YELLOW METHINE DYES

Abstract

The present invention relates to novel methine dyes, methods for the preparation thereof and use thereof for dyeing plastics, especially polyamides, so as to obtain yellow colorings with improved light fastness and improved thermostability.

Claims

1. A methine dye of the formula (I) ##STR00019## where R.sup.1 is hydrogen, halogen, COOH or COOR.sup.7, R.sup.2 is hydrogen, halogen, CF.sub.3, or CN, R.sup.3 is hydrogen, halogen, COOR.sup.8 or CN, R.sup.4 is alkyl or phenyl, R.sup.5 and R.sup.6 are each independently alkyl, R.sup.7 is alkyl, and R.sup.8 is alkyl.

2. The methine dye as claimed in claim 1, wherein: R.sup.4 is straight-chain or branched C.sub.1-C.sub.4-alkyl or phenyl, R.sup.5 and R.sup.6 are each independently straight-chain or branched C.sub.1-C.sub.4-alkyl, R.sup.7 is straight-chain or branched C.sub.1-C.sub.4-alkyl, and R.sup.8 is straight-chain or branched C.sub.1-C.sub.4-alkyl.

3. The methine dye as claimed in claim 1, wherein: R.sup.1 is hydrogen, fluorine, chlorine, COOH or COOCH.sub.3, R.sup.2 is hydrogen, fluorine, chlorine, CF.sub.3, or CN, R.sup.3 is hydrogen, chlorine, COOCH.sub.3 or CN, R.sup.4 is methyl or phenyl, and R.sup.5 and R.sup.6 are methyl.

4. The methine dye as claimed in claim 1, wherein for formula (I): R.sup.1 is —COOCH.sub.3, R.sup.2 and R.sup.3 are Cl, R.sup.4 is —CH.sub.3, and R.sup.5 and R.sup.6 are —CH.sub.3, or R.sup.1 is —COOCH.sub.3, R.sup.2 is H, R.sup.3 is Cl, R.sup.4 is —CH.sub.3, and R.sup.5 and R.sup.6 are —CH.sub.3, or R.sup.1 is —COOCH.sub.3, R.sup.2 is Cl, R.sup.3 is H, R.sup.4 is —CH.sub.3, and R.sup.5 and R.sup.6 are —CH.sub.3, or R.sup.1 is —COOCH.sub.3, R.sup.2 is H, R.sup.3 is —COOCH.sub.3, R.sup.4 is —CH.sub.3, and R.sup.5 and R.sup.6 are —CH.sub.3, or R.sup.1 is —COOCH.sub.3, R.sup.2 is H, R.sup.3 is CN, R.sup.4 is —CH.sub.3, and R.sup.5 and R.sup.6 are —CH.sub.3, or R.sup.1 is —COOCH.sub.3, R.sup.2 is F, R.sup.3 is H, R.sup.4 is —CH.sub.3, and R.sup.5 and R.sup.6 are —CH.sub.3, or R.sup.1 is —COOCH.sub.3, R.sup.2 is CF.sup.3, R.sup.3 is H, R.sup.4 is —CH.sub.3, and R.sup.5 and R.sup.6 are —CH.sub.3, or R.sup.1 is —Cl, R.sup.2 and R.sup.3 are Cl, R.sup.4 is —CH.sub.3, and R.sup.5 and R.sup.6 are —CH.sub.3, or R.sup.1 is —F, R.sup.2 and R.sup.3 are Cl, R.sup.4 is —CH.sub.3, and R.sup.5 and R.sup.6 are —CH.sub.3.

5. The use of at least one methine dye as claimed in claim 1 for the bulk coloration of plastics.

6. The use as claimed in claim 5, wherein the plastic is at least one plastic from the series of vinyl polymers, polyesters, polyolefins, polycarbonates and polyamides.

7. The use as claimed in claim 5, wherein the plastic is nylon-6 and/or nylon-6.6.

8. The use as claimed in claim 5, wherein the methine dye is used in an amount from 0.0001 to 1% by weight, especially 0.01 to 0.5% by weight, based on the amount of plastic.

9. A method for the bulk coloration of plastics with the at least one methine dye as claimed in claim 1, the method comprising incorporating the at least one methine dye into at least one plastic.

10. The method for the bulk coloration of plastics according to claim 9, wherein the incorporating comprises one of: melting a plastic material comprising at least one plastic, and adding the at least one methine dye to the molten plastic material to produce a mixture, and homogenizing the mixture; mixing the at least one methine dye in dry form with at least one comminuted plastic to produce a mixture, and melting and homogenizing the mixture; and grinding the at least one methine dye in dry form with at least one plastic to produce a mixture, and melting and homogenizing the mixture.

11. The method for the bulk coloration of plastics according to claim 9, wherein the incorporating comprises: mixing the at least one methine dye with monomeric starting components for preparing the at least one plastic; and subsequently polymerizing the mixture.

12. The method for the bulk coloration of plastics according to claim 11, wherein the plastic is polymethyl methacrylate (PMMA), the starting components comprise at least one methyl methacrylate monomer, and the polymerizing is done in the presence of at least one polymerization catalyst.

13. A plastic composition comprising the at least one methine dye as claimed in claim 1.

14. A molding comprising the at least one plastic composition as claimed in claim 13.

15. A method for preparing the at least one methine dye as claimed in claim 1, the method comprising contacting at least one aldehyde of the formula (II) ##STR00020## where R.sup.1 is hydrogen, halogen, COOH or COOR.sup.7, R.sup.4 is alkyl or phenyl, R.sup.5 and R.sup.6 are each independently alkyl, and R.sup.7 is alkyl, with at least one phenylacetonitrile derivative of the formula (III) ##STR00021## where R.sup.2 is hydrogen, halogen, CF.sub.3, or CN, R.sup.3 is hydrogen, halogen, COOR.sup.8 or CN, and R.sup.8 is alkyl.

16. An aldehyde of the formula (II) ##STR00022## where R.sup.1 is hydrogen, halogen, COOH or COOR.sup.7, R.sup.4 is alkyl or phenyl, R.sup.5 and R.sup.6 are each independently alkyl, and R.sup.7 is alkyl.

Description

1) PREPARATION OF THE INVENTIVE COMPOUNDS OF THE FORMULA (I)

Example 1

[0069] Preparation of the Compound According to the Invention

##STR00007## [0070] where R.sup.1=—COOCH.sub.3, R.sup.2 and R.sup.3=Cl, R.sup.4=—CH.sub.3 and R.sup.5 and R.sup.6=—CH.sub.3

[0071] In a charge of 100 ml of methanol, 25.9 g (=0.1 mol) of aldehyde of the formula (II), where R.sup.1=—COOCH.sub.3, R.sup.4=—CH.sub.3 and R.sup.5 and R.sup.6=—CH.sub.3, and 18.6 g (=0.1 mol) of 3,4-dichlorophenylacetonitrile were introduced. Subsequently, the pH was adjusted to around 10 with ca. 1 g of a 50% aqueous potassium hydroxide solution and the reactor contents were heated to a temperature of 60° C. and then stirred for ca. 6 hours. The mixture was then cooled to 25° C. and the reaction product isolated on a Nutsche filter. The filter cake was washed with ca. 50 ml of methanol and ca. 500 ml of water at a temperature of 90° C. The washed product was dried in a vacuum drying cabinet at a temperature of 80° C. and a pressure of 200 mbar.

[0072] Yield: 32.5 g (corresponds to 76% of theory), melting point 241° C.

Example 2

[0073] Preparation of the Compound According to the Invention

##STR00008##

where R.sup.1=—COOCH.sub.3, R.sup.2=H, R.sup.3=Cl, R.sup.4=—CH.sub.3 and R.sup.5 and R.sup.6=—CH.sub.3

[0074] In a charge of 100 ml of methanol, 25.9 g (=0.1 mol) of aldehyde of the formula (II), where R.sup.1=—COOCH.sub.3, R.sup.4=—CH.sub.3 and R.sup.5 and R.sup.6=—CH.sub.3, and 15.2 g (=0.1 mol) of 4-chlorophenylacetonitrile were introduced. Subsequently, the pH was adjusted to around 10 with ca. 1 g of a 50% aqueous potassium hydroxide solution and the reactor contents were heated to a temperature of 60° C. and then stirred for ca. 6 hours. The mixture was then cooled to 25° C. and the reaction product isolated on a Nutsche filter. The filter cake was washed with ca. 50 ml of methanol and ca. 500 ml of water (T=90° C.). The washed product was dried in a vacuum drying cabinet at a temperature of 80° C. and a pressure of 200 mbar.

[0075] Yield: 31.0 g (corresponds to 79% of theory), melting point 199° C.

Example 3

[0076] Preparation of the Compound According to the Invention

##STR00009##

where R.sup.1=—COOCH.sub.3, R.sup.2=Cl, R.sup.3=H, R.sup.4=—CH.sub.3 and R.sup.5 and R.sup.6=—CH.sub.3

[0077] In a charge of 100 ml of methanol, 25.9 g (=0.1 mol) of aldehyde of the formula (II), where R.sup.1=—COOCH.sub.3, R.sup.4=—CH.sub.3 and R.sup.5 and R.sup.6=—CH.sub.3, and 15.2 g (=0.1 mol) of 3-chlorophenylacetonitrile were introduced. Subsequently, the pH was adjusted to around 10 with ca. 1 g of a 50% aqueous potassium hydroxide solution and the reactor contents were heated to a temperature of 60° C. and then stirred for ca. 6 hours. The mixture was then cooled to 25° C. and the reaction product isolated on a Nutsche filter. The filter cake was washed with ca. 50 ml of methanol and ca. 500 ml of water (T=90° C.). The washed product was dried in a vacuum drying cabinet at a temperature of 80° C. and a pressure of 200 mbar.

[0078] Yield: 29.5 g (corresponds to 75% of theory), melting point 130° C.

Example 4

[0079] Preparation of the Compound According to the Invention

##STR00010##

where R.sup.1=—COOCH.sub.3, R.sup.2=H, R.sup.3=—COOCH.sub.3, R.sup.4=—CH.sub.3 and R.sup.5 and R.sup.6=—CH.sub.3

[0080] In a charge of 200 ml of methanol, 25.9 g (=0.1 mol) of aldehyde of the formula (II), where R.sup.1=—COOCH.sub.3, R.sup.4=—CH.sub.3 and R.sup.5 and R.sup.6=—CH.sub.3, and 17.5 g (=0.1 mol) of methyl 4-(cyanomethyl)benzoate were introduced. Subsequently, the pH was adjusted to around 10 with ca. 1 g of a 50% aqueous potassium hydroxide solution and the reactor contents were heated to a temperature of 60° C. and then stirred for ca. 6 hours. The mixture was then cooled to 25° C. and the reaction product isolated on a Nutsche filter. The filter cake was washed with ca. 50 ml of methanol and ca. 500 ml of water (T=90° C.). The washed product was dried in a vacuum drying cabinet at a temperature of 80° C. and a pressure of 200 mbar.

[0081] Yield: 31.2 g (corresponds to 75% of theory), melting point 246° C.

Example 5

[0082] Preparation of the Compound According to the Invention

##STR00011##

where R.sup.1=—COOCH.sub.3, R.sup.2=H, R.sup.3=CN, R.sup.4=—CH.sub.3 and R.sup.5 and R.sup.6=—CH.sub.3

[0083] In a charge of 200 ml of methanol, 25.9 g (=0.1 mol) of aldehyde of the formula (II), where R.sup.1=—COOCH.sub.3, R.sup.4=—CH.sub.3 and R.sup.5 and R.sup.6=—CH.sub.3, and 14.2 g (=0.1 mol) of 4-cyanophenylacetonitrile were introduced. Subsequently, the pH was adjusted to around 10 with ca. 1 g of a 50% aqueous potassium hydroxide solution and the reactor contents were heated to a temperature of 60° C. and then stirred for ca. 6 hours. The mixture was then cooled to 25° C. and the reaction product isolated on a Nutsche filter. The filter cake was washed with ca. 50 ml of methanol and ca. 500 ml of water (T=90° C.). The washed product was dried in a vacuum drying cabinet at a temperature of 80° C. and a pressure of 200 mbar.

[0084] Yield: 26.8 g (corresponds to 70% of theory), melting point 269° C.

Example 6

[0085] Preparation of the Compound According to the Invention

##STR00012##

where R.sup.1=—COOCH.sub.3, R.sup.2=F, R.sup.3=H, R.sup.4=—CH.sub.3 and R.sup.5 and R.sup.6=—CH.sub.3

[0086] In a charge of 200 ml of methanol, 25.9 g (=0.1 mol) of aldehyde of the formula (II), where R.sup.1=—COOCH.sub.3, R.sup.4=—CH.sub.3 and R.sup.5 and R.sup.6=—CH.sub.3, and 13.5 g (=0.1 mol) of 3-fluorophenylacetonitrile were introduced. Subsequently, the pH was adjusted to around 10 with ca. 1 g of a 50% aqueous potassium hydroxide solution and the reactor contents were heated to a temperature of 60° C. and then stirred for ca. 6 hours. The mixture was then cooled to 25° C. and the reaction product isolated on a Nutsche filter. The filter cake was washed with ca. 50 ml of methanol and ca. 500 ml of water (T=90° C.). The washed product was dried in a vacuum drying cabinet at a temperature of 80° C. and a pressure of 200 mbar.

[0087] Yield: 24.5 g (corresponds to 65% of theory), melting point 311° C.

Example 7

[0088] Preparation of the Compound According to the Invention

##STR00013##

where R.sup.1=—COOCH.sub.3, R.sup.2=CF.sub.3, R.sup.3=H, R.sup.4=—CH.sub.3 and R.sup.5 and R.sup.6=—CH.sub.3

[0089] In a charge of 200 ml of methanol, 25.9 g (=0.1 mol) of aldehyde of the formula (II), where R.sup.1=—COOCH.sub.3, R.sup.4=—CH.sub.3 and R.sup.5 and R.sup.6=—CH.sub.3, and 13.5 g (=0.1 mol) of 3-(trifluoromethyl)phenylacetonitrile were introduced. Subsequently, the pH was adjusted to around 10 with ca. 1 g of a 50% aqueous potassium hydroxide solution and the reactor contents were heated to a temperature of 60° C. and then stirred for ca. 6 hours. The mixture was then cooled to 25° C. and the reaction product isolated on a Nutsche filter. The filter cake was washed with ca. 50 ml of methanol and ca. 500 ml of water (T=90° C.). The washed product was dried in a vacuum drying cabinet at a temperature of 80° C. and a pressure of 200 mbar.

[0090] Yield: 24.5 g (corresponds to 65% of theory), melting point 199° C.

Example 8

[0091] Preparation of the Compound According to the Invention

##STR00014##

where R.sup.1=—Cl, R.sup.2 and R.sup.3=C, R.sup.4=—CH.sub.3 and R.sup.5 and R.sup.6=—CH.sub.3

[0092] In a charge of 200 ml of methanol, 11.8 g (=0.05 mol) of aldehyde of the formula (II), where R.sup.1=—Cl, R.sup.4=—CH.sub.3 and R.sup.5 and R.sup.6=—CH.sub.3, and 9.3 g (=0.05 mol) of 3,4-dichlorophenylacetonitrile were introduced. Subsequently, the pH was adjusted to around 10 with ca. 1 g of a 50% aqueous potassium hydroxide solution and the reactor contents were heated to a temperature of 60° C. and then stirred for ca. 6 hours. The mixture was then cooled to 25° C. and the reaction product isolated on a Nutsche filter. The filter cake was washed with ca. 50 ml of methanol and ca. 500 ml of water (T=90° C.). The washed product was dried in a vacuum drying cabinet at a temperature of 80° C. and a pressure of 200 mbar.

[0093] Yield: 18.2 g (corresponds to 90% of theory), melting point 239° C.

Example 9

[0094] Preparation of the Compound According to the Invention

##STR00015##

where R.sup.1=—F, R.sup.2 and R.sup.3=Cl, R.sup.4=—CH.sub.3 and R.sup.5 and R.sup.6=—CH.sub.3

[0095] In a charge of 200 ml of methanol, 11.0 g (=0.05 mol) of aldehyde of the formula (II), where R.sup.1=—F, R.sup.4=—CH.sub.3 and R.sup.5 and R.sup.6=—CH.sub.3, and 9.3 g (=0.05 mol) of 3,4-dichlorophenylacetonitrile were introduced. Subsequently, the pH was adjusted to around 10 with ca. 1 g of a 50% aqueous potassium hydroxide solution and the reactor contents were heated to a temperature of 60° C. and then stirred for ca. 6 hours. The mixture was then cooled to 25° C. and the reaction product isolated on a Nutsche filter. The filter cake was washed with ca. 50 ml of methanol and ca. 500 ml of water (T=90° C.). The washed product was dried in a vacuum drying cabinet at a temperature of 80° C. and a pressure of 200 mbar.

[0096] Yield: 13.6 g (corresponds to 70% of theory), melting point 238° C.

2) PREPARATION OF THE PRECURSORS

Example 10

[0097] Preparation of an Aldehyde of the Formula (II)

##STR00016##

where R.sup.1=—COOCH.sub.3, R.sup.4=—CH.sub.3 and R.sup.5 and R.sup.6=—CH.sub.3 [0098] a) Preparation of the Diazotization:

[0099] In a charge of 270 g of 30% hydrochloric acid, 139.9 g of p-aminobenzoic acid were introduced and the mixture was cooled to 0° C. by externally cooling. Subsequently, ca. 174 g of a 40% aqueous solution of sodium nitrite were added. After stirring for ca. 30 minutes, the nitrite excess was removed with ca. 0.5 g of amidosulfonic acid.

[0100] b) Preparation of the Hydrazone and Ring Closure:

[0101] In a charge of 250 g of water and 660 g of 39% sodium hydrogen sulfite, the pH was adjusted to ca. 6.5 with ca. 80 g of a 40% aqueous sodium hydroxide solution. Over the course of ca. 30 min, the diazotization solution described above was transferred while maintaining a pH of ca. 6.5 with ca. 100 g of a 40% aqueous sodium hydroxide solution.

[0102] The mixture was then stirred at a temperature of 40° C. for ca. 1 hour. Subsequently, 560 g of sulfuric acid (96%) and then 86.1 g of methyl isopropyl ketone were added dropwise. The reactor contents were heated to 70° C. and then stirred for ca. 4 hours. The reactor contents were subsequently heated to 80° C. and then stirred for ca. 4 hours. The reactor contents were then cooled to 25° C. and the pH was adjusted to ca. 6.5 with ca. 800 g of a 40% aqueous sodium hydroxide solution. After stirring for 30 minutes, the reaction product was isolated on a Nutsche filter and washed with 2 liters of water.

[0103] c) Preparation of the Aldehyde:

[0104] In a charge of 1200 g of water, the water-moist press cake of the ring closure product from stage b) was introduced. The pH was then adjusted to ca. 10 with ca. 70 g of a 40% aqueous sodium hydroxide solution. Over the course of ca. 1 hour, 325 g of dimethyl sulfate were added dropwise maintaining a pH here of ca. 8.5 by addition of ca. 200 g of a 40% aqueous sodium hydroxide solution. The reactor contents were heated to 40° C. and then stirred for ca. 5 hours. The reactor contents were subsequently heated to 60° C. and then stirred for ca. 1 hour. The reaction mixture was allowed to stand for ca. 1 hour until phase separation had occurred. The aqueous phase was then removed. Residual water was removed from the organic phase under reduced pressure at 80° C. and 20 mbar. 310 g of dimethylformamide were then added dropwise to the organic phase. Subsequently, 263 g of phosphorus oxychloride were metered in at 40° C. over the course of 3 hours. The reactor contents were then stirred for 5 hours. The mixture was then cooled to 20° C. and 160 g of methanol were added. The pH was then adjusted to ca. 11 with ca. 200 g of a 40% aqueous sodium hydroxide solution. After stirring for 60 minutes, the reaction product was isolated on a Nutsche filter and washed with 160 g of methanol and 2000 g of water. The washed product was dried in a vacuum drying cabinet at a temperature of 80° C. and a pressure of 200 mbar.

[0105] Yield: 176.3 g (corresponds to 68% of theory)

Example 11

[0106] Preparation of an Aldehyde of the Formula (II)

##STR00017##

where R.sup.1=Cl, R.sup.4=CH.sub.3 and R.sup.5 and R.sup.6=CH.sub.3

[0107] a) Preparation of the Diazotization:

[0108] In a charge of 268 g of 30% hydrochloric acid, 127.6 g of 4-chloroaniline were added dropwise and the mixture was cooled to 0° C. by externally cooling. Subsequently, ca. 174 g of a 40% aqueous solution of sodium nitrite were added. After stirring for ca. 30 minutes, the nitrite excess was removed with ca. 0.5 g of amidosulfonic acid.

[0109] b) Preparation of the Hydrazone and Ring Closure:

[0110] In a charge of 250 g of water and 660 g of 39% sodium hydrogen sulfite, the pH was adjusted to ca. 6.5 with ca. 80 g of a 40% aqueous sodium hydroxide solution. Over the course of ca. 30 minutes, the diazotization solution from stage a) described above was transferred while maintaining a pH of ca. 6.5 by addition of ca. 100 g of a 40% aqueous sodium hydroxide solution. The mixture was then stirred at a temperature of 40° C. for ca. 1 hour. Subsequently, 560 g of sulfuric acid (96%) and then 86.1 g of methyl isopropyl ketone were added dropwise. The reactor contents were heated to 70° C. and then stirred for ca. 4 hours. The reactor contents were subsequently heated to 80° C. and then stirred for ca. 4 hours. The reactor contents were then cooled to 25° C. and the pH was adjusted to ca. 6.5 with ca. 800 g of a 40% aqueous sodium hydroxide solution. After stirring for 30 minutes, the reaction product is isolated on a Nutsche filter and washed with 2 liters of water.

[0111] c) Preparation of the Aldehyde:

[0112] In a charge of 1200 g of water, the water-moist press cake of the ring closure product from stage b) was introduced. The pH was then adjusted to ca. 10 with ca. 5 g of a 40% aqueous sodium hydroxide solution. Over the course of ca. 1 hour, 153 g of dimethyl sulfate were added dropwise maintaining a pH here of ca. 8.5 by addition of ca. 90 g of a 40% aqueous sodium hydroxide solution. The reactor contents were heated to 40° C. and then stirred for ca. 5 hours. The reactor contents are subsequently heated to 60° C. and then stirred for ca. 1 hour.

[0113] The reaction mixture was allowed to stand for ca. 1 hour until phase separation had occurred. The aqueous phase was then removed. Residual water was removed from the organic phase under reduced pressure at 80° C. and 20 mbar. 275 g of dimethylformamide were then added dropwise to the organic phase.

[0114] Subsequently, 116 g of phosphorus oxychloride were metered in at 40° C. over the course of 3 hours. The reactor contents were then stirred for 5 hours, then cooled to 20° C. and 160 g of methanol were added. The pH was then adjusted to ca. 11 with ca. 180 g of a 40% aqueous sodium hydroxide solution. After stirring for 60 minutes, the reaction product was isolated on a Nutsche filter and washed with 160 g of methanol and 2000 g of water. The washed product was dried in a vacuum drying cabinet at a temperature of 80° C. and a pressure of 200 mbar.

[0115] Yield: 141.4 g (corresponds to 60% of theory)

Example 12

[0116] Preparation of an Aldehyde of the Formula (II)

##STR00018##

where R.sup.1=F, R.sup.4=—CH.sub.3 and R.sup.5 and R.sup.6=—CH.sub.3

[0117] a) Preparation of the Diazotization:

[0118] In a charge of 375 g of 30% hydrochloric acid, 155.5 g of 4-fluoroaniline were added dropwise and the mixture was cooled to 0° C. by externally cooling. Subsequently, ca. 244 g of a 40% aqueous solution of sodium nitrite were added. After stirring for ca. 30 minutes, the nitrite excess was removed with ca. 0.5 g of amidosulfonic acid.

[0119] b) Preparation of the Hydrazone and Ring Closure:

[0120] In a charge of 250 g of water and 918 g of sodium hydrogen sulfite solution (39%), the pH was adjusted to ca. 6.5 by the addition of ca. 120 g of a 40% aqueous sodium hydroxide solution. Over the course of ca. 30 minutes, the diazotization solution from stage a) described above was transferred while maintaining a pH of ca. 6.5 by addition of ca. 140 g of a 40% aqueous sodium hydroxide solution. The mixture was then stirred at a temperature of 40° C. for ca. 1 hour. Subsequently, 776 g of 96% sulfuric acid and then 120.4 g of methyl isopropyl ketone were added dropwise. The reactor contents were heated to 70° C. and then stirred for ca. 4 hours. The reactor contents were subsequently heated to 80° C. and then stirred for ca. 4 hours. The reactor contents were then cooled to 25° C. and the pH was adjusted to ca. 6.5 with ca. 1150 g of a 40% aqueous sodium hydroxide solution. After stirring for 30 minutes, the reaction product was isolated on a Nutsche filter and washed with 2 liters of water.

[0121] c) Preparation of the Aldehyde:

[0122] In a charge of 1200 g of water, the water-moist press cake of the ring closure product from stage b) was introduced. The pH was then adjusted to ca. 10 with ca. 10 g of a 40% aqueous sodium hydroxide solution. Over the course of ca. 1 hour, 194 g of dimethyl sulfate were added dropwise maintaining a pH here of ca. 8.5 by addition of ca. 120 g of a 40% aqueous sodium hydroxide solution. The reactor contents were heated to 40° C. and then stirred for ca. 5 hours. The reactor contents were subsequently heated to 60° C. and then stirred for ca. 1 hour. The reaction mixture was allowed to stand for ca. 1 hour until phase separation had occurred. The aqueous phase was then removed. Residual water was removed from the organic phase under reduced pressure at 80° C. and 20 mbar. 350 g of dimethylformamide were then added dropwise to the organic phase. Subsequently, 147 g of phosphorus oxychloride were metered in at 40° C. over the course of 3 hours. The reactor contents were then stirred for 5 hours, then cooled to 20° C. and 160 g of methanol were added. The pH was then adjusted to ca. 11 by addition of ca. 200 g of a 40% aqueous sodium hydroxide solution. After stirring for 60 minutes, the reaction product was isolated on a Nutsche filter and washed with 160 g of methanol and 2000 g of water. The washed product was dried in a vacuum drying cabinet at a temperature of 80° C. and a pressure of 200 mbar.

[0123] Yield: 162.8 g (corresponds to 53% of theory)

List of Substances Purchased:

[0124]

TABLE-US-00001 Molecular Manufac- Name: weight Cas. No. Content: turer: p-Aminobenzoic 137.2 150-13-0 98 Sigma- acid Aldrich Methyl isopropyl 86.1 563-80-4 99 Sigma- ketone Aldrich Isopropyl methyl ketone 4-Chloroaniline 127.6 106-47-8 98 Sigma- Aldrich 4-Fluoroaniline 111.1 371-40-4 99 Alfa Acer 3, 4-Dichlorophe- 186.0 3218-49-3 98 Alfa Acer nylacetonitrile 4-Chlorophenyl- 151.6 140-53-4 98 Alfa Acer acetonitrile 3-Chlorophenyl- 151.6 1529-41-5 99 Alfa Acer acetonitrile Methyl 4-(cyano- 175.2 76469-88-0 96 Sigma- methyl)benzoate Aldrich 4-Cyanophenyl- 142.2 876-31-3 97 Alfa Acer acetonitrile 3-Fluorophenyl- 135.1 501-00-8 98 Alfa Acer acetonitrile 10036-43-8 3-(Trifluorometh- 185.2 2338-76-3 97 Sigma- yl)phenylacetonitrile Aldrich

[0125] The results of the UV/VIS measurements and absorption values for the inventive compounds of Examples 1 to 9 are listed in Table 1.

TABLE-US-00002 TABLE 1 Absorption maximum E 1/1 Compound of UV/VIS spectrum.sup.1) value.sup.2) Example 1 427 nm 2498 Example 2 419 nm 1926 Example 3 425 nm 1402 Example 4 440 nm 1326 Example 5 445 nm 1464 Example 6 419 nm 1141 Example 7 422 nm 1128 Example 8 430 nm 1230 Example 9 428 nm 1156 .sup.1)The UV/VIS absorption spectra of the inventive compounds were all measured in the solvent 1-methoxy-2-propyl acetate (CAS No. 108-65-6). .sup.2)The E1/1 value specified is a hypothetical absorption value which would be obtained if a 1 percent solution by weight of the respective compound (dissolved in 1-methoxy-2-propyl acetate) were to be measured in a cuvette with a 1 cm path length.

3) PRACTICAL RESULTS

[0126] A) Description of the “Thermostability” Test Method

[0127] In a tumbling mixer, 2 g each of the dye to be tested were mixed with 1998 g of a PA6 granulate of the Durethan B30S type (commercial product from Lanxess Deutschland GmbH) with 1% TiO2 which had been dried at 80° C. for 4 hours. This mixture was extruded at a material temperature of at most 240° C. in a single-screw extruder (Stork, 25 mm screw), cooled with water, granulated using a granulator from Sheer and dried at 80° C. for 8 hours. The heat stability of the resulting plastic granules was tested according to DIN EN 12877-2 (“Determination of colour stability to heat during processing of colouring materials in plastics”) (method A) on an injection molding machine. A sample as standard was prepared at 240° C. with a residence time in the screw of 2.5 minutes. Compared to this standard sample, the samples to be determined were evaluated coloristically, which were prepared at a residence time of 5 minutes and temperatures of 240-320° C. Samples with an overall color difference of dE≦3.0 were evaluated as stable at the applied temperature.

[0128] The results of the thermostability determination of the inventive compounds of Examples 1 to 9 and also the non-inventive compounds of the prior art are listed in Table 2.

TABLE-US-00003 TABLE 2 Inventive compound Heat stable to (° C.) Example 1 300 Example 2 320 Example 3 320 Example 4 280 Example 5 260 Example 6 300 Example 7 280 Example 8 320 Example 9 320

Non-Inventive Comparative Compounds

[0129]

TABLE-US-00004 D.Y 201 (Macrolex Yellow 6G) Decolorization at 240° C. S.Y. 93 (Macrolex Yellow 3G) Decolorization at 240° C. S.Y 114 (Macrolex Yellow G) 240° C. S.Y 160:1 (Macrolex Fluor. <240° C. (dE 3.6 at 240° C.) Yellow 10GN)