, 400 MHz, δ ppm): 8.89-8.88 (d, 2 ArH), 8.47-8.44 (dd, 2 ArH), 7.67-7.64 (d, 2 ArH), 2.14 (s, 12H).

[0226] Cmpd. 5:

[0227] Cmpd 5 is prepared from intermediate I-5b in analogy to Cpmd. 1 in 69.5% yield. White solid, mp. 121-148° C., purity about 95% by .sup.1H-NMR.

[0228] .sup.1H-NMR (CDCl.sub.3, 400 MHz, δ ppm): 8.81-8.80 (d, 2 ArH), 8.30-8.28 (dd, 2 ArH), 7.68-7.66 (d, 2 ArH), 3.89 (bs, 2 OH), 1.74 (s, 12H).

Example 6: 2-(dimethylamino)-1-[8-[2-(dimethylamino)-2-methyl-propanoyl]phenoxathiin-2-yl]-2-methyl-propan-1-one (Cmpd 6)

[0229] ##STR00032##

Intermediate I-6a: [8-(2-methoxy-3,3-dimethyl-oxirane-2-carbonyl)phenoxathiin-2-yl]-(2-methoxy-3,3-dimethyl-oxiran-2-yl)methanone

[0230] To a stirred suspension of 2-bromo-1-[8-(2-bromo-2-methyl-propanoyl)phenoxathiin-2-yl]-2-methyl-propan-1-one (intermediate I-3b, 24.91 g, 0.05 mol) in 150 ml of methanol is added the solution of sodium methoxide (5.94 g, 0.11 mol in 45 ml of methanol at 0° C. within 30 minutes. The mixture is then stirred for 96 h at room temperature and the methanol is evaporated under reduced pressure. The residue is dissolved in 40 ml of water and 150 ml of dichloromethane, the organic layer is separated, washed with 50 ml of water, dried over MgSO.sub.4 and evaporated to afford 20.8 g of the crude title compound as a thick yellow oil.

[0231] .sup.1H-NMR (CDCl.sub.3, 400 MHz, δ ppm): 7.28-7.01 (m, 6 ArH), 3.23-3.19 (bs, 2 OCH.sub.3), 1.50 (bs, 2×CH.sub.3), 1.04 (bs, 2×CH.sub.3).

[0232] Cmpd. 6:

[0233] A 350 ml steel autoclave is charged with intermediate I-6a (20.35 g, ca 0.05 mol), 40 ml of xylene and dimethylamine (14.25 g of a 33% solution in ethanol, 0.104 mol). The autoclave is thereafter heated for 20 h at 130° C. and then cooled to room temperature.

[0234] The reaction mixture is evaporated and the oily residue is chromatographed on silica gel with ethyl acetate-heptane 1:6. The pure fraction is recrystallized twice from methanol to afford 9.22 g of the title compound as a light yellow solid, mp. 138-147° C. According to NMR it consists of two regiosomers in ca 1:1 ratio. The dimethylamino-isobutyroyl groups in these regioisomers are presumably in positions 2,7 respectively 2,8 of the phenoxanthiin ring system.

[0235] .sup.1H-NMR (CDCl.sub.3, 400 MHz, δ ppm): 8.34-8.16 (m, 4 ArH), 7.10-6.97 (m, 2 ArH), 2.26 (s, 6H, CH.sub.3), 2.25 (s, 6H, CH.sub.3), 1.28 (s, 6H, CH.sub.3), 1.27 (s, 6H, CH.sub.3).

Example 7: 2-(Dimethylamino)-1-[7-[2-(dimethylamino)-2-methyl-propanoyl]-9,9-dimethyl-xanthen-2-yl]-2-methyl-propan-1-one (Cmpd 7)

[0236] ##STR00033##

Intermediate I-7a: [7-(2-methoxy-3,3-dimethyl-oxirane-2-carbonyl)-9,9-dimethyl-xanthen-2-yl]-(2-methoxy-3,3-dimethyl-oxiran-2-yl)methanone

[0237] The intermediate l-7a is prepared from intermediate l-2b in analogy to intermediate l-6a in ca 99% yield (crude) as a thick yellow oil.

[0238] .sup.1H-NMR (CDCl.sub.3, 400 MHz, δ ppm): 7.51-7.49 (bs, 2 ArH), 7.31-7.28 (dd, 2 ArH), 7.08-7.06 (d, 2 ArH), 3.21 (s, 2×OCH.sub.3), 1.67 (bs, 2×CH.sub.3), 1.56 (s, 2×CH.sub.3), 1.03 (s, 2×CH.sub.3).

[0239] Cmpd. 7:

[0240] Cmpd 7 is prepared from intermediate l-7a in analogy to Cpmd. 6, Table 1 in 8% yield. White solid, mp. 152-173° C., purity about 95% by .sup.1H-NMR.

[0241] .sup.1H-NMR (CDCl.sub.3, 400 MHz, δ ppm): 8.72 (bs, 2 ArH), 7.52-7.50 (d, 2 ArH), 7.02-7.0 (d, 2 ArH), 2.28 (s 4×CH.sub.3), 1.68 (s, 2×CH.sub.3), 1.28 (s, 4×CH.sub.3).

APPLICATION EXAMPLES

Example A1: Photocuring of a Radically Polymerizable Clear Coating Formulation

[0242] The compounds of the invention are evaluated in a clear coat formulation consisting of the following mixture:

[0243] 20 wt. % of the polyester-acrylate Laromer@ PE 9079 (BASF) and

[0244] 80 wt. % of the amine-modified polyether-acrylate Laromer@ PO 94F (BASF).

[0245] Unless mentioned otherwise, each compound is evaluated at a level of 4 wt. % in this liquid radically curable coating formulation. After proper dissolution (clear solution) of the photoinitiator compound, the formulation is applied by means of the draw-down technique at a wet film thickness of 12 μm onto a white cardboard (100×150 mm). The coated substrate is then placed on the conveyor belt of an IST-M ETZ GmbH photocuring equipment (model “M-30-2x1-BLKU-TR-5-SS-N2-SLR”) fitted with air-cooled cold mirror reflectors (CMK) and with 1 medium pressure mercury lamp operated at 200 W/cm. The quality of the photocuring reaction under normal conditions, i.e. not under inert atmosphere), is assessed immediately after irradiation by means of the dry rub resistance (DRR) test: satisfactory curing is achieved when the coated surface is free from any trace after rubbing the surface with a paper tissue. The efficiency of the photoinitiator is quantified by the cure speed of the formulation, which is defined as the maximum belt speed (in m/min.) at which satisfactory cure (passed DRR test) is still achieved.

[0246] The results are summarized in Table 1. It is clearly seen that compounds of the present invention, e.g. compounds Nr. 2 and Nr. 5, exhibit significantly higher curing speed than the state of the art photoinitiator compounds, e.g. the monofunctional α-hydroxyketone (AHK) Irgacure® 184 (BASF) and Esacure®KIP 150 (Lamberti), as well as the difunctional AHK Esacure® One (Lamberti).

TABLE-US-00001 TABLE 1 Compound (weight-%) Curing speed (m/min) Cmpd 2 (4) 105 Cmpd 5 (4) 110 Irgacure ® 184 (4) 65 Esacure ® KIP 150 (4) 75 Esacure ® One (4) 85

Example A2: Photocuring of a Radically Polymerizable Blue Flexo Ink Formulation

[0247] The photoinitiator are evaluated in a the blue flexo ink formulation as detailed in Table 2.

TABLE-US-00002 TABLE 2 Blue flexo ink formulation wt % ingredient Product name 14.0 Polyester-acrylate Laromer ® LR 8800 (BASF) 12.0 Polyester-acrylate Ebecryl ® 450 (Allnex) 24.0 Polyether-acrylate Laromer ® PO 94F (BASF) 32.3 Pentaerythritol Laromer ® PPTTA (BASF) tetraacrylate (PPT- TA, diluent) 1.0 Dispersing agent Efka ® PX 4701 (BASF) 0.2 Levelling agent Efka ® 7305 (BASF) 16.0 Pigment Heliogen ® Blue D7110F (BASF) 0.5 PE wax Luwax ® AF 30 Mikropulver (BASF)

[0248] Unless mentioned otherwise, each compound is evaluated at a level of 5 wt. % in the radically curable blue flexo ink formulation (i.e. 5 g of the photoinitiator compound+95 g of the formulation as described in Table 2). The ink is applied by means of a laboratory flexo ink applicator “Prüfbau” (Prüfbau Mehrzweck Probedruckmaschine Typ MZ-2) at a wet film thickness of 1.6 g/m.sup.2 onto a freshly Corona treated white polyester (PE) film. The coated substrate is then placed on the conveyor belt of an IST-METZ GmbH photocuring equipment (model “M-30-2x1-BLKU-TR-5-SS-N2-SLR”) fitted with air-cooled cold mirror reflectors (CMK) and with 1 medium pressure mercury lamp operated at 200 W/cm. The complete through-cure of the ink under normal conditions (i.e. not under inert atmosphere), is assessed immediately after irradiation by means of the REL test (DIN EN 20105-A02&A03): satisfactory curing is achieved when the coated surface is free from any trace after rubbing the surface with a paper tissue. The efficiency of the photoinitiator is quantified by the cure speed of the formulation, which is defined as the maximum belt speed (in m/min.) at which satisfactory cure (passed REL test) is still achieved.

[0249] The results are summarized in Table 3. It is clearly seen that compounds of the present invention exhibit higher curing speed than the state of the art photoinitiators for flexo inks, i.e. the α-aminoketones (AAK) 2-(4-methylbenzyl)-2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-1-butanone (Irgacure® 379, BASF) and 2-methyl-1-[4-(methylthio)phenyl]-2-(4-morpholinyl)-1-propanone (Irgacure® 907, BASF), but also than the difunctional AH K 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]-phenyl}-2-methyl-propan-1-one (Irgacure® 127, BASF), used as reference materials.

TABLE-US-00003 TABLE 3 Compound (weight-%) Curing speed (m/min) Cmpd 2 (5) 110 Irgacure ® 379 (5) 80 Irgacure ® 907 (5) 70 Irgacure ® 127 (5) 55

Example A3: Photocuring of a Radically Polymerizable Yellow Flexo Ink Formulation

[0250] Considering the high efficiency of the photoinitiator comp 2 in both the clear coating formulation and the blue flexo ink, it is also evaluated into the yellow flexo ink formulation detailed in Table 4.

TABLE-US-00004 TABLE 4 Yellow flexo ink formulation wt % ingredient Product name 13.0 Amine-modified polyether- Laromer PO 94F (BASF) acrylate 11.0 Polyester-acrylate Laromer PE 44F (BASF) 36.0 Amine-modified polyether- Laromer LR 8996 (BASF) acrylate 24.5 Trimethylolpropane Laromer LR 8863 (BASF) ethoxy triacrylate (TMPETOA, diluent) 2.5 Dispersing agent Efka ® PX 4701 (BASF) 0.2 Levelling agent Efka ® 7305 (BASF) 12.4 Pigment Irgalite Yellow D1115/BAW (BASF) 0.4 PE wax Luwax ® AF 30 Mikropulver (BASF)

[0251] Each photoinitiator compound is evaluated at a level of 5 wt. % in the radically curable yellow flexo ink formulation (i.e. 5 g of PI+95 g of formulation in Table 5). The ink is applied by means of a laboratory flexo ink applicator “Prüfbau” (Prüfbau Mehrzweck Probedruckmaschine Typ MZ-2) at a wet film thickness of 1.6 g/m.sup.2 onto a freshly Corona treated white PE film. The coated substrate is then placed on the conveyor belt of an IST-METZ GmbH photocuring equipment (model “M-30-2x1-BLKU-TR-5-SS-N2-SLR”) fitted with air-cooled cold mirror reflectors (CMK) and with 1 medium pressure mercury lamp operated at 200 W/cm. The complete through-cure of the ink under normal conditions, i.e. not under inert atmosphere), is assessed immediately after irradiation by means of the REL test (DIN EN 20105-A02&A03): satisfactory curing is achieved when the coated surface is free from any trace after rubbing the surface with a paper tissue. The efficiency of the photoinitiator is quantified by the cure speed of the formulation, which is defined as the maximum belt speed (in m/min.) at which satisfactory cure (passed REL test) is still achieved.

[0252] The results are summarized in Table 5. It is clearly seen that compound Nr.2 of the present invention exhibits significantly higher curing efficiency than the state of the art photoinitiator for flexo inks, i.e. the α-aminoketone 2-(4-methylbenzyl)-2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-1-butanone (Irgacure® 379, BASF).

TABLE-US-00005 TABLE 5 Compound (weight-%) Curing speed (m/min) Cmpd 2 (5) 70 Irgacure ® 379 (5) 30