CH652733A5 - METHOD FOR PRODUCING 4-AZAPHTHALIDE COMPOUNDS. - Google Patents

Description

50 The present invention relates to a new process for the preparation of azaphthalide compounds which can be used as color formers in pressure- or heat-sensitive recording materials.

In pressure-sensitive, carbon-free copying systems, an oily solution of the chromogenic dye precursor, such as, for example, crystal violet lactone, benzoylleucomethylene blue, phthalides or fluoranes, is usually isolated in pressure-breakable microcapsules, which can either be present as a layer on a separate transfer sheet, 55 to form a mutually dependent pair of copy sheets or which may be located on the sensitized side of the copy receiving sheet itself to form a self-reactive paper sheet.

In such pressure-sensitive copier systems, mostly violet crystalline lactone [3,3-bis- (4'-dimethylaminophenyl) -6-dimethylaminophthalide] is used as the chromogenic dye precursor. A pressure generated with crystal violet lactone is known to fade very quickly when exposed to light, so that

652 733

constant attempts are made to find a suitable replacement for it.

Good substitute products which give a satisfactory blue print with improved light resistance are azaphthalides which contain an aminophenyl and an indoyl substituent in the 3-position. However, the preparation of these color formers always gives mixtures of isomers of 4- and 7-azaphthalides. Although an improvement in the light fastness and at the same time a reduction in the reactivity decrease (CB decrease) can be achieved with these isomer mixtures, an undesirable discoloration of the microcapsules containing the chromogenic substance usually occurs during the production of pressure-sensitive recording materials, due to the presence of 7-azaphthalide isomer is caused in the isomer mixture.

It has now been found that an isomer-free 4-azaphthalide compound can be obtained by carrying out the reaction of quinolinic anhydride with the indole compound in a specific organic reaction medium and in the presence of a metal salt of a polyvalent metal to produce the isomer-free keto acid required as an intermediate.

The present invention accordingly relates to a process for the preparation of 4-azaphthalide compounds of the formula

The process is characterized in that quinoline anhydride is quenched with an indole compound of the formula

î A 11 II ■ «•

vv

-z

(2),

10th

wherein A, Y and Z have the meaning given, in the presence of an inorganic or organic metal salt of a polyvalent metal in an organic reaction medium consisting of a lower aliphatic monocarboxylic acid 15 or a nitrii of this acid, the reaction product obtained with a compound of the formula

20th

fa

s \ s \ /

î A M fi • • »

^ /

/

vx- \

a / \ 9

CO

(1),

^ /

wherein

Hydrogen, unsubstituted or substituted by halogen, cyano, hydroxyl or lower alkoxy alkyl having at most 12 carbon atoms, acyl having 1 to 12 carbon atoms, benzyl or benzyl substituted by halogen, nitro, lower alkyl or lower alkoxy,

Hydrogen, lower alkyl or phenyl,

X -ORj or preferably -N <

Ri

VR,

H- <> "X V

(3),

25th

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35

40

45

and R2, independently of one another, are each hydrogen, unsubstituted or substituted by halogen, cyano, hydroxyl or lower alkoxy alkyl having at most 12 carbon atoms, cycloalkyl, phenyl, benzyl or phenyl or benzyl substituted by halogen, nitro, cyano, lower alkyl, lower alkoxy or lower alkoxycarbonyl or Rj and R2 together with the nitrogen atom connecting them form a five- or six-membered, preferably saturated, heterocyclic radical,

V is hydrogen, halogen, hydroxy, nitro, lower alkyl or

Mean lower alkoxy and in which ring A is unsubstituted or substituted by halogen, nitro, cyano, lower alkyl, lower alkoxy, lower alkoxycarbonyl, amino, mono-lower alkylamino or di-lower alkylamino.

wherein X and V have the meaning given, condensed further and the resulting reaction mixture has a pH of at least 6.

Lower alkyl and lower alkoxy are generally groups or group components in the definition of the residues of the 4-azaphthalides which have 1 to 5, in particular 1 to 3, carbon atoms, such as e.g. Methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl or amyl or methoxy, ethoxy or isopropoxy.

Acyl is especially formyl, lower alkylcarbonyl, e.g. Acetyl or propionyl, or benzoyl. Further acyl residues can be lower alkylsulfonyl, e.g. Be methylsulfonyl or ethylsulfonyl and phenylsulfonyl. Benzoyl and phenylsulfonyl can be substituted by halogen, methyl, methoxy or ethoxy.

If the substituents Rj, R2 and Y represent alkyl groups, they can be straight-chain or branched alkyl radicals. Examples of such alkyl radicals are methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, amyl, n-hexyl, 2-ethyl-hexyl, n-hep-tyl, n-octyl, isooctyl, n- Nonyl, isononyl or n-dodecyl.

If the alkyl radicals in R 1, R 2 and Y are substituted, it is primarily cyanoalkyl, haloalkyl, hydroxyalkyl, alkoxyalkyl, each preferably having a total of 2 to 4 carbon atoms, such as. B. ß-cyanoethyl, ß-chloroethyl, ß-hydroxyethyl, ß-methoxyethyl or ß-ethoxyethyl.

Examples of cycloalkyl with the meaning of Rx and R2 are cyclopentyl or preferably cyclohexyl.

Preferred substituents in the benzyl group of Rx, R2 and 50 Y and in the phenyl group of Rj and R2 are e.g. Halogens, nitro, methyl or methoxy. Examples of such araliphatic or aromatic radicals are p-methylbenzyl, o- or p-chlorobenzyl, o- or p-nitrobenzyl, o- or p-tolyl, xylyl, o-, m- or p-chlorophenyl, o- or p-nitrophenyl or o- or 55 p-methoxyphenyl.

If the substituents R.! and R2 together with the common nitrogen atom represent a heterocyclic radical, this is, for example, pyrrolidino, piperidino, pipecolino, morpholino, thiomorpholino or piperazino, e.g. B. N-methyl-piperazino. Preferred heterocyclic radicals are pyrrolidino, piperidino or morpholino.

X is preferably the amino group of the formula -NRaR2. V is preferably in the meta position to the substituent X.

The substituents R 1 and R 2 can be different from one another or are preferably identical. Rj and R2 are preferably benzyl or lower alkyl and especially methyl or ethyl.

60

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652 733

V is preferably hydrogen, methyl, methoxy or especially ethoxy.

The N-substituent Y is preferably benzyl, acetyl, propionyl or especially alkyl having 1 to 8 carbon atoms, such as. B. n-octyl, n-butyl, methyl or ethyl. A particularly preferred N substituent Y is ethyl or n-octyl. Z is preferably phenyl or especially methyl.

The benzene ring A is preferably not further substituted or substituted by halogen.

Halogen means for example fluorine, bromine or preferably chlorine.

When carrying out the process according to the invention, the substances involved in the reaction are preferably used in molar amounts.

The preparation of the azaphthalide compounds of the formula (1) is carried out in two stages and continuously in accordance with the so-called one-pot process.

The first stage, in which quinolinic anhydride is reacted with the indole compound of the formula (2) in organic solvents as defined and in the presence of an organic or inorganic metal salt, is expediently carried out at a temperature of 0 to 50 ° C., preferably at room temperature (17 to 30 ° C. ).

The reaction time depends on the temperature and the metal salt and solvent used as catalyst and is generally between 54 and 10 h, preferably 2 and 6 h.

The lower aliphatic monocarboxylic acid used as the reaction medium in the process according to the invention is expediently a carboxylic acid which is liquid under the reaction conditions and which can have 1 to 5 carbon atoms.

Suitable aliphatic monocarboxylic acids which form the reaction medium are formic acid, acetic acid, dichloroacetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid or mixtures of these acids.

Suitable nitriles, which can also be used as reaction medium in the process according to the invention, are, for. B. acetonitrile, propionitrile or butyronitrile.

However, preferred solvents are aliphatic monocarboxylic acids with 2 to 4 carbon atoms, e.g. Butyric acid, isobutyric acid, propionic acid or in particular acetic acid or also mixtures of these carboxylic acids.

The metal salts used according to the invention are advantageously derived from polyvalent metals with an atomic weight of 24 to 210, preferably 26 to 140 and in particular 26 to 120. Examples of such metals are aluminum, barium, lead, cadmium, calcium, chromium, iron, gallium, cobalt, copper, magnesium, manganese, molybdenum, nickel, mercury, strontium, tantalum, titanium, vanadium, tungsten, zinc, tin and zirconium. Aluminum, calcium, cadmium, iron, chromium, cobalt, copper, nickel, manganese, strontium, tin and zinc are preferred. The anionic component of these metal salts is advantageously derived from mineral acids or from organic acids, and z. B. is a sulfate, halide, nitrate, formate, acetate, propionate, citrate or stearate.

A fluoride, iodide, bromide or preferably a chloride and also a pseudohalide such as a rhodanide can be considered as the halide.

The metal salts can be used individually or as mixtures.

Preferred metal salts are sulfates or especially halides of metals from the group comprising aluminum, calcium, iron, cadmium, cobalt, copper, manganese, nickel, tin and zinc, such as, for. B. aluminum chloride, calcium chloride, nickel chloride, cobalt chloride, iron chloride, copper chloride, zinc chloride, tin chloride, tin bromide, manganese chloride, nickel bromide,

Calcium fluoride, cadmium iodide or mixtures thereof. In general, the best results are obtained in the presence of chlorides from aluminum, calcium, cobalt, iron, copper or zinc. Zinc chloride and aluminum chloride are of particular interest. A mixture of calcium chloride and zinc chloride, the mixing ratio preferably being 1: 9 to 2: 1, is also preferred.

The proportion of metal salt in the first reaction stage is advantageously 10 to 100 mol%, preferably 12 to 50 mol%, based on the quinolinic anhydride used.

After the end of the first reaction stage, the reaction product (non-isolated keto acid) is further condensed directly with the compound of the formula (3). This second reaction stage is preferably carried out in such a way that the reaction components are reacted in the presence of an acidic dewatering agent at a temperature of 20 to 80 ° C. Examples of such condensing agents are sulfuric acid, phosphoric acid, phosphorus oxychloride and especially acetic anhydride. When using acetic anhydride, temperatures between 20 and 60 ° C are preferred. The reaction time of the second stage is usually 1 to 4 hours, preferably 54 to 3 hours.

The reaction mixture is finally brought to a pH of at least 6. For this purpose, alkalis such as alkali metal hydroxides, e.g. As sodium or potassium hydroxide, ammonia or alkali metal carbonates or bicarbonates and mixtures of these compounds. A pH of 7 to 11 is preferably set.

The end product of the formula (1) is isolated in a generally known manner by separating off the precipitate formed, washing and drying or by treatment with suitable organic solvents, such as e.g. Methanol or isopropanol and optionally recrystallization of the product.

If ORj and / or V each represent hydroxyl in the reaction product of the formula (1), the hydroxyl group can subsequently be alkylated or aralky-lated in accordance with the definition of Rt and V.

The alkylation or aralkylation of the reaction products in which V and / or ORi is hydroxyl is generally carried out by known processes. For example, the reaction is carried out in the presence of an acid binding agent such as e.g. an alkali carbonate or a tertiary nitrogen base, such as triethylamine and optionally in the presence of an inert organic solvent, such as. B. acetone, isopropyl alcohol, chlorobenzene or nitrobenzene.

Suitable alkylating agents are alkyl halides, such as. B. methyl or ethyl iodide or chloride, or dialkyl sulfates, such as. B. dimethyl or diethyl sulfate. Particularly suitable aralkylating agents are benzyl chloride and the corresponding substitution products, such as. B. p-chlorobenzyl chloride or 2,4-dimethylbenzyl chloride, which is preferably in a non-polar, organic solvent, such as. As benzene, toluene or xylene can be used.

A particularly advantageous embodiment of the new process consists in dissolving or suspending quinolinic anhydride in a saturated aliphatic C2-C4-monocarboxylic acid, in particular acetic acid or also in acetonitrile, with an indole compound of the formula (2) and the mixture in the presence of an inorganic metal salt , in particular a metal halide, a polyvalent metal with an atomic weight of 26 to 66, such as. B. zinc chloride, calcium chloride, aluminum chloride, iron chloride, cobalt chloride or copper dichloride at room temperature, preferably 2 to 6 h. The compound of the formula (3) is then added and the reaction mixture, after addition of acetic anhydride, is advantageously heated to 30 to 60 ° C. for 1 to 3 hours. Then e.g. with an alkali metal hydroxide or aqueous

4th

5

10th

15

20th

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30th

35

40

45

50

55

60

65

5

652 733

Ammonia, a pH of 7.5 to 9 is set. The precipitated 4-azaphthalide compound of the formula (1) is separated off and, if desired, recrystallized.

The preferred 4-azaphthalide compounds of the formula (1) which are prepared continuously according to the one-pot process according to the invention are those in which V is hydrogen, methyl, hydroxyl, methoxy or especially ethoxy and X is a group of the formula -NRiR2, in which Rj and R2 is methyl or ethyl or -NRiR2 pyrrolidino or piperidino. Y is preferably alkyl having 1 to 8 carbon atoms, Z is especially methyl and ring A is preferably unsubstituted. The most preferred azaphthalide compounds of formula (1) are those in which the group

/ "\

N ± /

"f

V

-X

Represents 2-ethoxy-4-dimethylaminophenyl or 2-ethoxy-4-diethylamino-nophenyl, Y is ethyl or octyl and Z is methyl and ring A is unsubstituted.

A great advantage of the process of the present invention lies in the fact that it is technically easy to use and results in pure end products with very good yields without isolation of the intermediately formed keto acids. In particular, 4-azaphthalide compounds are obtained, all of the corresponding 7-azaphthalide isomers of the formula

(4)

A A / z, A / • «• • •

I A il II H I

a • »• •

V \ / \ <

• / c \ N

sx / \

1 11; -hem

Ï

are free.

The 4-azaphthalide compounds of the formula (1) prepared by the process according to the invention are normally colorless or at most weakly colored. They are particularly suitable as rapidly developing color formers for use in a heat-sensitive or, in particular, pressure-sensitive recording material, which can be both copying and registration material. When these color formers are mixed with a preferably acidic developer, e.g. H. brought into contact with an electron acceptor, they result in intense green-blue, blue or violet-blue hues which are sublimation-resistant and light-fast both on clays and especially on phenolic substrates.

Compared to the isomer mixtures of 4- and 7-azaphthalides previously known from DE-OS 2 842263 or DE-OS 3116 815, the disruptive 7-azaphthalide compound being reduced to a 2% content according to DE-OS 3116 815, The isomer-free 4-azaphthalides produced according to the invention are notable for the advantage that they do not cause any undesirable premature discoloration during the production or storage of the recording materials.

In the following examples, the percentages given are by weight unless otherwise specified.

example 1

20.0 g of quinolinic anhydride, 80 ml of acetic acid, 20.3 g of N-ethyl-2-methylindole and 2.74 g of zinc chloride are stirred at 20 ° C. for 5 hours. Then 23.6 g of 3- (N, N-diethylamino) -5 phenetol and 30 ml of acetic anhydride are added, whereupon the reaction mixture is heated to 50 to 60 ° C. and stirred at this temperature for 2 h. After adding 170 ml of 30% aqueous ammonia and 100 ml of water, the product precipitates as a dough and is separated off. 160 ml of iso-10 propanol are added to the dough and the mixture is refluxed for 1 h. After cooling, the recrystallized product is filtered off, washed with isopropanol and dried. 46.9 g of the isomer-free 4-azaphthalide compound of the formula are obtained

15

c2h5

(C2H5 ^ -Î

A / 0C2H5

.N

/ \ / ^

\ f

(11)

25th

30th

35

with a melting point of 156 to 158 ° C.

Example 2

6.0 g of quinolinic anhydride, 9.5 g of N-octyl-2-methylindole and 0.56 g of zinc chloride are stirred with 30 ml of glacial acetic acid at 20 ° C. for 5 hours. Then 6.6 g of 3-dimethylaminophenetol and 8 ml of acetic anhydride are added, whereupon the mixture is stirred at 50 ° C. for 2/1 h. After adding 30% aqueous ammonia, the product precipitates. This is separated off and recrystallized from isopropanol. 16.5 g of the isomer-free 4-azaphthalide compound of the formula are obtained

40

(c2h5) 2N-,

A / OC2H5

(12)

45

with a melting point of 113-118 ° C.

If, instead of 0.56 g of zinc chloride, 0.30 g of copper (II) dichloride or 0.53 g of aluminum trichloride is used and the procedure is otherwise as described in the example, 15.9 g or. 5016.8 g of the 4-azaphthalide compound of the formula (12) with a melting point of 113-116 ° C or 115-119 ° C.

Example 3

1.5 g of quinolinic anhydride, 2.3 g of N-octyl-2-methylindole, 5510 ml of glacial acetic acid and a mixture of 0.11 g of calcium chloride and 0.14 g of zinc chloride are stirred at 20 ° C. for 5 hours. Then 1.6 g of 3-diethylaminophenetol and 2 ml of acetic anhydride are added, and the reaction mixture is stirred at 50 ° C. for 2/4 h. After adding 30% aqueous 60% ammonia, the product precipitates. This is separated from the aqueous phase and recrystallized from isopropanol. 3.8 g of the isomer-free 4-azaphthalide compound of the formula (12) with a melting point of 114-117 ° C. are obtained.

If 0.19 g of iron trichloride or 0.14 g of cobalt dichloride is used instead of the specified metal salt mixture and the procedure is otherwise as described in the example, 3.3 g or 3.8 g of 4-azaphthalide compound of the formula (12) with a melting point of 113 are obtained -117 ° C or 113-116 ° C.

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Example 4

8 g of quinolinic anhydride, 1.1 g of zinc chloride, 40 ml of acetic acid and 9.95 g of N-butyl-2-methylindole are stirred at 20-23 ° C. for 5 hours. Then 9.3 g3- (N, N-diethylamino) phenetol and 7.5 ml acetic anhydride are added. The reaction mixture is then stirred at 50-60 ° C. for 2 hours. After the reaction has ended, the acetic acid solution is neutralized with 30% aqueous ammonia, the reaction product separating out. After removing the aqueous phase, the crude product is dissolved in glacial acetic acid and it is precipitated again with 30% aqueous ammonia. After recrystallization from ethanol, 16.8 g of the isomer-free 4-azaphthalide compound of the formula n-C H [4 9

i1 »^

-f Wch3 {

V V .V

ï I *? % / -

\ ^

ÌC2H5

(13)

10th

15

20th

Example 5

A solution of 3 g of the 4-azaphthalide compound of the formula (11) in 80 g of diisopropylnaphthalene and 17 g of kerosene is microencapsulated in a manner known per se with gelatin and gum arabic by coacervation, after which there is no discoloration of the microcapsules formed. The microcapsules obtained are mixed with starch solution and spread on a sheet of paper. A second sheet of paper is coated on the front with phenolic resin as the color developer. The first sheet containing microcapsules and the paper coated with color developer are placed on top of each other with the coatings adjacent. A pressure-sensitive copy paper is obtained which does not change color even during storage. Writing by hand or with a typewriter on the first sheet of paper exerts pressure, and an intense blue copy, which is excellent in lightfastness, immediately develops on the sheet coated with the developer.

Corresponding non-discolored pressure-sensitive copying papers and intense and lightfast blue copies by writing are also obtained using each of the other color formers obtained in Preparation Examples 2, 3 and 4.

with a melting point of 152-154 ° C.

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M

Claims (3)

652 733 PATENT CLAIMS (1), ^ V / "\ / /% • • • • • ! A II II II I • »• • • v v \\ a / \ bliss Y is hydrogen, unsubstituted or substituted by halogen, cyano, hydroxyl or lower alkoxy alkyl having at most 12 carbon atoms, acyl having 1 to 12 carbon atoms, benzyl or benzyl substituted by halogen, nitro, lower alkyl or lower alkoxy, Z hydrogen, lower alkyl or phenyl, X -ORi or -N < 'Ri Rj and R2, independently of one another, are each hydrogen, unsubstituted or substituted by halogen, cyano, hydroxyl or lower alkoxy alkyl having at most 12 carbon atoms, cycloalkyl, phenyl, benzyl or phenyl substituted by halogen, nitro, cyano, lower alkyl, lower alkoxy or lower alkoxycarbonyl or Benzyl or Ri and R2 together with the nitrogen atom connecting them a five- or six-membered heterocyclic radical, V hydrogen, halogen, hydroxy, nitro, lower alkyl or Lower alkoxy mean, and wherein the ring A is unsubstituted or substituted by halogen, nitro, cyano, lower alkyl, lower alkoxy, lower alkoxycarbonyl, amino, mono-lower alkylamino or di-lower alkylamino, characterized in that quinolinic anhydride with an indole compound is used at a temperature of at most 65 ° C of the formula i A fl II VY (2K Lower alkyl or benzyl or Rj and R2 together with the nitrogen atom connecting them represent pyrrolidino, piperidino or morpholino. 4. The method according to any one of claims 1 to 3, characterized in that V is hydrogen, methyl, methoxy or Means ethoxy. 5. The method according to any one of claims 1 to 4, characterized in that Y is alkyl with 1 to 8 carbon atoms, acetyl, propionyl or benzyl. 10 6. The method according to any one of claims 1 to 5, characterized in that Z is methyl or phenyl. 7. The method according to any one of claims 1 to 6, characterized in that the ring A is unsubstituted. 8. The method according to any one of claims 1 to 7, characterized 15 characterized in that the reaction of quinolinic anhydride with the indole compound of formula (2) is carried out at a temperature of 0 to 50 ° C, preferably at room temperature. 9. The method according to any one of claims 1 to 8, characterized in that an aliphatic monocarboxylic acid with 2 to 4 carbon atoms and preferably acetic acid is used as the organic reaction medium. 10. The method according to any one of claims 1 to 9, characterized in that the metal salt is derived from a polyvalent metal with an atomic weight of 24 to 210, preferably 26 to 140 and in particular 26 to 120. 11. The method according to any one of claims 1 to 10, characterized in that a halide of the metals aluminum, calcium, iron, cadmium, cobalt, copper, manganese, nickel, tin or zinc is used as the metal salt. 12. The method according to any one of claims 1 to 11, characterized in that the condensation of the reaction product obtained from quinolinic anhydride and the indole compound of formula (2) with the compound of formula (3) in the presence of an acidic dewatering agent at a temperature of 20 to 80 ° C is carried out. 13. The method according to any one of claims 1 to 12, characterized in that the reaction mixture is finally adjusted to a pH of 7 to 11. 40 14.4-Azaphthalide compounds of the formula (1), characterized in that they have been prepared by a process according to one of claims 1 to 13. 15. Use of a 4-azaphthalide compound according to claim 14 or mixtures thereof as a color former in a pressure-sensitive or heat-sensitive recording material. 25th 30th 35 wherein A, Y and Z have the meaning given, in the presence of an inorganic or organic metal salt of a polyvalent metal in an organic reaction medium consisting of a lower aliphatic monocarboxylic acid or a nitrii of this acid, the reaction product obtained with a compound of the formula /% H ~ * \ 1 / * ~ X T v (3), wherein X and V have the meaning given, condensed further and the resulting reaction mixture has a pH of at least 6. 1. Process for the preparation of 4-azaphthalide compounds of the formula 2. The method according to claim 1, characterized in that X represents the amino group of the formula -NRjR2. 3. The method according to any one of claims 1 and 2, characterized in that Ri and R2 are independent of one another