Alcoholates of orthophosphate salts of 4-amino, 3-methyl, N-ethyl, N-beta methanesulfonamidoethyl aniline
I United States Patent 1 [111 3,875,227  
 Kroll et al. Apr. 1, 1975 [54] ALCOHOLATES OF ORTHOPH QSPHATE 3,574,619 4/1971 Surask 96/66.l  
 SALTS ()F 4 AM]N(), 3 Y L, METHYL, 21/ gent et 21:. a 1 6m et a ANILINE OTHER PUBLICATIONS 75 Inventors: Harry Kroll, Warwick; Alderic R. JACS 731 3114 3116 3117 (1951) Bent Therrien, Woonsocket, both of RI. Primary E.\&#39;ammerHenry R. Jules Asslgnee: Phlhp Chemical Assistant Examiner-S. D. Winters Corporation, Pallsades Park, Attorney, Agent, or Firml(irschstein, Kirschstein, 22 Filed: Feb. 23, 1973 Ottmger &amp; Frank [21] Appl. No.: 335,341 57 ABSTRACT This invention discloses a new class of phosphate salts [52] U.S. Cl. 260/556 A, 96/22, 96/55, of N-ethyl, N-beta rnethanesulfonamidoethyl, 4-  
  96/566, 96/66 R, 96/66.l amino, 3-methyl aniline and a method for making [51] Int. Cl. C070 143/74 these salts. The phosphate salts of this invention are [58] Field of Search 260/556 A; 96/22 useful as color developing agents in developing solutions for processing photographic color negatives, [56] References Cited color positives, color plates and color cinemato- UNITED STATES PATENTS graphw films- 3,297.760 l/l967 Von Hessert et al. 96/66 R 8 Claims, N0 Drawings ALCOHOLATES OF ORTHOPI-IOSPHATE SALTS OF 4-AMINO, 3-METHYL, N-ETHYL, N-BETA METHANESULFONAMIDOETHYL ANILINE BACKGROUND OF THE INVENTION 1. Field of the Invention:  
  Color developing agents constituting alcoholates of orthophosphate salts of 4-amino, 3-methyl, N-ethyl. N- beta methanesulfonamidoethyl aniline, the incorporation of said compound as a principal functional component of a liquid packaged developer concentrate, the incorporation of such compound in color developing working solutions and the use of such compounds in the color development of color film.  
 2. Description of the Prior Art:  
  The formation of colored negative or positive images from exposed sensitized silver halide color emulsions is a demanding process which requires a high degree of purity in the color developing solutions. The chemistry and physics of the process are described by J. R. Thirtle and D. M. Zwick in Kirk-Othmer Encyclopedia of Chemical Technology, Volume 5, pages 812-845 (2nd edition). The process is applicable to the developing of photographic color negatives, photographic color positives, photographic color plates and colored cinematographic films. The developers currently and for many years past used in the trade to process such emulsions contain as the color developing agent N,N,disubstituted p-phenylenediamines. In the course of color development, the color developing agent reacts with phenolic or active methylene couplers that are incorporated in sundry layers of the emulsion on a transparent base or paper and forms non-diffusing dyes that constitute the final image.  
  Such color developing agents, when in contact with exposed silver halide, distributed in three separate emulsion layers, undergo oxidation to quinone diimines which, in turn, condense with the three different color couplers, each of which is present in a different emulsion layer. The amount of quinone diimine formed is directly proportional to the amount of silver halide that has been exposed and, therefore, determines the amount and, hence, the intensity, of dye that is formed. This process is known as oxidative coupling. The combination of the layers of yellow, cyan and magenta dyes in amounts determined by the exposed silver halide can be made to reproduce with a high degree of faithfulness the colors of the photographed subject.  
  It is apparent from this brief description that any impurities present in the working color developer bath which can oxidize the phenylenediamine to the quinone imine or which can couple with the color coupling agents can seriously degrade the quality of the colored image.  
  The color developers in the quinone diimine form can undergo undesirable side reactions which yield in termediates that interfere with the dye forming process. A reaction of this type takes place in a conventional alkaline developing solution. The quinone diimine undergoes an oxidative hydrolysis in which the color develyield quinone diimine in areas remote from the exposed silver halide. Since the quinone diimine formed can produce dye in unexposed areas, the quality of the color reproduction will be poor. The formation of these undesirable by-products can be measured by sensitometric techniques and can be quantitatively assessed. The procedures are described in Mees and James, The Theory of the Photographic Process, Third Edition, page 460.  
  Similar undesirable side reactions can also take place during the manufacture of the color developing agents. If these by-products are allowed to form and are not re moved from the color developing agent during its manufacture, these products are carried over into the developing bath and interfere with the reproduction of the true color values of the photographed image.  
  In some commercial color processes it is the practice to segregate different constituents of a working color developer bath into separate components (compositions), each of which is concentrated as far as is practical, and each of which is liquid to facilitate mixing and dilution with water (upon occasion some of the components may be dry), and each of which is compartmented, that is to say, packaged in a receptacle separate from other packaged components, all of the packaged components of a developer usually being contained in a single box. Any given component need not be, and usually is not, composed of a single ingredient such, for example, as a color developing agent. It is common, for example, to include a liquid solvent which may be water and/or an organic solvent and/or solubilizing agent and/or a mixture of different liquids as an ingredient of each component. The organic solvent and/or solubilizing agent, if present, may have as their sole function that of a carrier or they also may have a photographic function such, for example, as boosting the dye formed when the color developing agent reacts with a color coupler. Additionally, there are various adjuvants which are used in a working color developer bath, examples of which are pH buffering systems, preservatives, sequestrants, anti-foggants, enhancers, and the like. Some of these require different solvent systems and, for such reason, are separately compartmented. Others tend to be unstable when kept for periods of time in the same compartment with different ones of the compounds used. Others have a tendency to react with different ones of the compounds used. Others require the presence of co-solvents, etc. Hence, separate compartmenting of different components is an accepted practice in the art. The principles involving separate compartmentation and concentrating and allocation of different compounds to different compartments, as well as the concept of mixing the different compartmented compounds and diluting the same with water at the time of use, are well known.  
  There are a number of color developing agents produced commercially that are used in different color photographic processes. The compound which is used in the largest amounts as a color developing agent is 4- amino, 3-methyl, N-ethyl, N-beta methanesulfonamidoethyl aniline. This compound, as a complex sulfate salt (the sesqui-sulfate monohydrate) is marketed under the name of CD-3 and is used in the majority of photographic color processes developed by Eastman Kodak Co., Rochester, NY. CD-3 has the following structural formula:  
 CH CH N&#39;HSO CH Ky/ZZ 23 The synthesis of CD-3 base C H CH CH NHSO CH is described by R. L. Bent, et al. in the Journal of the American Chemical Society, 73,3100-3125 (1951). In the commercial manufacture of this color developing agent, the nitroso precursor is reduced with hydrogen to the CD-3 base in the presence of catalytic amounts of palladium. The solvents generally used in this step are the lower aliphatic alcohols such as methyl, ethyl, n-propyl or isopropyl alcohols. The solution is filtered from the catalyst and sulfuric acid containing the required amount of water is added to this solution to form the sesqui-sulfate monohydrate salt. A characteristic of the salt formation is that it separates as an oily liquid and, after a period of time, it solidifies. The length of time required for the crystal phase to form from the oil depends on the agitation, temperature, water content, and purity of the CD-3 base.  
 CD-3 base The initial formation of an oily liquid has several disadvantages, the major one being that any impurities present in the oil phase become trapped in the crystals. These impurities in the crystal solid are carried over to the concentrate and then to the photographic developing bath, and if they are reactive in the chemical system for color development described in the foregoing discussion, they seriously affect the quality of the color image, negative or positive.  
  The formation of deleterious impurities in CD-3 can be readily demonstrated by neutralizing the CD-3 base under a variety of conditions in which air or oxygen is in contact with the solution. The CD-3 sesqui-sulfate monohydrate thus isolated can be incorporated into a working color developer bath which is used to develop exposed test strips containing silver halide and color coupling agents. A11 preparations of CD-3 sesquisulfate monohydrate made under conditions where oxygen contact is permitted during the neutralization show a high blue fog in the sensitometric measurements. This can be interpreted as being due to the formation of a reactive impurity that can do any or all of the following:  
 1. be oxidized by silver halide to a reactive species;  
 2. can oxidize the phenylenediamine color developer to a reactive species;  
 3. can couple with the color forming agent to form a dye;  
 4. can diffuse throughout a given layer to develop color in non-exposed areas.  
  Although the reasons for the formation of the above described impurities are not completely clear, it is believed that their formation is due to an oxidative hydrolysis described by K. T. Finley and L. K. J. Tong in their chapter Quinonediimines and Related Compounds in The Chemistry of Carbon-Nitrogen Double Bond&#34; 1st Edition), edited by Saul Patal. In the cited publication, quinone diimines, the oxidation products of 1,4- phenylenediamines, are hydrolyzed to quinone monoimines. The complicating and undesirable effects of quinone monoimines in the color development process are described by J. R. Thirtle and D, M. Zwick in Color Photography&#34; Kirk-Othmer Encyclopedia of Chemical Technology (2nd Edition), Vol. 5, page 821.  
  The oxidative hydrolysis that may occur with CD-3 can be depicted by the following equations:  
 quinone diimine The formation of the quinone monoimine in Equation 2 is supported by chemical data disclosed in the cited references. The deleterious effects of quinone monoimines on the color quality of color negatives and positives is recognized and requires no additional documentation.  
 SUMMARY OF THE INVENTION 1. Purposes of the Invention It is the primary object of the present invention to provide an improved color developing agent and method of making the same which is not subject to the foregoing drawbacks.  
  More specifically, it is an object of the invention to provide a new class of alcoholates of orthophosphate salts of 4-amino, 3-methyl, N-ethyl, N-beta methanesulfonamidoethyl aniline which can be used as color developing agents in concentrates, in working color developer baths and in color development methods to develop images in exposed color negatives, positives, plates and cinematographic films based on the Eastman Kodak system for developing Kodak Kodacolor film.  
  A further object of the invention is to provide a method for making the aforesaid orthophosphate salts as alcoholates which method eliminates the formation of undesirable impurities that interfere with the color developing process.  
  The use of the new alcoholates of orthophosphate salts in photographic developing baths are disclosed and claimed in co-pending application Ser. No. 335,343 filed by David K. Bulloch and Hong Zoon Kim on Feb. 23, 1973 for N,N, DISUBSTITUTED p- PHENYLENEDIAMINE PHOSPHATES, A LIQUID PACKAGED DEVELOPER CONCENTRATE CON- TAINING THE SAME FOR ADMIXTURE WITH OTHER MATERIALS IN A MULTI-PACKAGE CARTON AND FOR DILUTION WITH WATER TO FORM A COLOR DEVELOPER WORKING SOLU- TION. A COLOR DEVELOPER CONCENTRATE quinone monoimine CONTAINING SUCH A PHOSPHATE AND A METHOD OF USING SAID WORKING SOLUTION FOR COLOR DEVELOPMENT OF COLOR FILM.  
  Other objects of the invention in part will be obvious and in part will be pointed out hereinafter.  
 2. Brief Description of the Invention:  
  The new color developing agent of the present invention is a methyl, ethyl or propyl alcoholate of 4-amino, S-methyl, N-ethyl, N-beta methanesulfonamidoethyl aniline orthophosphate. 4-amino, 3-methyl, N-ethyl, N-beta methanesulfonamidoethyl aniline hereinafter will be referred by the acronym AEMT which is derived from its alternate name in the Geneva system of nomenclature to wit, 4-amino-N ethyl, N-beta methanesulfonamidoethyl-m-toluidene. The term alcoholate&#34; as used herein denotes the presence of an alcohol of crystallization. This new color developing agent can be employed as the major ingredient of a color developing agent concentrate including at least said color developing agent in a water solution which concentrate is to be mixed with other concentrates of different compounds and water to form a working color developer bath that is used for the color development of color film. Such alcoholates are manufactured by the catalytic hydrogenation of a nitroso precursor in a lower aliphatic alcohol such as methyl alcohol, ethyl alcohol, n-propyl alcohol or isopropyl alcohol and reacting of the resultant base with orthophosphoric acid.  
 PREFERRED EMBODIMENTS OF THE INVENTION The base required for the orthophosphate salt is prepared by the catalytic hydrogenation of 4 nitroso, 3- methyl, N-ethyl, N-beta methanesulfonamidoethyl aniline. The reduction can be carried out in a lower aliphatic alcohol such as methyl alcohol, ethyl alcohol, n-propyl alcohol or isopropyl alcohol. When the nitroso intermediate has been reduced to the AEMT base, one mole of orthophosphoric acid is added for each mole of AEMT. This amount is the amount required for a stoichiometric reaction. If desired, an additional amount of the acid can be employed, a 5% excess yielding excellent results and up to a 200% excess providing commercially satisfactory results. At temperatures above 50C, the reaction mixture remains clear. The solution is filtered to remove the catalyst. The filtered solution, when cooled to room temperature or below, deposits a white crystalline solid. This solid has the composition:  
 \ -H PO -ROH CH3\ CH- CH3/ and corresponds to the alcohol used in the reduction. The incorporation ofthe alcohol ofcrystallization is totally unexpected and has not been previously observed. [See Bent, et al.. Journal of American Chemical Society, 73,3100 (1951)].  
  In the preferred embodiment of the invention, the reduction and acidification steps are carried out in a single vessel by introducing the orthophosphoric acid directly into the reactor containing the palladium catalyst and the reduced nitroso precursor in solution with the lower aliphatic alcohol. thereby eliminating the possibility of forming the undesirable quinone monoimine since the reducing environment prevents this oxidation reaction from taking place. Another and particularly desirable feature is that the orthophosphate salt prepared in a lower aliphatic alcohol crystallizes directly to the solid without the separation of a liquid phase prior to solidification; the direct crystallization of the alcoholates of the orthophosphate salt results in a purer product than that which is obtained by the solidification of an oil.  
  Although it is possible to add sulfuric acid directly to a lower aliphatic alcoholic solution of the base containing a palladium catalyst to make an alcoholate ofCD-3, there are practical problems which prevent this procedure from being used in a manufacturing operation. The main difficulty is the separation of the oil which makes the removal of the catalyst cumbersome when conventional filtering equipment is used.  
  The lower aliphatic alcoholates of orthophosphate salts of AEMT can be incorporated in working color developer baths to produce colored photographic images as descried in the examples given by Weissberger in US. Pat. No. 2,193,015 or can be incorporated in the concentrates and in the formulations given for working color developer baths as set forth in the aforesaid co-pending application. The amount of such alcoholate of orthophosphate salts is such that the free AEMT base of the color developing agent is present in an amount by weight of free base in the aforesaid formulations.  
  The following are specific examples of manufacturing steps for alcoholates of the present invention and analytical fingerprints of such alcoholates.  
 EXAMPLE 1 In a 1 liter Parr low pressure hydrogenator (Parr Equipment Co., 211 Fifty-Third Street, Moline, 111. 61265) there is charged 122 g. (0.566 moles) of 4- nitroso, 3-methyl. N-ethyl, N-beta methanesulfonamidoethyl aniline. 400 g. of methyl alcohol, and a catalyst composed of 4.0 g. of 5% palladium on charcoal and 6 g. Dareo KB (Atlas Chemical Co., Wilmington, Del.), an activated carbon. The mixture is warmed to C and then the air in the head space in the hydrogenator is evacuated until the methyl alcohol begins to boil. Hydrogen thereupon is introduced into the reactor to a pressure of 40 to psi, the reactor contents being maintained at a temperature of 40-50C. As the hydrogen is taken up by the reductions reaction, more hydrogen is introduced to maintain a pressure of 40-60 psi. When hydrogen no longer is consumed, the gas in LII the reaction flask is vented and 44 g. (0.388 moles) of orthophosphoric acid is thoroughly mixed into the solution which upon such acidification contains the methyl alcoholate, i.e., methanolate, of the orthophosphate salt ofAEMT in the lower aliphatic alcohol. The solution at 50C, is filtered through a Buckner funnel precoated with a filter aid to remove the catalyst. The clear filtrate is cooled to 15C and held for several hours during which time a slightly off-white crystalline solid is deposited. Said solid is removed by filtration, washed with cold methyl alcohol and the filter cake dried in vacuo at 50C. The yield of solid is 125 g.  
 The product has the following structure:  
 I -H PO -CH OH l CH 3 4- 3 The analytical data for the solid are:  
 Calculated for C H- O N PS Theory (0?) Found /l Carbon 38.) 38.7 Hydrogen 6.97 6.87 Nitrogen 10.45 10.52 Phosphorous 7.75 7.80 Methyl alcohol l l 8.0 7.8 Phosphoric acid (2) 24.4 24.2  
 t l J Determined by gas chromatography. (2) Determined by titration with standard base in isopropyl alcohol.  
 lnfra Red Spectrum:  
 lonic phosphate band present at 1000 to l cm.  
 Melting point (uncorr.) l34l35C NMR Spectrum:  
 Absorption band of protons of methyl group of methyl alcohol present at 3.4 ppm.  
 EXAMPLE 11 The same reaction was carried out as described in Example 1 except that the methyl alcohol was replaced with ethyl alcohol. The orthophosphate salt of AEMT contained 10.7% ethyl alcohol, i.e. ethanolate. Theory for one ethyl alcohol of crystallization is 11.1%. Melting point (uncorr.) 134l40C.  
 EXAMPLES Ill and IV The same reactions were carried out as described in Example 1 except that the methyl alcohol was replaced with n-propyl alcohol for Example 111 and isopropyl alcohol for Example IV. The resultant products were respectively the n-propyl alcoholate and the isopropyl alcoholate of the ortho-phosphate salt of AEMT.  
  The amount of palladium-charcoal catalyst may vary from 0.1% by weight to 10% by weight of the alcohol solution of the AEMT.  
  It thus will be seen that there are provided compounds and method of making the same which achieve the several objects of the invention and which are well adapted to meet conditions of practical use.  
  As various possible embodiments might be made of the above invention. and as various changes might be made in the embodiments above set forth. it is to be un derstood that all matter herein described is to be interpreted as illustrative and not in a limiting sense.  
  Having thus described the invention there is claimed as new and desired to be secured by Letters Patent:  
  1. A crystal orthophospate salt of 4-amino. 3-methyl. N-ethyl, N-beta-methanesulfoimmidoethyl aniline containing an alcohol of crystallization and having the structure:  
 where ROH is an aliphatic alcohol having one to three carbon atoms selected from the group consisting of methyl alcohol. ethyl alcohol. n-propyl alcohol and isopropyl alcohol.  
  2. A method for making a salt of claim 1 which comprises reacting 4-nitroso. 3-methyl. N-ethyl, N-betamethanesulfonamidoethyl aniline with hydrogen in the presence of a hydrogenating palladium-charcoal catalyst and concurrently reacting in the presence of the hydrogen the 4-amino. 3-methyl. N-ethyl. N-betamethanesulfonamidoethyl aniline formed by the aforesaid hydrogenation with at least a molar equivalent of orthophosphoric acid and with a low molecular weight aliphatic alcohol having one to three carbon atoms selected from the group consisting of methyl alcohol. ethyl alcohol. n-propyl alcohol and isopropyl alcohol. the catalyst being present in an amount of from 0. 171 by weight to 10% by weight of the total weight of the foregoing components.  
  3. A method as set forth in claim 2 wherein the alcohol is methyl alcohol.  
  4. A method as set forth in claim 2 wherein the alcohol is ethyl alcohol.  
  5. A method as set forth in claim 2 wherein the alcohol is n-propyl alcohol.  
  6. A method as set forth in claim 2 wherein the alcohol is isopropyl alcohol.  
  7. A method as set forth in claim 2 wherein the reaction between the acid and the aniline takes place in a reducing environment.  
  8. A method as set forth in claim 2 wherein the addition takes place at a temperature of at least 50C. wherein the reaction mixture is filtered to remove the catalyst and wherein the filtered reaction mixture is cooled to at least room temperature to deposit the alcoholate as a crystalline solid.