US3244728A - Chromogenous amino derivatives of diphenylphthalan and marking method using same - Google Patents

Description

April 5, 1966 J. R. JOHNSON ETAL,

AND MARKING METHOD USING SAME Filed Aug. 51, 1961 L/ DERIVATIVE 1 COATING ON FACE CONTAINING l ELECTROPHILIC COLOR DEVELOPER BASE WEB ORIGINAL COATING ON BACK CONTAINING I,l-B|S(p-AMINOPHENYL) PHTHALAN BASE WEB, DUPLIGATEJ COATING ON BACK (OPTIONALll INVENTORS. EARL J. GOSNELL BY JOHN R. JOHNSON ATTORNEY United States Patent 3,244,728 CHROMOGENOUS AMINO DERIVATIVES 0F DI- PHENYLPHTHALAN AND MARKING METHOD USlN G SAME John R. Johnson, Ithaca, and Earl I. Gosnell, Erondequoit, N.Y., assignors to Burroughs Corporation, Detroit, Mich, a corporation of Michigan Filed Aug. 31, 1961, Ser. No. 135,307 3 Claims. (Cl. 260-336) This invention pertains to chromogenous compounds which are related generally to the amino-substituted triphenylmethanes and phthaleins, and which have the form of colorless, that is, white, or lightly colored solids, or approach being colorless when in liquid solution, but which may be converted to dark-colored forms upon contact with suitable color-developing substances. As applied to the printing and duplicating arts, marking in desired areas on base sheets may be accomplished by effecting localized contact, in areas where image elements are to be printed, between the chromogenous compound and the color-developing substance. Webs coated with films carrying individually the chromogenous compound and the color developer may be assembled in a manifolded set, so that localized pressure or impact will cause transfer of material from a coating on the web surface of one manifolding unit to a coating on a contiguous web surface, Where the desired localized contact is made to form the dark-colored materials in the image-making areas.

Marking systems of these general types have been disclosed which utilize known chromogenous compounds. As examples of such chr-omogenous compounds there may be mentioned the following: the leuco, or simple aminosubstituted triphenylmethane, forms of malachite green, crystal violet, and ethyl violet; the corresponding aminosubstituted triphenylmethyl carbinols; the lactone forms, which are amino-substituted diphenylphthalides, corresponding to the above-mentioned leuco forms; and the lactones or colorless bases of the rhodamine dyes. These types of chromogenous compounds have their peculiar properties with respect to stability of the colorless or leuco forms against spontaneous color development, and with respect to their reactions with various color-developing agents having otherwise acceptable characteristics for use as coatings on paper webs. The color-developing response may be too easily triggered in somes cases and too sluggish in others, with same substances even requiring heating to develop a good dark mark. Thus problems often arise from excessive background color in a coating containing the chromogenous compound after periods of storage or long exposure to light or heat, from slow or insufficient production of dark-colored materials upon contact with color-activating substances, and from limitations in the color hues and intensities of the dark-colored forms which can be developed from the chromogenous substances. To find the best answer to these problems for any given application it is advantageous to have available a choice of additional different chromogenous substances.

Accordingly it is an object of the present invention to provide new and improved substances having chromogenous properties, which advantageously may be incorporated in a transferable coating on a web surface to provide a novel manifolding unit, and which are useful in carrying out improved methods of marking involving contact with a color-activating material to develop darkcolored materials in areas where marking is desired.

It is another object of the invention to provide, modified compounds, based upon the triphenylmethane structures, which are colorless or lightly colored, offering a new and improved variety of chrornogenous characteristics, and developing novel dark-colored substances upon contact with color-activating materials.

3,244,728 Patented Apr. 5, 1966 "ice (B) the compound A in which the two para-aminophenyl radicals, having bonds to the carbon atom designated 1, are linked by an epoxy bridge between respective positions in these radicals ortho to the positions of such bonds, (C) the S-amino derivatives of each of the compounds A and B, and (D) N-substituted derivatives of each of the compounds A, B, and C in which each N-substituent is selected from the group consisting of an alkyl radical of not more than four carbon atoms, the benzyl radical, and the phenyl radical.

In accordance with another feature of the invention, a new composition of matter'comprises the dark-colored substance, having a quinonoid resonant form, developed by contact of a color-activating material with a colorless or lightly colored chromogenous compound selected from the above-mentioned group consisting of the compounds A, B, and C and their N-substituted derivatives D, the color-developing or activating material being an electrophylic substances for opening the bond from the carbon atom designated 1 in the structural formula given above to the oxygen atom designated 2 to convert the chromogenous compound to the quinonoid resonant form.

In a manifolding unit comprising a base web having on one side a coating made up of a film-forming material containing a colorless or lightly colored chromogenous compound transferable upon impact from the coating to a surface contiguous therewith, the improvement is provided, in accordance with a related feature of the invention, in which the chromogenous compound is selected from among the above-mentioned compounds A, B, C, and D, such compound being adapted to produce a darkcolored material, having a quinonoid resonant form, upon transfer to the contiguous surface and contact thereon of the chromogenous compound with an e-lectrophylic coloractivating material, carried by the contiguous surface, for opening the aforementioned carbon-oxygen bond to convert the chromogenous compound to the dark-colored quinonoid resonant form.

In accordance with a method feature of the invention, the method of marking by developing dark-colored materials from colorless or lightly colored chromogenous compounds comprises providing a chromogenous compound selected from among the above-mentioned compounds A, B, C, and D, and bringing such chromogenous compound into contact, in areas where marking is desired, with an electrophylic color-activating substance to produce likewise a dark-colored quinonoid resonant form of the chromogenous compound by the action thereon in said areas of said electrophylic substance.

For a better understanding of the present invention, together with other and further objects thereof, reference is had to the following description taken in connection with the accompanying drawing, and its scope will be pointed out in the appended claims.

The single figure of the drawing shows in exploded View two manifolding units, suitable for use together in face to face contiguity, with or without additional similar manifolding units, in a manifold set. The manifolding units are illustrated in cross section with the thicknesses of the base webs and of the coatings on the web surfaces greatly exaggerated. for convenience of illustration.

A manifolding unit embodying the present invention is shown in the upper portion of the exploded view of the drawing. In such a manifolding unit, comprising a base Web 11 having on one side, usually on the back surface, a coating 12 made up of a film-forming material containing a colorless or lightly colored chromogenous compound transferable upon impact from the coating to a surface contiguous therewith such as the surface on the face of another base web 13, the improvement is provided in which the chromogenous compound is the novel substance of the present invention.

The novel substance of the invention is selected from the group consisting of (A) the compound l,1-bis(paminophenyl)-phthalan having the structural formula HzN- N Z 6/ all 1 f 7 CH2 w (C) the S-amino derivative of each of the compounds A and B, namely 5 amino 1,1 bis(p aminophenyl)- phthalan loam HZN N Hz 4 and 3',5,6'-triaminospiro(phthalan-l,9-xanthene) o H2N- NH:

l N z respectively; and (D) N-substituted derivatives of each of the above-listed compounds A, B, and C in which each N-substituent is selected from the group consisting of an alkyl radical of not more than four carbon atoms, the benzyl radical, and the phenyl radical. All of these substances are colorless or very lightly colored compounds which, upon suitable contact with appropriate developer materials, produce substantially dark-colored materials. Examples of the type D N-substituted substances now will be given with particular reference to those compounds, based upon the structure of 1,l-bis(p-aminophenyl) phthalan, which in many environments are most suitable for providing intensely dark-colored marking materials upon contact with a developer material.

For use in a system for developing dark-colored marks upon contact with a color-developing substance, one of the chromogenous compounds A, B, or C is preferred in which many or most of the amino hydrogen atoms, being four hydrogen atoms in A and B and six in C, are replaced by methyl or ethyl substituents. These compounds are included among the N-substituted derivatives D. As an example of such compounds based on the compound A there may be mentioned 1,1-bis(p-methylaminophenyl) phthalan HaCN- NCH; H H

Preferably, however, a compound is used having the structural formula in which each individual substituent R is selected from the group consisting of an alkyl radical of not more than four carbon atoms, the benzyl radical, and the phenyl radical. Examples of such compounds having benzyl or phenyl radicals will be given hereinbelow. Advantageously, however, the compound has the structural formula of 1,l-bis(p-aminophenyl)phthalan, but in which each of the four amino hydrogen atoms is replaced by an 7 alkyl substituent having not more than two carbon atoms;

these compounds, also based on the compound A, include 1,1-bis-(p-dimethylaminophenyl)phthalan and 1, l-bis (p-diethylaminophenyl) phthalan N-substituted derivatives based on the compound B include the compound 3,6-bis(ethylamino)spiro(phthalan- 20 at C Preferably, however, a compound is used having the structural formula 0 RzN- NR2 in which each individual substituent R is selected from the group listed hereinabove; these compounds, also based on the compound B, include, for example, 3,6-bis(diethylamino)spiro(phtha1an-l,9-xanthene) Additional substances in the category of the compounds D may be illustrated by the N-substituted derivatives of a compound C having the S-amino group. Such comsame group R, defined hereinabove. An example is 6 pounds, when based on the compound C as derived from the compound A, preferably have the structural formula in which each individual substituent is selected from the same group defined hereinabove. Examples are S-dimethylamino-1,l-bis(p-dimethylaminophenyl) phthalan.

and 1,1 bis(p diethylaminophenyl)-5-dimethylaminophthalan 2H5) rN- N (C H 3 O Olin Still further compounds of this N-su'ostituted category may .be based on the compound C, but derived from the compound B having the epoxy bridge. Mono-substituted amino groups, and N-phenyl and N-benzyl substituents, are useful, as with the other N-substituted categories already described. Again, however, a compound is preferred having a structural formula with the disubstituted amino groups NR viz.

in which each individual N-substituent is selected from the 3,5,6 tris n (dirnethylamino)spiro(phthalan 1,9-xanthene) Excellent results also can :be obtained with the straight chain propyl and =butyl radicals as the N-substituted groups, and isopropyl and branched chain butyl substituents also are suitable. Thus the N-substituted methyl or ethyl radicals in the compounds listed above may be replaced, for example, by normal propyl or butyl radicals. Variations in these substituents produce generally minor modifications of color depth or intensity and of spectral response in the dark-colored products which may be developed from the N-substituted chromogenous compounds. Thus the substituents may replace only one or more, but preferably most, of the amino hydrogen atoms, and best results frequently are obtained when all but one, or every one, of the available amino hydrogen atoms are or is replaced. Accordingly, the novel subances useful as chromogenous compounds, of which those mentioned hereinabove are examples, not only include the unsubstituted 1,1-bis(p-aminophenyl)phthalan A, its epoxy derivative B, and the compounds C in which A and B also carry a S-amino group, but also include N-substituted derivatives of those compounds in which each of the one or more substituents is an alkyl radical of not more than four carbon atoms. Equivalent results also may be obtained for example, with various saturated monoalkyl radicals having five carbon atoms as N- substituuents, or with mono-n-hexylamino groups instead of the dimethylarnino or diethylamino groups, or with N-substituted cyclopropyl groups, but these substituents for the amino hydrogen atoms are not preferred.

Good color-forming properties furthermore are obtained, as indicated above, with certain N-substituted aralkyl and aryl radicals. Thus in general the N-substituted derivatives D of the compounds A, B, and C should be those in which each N-substituent is selected from the group consisting of an alkyl radical of not more than four carbon atoms, the benzyl radical, and the phenyl radical. Further examples of such substances are 1,1-bis(p-(methylphenylamino)phenyl)phthalan and 1,1 bis(p benzylaminophenyl) 5-dimethylamino- I K aM It will be understood that similar N-substituted compounds, based on the compound B with the epoxy bridge, also are available.

Variations in the dark-colored materials which can be developed irom the chromogenous compounds of the present invention also may be effected by certain additional rather minor modifications in molecular structure of the chromogenous compounds. These color variations follow in a general Way the reported effects on the spectral response of p-a-mino-substituted triphenylmethane dyes which result from modification of the molecular structure of such dyes in a similar manner. For example, N- phenyl-substituted compounds may be modified by including naphthyl radicals instead of phenyl radicals as b -substituents, or certain small additional substituents may be included on the N-substituted radicals mentioned above, and generally equivalent properties still Will be obtained; in this connection such N-substituted groups as the chlorornethyl, hydroxyethyl, sulfophenyl, tolyl, or one of the methylbenzyl radicals may be mentioned. It will be appreciated likewise that substantially equivalent properties also are obtainable in such chrornogenous compounds when one small substit-uent or several small substituents, notably one or more methyl, chloro, or nitro radicals is or are substituted for one or more of the available hydrogen atoms on the benzene rings; such substituents tend to increase the stability against spontaneous color development and to decrease the readiness with which a darkcolored material may be developed by contact of the chromogenous compound with color-developing materials, but with little tendency to change the spectral response.

Referring again to the manifoldin-g unit comprising the base web 11 having the back coating 12, it is possible to incorporate the chromogenous material in the solid state in a back coating of waxy or thermoplastic film-forming material, which may be transferred from the base web upon impact to deposit some of the chromogenous material on a surface carrying a color-activating material. Production of the colored form occurs best, however, if the chromogenous substance is dissolved in a solvent, permitting intimate contact of the molecules of the chromogenous substance with the color-developing material. It is possible to provide some of this-solvent on the surface carrying the color-developing material. Preferably, however, the film-forming material of the back coating 12, which is rupturable upon impact or other localized pressure, contains as a finely dispersed phase numerous cells of -a liquid vehicle carrying the colorless or lightly colored ohrornogenous compound. An oily solvent vehicle advantageously is used, such as chlorinated biphenyl, a partially hydrogenated mixture of isomeric terphenyls (Monsanto H8 10), benzyl butyl phthalatc, la'uryl bromide, butyl oleate, benzyl salicylate, halogenated diphenyl ethers, or mixtures of such vehicles. A solution of from about 1% to 10% by weight of the chromogenous compound in such a solvent vehicle may be prepared, for example, and then emulsified in a conventional aqueous film-forming material such as polyvinyl alcohol in colloidal solution, or such as a colloidal aqueous solution of casein, gelatin, or the like. The resulting emulsion is coated on the back surface of the base web 11, which may be a strip or sheet made of paper or other fibrous ma terial or of a plastic film base, and then is dried to form the coating 12 containing numerous liquid cells of the water-insoluble solvent vehicle carrying the chromo-.

genous substance, these liquid cells being finely dispersed throughout the solid dried film of hydrophilic material which makes up the continuous phase in the coating 12. The dried coating 12 may be about 0.001 inch thick.

The chromogenous compounds of the invention are adapted to produce a dark-colored material upon rupture of the coating 12 and contact of the chromogenous compound in the liquid vehicle with a contiguous surface can .rying an inorganic electron acceptor material. Solid particles of the latter material conventionally may be dispersed in water, mixed with an aqueous paper-coating starch solution in the proportions of roughly five parts by weight of the inorganic material to one part of starch on a dry basis, coated on the face of the base web 13 of paper or the like, and dried to form a dry coating 14 roughly 0.0005 inch thick. Alternatively an aqueous latex of polybutadiene-styrene plastic material may replace some or all of the starch as the film-forming material. Thus the coated web 13, shown in the lower portion of the exploded view of the drawing, forms a second manifolding unit for use with the upper manifolding unit provided by the coated web 11.

For use as a manifolded set, the base webs 11 and 13 are maintained in position together, as suggested by the bracket at the left of the drawing, with the coating 12 on the back of sheet 11, containing 1,1-bis(p-aminophenyl) phthalan or one of its derivatives described hereinabove as chromogenous materials suitable for this purpose, held in contiguity with the coating 14 on the face of the sheet 13, containing the inorganic electron acceptor material. For producing simultaneously an original and one copy sheet by use of a typewriter, for example, or by direct writing with pen or pencil, the web 11 advantageously serves as the original and the face-coated web 13 serves as the duplicate. These manifolding units may be fastened together in a pad, or simply laid one over the other on a writing surface, or held together on the platen of a typewriter. Typing or writing impact, or other printing pressure, on the face of the sheet 11 causes localized rupture of the back coating 12. This releases the vehicle, carrying the colorless or lightly colored chromogenous material, from those ones of the tiny cells in the coating 12 which occupy the areas immediately beneath the areas of impact on the original printing or writing surface. Thus the chromogenous material in solution is transferred to the surface having the coating 14. This coating, made as previously described, permits adequate adsorptive contact of the chromogenous material, so transferred in the image areas to be duplicated, with the many small particles of the inorganic electron acceptor material in those areas of the coating 14. Where this contact occurs, the dark-colored material is developed by the action of the inorganic electron acceptor substance on the ohromogenous compound, thus forming the duplicate image on the face of the duplicate sheet 13.

It will be understood that, if desired, a coating 15 may be formed on the back surface of the duplicate web 1;, in just the same manner as the back coating is formed on the original web 11. With this optional back coating 15 on the web 13, one or more additional duplicate coated webs, identical with the coated web 13, may be manifolded beneath the web 13, permitting simultaneous production of triplicate and quadruplicate copies. In fact, most of the electron acceptor materials, when applied in face coatings such as the coating 14 described above, themselves provide good original printing or writing surfaces, so that a sheet such as the sheet 13, when provided with the back coating 15 as well as the face coating 14, may serve either as an original sheet or as a duplicate sheet in a man-ifolded set or stack. Thus identical paper sheets, each having white or light-colored face and back coatings acceptable as oridinary paper surfaces to most users, may be manifolded in sets of two or more, or several sheets may be manifolded in which the face coating may be omitted from the top sheet only and the back coating may be omitted from the bottom sheet only. No smudging or soiling of the paper sheets or of the users hands occurs in ordinary usage, and darkcolored material is formed only in the duplicate image areas by the aforementioned action of the developer material on the colorless or white, or very light colored, chromogenous material.

Numerous inorganic electron acceptor materials are available for incorporation as small solid particles in the face coating 14-. These materials include certain clays,

siliceous materials, and other inorganic materials such as attapulgite and argosite clay, silicates of magnesium, calcium, and aluminum, calcined diatornaceous silica, activated silica, sodium aluminum zeolite material and related silicate Zeolite materials in which sodium is re placed by the cations of potassium or other metals having similar functions, attapulgite with similar cation replacements, pyrophyllite, bentonite, halloysite, magnesium montmorillonite, calcium sulfate, zinc sulfate, barium sulfate, basic aluminum sulfate (aluminum hydrate), and calcium fluoride.

In more general terms, the chromogenous compound in the coating 12 is adapted to produce a dark-colored material having a quinonoid resonant form upon transfer to the contiguous surface of the web 13 and contact of the chromogenous compound with an electrophylic color-activating material, carried by that contiguous surface in a coating generally similar to the face coating 14 on the web 13. An electrophylic material such as a source of proton, preferably a weakly acid proton source, or an aprotic acid (a Lewis acid), serves as a coloractivating or developing material for opening the bond from the carbon atom designated 1 to the oxygen atom designated 2 in the structural formula of 1,1-bis(p-amino phenyl)phthalan as given hereinabove, or of the other above-described related chrornogenous compounds. The cleavage of the cyclic ether structure in the chromogenous compound converts the compound to a quinonoid resonant form having the desired dark-colored characteristic. It may be speculated that, when this cleavage is accomplished by a proton source, the dark-colored mate rial is an o-hydroxymethyl derivative of a p-amino-substituted triphenylmethane quinonoid structure which is related to the structure of the original chromogenous substance; or that, when the electrophylic material is an aprotic acid, the dark-colored form is a similar methoxide derivative carrying an aprotic acid residue. Nevertheless, whatever the exact arrangement of substituents in the structure of the resulting quinonoid resonant form, the dark-colored substance having that form, developed by contact of the electrophylic color-activating substance with the colorless or lightly colored chromogenous compound, is a new composition of matter, valuable in the formation by such contact of dark marks or image areas made up of the dark-colored material. A new composition of matter also is provided in the production of the dark-colored substance obtained by contact of an inorganic electron acceptor material with one of the colorless or lightly colored chromogenous compounds of the present invention.

It will appear from the above that marking or printing may be accomplished, without the use of conventional inks containing dyes and pigments, by using instead of such inks an oily ink vehicle in which the chromogenous compound is dissolved. For letterpress printing the resulting oily vehicle is applied to the type, which then is impressed on a web surface having a coating such as the aforementioned face coating 14 containing an electrophyl-ic color-activating substance. Alternatively sheets having such a face coating may be used in a typewriter provided with a ribbon impregnated with an oily ribboninking vehicle containing the chromogenous substance in solution. A ribbon so impregnated will not soil the fingers or clothing while being installed on or removed from the typewriter.

Such arrangements involve embodiments of the method, in accordance with the invention, of marking by developing dark-colored materials from colorless or lightly colored chromogenous compounds. This method accordingly comprises providing a chromogenous compound selected from among the categories of compounds A, B, C, and D described hereinabove, and bringing this chromogenous compound, which preferably is dissolved in an oily vehicle, into contact, in areas where marking is de sired, with the electrophylic color-activating substance,

which may be a weak acid such as citric acid powder. In another embodiment of this method, the solid colorless or lightly colored chromogenous compound is incorporatedin a surface coating and brought into contact with an electrophylic substance by applying such substance, in the form of liquid droplets of acetic acid, to the surface coating where dark-colored marks are desired. The method, of course, may be carried out also by the use of the manifolded set shown in the drawing. To complete the latter illustration of the method of the invention, the back coating 12 on the web 11 advantageously contains cells of an oily liquid in which is dissolved a chromogenous compound in the form of l,l-bis(paminophenyl)phthalan, or 3,6-diaminospiro(phthalanl,9'-Xanthene), or the S-amino-substituted derivative of one of these substances, all of the amino hydrogen atoms of such chromogenous compound being replaced, however, by methyl or ethyl radicals. Thus there is provided a chromogenous compound which, under marking, printing, or writing impact or pressure applied to the face of the web 11, is for ed from the cells in the coating 12 and brought into contact, in localized areas on the face coating 14 carried by the duplicate web 13, with an inorganic electron acceptor subtance in the coating 14 to develop a dark-colored material in the areas of the marks to be duplicated by the action of such substance on the chromogenous compound.

The novel chromogenous compound 1,1-bis(p-aminophenyl)phthalan having the structural formula (NHz) its S-amino derivative (the S-amino group is included in parentheses in the structural formula shown here), and the N-substituted derivatives of these two compounds conveniently may be synthesized by reduction of the corresponding lactones of p-ainino-substituted triphenylmethanes having the general structural formula zN- NH2 (l lHz) These lactone compounds in turn may be formed by oxidation under dehydrating conditions of the o-carboxylic acid derivatives of the corresponding triphenylmethanes, which are benzoic acid derivatives having the general structural formula HzN- NH2 O (LE2 (i lHz) in which the (Ni-I su'bstituent shown in parentheses may not be present, and in which the various N-su bstituted radicals disclosed hereinabove may be present. The chromogenous compounds represented by the structural formula just given conveniently may be synthesized by reduction of the corresponding lactones, sometimes called the colorless bases, of rhodamine dyes. These lactones or colorless bases of the rhodamine dyes are available on the market. Their synthesis may be accomplished by reaction, in the presence of ZnCl of one mole of phthalic anhydride (or 4-aminophthalic anhydride) and two moles of m-aminophenol where each radical R may be, instead of hydrogen, an alkyl radical of not more than our carbon atoms, the

benzyl radical, or the phenyl radical, to form the rhodamine lactone or colorless base having the general structural formula O to as suggested generally in the book Organic Chemistry by L. F. Fieser and M. Fieser, Reinhold Publishing Corporation, New York, Third Edition, 1956, page 898. It will appear that, when an N-substituted aminophthalic anhydride is used, its N-substituents, R, need not be the same as the N-substituents also represented by R in the m-aminophenol.

As an example of the synthesis of the chromogenous compounds of the present invention, the starting material may be 3,3-bis (p-dimethylaminophenyl)phthalide, which is the lactone of malachite green and which has the structural formula Sources of such a lactone substance are mentioned hereinabove. Reduction to the cyclic ether form of the present invention is achieved with the use of alumnium lithium hydride, AlLiH Ten grams of this hydride were added to 350 ml. of ethyl ether, previously rendered anhydrous by drying over metallic sodium, and partial solution in the ether was achieved by refluxing and stirring for 1 hour. During a further period of minutes, 9.3 grams (0.25 mole) of the malachite green lactone were added to the ether solution stepwise in small portions to control the rapid refluxing of the solvent due to evolution of heat from the reduction of the lactone. The mixture then was refluxed for another 2 hours. The mixture was cooled to room temperature, and about 15 ml. of water were added dropwise with effective stirring until the solid material in the mixture had a granular appearance. The ether layer then was decanted, and the residue was washed several times with fresh ether. The portions of ether solution thus obtained were combined and passed through anhydrous sodium sulfate. Evaporation of the ether then left a yellowish-green material of slightly resinous texture which slowly achieved a crystalline form. Redissolving in ether containing a decolorizing adsorptive material such as activated carbon, and again recovering the crystalline material, produced a still paler green substance, and repeated purification yields a creamy white solid, 1,l-bis(p-dimethylaminophenyl)- phthalan When the purified or' partially purified substance is, for example, dissolved in chlorinated biphenyl and brought into contact with magnesium trisilicate, which is a precipitated hydrate silicate having the approximate formula Mg Si O .5H 0, a dark-colored quinonoid form having intense green color is produced; this quinonoid form also is produced upon contact, for example, with an electrophylic material such as tartaric acid.

The same reactions may be carried out with diethylamino instead of dimethylamino substituents, and the resulting almost colorless substance, 1,1-bis(p-diethylaminophenyl)phthalan, likewise forms an intense green dark-colored material. If a lactone having monomethylamino or monoethylamino instead of dimethylamino substituents is used, the resulting chromogenous compound is 1,l-bis(p-methylaminophenyl)phthalan or 1,1- bis-(p-ethylaminophenyl)phthalan, respectively, each of which gives a greenish blue dark-colored quinonoid form.

The same reducing operation again may be carried out on 3,3-bis(p-aminophenyl)phthalide to produce a very lightly colored chromogenous substance, varying from a light pink to light cream color depending on the degree id of purification. This is 1,l-bis(p-aminophenyl)phthalan itself, which upon contact with magnesium trisilicate forms a violet dark-colored material.

Further variations in the color of the dark-colored products formed from taese chromogenous compounds are obtainable with different N-substituents. For example, l,l-bis(p-benzylaminophenyl)phthalan and 1,1- bis(p dibenzylaminophenyl)phthalan give quinonoid forms having a greenish blue color. If the lactone used in the synthesis of the 1,l-bis(p-dimethylarninophenyl)- phthalan is modified by replacing two of the methyl radicals with phenyl radicals, giving the chromogenous compound 1,1 bis(p-(methylphenyiamino)-phenyl)phthalan, mentioned above, the corresponding dark-colored form becomes yeliowish green, While the quinonoid form of l,1-bis(p-diphenylaminophenyl)-phthalan is a somewhat lighter yellow-green.

In another example of the synthesis of the chromogenous compounds of the present invention, the starting material used was 6-dimethylamino 3,3 bis(p-dimethylaminophenyl)phthalide, which is the lactone of crystal violet having a melting point of l-181 C. and Which has the structural formula Again, aluminum lithium hydrate was used to reduce the lactone to the cyclic ether form, following the steps given above for reduction of the lactone of malachite green. Ten grams of the hydride were added to 350 ml. of anhydrous ether, refluxed and stirred, and 10.4 grams (0.025 mole) of the crystal violet lactone were added in small portions. After completion of the reduction reaction and dropwise addition of water, the product was recovered in the ether solution, the ether evaporated, and the resulting crystalline material redissolved in ether and eventually recovered in fairly pure form as a creamy or light tan solid, in other words, substantially white or colorless. This creamy white solid is 5-dimethylamino-1,1-bis (pdimethylaminophenyl)phthalan, having a melting point of 147-148 C. and the structural formula The actual yield of 3.4 grams compares with a theoretical yield of 10.0 grams. When dissolved in chlorinated biphenyl and placed in contact with magnesium montmorillonite, which is a magnesium-substituted hydrous aluminum silicate, a dark-colored quinonoid form having an intense bluish violet color is produced.

Analogous procedures are used to make the related cyclic ethers S-diethylamino 1,1 bis(p-diethylaminophenyl)phthalan and 1,1- bis(p-diethylaminophenyl)-5- dimethylaminophthalan, which also form bluish violet dark-colored products. In general these cyclic ethers of N-hexaalkyl triaminotriphenylmethanes give very bright or intense dark-colored forms. The compound S-amino- 1,1 bis(p methylaminophenyl)phthalan, a triaminotriphenylmethane cyclic ether having only two N-substituted methyl groups, also gives a bluish violet, but less intense, dark-colored form. As to the related compounds having aryl and aralkyl N-substituents, examples are the triphenyl-substituted compound 5 phenylamino-l,1-bis(pphenylaminophenyl)phthalan, the alkyl-aryl-trisubstituted compound 5 methylphenylamino 1,1 bis(p-(methylphenylamino)phenyl)phthalan, and the compound 1,1- bis(p-benzylaminophenyl) 5 dimethylaminophthalan, mentioned above. These compounds form blue darkcolored quinonoid materials. The same type of reducing operation used to produce these chromogenous compounds also may be carried out on 6-amino-3,3-bis(paminophenyhphthalide to produce a chromogenous solid of creamy white color when, moderately pure. This is 5- amino-l,1-bis(p-aminophenyl)phthalan itself, which upon contact with magnesium montmorillonite or another inorganic electron acceptor material forms a violet-red or bluish red dark-colored material.

For preparing the cyclic ethers of the above-mentioned category B with the epoxy linkage, a suitable starting material is rhodamine lactone, usually having N-substituted radicals. These starting substances themselves may be prepared as outlined hereinabove. An example of the synthesis of the novel chromogenous compounds embodies the use of the lactone of Rhodamine B, which is the compound 3',6'-bis(diethylamino)fluoran having the structural formula (C 2115) zN- 1 N(C2H5) 2 Proceeding as in the syntheses described above, 10 grams of aluminum lithium hydride are dissolved partially in 350 ml. of anhydrous ether by refluxing and shaking, after which 11.0 grams (0.025 mole) of the Rhodamine B lactone are added, a portion at a time. The mixture is refluxed for 2 hours, cooled to room temperature and 15 to 20 ml. of water added dropwise to the point where the inorganic complex becomes granular. The ether portion is decanted and dried. by running through anhydrous sodium sulfate. The ether then is evaporated, yielding 5 to 8 grams of a light pink, crystalline, chromogenous solid, 3,6-bis(diethylamino)spiro phthalan- 1,9 -xanthene 'N (C 2H5) 2 UZH:

its greater stability in the presence of moisture, it being notably stable even to boiling water and to polar solvents such as acetone, alcohols, and the like. The rhodamine lactone, on the other hand, is much more prone to oxidation by atmospheric oxygen and is extremely diificult to obtain in a substantially colorless, or white, form; the lactone changes readily even in the solid state to a deep red color in the presence of atmospheric moisture, and it has a very strong tendency to change to a dark-colored form in the presence of polar solvents.

Cyclic ethers such as that produced by this reduction procedure described here-inabove have a somewhat greater tendency for spontaneous conversion to colored forms than do the above-described chromogenous compounds without the epoxy linkage. This disadvantage may be overbalanced by the greater ease of development of colored marks when brought into contact with an electrophylic color-activating material. The compound 3,6-bis- (diethylamino)spiro(phthalan-l,9'-xanthene), produced as described above, produces a deep bluish red darkcolored substance when brought into contact with an attapulgite electrophylic developer material. The quinono'id form of the compound 3,6'-bis(ethylamino)spiro- (phthalan-l,9-Xanthene), mentioned hcreinabove, has a very similar dark, bluish red color. The compound 3',6' bis(dimethylamino)spiro(pht-halan-1,9 xanthene) produces a dark red quinonoid form. Further rather minor variations in the hue of the quinonoid forms are obtained by other changes in the N-substitutents, for example by inclusion of different N-substituted alkyl or aryl groups of the character mentioned hereinabove. changes provide chromogenous compounds which produce dark-colored materials having the familiar red or bluish red colors of the rhodamine dyes.

Still further variations in the color of the quinonoid forms are obtainable by adding a 5-amino radical, preferably carrying alkyl, benzyl, or phenyl substitucnts, to the above-discussed chromogenous cyclic ethers having the epoxy linkage. For example, the compound 3',5,6- tris (dimethylamino)spiro (phthalan-1,9-xanthene) gives a more bluish-colored quinonoid form than the red darkcolored material produced from the compound 3,6-bis- (dimethylamino)spiro(phthalan-1,9'-xanthane). In general, the bluish red quinonoid forms of the other epoxylinked cyclic ethers mentioned above become a deeper, darker, and more punple color with the addition of the S-amino group. Accordingly, it appears that the present invention provides a group of novel compounds offering a new and very useful choice of chromogenous characteristics.

While there have been described what at present are considered to be the preferredembodiments of this invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention. It is aimed, there fore, in the appended claims to cover all such changes and modifications which fall within the true spirit and scope of the invention.

What is claimed is:

1. A substance selected from the group consisting of (A) the compound 1,l-bis(paminophenyhphthalan having the structural formula I Such (B) the compound (A) in which the two para-aminophenyl radicals, having bonds to the carbon atom designated 1, are linked by an epoxy bridge between respective positions said radicals ortho to the positions of said bonds, (C) the S-amino derivative of each of the compounds A and B, and (D) N-rslu'bstituted derivatives of each of said compounds A, B, and C in which each N- substituent is selected from the group consisting of alkyl of not more than four carbon atoms, benzvl, and phenyl.

2. The compound 3',6-bis(diethy1amino)spiro(phthalan-1,9'-xanthene) having the structural formula 3. The compound S-dimethylamino-1,1-bis(p-dimethy1- aminophenyi) phthalan having the structural formula References Cited by the Examiner UNITED 25 WALTER A. MODANCE, Primary Examiner.

M. KATZ, Examiner.

Claims (1)

1. A SUBSTANCE SELECTED FROM THE GROUP CONSISTING OF (A) THE COMPOUND 1, 1-BIS (P-AMINOPHENYL) PHTHALAN HAVING THE STRUCTURAL FORMULA

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