CA1307273C - Chromogenic substituted 4,7-diazaphthalides - Google Patents

Abstract

Abstract The invention relates to novel substituted 4,7-diazaphthalides of the general formula wherein X and Y each independently of the other, are optionally substituted aminophenyl, indolyl, benzoindolyl, jujolidinyl or kairolyl radicals; and R1 and R2, each independently of the other, are hydrogen, lower alkyl or optionally substituted phenyl, provided that both R1 and R2 are not hydrogen.
These compounds are particularly suitable for use as color formers in pressure-sensitive or heat-sensitive recording materials.

Description

~3~ 73 Chromogenic Substituted 4,7-diazaphthalides The present invention relates to chromogenic substituted 4,7-diazaphthalides, to the preparation thereoE and to the use thereoE as color formers in pressure-sensitive or heat-sensitive recording materials.
The substituted 4,7-diazaphthalides have the general formula X~ ~ Y
C O

i~

wherein X and Y, each independently of the other, are optionally substituted aminophenyl, indolyl, benzoindolyl, julolidinyl or kairolyl radicals; and Rl and R2, each independently of the other, are hydrogen, lower 0 alkyl or optionally substituted phenyl, provided that both Rl and R2 are not hydrogen.
U.S. Patent Nos. 3,775,424 and 3,853,869 and Japanese Publication Nos.
48-3204 and 48-3205 describe 4,7-diazaphthalide compounds.

3~3~ 7~3 ~ olorable novel chromogenic substituted ~,7-diazaphthalide eompounds have been discovered. These compounds are initially substantially eolorless but produce colored products on reaction with certain aeidie developer materials. It is an object of this invention to provide such substituted 4,7-diazaphthalide compounds, methods for making them and mark-forming record systems containing them.
It is another object of this invention to provide ehromogenie eompounds whieh are substantially unreaetive to base paper.
It is yet another objeet of this invention to provide chromogenic 0 compounds whieh produce substantially no premature eoloration during the process of microencapsulating a eomposition containlng said ehromogenic compound.
It is still another object of this invention to provide ehromogenic compounds which possess an improved lightfastness of their eolored form.
U.S. Patent Nos. 3,775,424 and 3,853,B69, diselose eertain 4,7-diazaphthalide (pyrazine~ eompounds whieh have utility as color formers in pressure-sensitive and heat-sensitive recording systems. These compounds do, however, have the disadvantage that they are too sensitive in their color-forming function. This exeess sensitivity of the compounds results in inadvertent coloration when the compounds come in contact with the base paper upon which pressure-sensitive or heat-sensitive compositions are eoated. The e~cess sensitivity also results in premature coloration when a composition eontaining the compound is microencapsulated. The eompounds of the present invention, surprisingly, have the ability to produce intense coloration when brought into eontaet with acidie developer materials but produee substantially no eolor when a composition containing same is mieroencapsulated or is brought into contaet with paper base stock.

,~'' Important groups of colorable chromogenic compounds of the present invention may be defined by the formula X~ ~Y
C o N/~ C-O
R~N

wherein X and Y, each independently of the other, are optionally substituted aminophenyl, indolyl, benzoindolyl, julolidinyl or kairolyl radicals; and Rl an~ R2, each independently of the other, are hydrogen, lower alkyl or optionally substituted phenyl, provided that both Rl and R2 are nothydrogen.
Among the more important compounds of this invention are the ones defined by the formula ~Y
C - o N~C=O

Rl~

wherein X and Y, each independently of the other, are A-~ ~ R ~ R8 R

R
A is -N 3 or -N
4 ~
Rl ano R2, each independently of the other, are hydrogen, lower alkyl or phenyl, provided that both Rl and R2 are not hydrogen;
R3 and R4, each independently of the other, are Cl-C8 alkyl, cyclohexyl, phenyl, or phenyl substituted by lower alkyl or lower alkoxy;
R5 is hydrogen or Cl-C8 alkoxy;
R6 is Cl-C8 alkyl or cyclohexyl;
R7 is lower alkyl; and R8 is hydrogen or lower alkyl.
In the context of the present invention lower alkyl are those alkyl groups containing one through :Eour carbon atoms and lower alkoxy are those alkoxy groups containing one through four carbon atoms.
The more preferred among the compounds of this invention are the ones represented by the following formula X~ ,Y
C - o ~ j wherein X and Y, each independently of the other, are R~

~3~
,R
A iS -N or -N
4 ~
Rl and R2, each independently oE the other, are hyd~ogen or lower alkyl, provided that both Rl and R2 are not hydrogen;
R3 an~ R4, each independently of the other, are Cl-C8 alkyl, 5 cyclohexyl, phenyl or phenyl substituted by lower alkyl or lower alkoxy;
R5 is hydrogen or lower alkoxy;
R6 is Cl-C~ alkyl;
R7 is lower alkyl; and R8 is hydrogen or lower alkyl.
Most preferred among the compounds of this invention are those represented by the formula R3~ R5 N~
N~ R6 1`~' N
CH3 1~

wherein R3 and R4, each independently of the other, are Cl-C8 alkyl, cyc~ohexyl, phenyl, or phenyl substituted by lower alkyl or lower alkoxy;
R5 is lower alkoxy;

R7 is lower alkyl.
One process for the preparation of the compounds of the present invention, hereinafter referred to as process I, consists of the following series of reaction wherein Rl, R2, R3, R4, R5~ R6, R7 and R8 have the given meanings.

:~3~
The first step consists of oxidizing substituted quinoxaline to substituted pyrazine-2,3-dicarboxylic acid accordiny to the follo~ing process.

Xo~ KMnO4 ~ X NOX

The resulting dicar~oxylic acid is converted to the anhydride by heating ~ith acetic anhydride.

~7~273 The resulting ar,nydride can then be conclensed with an indole to give a keto-acid intermediate R2 1 ~ R ~ ~ ~

Rl J~2, The final chromogenic compound is then obtained by condensation of the keto-acid with the appropriate amine.

~ T + ~ ~

N ( ~ COOH

Rz R3` ~--~R5 R~C=O R6 The pLeceding steps have exempliiied the process to make \C/--O
~CI-O
Rl~ ' wherein X is an optionally substituted aminophenyl radical and Y is an optionally substituted indolyl radical.
The process in its broadest sense involves condensing the anhydride with the appropriate X compound to produce the keto-acid intermediate l Xx + X Tol uene >
N G~ COOH
Rl~fN

which is then condensed with the appropriate Y compound to form the final chromogenic compound X- -o x 1~ Y

R~ Y -- ~ ~ C=O

wherein X, Y, Rl and R2 have the given meanings.

An alternative process for ttle compounds of the present invention, hereinafter referred to as process II, consists of the following series of reactions wherein Rl and R2 have the given meanings.
The first step in process II consists of reacting diaminomaleonitrile with the appropriate c~-ketoaldehyde or C~ ,~ -diketone to produce a dinitrile.
C O C ~ R XN X Cl1 The resulting dinitrile is then hydrolyzed to the substituted pyrazine 2,3-dicarboxylic acid.
R1 N CN 1~ N COOH
`~ hYdr( lYZe ~ ~ ~
R2 N1 CN ~ R ~J ~COOH

Once the proper substituted pyrazine 2,3-dicarboxylic acid is obtained, the remainder of the steps in process I are followed, resulting in the appropriate chromogenic compound.
The following is provided as a detailed example of the production of a chromogenic compound of the present invention by process I.

Example 1 Preparation of 5,6-dimethylpyrazine-2,3-dicarboxylic acid.
~ solution of 24 g. (~.152 mole) of 2,3-dimethylquinoxaline in 1150 ml.
of water was heated to 80 C. Good stirring was maintained while 150 g.
(0.95 mole) of potassium permanganate was added in approximately 4 9.
portions over a 2.5 hour period. The temperature was held at 8U-85 C
during this addition. The reaction mixture was heated one additional hour at 90C .
The manganese dioxide was removed by filtration (hot) and washed several times with 25 ml. portions of hot water.
The filtrate was evaporated to approximately one half volume under reduced pressure. The aqueous solution was treated with 75 ml. of 37%
hydrochloric acid. Evaporation was continued to a volume oE 200 ml. On cooling there was obtained 23 9. (77%) of desired product, mp. 187-188 C.
Preparation of 5,6-dimethylpyrazine-2,3-dicarboxylic anhydride.
A mixture of 23 g. (0.117 mole) of 5,6-dimethylpyrazine-2,3-dicarboxylic acid and 80 ml. of acetic anhydride was heated for 5 hours at 90 C. The hot reaction mixture was filtered to remove some insoluble material.
The filtrate was evaporated under reduced pressure until precipitation started. The mixture was cooled, filtered and the solid washed with hexane.
20 The yield of anhydride was 11.8 g. (61~), mp. 170-171 C. Infrared showed anhydride carbonyl peaks at 1792 nm. and 1734 nm. No free acid peaks were present.
Preparation of (l-ethyl-2-methylindol-3-yl)(2-carboxyl-5,6-dimethylpyrazin-3-yl)ketone.
To a solution of 12.72 g. (0.08 mole) of 1-ethyl-2-methylindole in 90 ml. of toluene and 10 ml. of acetonitrile was added 11.8 g. (0.073 mole) of 5,6-dimethylpyrazine-2,3-dicarboxylic anhydride. The reaction was run 20 hours at 55C.
The reaction solution was added to 300 ml. of water containing ~ g. of sodium hydroxide. The toluene and aqueous layers were separated and the aqueous layer extracted twice more with 50 ml. portions of toluene.

:~L3~ 3 The aqueo-ls layer, on acid~fication with hydrochloric acid, yielded 14.~8 g. (67%) of tne desired keto-acid, mp. 142-144 C. Infrared showedacid carbonyl at 1742 nm. and ketone carbonyl at 1626 nm. The mass spectrum oi the keto-aci~ (mw 337) gave a parent peak of m/z, 337 and base peak of m/z, 292 (tacile loss of CO2H).
Preparation of 5-(1-ethyl-2-methylindol-3-yl)-5-(4-diethylamino-2-ethoxyphenyl)-5,7-dihydrofu roL3,4-b1-2,3-dimethylE,yrizin-7-one.
A mixture of 4.04 9. (0.012 mole) of 10(1-ethyl-2-methylindol-3-yl)(2-carboxy-5,6-dimethylpyrazin-3-yl)ketone, 2.31 g. (0.012 mole) of N,N-diethylamino-m-phenetidine and 25 ml. of acetic anhydride was heated three hours at 55-60C.
'l'he reaction solution was slowly dropped into 200 ml. of water containig 22.5 g. oL sodium hydroxide. Atter one hour stirring at 45 C the solid was filtred, washed well with water and finally with hexane.
The crude product (5.3 g.) was purified by two treatments, one with 15 ml. and one with 10 ml. of methyl alcohol. In each treatment the slurry was heated to reflux, cooled and filtered. The yield of purified color former was 4.17 g. (68~), mp. 179-180 C. The infrared lactone carbonyl peak was 20found at 1772 nm. The mass spectrum of the dye (mw 512) gave a parent peak of m/z, 512.
The chromogenic compounds of this invention are eligible for use in pressure-sensitive and thermally-sensitive mark-forming systems.
Pressure-sensitiVe mark-forming systems provide a marking system of disposing on and/or within sheet support material unreacted mark-forming components and a liquid solvent in which one or both of the mark-forming components is soluble, said liquid solvent being present in such form that it is maintained isolated by a pressure-rupturable barrier from at least one of the mark-forming components until application of pressure causes a breach of the barrier in the area delineated by the pressure pattern. The mark-forming components are thereby brought into reactive contact, producing a distir.ctive mark. In such pressure-sensitive mark-forming systems the chromogenic compounds of this invention will typically be used in r ~7 ~

com~irldtlon with other chromogenic compounds which individually produce marks of different colors so that in combination the reaction between the chromogenic materials and the acidic color developer material produce a mark having a black perceived image. This black mark-forming system constitutes a specific subsidiary feature of the invention.
The pressure-rupturable barrier, which maintains the mark-forming components in isolation, preferably comprises microcapsules containing liquid solvent solution. The microencapsulation process utilized can be chosen from the many known in the art. ~ell known methods are disclosed in U.S. Patent Nos. 2,800,457; 3,041,29; 3,533,958, 3,755,190; 4,001,140 and 4,100,1U3. Any of these and other methods are suitable for encapsulating the liquid solvent containing the chromogenic compounds of this invention.
The method of marking comprises providing a chromogenic compound of the present invention and bringing such chromogenic compound into reactive contact, in areas where marking is desired, with an acidic color developer material to produce a colored form of the chromogenic compound.
The acidic materials can be any compound within the definition of a l.ewis acid, i.e. an electron acceptor. These material include clay substances such as attapulgite, bentonite and montmorillonite and treated clays such as silton clay as disclosed in U.S. Patent Nos. 3,622,364 and 3,753,761, materials such as silica gel, talc, feldspar, magnesium trisilicate, pyrophyllite, zinc sulfate, zinc sulfide, calcium sulfate, calcium citrate, calcium phosphate, calcium fluoride and barium sulfate, aromatic carboxylic acids such as salicyclic acid, derivatives of aromatic carboxylic acids and metal salts thereof as disclosed in U.S. Patent No.

4,022,936, acidic polymeric material such as phenol-formaldehyde polymers, phenol-acetylene polymers, maleic acid-rosin resins, partially or wholly hydrolyzed styrene-maleic anhydride copolymers and ethylene-maleic anhydride copolymers, carboxy polymethylene and wholly or partially hydrolyzed vinyl methyl ether maleic anhydride copolymers and mixtures thereof as disclosed in U.S. Patent No. 3,672,935, biphenols as disclosed in U.S. Patent No.
3,244,550 and addition products of a phenol and a diolefinic alkylated or alkenylated cyclic hydrocarbon as disclosed in U.S. Patent No. 4,573,063.

:~3~
Particularly useful as acldic color developer substances are the metal-modified phenolic resins. Record sheet material coated with such resins is disclosed in U.S. Patent No. 3,732,120. An example of the compositions which can be coated onto the surface oE a sheet to react with the chromogenic compounds of this invention is listed below in Table 1.

Table 1 _ Coating Composition Zinc-modified phenolic polymer 13.6 Paper coating kaolin 67.9 o Calcium carbonate 6.0 Styrene-butadiene latex 6.0 Etherified corn starch 6.5 Thermally-sensitive mark-forming systems are well known in the art and are described in many patents, for example U.S. Patent Nos. 3,539,375;
3,674,535, 3,746,675; 4,151,748; 4,181,771 and 4,246,318. In these systems basic chromogenic material and acidic color developer material are contained in a coating on a substrate which, when heated to a suitable temperature, melts or softens to permit said materials to react, thereby producing a colored mark.
The following examples are given merely as illustrative of the present invention and are not to be considered as limiting.
The intermediates required for the preparation of the novel chromogenic compounds of this invention are classes of compounds readily obtained by procedures well known in the prior art~
Using either process I or process II, supra, the Examples represented by the structures listed in Table 2, based upon the following general formula, were prepared by the corresponding process listed.

X~ ,Y
C - o N~--C=O
R ~N

~3~ 3 _c~ble 2 Ex.
No. 2 5 Rl- R2_ Process ( 2 5)2 ~ CH3 ~ -CH3 -C33 OC2~15 C2H5 2- (C2H5)2N~ CH3 -C~13 -CH3 II

( 2 5)2 ~ ~ 12 ~ 2H5CH3 -CH3 II

4. (C2H5)2N ~ 2H5 ( 2 5 2 ~ -CH -CH3 II

5. (C2H5)2N ~ ~ ~; ~ ~ -C~3 -CH3 II

C2~15 6. ~ N ~2H5 C~ -CH3 -CH3 I & II

p )~ J ~ 3 Ta~le 2 (cont.) Ex.
No. X Y - 1-R2- Proce~

7- ~ N ~ CH3 -CH3 II

8 . ~ 1 6 ~2 5 ~ 3 3 II

~2H5 9 4 ~ 12 ~ 2 ~ ~-CH3 -CH3 Il a CH3 o ~H~ C~13 -C~13 12. ~ C2H~2 5 ~ -CH3 -CH3 II

~3~ 7~

r~lable 2 (cont. ) ~x .
No. X Y Rl-- --2-- Process C ~ , C ~ 3 3 I I

C2H5 C2~15 5 l 4 . ~,~ C; ~ 3 3 I I
C8H17 C8~117 2 5 2 ~ C H 3~ - C H 3 - C H 3 I I

16 . ( C 2H 5 ) 2N~2 5 ~ -CH 3 -C 2H 5 I I

17. ~C2H~C2H5 ~ -CH -C H II

1~. ~ C2H~ C; ~ 3 3 b ~3~

T~ble 2 (cont. ) Ex .
No. X _ Y Rl_ R2-- Process CH3~ ~ CH -C H Il C2~15 C2H5 ,OC2H5 5 2U . (C2H5 )2N~ ~ 2 5 2 5 II

21. ~ 1 2 _~ CH3~;~ 2 5 2 5 II

22 . (C2H5 )2N~ CH~ -H ~ II

23 . HgC4~ N ~ 3 1 -H ~ I I

C4Hg C2H
-H ~> II

~3~`73 Table 2 (con-t.) Ex.

No X Y R R Process _ _ ~ 2 25. (C2H5)2~ H -C33 II

26. (C2H5) 2N~ Cl'~ CH3 ~ II

27. ~ C ~ CH~ ~\ -H CH3 II

Reference (C2Hs)2N ~ ~ -H -H

Compound* CH3 The compounds of Examples 16, 17, 19, 22, 23, 24, 25, 26 and 27 were actually mixtures of the isomers (1) wherein the substituen-ts for Rl and R2 are as indicated and (2) wherein the subs-tituents for Rl and R2 are reversed from what is indicated.

*See Example III of U.S. Patent No. 3,853,869 to Farber.

~ Lable 3 ar~ l~sted, fot each Example of Table 2, the respective melting point, molecular weight as determined by mass spectrometry, color developed when applied to a metal-modified pheno]ic resin color developer composition as disclosed in Table l, amount of color developed in a test designed to simulate coloration on base paper and amount of color developed in a test designed to simulate microencapsultion conditions.
The test designed to simulate coloration on base paper consisted of the preparation of a 2.06 x lO molar solution oE each Example compound in toluene, the application of a 0.02 ml. portion of thAe resulting solution to ~Y eVC~,p~ r~,G ~
0 Whatman'~#l filter paper, and, after e~pe~r-a-i~r-~- of the toluenel the measurement of the amount of color development on the filter paper reported as the ratio of the reflectance of the colored area to that background reflectance of the filter paper (I/Io). The greater the numerical value of this ratio, the lower the quantity of color produced.
The test designed to simulate color development under microencapsulation conditions consisted of mixing and agitating a 2.0 ml. portion of a 2.06 x molar solution of each Example compound in toluene with 2.0 ml. of water. The water and toluene layers were separated and the absorbance of the water layer was measured at respective visible absorption maximum of the Example compound.

e - r~

-lg-~3~ 3 Table 3 Example Melt~ng Molecular Base Paper Microencapsulation No.Point Weight ColorColor Color 1179-130 C 512 blue 0.72 1.23 2 78- 82 C 596 blue 0.78 0.06 3182-183 C 594 blue-green0.94 0.04 4145-146 C 546 blue-green0.85 0.23 5109-110 C 596 blue 0.71 0.10 6156-158 C 560 blue 0.92 0.27 0 7 85- 88 C 588 blue 0.94 0-05 8171.5-173 C 616 blue 0.95 0.02 9 155-158C 616 blue 0.92 0.02 10210-212 C 510 blue 0.72 1.11 1198-100 C 508 blue 0.94 0.18 1265- 68 C 644 blue 0.78 0.06 13208-210 C 478 red 0.78 3.13 14112-113 C 646 red 0.79 0.10 15112-114 C 540 blue 0.76 0.59 16174-177 C 526 blue 0.76 0.29 17135-138 C 574 blue 0.91 0.18 18197-198 C 614 blue 0.89 0.02 19104-107 C 492 red 0.69 1.53 20167-168.5 C 540 blue 0.64 0.29 21165-168 C 588 blue 0.86 ~ 0.02 22171-174 C 560 blue 0-59 ~0.02 23 92-95C 664 blue 0.84 ~ 0.02 24118-123C 636 blue 0.88 < 0.02 25163-165C 498 blue 0.58 1.48 26118-122C 574 blue 0.54 0.07 2784-87 C 546 blue 0.80 0.07 Reference 175-176 C 484 blue 0.68 1.89 Compound From the àata of Table 3 it is readily apparent that the chromogenic compounds of the present invention possess unexpectedly improved resistance to base stock coloration and/or improved resistance to coloration during microencapsulation compared to compounds disclosed in the prior art.
The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications are intended to be included within the scope of the following claims.

Claims (22)

1. A compound represented by the formula:

wherein X and Y, each independently of the other, are:

or ;

A is or ;

R1 and R2, each independently of the other, are hydro-gen, lower alkyl or phenyl, provided that both R1 and R2 are not hydrogen;
R3 and R4, each independently of the other, are C1-C8 alkyl, cyclohexyl, phenyl or phenyl substituted by lower alkyl or lower alkoxy;
R5 is hydrogen or C1-C8 alkoxy;
R6 is C1-C8 alkyl or cyclohexyl;
R7 is lower alkyl; and R8 is hydrogen or lower alkyl.

2. The compound of claim 1 wherein X is .

3. The compound of claim 2 wherein A is .

4. The compound of claim 3 wherein Y is .

5. The compound of claim 4 wherein:
R6 is C1-C8 alkyl; and R8 is hydrogen.

6. The compound of claim 5 wherein R6 is lower alkyl.

7. The compound of claim 6 wherein:
R6 is ethyl; and R7 is methyl.

8. The compound of claim 7 wherein R1 and R2, each inde-pendently of the other, are lower alkyl.

9. The compound of claim 8 wherein R1 is methyl and R2 is lower alkyl.

10. The compound of claim 9 wherein R1 and R2 are methyl.

11. The compound of claim 10 wherein one of R3 and R4 is cyclohexyl, phenyl or phenyl substituted by lower alkyl and the other of R3 and R4 is C1-C8 alkyl.

12. The compound of claim 11 wherein R3 is phenyl.

13. The compound of claim 12 wherein R4 is butyl.

14. The compound of claim 12 wherein R4 is hexyl.

15. The compound of claim 11 wherein R3 is ethyl.

16. The compound of claim 15 wherein R4 is cyclohexyl.

17. The compound of claims 13, 14 or 16 wherein R5 is lower alkoxy.

18. The compound of claim 17 wherein R5 is lower alkoxy.

19. The compound of claim 18 wherein R5 is ethoxy.

20. A pressure-sensitive or heat-sensitive recording materi-al comprising the compound of claim 1.

21. The recording material of claim 20 wherein the material is pressure-sensitive.

22. The recording material of claim 20 wherein the material is heat-sensitive.