US2490745A - Cellulose carboxylic ester silver halide emulsions sensitized with benzothiazole and benzoselenazole quaternary salts - Google Patents

Description

Patented Dec. 6, 1949 UNITED STATES PATENT OFF-ICE Burt H. Carroll and William West, Rochester, N. Y., assignors to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey No Drawing. Application January 13, 1948, Serial No. 2,126

This invention relates to sensitized photographic emulsions and more particularly to cellulose carboxylic ester silver halide photographic emulsions sensitized with benzothiazole and benzoselenazole quaternary salts.

It is known that benzothiazole, benzoselenazole, benzoxazole, napthothiazole, simple thiazole and thiazoline quaternary salts when incorporated in gelatino-silver-halide emulsions for example in a concentration of from 2 to 8 mg. per 100 cc. of emulsion, act as antifoggants for the emulsions. (See United States Patent 2,131,038, dated September 27, 1938.) It is also known that pyridinium and quinolinium quaternary salts act to supersensitize cyanine dyes in photographic silver halide emulsions. (See United States Patent 2,334,864, dated November 23, 1943.) It is also known that surface active quaternary ammonium salts sensitize photographic silver halide emulsions. (See United States Patent 2,271,623, dated February 3, 1942.)

We have now found that substantially non- I surface. active quaternary salts of the benzothiazole and benzoselenazole series sensitize cellulose carboxylic ester silver halide emulsions, although these same quaternary salts act as antifoggants in gelatino-silver-halide emulsions. Moreover, we have found that substantially nonsurface active quaternary salts of simple thiazoles, napthothiazoles and tetrahydrobenzothiazoles do not sensitize cellulose carboxylic ester silver halide emulsions.

It is an object of our invention, therefore, to provide sensitized cellulose carboxylic ester silver halide emulsions. A further object is to provide a process for preparing such emulsions. Other objects will become apparent hereinafter.

The quaternary salts which we employ in practicing our invention are substantially colorless,

substantially non-surface active quaternary salts of the benzothiazole and of the benzoselenazole series, which are devoid of nitro groups. A pre fered group of these quaternary salts are represented by the following general formula:

wherein D represents an o-arylene group of the benzene series containing from 6 to 8 carbon atoms and which is devoid of nitro groups, e. g. the o-phenylene group, a chloro-o-phenylene v n-propylmercapto, n-butylmercapto,

13 Claims. (Cl. 957) group, a methyl-o-phenylene group, a methoxyo-phenylene group, a bromo-o-phenylene group, an ethoXy-o-phenylene group, an ethyl-o-phenylene group, a dimethyl-o-phenylene group, etc., Q represents a sulfur atom or a selenium atom, R represents a primary alkyl group containing from 1 to 4 carbon atoms, 1. e. methyl, ethyl, n-propyl, isobutyl and n-butyl, a primary alkenyl group containing from 3 to 4 carbon atoms, 1. e. allyl, 2-butenyl and 3-butenyl, a. primary hy-, droxyalkyl group containing from 2 to 4 carbon atoms, i. e. B-hydroxyethyl, Y-hydroxypropyl, c hydroxypropyl, 5 hydroxybutyl, 'y hydroxybutyl and fi-hydroxybutyl, a primary alkoxyalkyl group, containing from 3 to 4 carbon atoms, e. g. ,B-methoxyethyl, ,s-ethoxyethyl, B-methoxypropyl and Y-methoxypropyl, R1 represents a hydrogen atom, a methyl group, an ethyl group, an alkylmercapto group containing from 1 to 4 carbon atoms, e. g. methylmercapto, ethylmercapto,

isobutylmercapto, an arylmercapto group containing from 6 to 8 carbon atoms and devoid of nitro groups, e. g. phenylmercapto, p-tolylmercapto, p chlorophenylmercapto, etc., a primary amino group (i. e. -NH2), an alkylamino group containing from 1 to 4 carbon atoms, e. g. methylamino, ethylamino, n-propylamino, n-butylamino, etc., a dialkylamino group containing from 2 to 4 carbon atoms, e. g. dimethylamino, diethylamino, etc., an arylamino group containing from 6 to 8 carbon atoms and devoid of nitro groups, e. g. phenylamino, B-tolylamino, pchlorophenylamino, p-methoxyphenylamino, N-methyl- N-phenylamino, etc., or an aralkylamino group containing from 6 to 8 carbon atoms, and devoid of nitro groups, e. g. N-methyl-N-benzylamino, benzylamino, p-phenylethylamino, etc., and X :represents an anion, e. g. chloride, bromide,

iodide, methylsulfate, ethylsulfate, p-toluenesulinnate; benzen'esulfonate, perchlorate, acetate,

pr'opionate, n-butyrate, thiocyanate, sulfamate, etc

" Examples of the aboveformulated quaternary '..salts which are especially useful are: benzothiazole ethiodide, benzothiazole metho-p-toluenesulfonate, Z-methylbenzothiazole metho-=p-tolu-' ene-sulfonate, 2 -methylbenzothiazole etho-ptoluenesulfonate, 2-methylbenzothiazole alliodide, 2 methylbenzothiazole n butiodide, 5- chloro-2-methylbenzothiazole etho--p-toluenesulfonate, 2-methylmercaptobenzothiazole metho-ptoluenesulfonate, 2-phenylmercaptobenzothiazolej ethiodide, 2-anilinobenzothiazole ethiodide, 2-

The speed increase may be accompanied by a loss in contrast. In the case of cellulose carboxylic ester silver halide emulsions which are optically sensitized by the addition of a sensitizing dye, the increase in speed is approximately the same in the color-sensitized and non-color-sensitized regions of spectral sensitivity. Benzothiazole methiodide or metho-p-toluenesulfonate effect a large speed increase, but with a considerable lowering of contrast. Z-methylbenzothiazole etho-p-toluenesulfonate is very active in increasing speed, with I out reducing contrast as much as the unsubstituted benzothiazole quaternary salt. Z-methylmercaptobenzothiazole metho-p-toluenesulfonate and2-phenylmercaptobenzothiazole ethiodide are very active.

To sensitize cellulose carboxylic ester silver halide emulsions with these quaternary salts, it is only necessary to disperse the quaternary salts inthe emulsion. It is convenient'to add the quaternary salts to the emulsions from solutions in appropriate solvents. Water, methyl alcohol or ethyl alcohol or mixtures of these three solvents are suitable. The concentration of the quaternary salts in the emulsion can vary widely. Usually the optimum sensitizing eifect is obtained at from 0.01 to 0.05 gram per liter of emulsion. However, higher or lower concentrations can be used. The quaternary salts con be addedto the emulsion at any stage of its preparation, but are most advantageously added to the. finished emulsions just vprior to coating the for the quaternary salts. The concentration of the sensitizing dye can vary widely, e. g. from 5 to 100 mg. per liter of emulsion. Ordinarily from 10 to 50 mg. of dye perliter of emulsion sufiices to produce optimum optical sensitization. Both the sensitizing dyes and the quaternary salts should be thoroughly dispersed throughout the emulsions by stirring or other means.

Aseellulose carboxylic ester silver halide emulvsions those described in United States Patent 2,110,491, dated March 8, 1931, in United States :Patent 2,276,322, dated March 17, 1942, and in United States-Patent 2,127,573, dated August 23, 1938, .areexamples. Photographic silver halide emulsions prepared using as vehicle or carrier hydrolyzed cellulose carboxylic esters, such as ;-hydrolyzed cellulose acetate or hydrolyzed cellulose acetate propionate containing from 19 to ,33 per cent by weight of acyl groups are especially useful in practicing our invention. Those containing 20 to 26 per cent by weight. of acyl groups are most advantageously employed. Any cellulose compound especially thosefccntaihifl only carbon, hydrogen, oxygen and amino nitrogen atoms, or ammonium nitrogenatoms, which are soluble in a mixture of ethyl'alcohol and water (containing from to 50 per cent by-volumeof ethyl alcohol) to the extent of 10 g.,per 100 g..of solvent can be employed as the vehicle or carrier for the silver halide. The silver halides can be silver chloride, silver bromide, silver iodide or mixtures of one or more of these silver halides, for example.

The following table illustrates results which can be obtained in accordance with our invention. The emulsionemployed was a hydrolyzed cellulose acetate silver chlorobromoiodide emulsion in which the cellulose acetate contained from 23 to 24 per cent by weight. ofacetyl groups.

Table Speed Gradient Q t Salt 13 ua ems-1W1 1 er 0 v emulsion Total Blue. Total {335 mm Light Blue 1 Light 1 Light Blue None 3, 610 202 1. O0 1.22 Benzothia'zole'methiodide; 0. 025 5, 890 372 1. 1. 19

None 3 7, 230 2, 880 275 v 1. 54 1. 42 1. 32 Benzothiazole methiodide 0. 013 9, 800 4, 680 468 1. 42 1. 05 1. 27 do 0.050 14, 400 5, 600 455 1.04 1.07 0. 97 Benzothiazolc metho-p-toluen ulfonate. 0.025 10, 200 5, 300 478 0. 98 1. 38 1. 21

None 3 2, 950 950 169 1. 41 1.50 1. 36 Z-Methylbenzo-thiazole metho-p-toluene- O 025 4, 780 1, 480 282 1. 31 1. 38 1. 12

sulfonate. (i) do O. 050 6, 610 1, 940 331 1. 1. 27 1. 12 (j) 2-Methylb enzo-thiazole etho-p-toluene- O. 025 4, 660 1, 660 245 l. 46 1. 48 l.

sulfcnate.

(k) None 3 3,160 1, 200 123 1. 62 1. G2 1.62 (2)"-.. 2 l\/Iethyl'mercaptobenzo-thiazole metho- 0 025 4, 160 174 1. 5O l. 58

' ptoluene-sulfonate. (1a)..-. 2-glganylmercaptorbenzothiazolc et l1i0* 0 025 7, 230 2, 950 324 1. 84 1. 25 1. 20

l Total ininus-blu e speed' was measured through .a iilter' whichtransmittedsubstantially 110 light of wave length shorter than 500 ,u. 9 Blue light speed was measuredl through a'filter which transmitted substantially no light except between 360 and 500 p 2,3'-dieth' 1-4=methyloxathiazolocarbccyzmine iodide used in the emulsion in a concentration of 20 mg. per

literoi emulsion,. as colorsensitizen. emulsions. One or more of the quaternary salts can be employed.

The quaternary salts can be employed inconjunctionwith sensitizingdyes and the quaternary salts can be added to the emulsion before, after or simultaneouslywith the sensitizing dyes. One or more sensitizing dyes can be used. The sensitizing dyes can be added to the emulsions in the usual manner from a solution, in an appropriate solvent, e. g. the solvents'set forth above tizing dyes of these kinds are described and defined for example .in The Theory of the P110130. graphic Process by C. E. K. Mees, The Macmillan Company, New York, 19.42. erocyanine dyes are. also described by L. G. S.. Brooker in.

15 United States Patent 2,170,803, dated August 29.

1939 and in United States Patent 2,078,233, dated April 27, 1937. Hemicyanine dyes are described by F. L. White and G. H. Keyes in United States Patent 2,263,749, dated November 25, 1941. Hemioxonol dyes are described by G. H. Keyes in United States Patent 2,186,608, dated January 9, 1940.

The quaternary salts which we employ in practicing our invention for the most part can be prepared from the corresponding benzothiazcle or benzoselenazole bases by heating the heterocyclic base with the appropriate alkyl salt, using a closed tube where higher temperature are desired or the volatility of the reactants demands. Methods for preparing hydroxyalkyl, alkoxyalkyl and other substituted alkyl quaternary salts are described in United States Patents 2,231,658, dated February 11, 1941 and 2,213,238, dated September 3, 1940. Alkylmercaptobenzothiazoles and alkylmercaptobenzoselenazoles can be prepared by alkylating the corresponding mercapto compounds. The resulting alkylmercapto benzothiazoles and benzoselenazoles can then be quaternarized by heating with an alkyl salt. 2-arylmercaptobenzothiazoles can be prepared from 2- chlorobenzothiazoles by treating the 2-chlor0- benzothiazoles with an aryl mercaptan, in the presence of triethylamine (Breaker et al., Jour. Am. Chem. Soc. 63, 3200 (1941)). The arylmercaptobenzothiazoles can then be quaternarized by heating with alkyl salts (Brooker et al., supra). 2-arylmercaptobenzoselenazoles can be prepared in the same manner. 2-chlorobenzoselenazole can be prepared as described by Hasan et a1. Jour. Chem. Soc. (London) 1935, 1762. 2- arylaminobenzothiazole quaternary salts can be prepared by condensing 2-phenylmercaptobenzothiazole quaternary salts with a primary aromatic amine or a N-alkyl aromatic amine (Brooker et al., supra). Instead of 2-phenylmercaptobenzothiazole quaternary salts, 2-ethylmercaptobenzothiazole quaternary salts can be used. 2-alky1amino-, 2-dia1kylaminoand 2- aralkylaminobenzothiazole quaternary salts can be similarly prepared using a primary aliphatic amine, a secondary aliphatic amine or an aralkylamine instead of the aryl amine. 2-amino-, 2- methylaminoand 2-anilinobenzoselenazole are described by Hasan et al., supra. Starting with 2-ethylmercaptobenzoselenazole quaternary salts, 2-arylamino-2-aralkylaminoand 2-alkylaminobenzoselenazole quaternary salts can be pre'- pared as described above for the corresponding benzothiazole compounds. 2-aminobenzothiazole quaternary salts can be prepared by adding hydrogen chloride to 3-alky1-2-iminobenzothiazoline. 2 aminobenzoselenazole quaternary salts can be similarly prepared from 3-alkyl-' 2-iminobenzoselenazolines (described by Hasan et al., supra). The chloride anion of any of these quaternary chlorides can be converted to the bromide or iodide anion by treating an aqueous or methyl or ethyl alcoholic solution of the quaternary chloride with an aqueous solution of potassium bromide or iodide. The quaternary chlorides, bromides or iodides can be converted to quaternary perchlorates by treating a hot alcoholic solution of the quaternary halide with an aqueous solution of sodium perchlorate. Quaternary iodides can be converted to quaternary chlorides, quaternary acetates or quaternary thiocyanates by heating the quaternary iodide with a suspension of silver chloride, silver acetate or silver thiocyanate in methyl alcohol. Similar conversions of quaternary iodides to quaternary chlorides can be made by heating the quaternary iodide with silver chloride in a phenol. (See United States Patent 2,245,249, dated June 10,

The 2-methlybenzothiazole bases from which 2-methylbenzothiazole quaternary salts can be prepared by heating with an alkyl salt, are for the most part preparable by the method of Fries et al., Ann 407, 208 (1915) in which the appropriate thioacetylaniline is oxidized with alkaline potassium ferricyanide. Thus, p-chlorothioacetanilide gives 6 chloro 2 methylbenzothiazole. The thioacetylanilines can be prepared by treatme the corresponding acetylaniline with phosphorus pentasulfide in dry benzene or Xylenes. The acetylanilines can be prepared by the action of acetic anhydride or acetyl chloride on the corresponding aniline compound. Several of the 2-methylbenzothiazole bases can also be prepared by reducing bis(o-nitrophenyl)disulfides with zinc dust and acetic acid, acetylating the reduction mixture with acetic anhydride and closing the ring by heating the resulting mixture. The bis(o-nitrophenyl)disulfides can be prepared irom the corresponding o-bromonitrobenzenes by heating the o-bromonitrobenzene with sodium disulfide in methyl alcohol. Thus, 2-bromo-4- chloronitrobenzene gives bis(5-chloro 2 nitrophenyDdisulfide which, on reduction, acetylation of the reduction product and heating gives 2 methyl-6-chlorobenzothiazole. 2-methylb'en-' zoselenazole bases can be prepared by reducing bis(o-nitrophenyl) diselenides with zinc dust and acetic acid, acetylating the reaction mixture with acetic anhydride, and closing the ring by heating the resulting mixture. The bis(o-nitrophenyl) diselenides can be prepared from the corresponding o-bromonitrobenzenes by heating the o-bromonitrobenzenes with sodium selenide in methyl alcohol. See also Clark, J. Chem. Soc. (London), 1928, 2313.

What we claimas our invention and desire to be secured by Letters Patent of the United States is:

1. A photographic silver halide emulsion in which the silver'halide is dispersed in a hydrolyzed cellulose carboxylic ester containing from 19 per cent to 33 per cent by weight of acyl groups, said emulsion being sensitized with at least one quaternary salt selected from the group of quaternary salts represented by the following general formula: Y

Q 1) o-R,

wherein D represents an o-arylene group of the benzene series containing from 6 to 8 carbon atoms and which is devoid of nitro groups, Q represents a member selected from the group consisting of a sulfur atom and a selenium atom, R represents a member selected from the group consisting of a primary alkyl group containing from 1 to 4 carbon. atoms, a primary alkenyl group containing from 3 to 4 carbon atoms, a primary hydroxyalkyl group containing from 2 to 4 carbon atoms, and a primar alkoxyalkyl group containing from 3 to- 4 carbon atoms, R1 represents a member selected from-the group consisting of a hydrogen atom, a methyl group, an ethyl group, an alkyl mercapto group containing from 1 to 4 carbon atoms, an arylmercapto group containing from 6 to 8 carbon atoms and which is devoid of nitro groups, a primary amino group, an

alkyl amino group containing'from 1 to 4 carbon amazes 7 atoms, a dialkylamino group containing "from? :to 4 carbon atoms, an arylamlno group containing ,from 6 to '3 carbon atoms andwhich 'isdevoid of nitro groups and an aralkylamino group contain- :ing from 6 .to 8 carbonatoms and which is devoid of nitro groups, and X represents an anion.

'2. A photographic silverhalide emulsion in which the silver halide is :dispersed in a hydrolyzed cellulose carboxylic ester containing from 19 per cent'to 33 per cent by weight of acyl groups, said emulsion being sensitized with at least one quaternary salt selected from the group consisting-ofthose quaternary salts represented bya'the following general formula:

wherein D represents an o-arwlene. grouplof the benzene series, containing .irom 6 to, 8 carbon atoms and which is devoid of nitro. groups, ,3 represents a primary alkyl group containing from 1 to 4 carbon atoms, and Xrepresents an anion.

S3. A photographic .silver halide emulsion in which the silver halide is dispersed in a hydrolyzed cellulose acetate containingfromldper cent to 33 per cent by weight of acetyl groups, said emulsion :being sensitizedwithat least one quaternary salt selected fromthe group consisting of those quaternary salts represented bythe following general formula:

o ccrn f /N R X wherein D represents an o-arylene group of the benzene series containing'from 6 to 8 carbon atoms and which is devoid of nitro groups, R represents a primary alkylgroup containing from 1 to 4 carbon atoms, vand")! represents an anion.

4. A photographic silver halide emulsion in which the silver halide is dispersed in a hydrolyzed cellulose acetate containing-from per cent to 26 per cent by weightof acetyl groups, said emulsion being sensitized with at least one quaternary salt selectedafrom the group consisting of those quaternary-salts represented by the following general formula:

lyzed-cellulose carboxylic ester containing from 1 19 per cent to 33 per cent by-weight of acyl groups, said emulsion being sensitized with at least one quaternary salt selected from the group consisting of those quaternary 'saltsrepresented by the following general formula:

wherein D represents an o-arylene :group of the benzene series containingirom 6 :to 8 carbon atoms and-which is devoid of nitro groups,-R

represents a primary alkyl group containing 'from 1 to 4 carbon atoms, R1 represents an alkylmercapto group containing from 1 to 4 carbon atoms, and X represents an anion.

-:6. ,A photographic silver halide emulsion in which the silver halide is dispersed in a hydrolyzed cellulose acetate containing from 19 130 33 per cent by weight of acetyl groups, said emulsion being sensitized with at least one quaternary salt selected from the group consisting of those quaternary salts represented by the following general formula:

of those quaternary salts represented by'the 01 til lowing general formula:

R X wherein D represents an o-arylene group ,of'the benzene series containing from 6 to 8 carbon atoms and which is devoid of nit-r0 groups, 13, represents a primary alkyl group containing from 1: to dearbon atoms, R1 represents anralkylmercapto groupcontaining from M04 carbon atoms and X represents ananion,

8. A photographic silver halide emulsion in which the silver halide is dispersed in a hydrolyzedcellulose acetate containing from 20 to '26 percent by weight of acetyl groups, said emulsionbeing senitized with ,zemethylbenzothiazole etho-p-toluenesulfonate.

9. A photographic silver halide. emulsion ,in whichthe silver halide is dispersed ina hydrolyzed cellulose acetate containing from 20 .to 26 per cent by weight of, acetyl groups, said emulsion being, sensitized with 21methylmercaptobenzothiazole metho-p-toluenesulfonate.

'10. A photographic silver halide emulsion in which the silver halide ,isdispersed inahydroe lyzed cellulose carboxylicester containingirom 19 to 33,per cent by weight of .acylgroups, said emulsion beingsensitized withat least one quaternary salt selected from the group consisting of those quaternary salts represented by the following general formula:

wherein D representsan o-arylenegroupof the 9 atoms and which is devoid of nitro groups, R represents a primary alkyl group containing from 1 to 4 carbon atoms, R1 represents an arylmercapto group containing from 6 to 8 carbon atoms and devoid of nitro groups, and X represents an anion. 11. A photographic silver halide emulsion in which the silver halide is dispersed in a hydrolyzed cellulose acetate containing from 19 to 33 per cent by weight of acetyl groups, said emulsion being sensitized with at least one quaternary salt selected from the group consisting of those quaternary salts represented by the following general formula:

s D/ )o-sn,

\N R/ x where in D represents an o-arylene group of the benzene series containing from 6 to 8 carbon atoms and which is devoid of nitro groups, R represents a primary alkyl group containing from 1 to 4 carbon atoms, R1 represents an arylmercapto group containing from 6 to 8 carbon atoms and devoid of nitro groups, and X represents an anion.

12. A photographic silver halide emulsion in which the silver halide is dispersed in a hydrolyzed cellulose acetate containing from 20 per cent to 26 per cent by weight of acetyl groups, said emulsion being sensitized with at least one quaternary salt selected from the group consisting of those quaternary salts represented by the following general formula:

wherein D represents an o-arylene group of the benzene series containing from 6 to 8 carbon atoms and which is devoid of nitro groups, R represents a primary alkyl group containing from 1 to 4 carbon atoms, R1 represents an arylmercapto group containing from 6 to 8 carbon atoms and devoid of nitro groups, and X represents an anion.

13. A photographic silver halide emulsion in which the silver halide is dispersed in a hydrolyzed cellulose acetate containing from 20 per cent to 26 per cent by weight of acetyl groups, said emulsion being sensitized with 2-phenylmercaptobenzothiazole ethiodide.

BURT H. CARROLL. WILLIAM WEST.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,110,491 Salo Mar. 8, 1938 2,131,038 Brooker et a1 Sept. 2'7, 1938 2,271,623 Carroll Feb. 3, 1942 2,334,864 Carroll et a1 Nov. 23, 1943 FOREIGN PATENTS Number Country Date 496,049 Great Britain Nov. 21, 1938