Novel Sulfam(na)phthaleins

1. Field of the Invention

The present invention relates to novel chemical compounds and, more specifically, it relates to novel sulfam(na)phthaleins useful as optical filter agents and filter agent precursors in photographic processes for protecting an exposed photosensitive material from post-exposure fogging during development in the presence of ambient light.

2. Description of the Prior Art

A number of diffusion transfer processes for producing photographic images in both black-and-white and in color have been proposed. Of particular interest are diffusion transfer processes wherein the image-receiving layer carrying the transfer image is not separated from the developed photosensitive layer(s) after processing but both components are retained together as a permanent laminate. Included as part of the laminate is a layer of light-reflecting material, preferably titanium dioxide, positioned between the image-carrying layer and the developed photo-sensitive layer(s). The light-reflecting layer separating the image-carrying and photosensitive components provides a white background for the transfer image and masks the developed photosensitive layer(s). In addition to these layers, the laminate usually includes dimensionally stable outer layers or supports, at least one of which is transparent so that the resulting transfer image may be viewed by reflection against the background provided by the light-reflecting layer. Diffusion transfer processes for forming images viewable without separation of the photo-sensitive and image-receiving components and integral negative-positive film units useful in such processes, i.e., film units wherein the negative or the photosensitive component and the positive or image-receiving component ae retained as a permanent laminate after processing are described in U.S. Pat. Nos. 3,415,644, 3,415,645 and 3,415,646 issued Dec. 10, 1968 to Edwin H. Land, U.S. Pat. Nos. 3,573,043 and 3,573,044 issued Mar. 30, 1971 to Edwin H. Land and U.S. Pat. Nos. 3,594,164 and 3,594,165 issued July 20, 1971 to Howard G. Rogers.

U.S. Pat. No. 3,647,437 issued Mar. 7, 1972 to Edwin H. Land is concerned with diffusion transfer processes wherein the resulting photograph comprises the developed photosensitive layer(s) retained with the image-receiving layer as part of a permanent laminate. In the processes disclosed in this patent, a photographic film unit comprising a photosensitive element is developed in ambient light but further undesired exposure during processing is prevented by a light-absoring material or optical filter agent which is retained in the processed film unit. In a preferred embodiment, the optical filter agent is a pH-sensitive dye, i.e., a dye possessing spectral absorption characteristics that are reversibly alterable in response to changes in environmental pH and particularly, a pH-sensitive dye having a colored or light-absorbing form above a given alkaline pH and a colorless or non-light-absorbing form below said pH. Though the pH-sensitive dye is usually included in the processing composition, it may be initially positioned in the film unit, for example, in a layer over the photosensitive element provided it is in its colorless form if photoexposure is to be effected through that layer. Upon application of an alkaline processing composition, the pH-sensitive dye is converted to its colored form, and after the desired processing time, it is converted back to its colorless form by reducing the environmental pH, e.g., by including an acid-reacting layer as part of the film unit. Examples of pH-sensitive dyes found particularly useful as optical filter agents are the phthalein and naphthalein dyes disclosed in U.S. Pat. No. 3,702,244 issued Nov. 7, 1972 to Stanley M. Bloom, Alan L. Borror, Paul S. Huyffer and Paul T. MacGregor and in U.S. Pat. No. 3,702,245 issued Nov. 7, 1972 to Myron S. Simon and David P. Waller and also the 9-pyridyl fluorene dyes disclosed in U.S. Pat. No. 3,726,675 issued Apr. 10, 1973 to Alan L. Borror.

Copending U.S. Patent Application Ser. No. 836,006 of Stanley M. Bloom, Alan L. Borror and James W. Foley filed concurrently herewith is concerned with the use of a different class of optical filter agents in integral negative-positive film units which are generated from substantially colorless filter agent precursor compounds and are capable of being discharged independently of a change in pH. The colorless filter agent precursor is initially disposed in a layer of the film unit, for example, in a layer coated over the photosensitive element, and subsequent to imagewise exposure of the photosensitive element, the colored optical filter agent is generated by contacting the colorless precursor with base, e.g., an aqueous alkaline processing composition. After remaining in contact with said base for a given time, the colored optical filter agent is discharged by forming a new compound which is substantially colorless and which is different from and non-reversible by a pH change to either said optical filter agent or said precursor. Compounds, i.e., optical filter agent precursors found useful for generating a colored optical filter agent above a given alkaline pH which, in turn, generates a colorless product above said given pH are those possessing (i) an ionizable proton removed in base to generate a chromophore and (ii) a moiety that undergoes an irreversible cleavage reaction with base with resultant destruction of said chromophore to yield a substantially colorless product.

Dutt, J. Chem. Soc., 121 p. 2389 (1922) reported the condensation of saccharin with aromatic amines and phenols in the presence of concentrated sulfuric acid and also in the presence of a fused zinc chloride. The resulting condensation products with saccharin were named "sulfamphthaleins" by analogy to "phthaleins" and "sulfonephthaleins". Though the structure 3,3-di(4'-hydroxyphenyl)2,3-dihydrobenz[d]isothiazole-1,1-dioxide (named "phenolsulfamphthalein") was assigned to the condensation product obtained with saccharin and phenol, it has been determined that the compound corresponding to the proposed structure has properties different from those reported, for example, colorless rather than pink in alkali. Also, it has been found that the compound corresponding to the structure given could not be synthesized by repeating the procedures reported by Dutt.

The present invention is directed to novel sulfam(na)phthaleins which find utility in the above-described photographic products and processes as colorless precursors for providing colored optical filter agents for protecting an imagewise exposed photosensitive element from further undesired exposure during processing in ambient light.

It is therefore the primary object of the present invention to provide novel sulfam(na)phthaleins.

It is a further object of the present invention to provide novel sulfam(na)phthaleins useful as optical filter agents and filter agent precursors in photographic processes conducted in ambient light and in photographic products useful in such processes.

Other objects of this invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the products and compositions possessing the features, properties and the relation of elements which exemplified in the following detailed disclosure, and the scope of the application of which will be indicated in the claims.

According to the present invention, novel 3,3-disubstituted sulfam(na)phthaleins are provided which possess certain substituents on the N atom, i.e., in the 2-position of the sulfam(na)phthalein ring. The 3,3 substituents may be the same or different, and at least one of the 3,3 substituents is a color-producing moiety, i.e., a moiety possessing an ionizable proton that is removed in base to generate a chromophore. These compounds will be defined with greater particularity hereinafter.

As noted above, the subject compounds are useful as optical filter agents and filter agent precursors in photography. Depending upon the 2-substituent of the sulfam(na)phthalein ring, some of the compounds of the present invention function as classical pH-sensitive dyes, i.e., they have a colorless form below a given alkaline pH and in the presence of base above said alkaline pH, generate a light-absorbing form or colored optical filter agent that is decolorized by reversal to the original colorless precursor which is effected by reducing the pH below said alkaline pH. The remaining compounds also generate a light-absorbing from or colored optical filter agent above a given alkaline pH but are rendered colorless without reversal to the original colorless precursor and without a pH reduction. The colored optical filter agents generated by the latter compounds decolorize by undergoing an irreversible cleavage reaction with base at a pH above said alkaline pH to yield a colorless product. Because of their ability to clear independently of a pH reduction, these compounds may be employed in photographic processes where the pH of the system remains substantially unchanged subsequent to processing and also may be employed to permit early viewing of the final image in processes where the pH is reduced during the final stages of processing. Also, because the optical filter agent is irreversibly decolorized to a colorless product inert to changes in pH, the possibility of color reappearing in time due to accidentally increasing the pH is obviated.

For a fuller understanding of the nature and objects of the present invention, reference should be had to the following detailed description.

According to the present invention, there are provided certain ##STR2## 3-disubstituted sulfam(na)phthaleins where one of the 3,3 substituents is a 4'-hydroxyphenyl or a 4'-hydroxynaphthyl moiety and R is selected from lower alkyl having 1 to 4 carbon atoms and phenyl, unsubstituted or substituted with at least one electron-withdrawing group. These compounds in the presence of base above a given alkaline pH are converted from a colorless to a colored compound by the removal of the ionizable proton from the functional --OH of the 4'-hydroxyphenyl (or 4'-hydroxynaphthyl) moiety which is accompanied by the opening of the sulfam(na)phthalein ring. Where the said R is lower alkyl or unsubstituted phenyl, the colored compound formed is rendered colorless by reducing the pH below said alkaline pH. Where the said R is phenyl substituted with at least one electron-withdrawing group, the colored compound formed in the presence of base is converted to a new compound, which is colorless, by irreversible cleavage of the 2-substituent of the sulfam(na)phthalein ring after remaining in contact with said base above a given alkaline pH, usually pH 10, for a predetermined time. The new compound produced, which possesses a different substituent in the 2-position of the sulfam(na)phthalein ring, not only is different from the colored compound and from the colorless precursor but also is non-reversible to either the colored compound or the colorless precursor by changes in pH.

The compounds of the present invention useful in providing colored optical filter agents in the manner described above may be represented by the formula: ##STR3## wherein A' is a 4'-hydroxyphenyl moiety or a 4'-hydroxynaphthyl moiety; B' is a phenyl moiety or a naphthyl moiety provided that A' is a 4'-hydroxyphenyl moiety when B' is a naphthyl moiety; X' represents the atoms necessary to complete a ring-closing moiety selected from a sulfamphthalein moiety and a sulfamnaphthalein moiety; and R is selected from lower alkyl having 1 to 4 carbon atoms and phenyl, unsubstituted or substituted with at least one electron-withdrawing group. By "electron-withdrawing group" is meant a group having a positive sigma value as defined by Hammett's Equation.

By "sulfamphthalein" is intended a 2,3-dihydrobenz-[d]isothiazole-1,1-dioxide moiety and by "sulfamnaphthalein" is intended a 2,3-dihydronaphtho[1,8-de]-1,2-thiazine-1,1-dioxide moiety. The respective 2,3-dihydrobenz[d]isothiazole-1,1-dioxide and 2,3-dihydronaphtho[1,8-de]-1,2-thiazine-1,1-dioxide ring-closing moieties are illustrated below: ##STR4##

It will be understood that the A' moiety and/or the B' moiety and/or the ring-closing moiety of the compounds represented in formula I above may contain one or more substituents in addition to those specified, which substituents should not interfere with the intended use of the compounds.

In a preferred embodiment, the compounds of the present invention may be represented by the formula: ##STR5## wherein A is a 4'-hydroxy-1'-phenyl moiety or a 4'-hydroxy-1'-naphthyl moiety; B is a phenyl moiety or a naphthyl moiety, provided A is said 4'-hydroxy-1'-phenyl moiety when B is said naphthyl moiety; X represents the carbon atoms necessary to complete 2,3-dihydrobenz[d]isothiazole-1,1-dioxide or 2,3-dihydronaphtho[1,8-de]-1,2-thiazine-1,1-dioxide; and R.sup.9 is selected from lower alkyl having 1 to 4 carbon atoms and phenyl, unsubstituted or substituted preferably in the para position with at least one electron-withdrawing group. When substituted with two or more electron-withdrawing groups, they may be the same or different and preferably, are the same.

Typical substituents include branched or straight chain alkyl, such as, methyl, ethyl, isopropyl, n-butyl, t-butyl, hexyl, octyl, dodecyl, hexadecyl, octadecyl and eicosanyl; aryl, such as phenyl and naphthyl; alkaryl and aralkyl, preferably, alkyl-substituted phenyl and phenyl-substituted alkyl, such as p-ethylphenyl, p-octylphenyl, p-dodecylphenyl, benzyl, phenethyl, phenylhexyl and phenyldodecyl; alkoxy, such as, methoxy, ethoxy, butoxy, octadecyloxy, 1-ethoxy-2-(.beta.-ethoxyethoxy); aryloxy, such as phenoxy, benzyloxy and naphthoxy; alkoxyalkyl, such as, methoxymethyl, ethoxymethyl, and dodecyloxyethyl; halo, such as, fluoro, bromo and chloro; trihalomethyl, such as, trifluoromethyl and trichloromethyl; sulfonamido (--NH--SO.sub.2 R.sup.0 wherein R.sup.0 is alkyl, aryl, alkaryl or aralkyl); sulfamoyl (--SO.sub.2 --NH--R.sup.0 wherein R.sup.0 has the same meaning given above); acyl ##STR6## wherein R.sup.0 has the meaning given above); sulfonyl (--SO.sub.2 --R.sup.0 wherein R.sup.0 has the same meaning given above); sulfo; cyano; carboxy; hydroxy; and amino including mono- and disubstituted amino (--NR'R" wherein R' and R" each are hydrogen, alkyl, aryl, alkaryl or aralkyl and R' and R" taken together represent the atoms necessary to complete a saturated heterocyclic ring, such as piperidino, pyrrolidino, N-lower alkylpiperazino, morpholino, thiomorpholino and tetrahydro-2H,4H-1,3,6-dioxazocino or a fused heterocyclic ring system, e.g., quinolizidine.

In a particularly preferred embodiment, the compounds of the present invention may be represented by the formula ##STR7## wherein R.sup.1 and R.sup.2 each are selected from hydrogen, alkyl, alkoxy, chloro and fluoro; R.sup.3 is hydrogen, alkyl, alkoxy or hydroxy; R.sup.2 and R.sup.3 taken together represent the carbon atoms necessary to complete a fused benzene ring; R.sup.4 and R.sup.6 each are selected from hydrogen, alkyl, alkoxy, chloro and fluoro; R.sup.7 is hydrogen, hydroxy, alkyl or alkoxy; R.sup.6 and R.sup.7 taken together represent the carbon atoms necessary to complete a fused benzene ring provided R.sup.2 and R.sup.3 are taken separately when R.sup.6 and R.sup.7 are taken together; R.sup.5 is selected from hydrogen, hydroxy, alkyl, alkoxy, --N,N-(dialkyl)amino, --N,N-(w-R.sup.8 alkyl).sub.2 amino wherein R.sup.8 is hydroxy or halo, preferably chloro, --NHCOCH.sub.3, piperidino, pyrrolidino, N-methylpiperazino, morpholino, thiomorpholino or tetrahydro-2H,4H-1,3,6-dioxazocino; R.sup.4, R.sup.5 and R.sup.6 taken together represent the atoms necessary to complete a fused [ij]quinolizidine ring; X represents the atoms necessary to complete 2,3-dihydrobenz[d]isothiazole-1,1-dioxide or 2,3-dihydronaphtho[1,8-de]-1,2-thiazine-1,1-dioxide; and R.sup.9 has the same meaning given in formula (II) above.

Usually, the alkyl and alkoxy substituents comprising R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6 and R.sup.7 are lower alkyl having 1 to 4 carbon atoms, such as, methyl, ethyl, n-propyl, isopropyl and n-butyl and lower alkoxy having 1 to 4 carbon atoms, such as, methoxy, ethoxy, propoxy and butoxy. Also, the alkyl groups of the --N,N-(dialkyl)amino and --N,N-(w-R.sup.8 alkyl).sub.2 amino substituents comprising R.sup.5 usually are lower alkyl having 1 to 4 carbon atoms. Illustrative electro-withdrawing groups include halo, e.g., fluoro, chloro and bromo; cyano; --SO.sub.2 CH.sub.3 ; ##STR8## and --COCH.sub.3.

In a particularly preferred embodiment X in formula (III) above represents the atoms necessary to complete 2,3-dihydrobenz[d]isothiazole-1,1-dioxide.

Specific examples of compounds within the scope of the present invention are as follows: ##STR9##

The compounds of the present invention may be prepared by reacting (a) a 3-(4'-OP-1'-phenyl/4'-OP-1'-naphthyl)-3-(phenyl/naphthyl)-2,3-dihydrobenz[ d]isothiazole-1,1-dioxide wherein P is a protecting group compatible with organometallic reagents and (b) an acylating agent, ##STR10## wherein W is chloro or bromo and R has the same meaning given above in pyridine to give the corresponding ##STR11## 3,3-disubstituted-2,3-dihydrobenz[d]isothiazole-1,1-dioxide. The N-acylated compound is then treated with weak acid to remove the protecting group(s) to yield the 3,3-disubstituted-2,3-dihydrobenz[d]isothiazole-1,1-dioxide product. Optionally, the N-acylation step may be conducted by sequentially reacting (a) with an alkali metal hydride to form the corresponding N-alkali metal salt followed by reaction with the acylating agent. The compounds containing a 2,3-dihydronaphtho[1,8-de]-1,2-thiazine-1,1-dioxide as the ring closing moiety are prepared by employing a 3-(4'-OP-1'-phenyl/4'-OP-1'-naphthyl)-3-(phenyl/naphthyl)-2,3-dihydronapht ho[1,8-de]-1,2-thiazine-1,1-dioxide in the foregoing procedure. The above described method of synthesizing the compounds of the present invention forms the subject matter of copending U.S. Patent Application Ser. No. 836,010 of Stanley M. Bloom, Alan L. Borror and James W. Foley filed concurrently herewith.

The 3-(4'-OP-1'-phenyl/4'-OP-1'-naphthyl)-3-(phenyl/naphthyl)-2,3-dihydrobenz[ d]isothiazole-1,1-dioxides employed as the intermediates, (a), in the above method may be synthesized by reacting a 3-(4'-OP-1'-phenyl/4'-OP-1'-napthyl)benz[d]isothiazole-1,1-dioxide and a phenyllithium or a naphthyllithium reagent as disclosed and claimed in copending U.S. Patent Application Ser. No. 836,008 of Alan L. Borror, Louis Cincotta, James W. Foley and Marcis M. Kampe filed concurrently herewith. The 3-(4'-OP-1'-phenyl/4'-OP-1'-naphthyl)benz[d]isothiazole-1,1-dioxide is prepared by converting a blocked 4-halophenol or a blocked 4-halo-1-naphthol to the corresponding Grignard or lithium reagent and then reacting this reagent with saccharin or saccharin pseudo-chloride. 3-(4'-OP-1'-phenyl/4'-OP-1'-naphthyl)benz[d]isothiazole-1,1-dioxides form the subject matter of copending U.S. Patent Application Ser. No. 836,024 of Alan L. Borror, Louis Cincotta, Ernest W. Ellis, James W. Foley and Marcis M. Kampe filed concurrently herewith.

The method of aforementioned application Ser. No. 836,008 is useful in synthesizing intermediates for the subject compounds wherein the A and B moieties are either the same or different. Intermediates for the subject compounds wherein the A and B moieties are the same, i.e., identical, also may be prepared by reacting two equivalents of a blocked phenol (or blocked 1-naphthol) as a Grignard reagent with one equivalent of 3-chlorobenz[d]isothiazole-1,1-dioxide (or 3-chloronaphtho[1,8-de]-1,2-thiazine-1,1-dioxide) as disclosed and claimed in copending U.S. Patent Application Ser. No. 836,004 of Stanley M. Bloom, Alan L. Borror and James W. Foley filed concurrently herewith.

As discussed in the aforementioned applications, the protecting groups selected for preparing the blocked phenols or 1-naphthols and for blocking other substituents as may be necessary should be compatible with lithium and Grignard reagents and should protect the hydroxyl and other groups against reaction under conditions encountered in the synthesis of the starting materials and the intermediates and in the subsequent steps in the synthesis of the products. In addition, the protecting group(s) selected should be capable of being easily removed under neutral or weakly acid conditions to regenerate the hydroxyl and other groups and yield the desired product.

For convenience, the specifications of aforementioned applications Ser. Nos. 836,004, 836,008, 836,024, and 836,010 are incorporated herein.

The following examples are given to further illustrate the present invention and are not intended to limit the scope thereof.

Preparation of the compound having the formula: ##STR12## (a) 2'-tetrahydropyranyl 4-bromophenyl ether (9.0 g.) in 20 ml. of tetrahydrofuran was added dropwise to 0.85 g. of magnesium in 20 ml. of tetrahydrofuran under nitrogen. After addition was complete, the dispersion was refluxed for 2 hours and then saccharin pseudo-chloride (3.5 g.) was added portionwise. An exotherm was observed, and the green solution that formed turned yellow-brown. The reaction solution as stirred overnight and then slowly added to 500 ml. of water. The precipitate that formed was slowly filtered and the solid obtained was dissolved in ether, dried and evaporated to yield 8.5 g. of light yellow solid having the formula: ##STR13## (b) The compound as prepared in step (a) (1.0 g.) was placed in 10 ml. of dioxane and 0.08 g. of sodium hydride (as 57% oil dispersion) was added at room temperature under nitrogen. (Hydrogen evolution was slow). The solution went from light yellow to greenish then to yellow. The reaction was accelerated by heating to about 50.degree. C. and then allowing the solution to cool to room temperature, about 1 hour. To the resulting solution comprising the N-sodium salt of Compound A was added 0.18 ml. of ethylchloroformate and the reaction mixture was stirred over the weekend. (c) To remove the protecting groups, the solution was poured into 20 ml. of conc. HCl. After stirring for 15 minutes, the solution went from pink-red to brown. The precipitate that formed was filtered and dried under vacuum. Crystallization from 1:1 methanol-water gave 0.5 g. of the title compound as a white solid.

Tetrahydropyranylation of p-bromophenol was carried out as follows:

To 10.5 ml. of dihydropyran containing 2 drops of conc. HCl was added 10.0 g. of p-bromophenol. (The reaction was exothermic; temperature rose to 35.degree. C.) After the addition was complete, the colorless solution obtained was heated to 50.degree. C. and allowed to cool with stirring for 1 hour. The solution was extracted with 20 ml. of ether and 10 ml. of 10% NaOH. The ether layer was dried over anhydrous Na.sub.2 SO.sub.4 and evaporated under reduced pressure to leave an oil. 80 ml. of ethanol was added to the oil and the resulting ethanol solution was allowed to stand. The white crystals that formed were recovered by filtration and dried under vacuum to yield 7.3 g. of the blocked phenol. The mother liquor was concentrated to 0.5 its original volume and cooled. More crystals formed which were isolated to yield an additional 2.1 g. of blocked phenol.

Preparation of the compounds having the formulae: ##STR14##

The title compounds were prepared according to the procedure described in Example 1 above except that the acylating agents employed in step (b) were ##STR15## respectively.

The intermediate having the formula was prepared as follows: ##STR16##

(a) N-(p-bromophenyl)morpholine (0.4 g.) was added to 20 ml. of tetrahydrofuran (THF) and the solution cooled to -65.degree. C. To the solution was added 0.69 ml. of 2.4 M butyllithium in hexane with stirring and stirring was continued for 1 hour. (After 15 minutes the solution became cloudy and a white precipitate formed.) To this solution was added 0.5 g. of 3-(3',5'-dimethyl-4'-methoxymethoxy-1'-phenyl)benz[d]-isothiazole-1,1-diox ide in 2 ml. THF at -65.degree. C. under nitrogen. The resulting reaction mixture was a clear orange-yellow solution. The reaction mixture was stirred for 1 hour, poured into 100 ml. of water, made acidic with conc. hydrochloric acid (pH 6), and extracted with ether. The ether was dried over Na.sub.2 SO.sub.4 and evaporated leaving an oil. The oil was taken up in ligroin (boiling range 30.degree.-60.degree. C.) and refluxed for 1 hour. The white solid that formed was collected to give 0.7 g. of the title compound.

The intermediates having the formulae ##STR17## were prepared by reacting 3-(3',5'-dimethyl-4'-methoxymethoxy-1'-phenyl)benz[d]isothiazole-1,1-dioxi de with the selected aryl lithium reagent as described above. The lithium reagents employed were ##STR18##

N-(p-Li-phenyl)tetrahydro-2H,4H-1,3,6-dioxazocine may be prepared by reacting the corresponding p-halophenyl compound with n-butyllithum. The N-(p-halophenyl)tetrahydro-2H,4H-1,3,6-dioxazocines are prepared by reacting p-halo-N,N'-di(.beta.-hydroxyethyl)aniline with certain dihalomethanes in the presence of a solid alkali metal hydroxide or concentrated aqueous solution thereof and a quaternary ammonium salt. These compounds and their preparation form the subject matter of U.S. Patent Application Ser. No. 836,066 of Louis Cincotta, James W. Foley and Marcis M. Kampe filed concurrently herewith.

The 3-(3',5'-dimethyl-4'-methoxymethoxy-1'-phenyl)benz[d]isothiazole-1,1-dioxi de having the formula: ##STR19## used above was prepared as follows:

(i) Into a 2 liter three neck flask, fitted with a mechaical stirrer, nitrogen inlet and a dropping funnel, was placed 700 ml. of dry chloroform. The flask as immersed in an ice-water bath. Powdered phosphorus pentoxide (300.0 g.) was added to the vigorously stirred, cold chloroform. To this mixture was added over a 1 hour period a solution of 4-bromo-2,6-dimethylphenol (201.0 g.) in 400 ml. of dry dimethoxymethane. During this time the phosphorus pentoxide powder fused into an amorphous mass and stirring became difficult. TLC analysis (9:1 petroleum ether-ethyl acetate on silica gel) indicated that much unreacted starting phenol was still present. The temperature of the reaction mixture was allowed to rise to about 25.degree. C. Additional 50 g. increments of phosphorus pentoxide were added to the stirred reaction mixture every 30-45 minutes until TLC analysis indicated the absence of starting phenol. The organic layer was decanted, washed with two 250 ml. portions of aqueous 10% sodium hydroxide and dried over calcium sulfate. The solent was removed under reduced pressure leaving a pale yellow oil which was distilled from 25 g. of anhydrous potassium carbonate to give 220.0 g. of 4-bromo-2,6-dimethylmethylenemethoxypheny ether as a colorless oil (boiling point 112.degree. C. and 0.5 mm Hg).

(ii) 4-Bromo-2,6-dimethyl-methylenemethoxyphenyl ether (85.04 g.; 0.347 mole) was dissolved in approximately 800 ml. of tetrahydrofuran. The solution was cooled to -75.degree. C. under a nitrogen blanket, and 2.4 M n-butyllithium in hexane (144.8 ml; 0.346 mole) was added dropwise. Addition was completed within a 2 hour period giving a white slurry.

(iii) Saccharin (61.2 g; 0.334 mole) was dissolved in 600 ml. of dry tetrahydrofuran, and the solution was cooled to approximately -75.degree. C. 2.4 M n-butyllithium in hexane (130.4 ml; 0.311 mole) was slowly added dropwise to the cooled solution under a nitrogen blanket. The temperature was not allowed to rise above -70.degree. C. Addition was completed in about 90 minutes, giving a clear, very pale yellow solution.

(iv) The yellow solution obtained in step (iii) was slowly added (over a 3 hour period) to the white slurry obtained in step (ii) while keeping the temperature at -70.degree. C. During this time the solids disappear giving a clear, caramel colored reaction mixture that first tends to darken with time and then gradually lightens. The reaction mixture was allowed to come to room temperature overnight and then was treated with 36.0 g. of ammonium chloride in 250 ml. of water, while cooling in an ice-water bath. The organic portion was decanted and dried over anhydrous calcium sulfate. The solvent was removed under reduced pressure to give a pink colored oil that became solid on standing in open air. The solid was recrystallized twice from 1-propanol, washed with a 60:40% mixture of petroleum ether-tetrahydrofuran and dried under vacuum to give 68.0 g. of the title compound as a white, crystalline solid.

3-(3',5'-dimethyl-4'-methoxymethoxy-1'-phenyl)-benz[d]isothiazole-1,1-dioxi de also was prepared as follows:

Dry tetrahydrofuran (10-15 ml.) was added to magnesium turnings (0.20 g.) under nitrogen. A solution of 4-bromo-2,6-dimethyl-methylenemethoxyphenyl ether (2.0 g.) in tetrahydrofuran (30 ml.) was added gradually to the magnesium turnings with stirring and heating. After about twenty minutes of external heating to reflux, a self-sustaining reaction was oberved. The remaining solution of phenyl ether was then added at a rate to maintain a comfortable reaction. Refluxing with external heating was continued after addition was complete and after one hour, the solution was cooled to room temperature and held under nitrogen. A solution of saccharin pseudochloride (1.89 g.) in tetrahydrofuran (40 ml.) was cooled to -78.degree. C. and the previously prepared solution of magnesium bromide reagent was added dropwise to the pseudo-chloride solution under nitrogen. The resulting reaction mixture was stirred cold for about 2 hours and then stirred at room temperature overnight. The reaction mixture was then cooled in an ice water bath and treated with saturated aqueous ammonium chloride solution. The aqueous solution was extracted with chloroform several times and the combined chloroform extracts washed with water and dried over anhydrous sodium sulfate followed by drying over anhydrous calcium sulfate. Upon removing the chloroform, a colorless oil was obtained which was extracted several times with small portions of light petroleum ether to leave behind a pale yellow tacky tar. The yellow tar was treated with ether leaving behind an off-white solid. The off-white solid was dissolved in a small amount of chloroform, treated with carbon black and filtered through Celite. Upon removing the solvent, the title compound was obtained as an off-white solid which was dried under vacuum in the presence of P.sub.2 O.sub.5. Yield 0.520 g.

3-chlorobenz[d]isothiazole-1,1-dioxide (saccharin pseudo-chloride) was prepared as follows:

35 g. of saccharin and 43.7 g. of PCl.sub.5 were heated at 170.degree. C. for 11/2 hours during which time complete solution occurred and POCl.sub.3 began to reflux. The POCl.sub.3 was removed at reduced pressure to leave a crystalline residue. Diethyl ether was added to the crystalline residue and stirred well. The title compound was recovered as white crystals, 12.5 g. (melting range 146.degree.-147.degree. C.).

The N-(p-bromophenyl)morpholine having the formula ##STR20## was prepared as follows:

25 g. of N-phenylmorpholine was dissolved in 200 ml. of carbon tetrachloride and stirred well. To this was added all at once 27.2 g. of N-bromosuccinimide. There was an exotherm to 45.degree. C. The reaction solution was stirred until the temperature began to decrease and then was heated to reflux for 3 hours. TLC on silica gel with 3/2 petroleum ether/ether indicated that the reaction was complete. The reaction solution was then cooled, the succinimide removed by filtration and the solution evaporated to yield a yellow solid. The solid was dissolved in 250 ml. of ethanol and cooled to give 22 g. of the title compound as white crystals.

The intermediates having the formulae: ##STR21## were prepared according to the procedure given above except that 3-(3',5'-dimethoxy-4'-methoxymethoxy-1'-phenyl)benz[d]isothiazole-1,1-diox ide was reacted with the appropriate lithium reagent, namely, ##STR22## respectively.

The 3-(3',5'-dimethoxy-4'-methoxymethoxy-1'-phenyl)-benz[d]isothiazole-1,1-dio xide used above was prepared as follows:

(i) Using an 18 gauge needle-syringe, 20.0 mls. of n-butyllithium (2.4 M in hexane) was added dropwise over 1 hour to a solution of 9.16 g. of saccharin (previously dried overnight at 80.degree. C. in vacuo) in 250 mls. of dry tetrahydrofuran under nitrogen at -75.degree. C. to -73.degree. C. with rapid stirring. The reaction solution comprising the N-lithium salt of saccharin in tetrahydrofuran was used directly in step (iii) without isolating the lithium salt.

(ii) In a dried 1 l. flask, 13.86 g. of 4-bromo-2,6-dimethoxy-methylenemethoxyphenyl ether was dissolved in 300 mls. of dry tetrahydrofuran under nitrogen, and 20.83 mls. of n-butyllithium (2.4 M in hexane) was added dropwise with stirring at -75.degree. C. After addition was complete, the reaction solution was stirred at -75.degree. C. for about 30 minutes.

(iii) The solution of saccharin lithium salt prepared in step(i) was transferred to an addition funnel using a double-tip needle under nitrogen pressure and added to the solution of 4-Li-2,6-dimethoxy-methylenemethoxyphenyl ether prepared in step (ii) over about 15 minutes with stirring at a temperature of -75.degree. C. to -70.degree. C. The reaction mixture was stirred for about 2 hours at -75.degree. C. and then warmed to 0.degree. C. during an hour.

(iv) A solution of 5.2 g. of ammonium chloride in 175 mls. of water was added dropwise to the reaction mixture of step (iii) and the reaction mixture was transferred to a 1 l. separatory funnel. After the two phases separated, the aqueous phase was removed and the pH was lowered from about 11 to about 6-7 by the dropwise addition of aqueous 5% hydrochloric acid solution. (A color change from yellow to colorless was observed). The aqueous phase was returned to the separatory funnel, partitioned and the aqueous phase again separated and then extracted with fresh ether (100 mls.). The ether and tetrahydrofuran/hexane extracts were combined, dried over magnesium sulfate overnight, filtered and the solvent removed to leave a yellow oil which crystallized. Ether (100 mls.) was added to the crystalline material and the crystalline material was ground under ether in a mortar, filtered, washed with more ether followed by petroleum ether and air dried. A second crop was collected from the filtrate to give a total yield of 13.0 g. of the title compound.

The methoxymethylation of 4-bromo-2,6-dimethoxyphenol was carried out as follows:

To a 3 liter flask was added 300 g. of P.sub.2 O.sub.5 under nitrogen and 800 ml. of chloroform (previously dried over P.sub.2 O.sub.5). The mixture was cooled to -15.degree. C. with a dry-ice acetone bath and then 50 g. of 4-bromo-2,6-dimethoxyphenol in 800 ml. of dimethoxymethane was added over a 25 minute period while maintaining the temperature at -15.degree. C. or below. To the resulting reaction mixture was added 1 ml. of conc. sulfuric acid and then the temperature was allowed to come to room temperature. During this time, a tacky mass of P.sub.2 O.sub.5 developed. The reaction mixture was stirred for 3 hours. TLC indicated that the reaction was complete. The chloroform was then decanted into 400 ml. of 10% aqueous sodium hydroxide, stirred well and the chloroform layer separated, washed with water, dried over Na.sub.2 SO.sub.4 and evaporated to leave light tan crystals. n-Propanol was added to the crystalline residue, stirred and filtered to give 32.7 g. of the title compound as white crystals (melting range 98.degree.-100.degree. C.).

The intermediate having the formula was prepared as follows: ##STR23##

55 g. of 4-bromo-2,6-dimethoxy-methylenemethoxyphenyl ether was dissolved in 300 ml. of anhydrous tetrahydrofuran under a stream of nitrogen. The solution was cooled to -65.degree. C. during which time some of phenyl ether reprecipitated. To this was added 79 ml. of butyl-lithium (2.4 M in hexane) at a range to keep the temperature below -50.degree. C. The resulting solution was cooled to -65.degree. C. and was stirred for 30 minutes. To this solution was added 19 g. of saccharin pseudo-chloride in two portions so as to keep the temperature below -40.degree. C. The reaction solution was cooled to -65.degree. C. and was stirred for 40 minutes. TLC showed one main spot on silica gel with 10 ml. ether/2 drops methanol. The reaction solution was poured into 2000 ml. of water and made acidic to pH 6. The mixture changed color from orange to yellow at this pH. The mixture was extracted two times with ether (2 liters) and the ether washed with water. The ether was dried over sodium sulfate and evaporated to leave a light yellow solid. The solid was recrystallized from 450 ml. of n-propanol to give 42 g. of the title compound as off-white crystals (melting range 151.5.degree.-152.5.degree. C.).

It will be appreciated that using the procedures described in the foregoing Examples, the above intermediates may be reacted with an acylating agent of the formula ##STR24## wherein W and R have the same meaning given previously to yield the corresponding ##STR25## compounds which compounds may be treated with weak acid to remove the protecting group(s) and give the respective products.

Also, it will be appreciated that 1-naphthols may be substituted for phenols in the procedures described in the foregoing examples to give the corresponding 4'-hydroxy-1'-naphthyl compounds. For example, the methoxymethyl ether and the 2'-tetrahydropyranyl ether of 4-bromo-1-naphthol were prepared according to the methoxymethylation and tetrahydropyranylation procedures described above followed by conversion to the corresponding 4-lithium derivatives by reaction with n-butyllithium also as described above. The lithium derivatives may be reacted with the N-lithium salt of saccharin to give the corresponding 3-(4'-OP-1'-naphthyl)-benz[d]isothiazole-1,1-dioxide which, in turn, may be reacted with the selected phenyllithium reagent to give the corresponding 3-(4'-OP-1'-naphthyl)-3-(phenyl)-2,3-dihydrobenz[d]isothiazole-1,1-dioxide .

Where it is desired to prepare sulfamnaphthaleins, 2,3-dihydro-3-oxo-naphtho[1,8-de]1,2-thiazine-1,1-dioxide or its pseudo chloride may be substituted for the saccharin reagents used in the foregoing Examples to give the corresponding sulfamnaphthalein intermediates and products. The pseudo-chloride may be prepared from the 3-oxo thiazine by reaction with PCl.sub.5 as described above for the preparation of saccharin pseudo-chloride.

As noted above, some of the compounds of the present invention are useful as pH-sensitive indicator dyes and have reversibly alterable spectral absorption characteristics in response to changes in pH. The remaining compounds generate a colored form above a given alkaline pH but decolorize independently of a pH reduction by undergoing cleavage above said alkaline pH to yield a new compound which is colorless. For example, the colored compound generated from a precursor possessing a ##STR26## moiety in the 2-position of the benz[d]isothiazole-1,1-dioxide ring has a half-life (T1/2) in approximately 1 N NaOH of about 2.5 minutes. By T1/2 is meant the time measured for one-half of the colored species to decolorize.

The use of compounds in photographic products and processes as colorless precursors for providing colored optical filter agents capable of decolorizing independently of a pH change forms the subject matter of copending U.S. Patent Application Ser. No. (Case 5485) of Stanley M. Bloom, Alan L. Borror and James W. Foley filed concurrently herewith. For convenience, the specification of this application is incorporated herein.

Since certain changes may be made in the above product and process without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.