US2937090A - Photographic emulsions sensitized with quaternary dithiocarbamates - Google Patents

Description

U ited tews Patent O ce 2,931,090 Patented May 17, 1960 flinorocnArmc EMULSIONS SENSITIZED WITH QUATERNARY DITHIQCARBAMATES Kenneth C. Kennard and DonaldM. Burness, Rochester,

N.Y., assiguors to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey No Drawing. Application May 19, 1958 Serial No. 135,921

4 Claims. (Cl. 95-107 -This application relates to photography and particularly to sensitizing photographic emulsions.

It is well known that silver halide emulsions may be chemically sensitized with a variety of materials in order to increase the speed and generally'the gamma of the emulsion, as opposed to optical sensitization'in-which the optical range of sensitivity is increased. Chemical sensitization usually results either-from theforrnation of silver sulfide on the surface of the silver halide "crystal, thus increasing sensitivity, or from, the formation of small amount'of silver fromthe reduction of silver halide Other classes'ofcomp'ofunds, such as certain ethylene oxide condensation products and certain cationic surface-active salts increase sensitivity of silver halides 'without apparently entering into chemical combinationwith the silver halide. p 1

' Carroll US. Patent 2,271,623, Carroll and Allen U.S. Patent 2,288,226 and Carroll and Spence U.S. Patent 2,334,864 describe the chemical sensitiz'a'tionof silver halide emulsions with quaternary ammonium compounds.

-We'hav'e now found that the light sensitivity of silver.

halide emulsions, with or without optical sensitizing dyes, may be further increased by incorporating, in the emulsions certain quaternary dithiocarbamates. These compounds are incorporated-in the emulsion after digestion but-before coating and exposure. .Thecompounds which We propose to use havethe following-structure:

in which R represents an alkyl or substituted alkyl group such as methyl, ethyl; propyl,hydroxyethyl, sulfoalkyl or carboiiyalkyl, R represents a lower alk'yl group such as' inethyl or ethyl, x is 1, 2 or'3,' andXisan anion or acid radical, for example, halide, ptoluene s'ulfonate, a1-

y ateor perchlorate. f1;-

The following specific compoundsmay be employed as 'sensitizers according to our invention.

goinpsor.

n- 9 1 CBFzSCN( CHa)z censor- 1. i The preparation of silver halide emulsions involves V (4) V era-N cmnsiimonm (nor (in s u em-Qmmnsoummn (6) OHil-IQ l OHzSON( s)n The emulsions may be chemically sensitized by any of the accepted procedures, for example, by digestion with naturally active gelatin or the addition of sulfur compounds such asthose described in Sheppard U.S. Patents 1,574,944 and 1,623,499 and Sheppard and Brigham U.S. Patent 2,410,689.

The emulsions may also be treatedwith salts ofthe noble metals such as ruthenium, rhodium, palladium,

iridium and platinum, an of which belong to group VIII of the periodic-table of elements and have an atomic? weight greater'th'an 1 00. Representative compounds are" M ammonium" chloropalladate, potassium chloroplatinat'e j and sodium chloropalladite, which'are used for sensitizing in amounts below that which produces any substantial fog inhibition, as described in Smith and Trivelli U.S. Patent 2,448,060, and as anti-foggants in higher amounts, as described in Trivelli and Smith U.S. Patents 2,566,245

' and 2,566,263. r

The emulsions may'also be chemically sensitized with goldsalts as, described in Waller and Dodd U.S. Patent 2,399,083 or stabilized with goldsalts as described in Damschroder U.S. Patent 2,597,856 and Yutzy and Leer makers U.S. Patent 2,597,915. 3 Suitable compounds are potassium chloroau'rite, potassium .aurithiocyanate, potas:

sium' chloroaurate, auric trichloride and Z-aurosulfobenzothiazole methochloride. i a p 1 The emulsions may also be chemicallysensitized with reducing agents such as' stannous saltsl (Carroll U.S. Pat.- ent- 2,487,850), 'poly'amine's such asdiethylene triamine v (Lowe and Jones U.S. Patent 2,518,698), polyaminesg such as spermine (Lowe and Allen US. :Patent 2,521,-" 925), or bis-(p-aminoethyl) sulfide andits water-soluble salts (Lowe and Jones U.S. Patent 2,521,926).

The emulsions may also be stabilized with the mercury compounds of Allen, Byers and Murray U.S. application Serial No. 319,611, Carroll and Murray U.S. application Serial No. 319,612 and Leubner and Murray U.S.

it application Serial No. 319,613, all filed'November 8,

1952, now U.S. Patents 2,728,663,'2,728,664 and 2,728,:

665 respectively, granted December 27, 5

Other stabilizing agents may be-added to the emulsions containing the quaternary ammonium' compounds and polyalkylene oxides such as cadmium chloride, cadmium nitrate, cobalt nitrate, manganese chloride, manganese sulfate, zinc chloride, zinc nitrate and zinc sulfate.

The emulsions sensitized with quaternary dithiocarbamates may be additionally sensitized with alkylene oxide polymers or derivatives of alkylene oxides.

The alkylene oxide polymers used to sensitize the emulsions may be of various types. The alkylene oxides from which the polymers are derived contain from 2 to 4 carbon atoms, e.g., ethylene oxide, propylene oxide and butylene oxide. The preparation of polymers from these compounds is described in Ellis, The Chemistry of Synthetic Resins (1935), pages 990 to 994. These compounds are also referred to as polyalkylene glycols and their use as sensitizers for silver halide emulsions is described in US. Patents 2,423,549 and 2,441,389. The alkylene oxide derivatives may be prepared by condensing an organic compound containing an active hydrogen atom with an alkylene oxide polymer, or by condensing the active hydrogen compound with the alkylene oxide during the polymerization of the latter material.

Various derivatives of alkylene oxides may also be used to sensitize the'emulsions, e.g., condensation products of alkylene oxide with organic compounds containing an active hydrogen atom. Examples of active hydrogen organic compounds, i.e., compounds in which a hydrogen atom may be replaced by reaction of the compound with metallic sodium, methylmagnesium iodide, etc., include alcohols, amines, mercaptans, acids, amides, hydrocarbons such as acetylene, and compounds having the active hydrogen in a methylene group such as dibenzoylmethane. More specifically, we may employ condensation products of alkylene oxide with glycols such as those having from 8 to 18 carbon atoms as described in US. Patent 2,240,472 and British Patent 443,559 as well as condensation products of alkylene oxides with aliphatic alcohols, condensation products of alkylene oxides with aliphatic acids, e.g., lauric acid and glycine, condensation products of alkylene oxides with aliphatic amines orv amides, e.g., glycine and lauryl amide, and

Our invention is further illustrated by reference to the following example:

EXAMPLE To portions of an optically sensitized gelatino-silver bromoiodide emulsion containing about mol of silver halide per liter, which had been digested with a sulfur compound such as disclosed in Sheppard U.S. Patent 1,574,944, and a gold'compound such as disclosed in US. Patent 2,399,083, and stabilized with an azaindene, were added the amounts of Compound 5 shown in the following table:

Amount Relative Compound per mole Speed Gamma Fog of AgBrI Control -1 115 1.22 12 Compound 5 75 166 1. 03 16 Compound 5 3.0 174 96 18 The emulsions Were coated on film support in the conventional manner, exposed on an Eastman-type l-b sensitometer and processed for 5 minutes in-DK-SO-developer having the following composition with the results shown in the table, speed being shown as a relative speed in each case with the control being designated Developer DK50: Grams N-methyl-p-aminophenol sulfate 2.5 Hydroquinone 2.5 Sodium sulfite, desiccated 30.0 Sodium metaborate -5. 10.0 Potassium bromide 0.5

Water to make 1 liter. 7

The compounds'which we use maybe prepared as follows:

Compound 5 'y-3-CHLOROPROPYLPYRIDINE tracted with 150 ml. of chloroform, and the combined chloroform extracts weredecolorized with activated carbon and dried over magnesium sulfate, The volatiles were then removedin vacuo, and the residuewas dis tilled, giving 80-85 percent of -3-chloropropylpyridine.

Analysis.-Calcd. for C H NClz N, 9.0. FonndaN, 9.2.

This compound was stored at 20 to prevent polymerization which occurs slowly at room temperature. Although a larger quantity may be prepared inone ex periment, attempts to distill more than about g.

at one time resulted in a lower yield and occasionally led to a violent, exothermic polymerization in the distillation flask.

V 3-(y-PYRIDYL)PROPYL DIMETHYLDITHIOCABBAMATE To 10.1 g. .of sodium dissolved in 500ml. of'dry methanol was added .73 g. of dimethylammonium .di'-' methyldithiocarbamate with stirring. The yellow-togreen solution was treated with 45 g. of 'y-3-chloropro pylpyridine, and the reaction mixture was heated with stirring for 6.5 hours. The volatiles wereremoved on the steam bath until the volume of solution was about 250 ml. This boiling residue was treated with activated carbon and. filtered. The filtrate was cooled, and 250 ml. of waterwas added with cooling. andscratching of the flask with a glass rod. After standing in the refrigerator overnight, the light brown crystals were filtered and recrystallized from hexane-chloroform solution, yielding 41.5 g. (60 percent.) of 3-(' -pyridyl)propyl dimethyldithiocarbamate which melted at 60.5-63. Further recrystallization from the same solvent afiorded an analytical sample, M.P. 62-4". I 7

Analysis.--Calcd. for C H N S C, 55.0, H, 6.7; N,

11.6. Found: C, 55.0; .H,.6.7; N, 11.6. I

v [3 (DIMETHYLDITHIOCARBAMATO)PROPYL] N- METHYLPYRIDINIUM p I'OLUEN'ESULFONATE (COM- POUND 5) To 3.8 g. of 3-( y-pyridyl)propyl dimethyldithiocarbamate in 50 ml. of dry ether was added 3.5 g. of freshly distilled methyl p-toluenesulfonate,,and the solution was heated under reflux for 3-6 hours. The precipitate was filtered and twice recrystallized from acetone. The [3 (dim'ethyldithiocarbamato)propyl] N-methylpyridium p-toluenesulfonate thus prepared weighed 4.8 g. (71 percent of the theoretical) and melted at 1095-11".

Analysis.-Calcd. for C H N O S C, 53.6; H, 6.1; 'N, 6.6; S, 22.5. Found: C, 53.8; H, 6.0; N, 6.7; S, 22.8.

Compound 1 'Y-PICOLYL DIM'ETHYLDITHIOCARBAMATE By essentially the procedure described above for 3-( pyridyDpropyl dimethyldithiocarbamate, using 'y-picolyl chloride hydrochloride, 'y-picolyl dimethyldithiocarbamate was prepared. Recrystallization of the crude product from chloroform-hexane solvent pair afforded a pure sample, in 59 percent yield, which melted at 675-69".

Analysis.-Calcd. for c,H ,N s C, 51.0; H, 5.7; N, 12.7. Found: C, 51.4; H, 6.0; N, 12.6.

7DIMETHYLDITHIOCARBAMATOMETHYL-N-METHYL- PYRIDINIUM p-TOLUENESULFONATE (COMPOUND 1) This compound was prepared in 68 percent yield from fi-picolyl chloride HCl. It is a yellow oil.

Analysis.Calcd. for cgHuNzsgi C, 51.0; H, 5.7. Found: C, 51.0; H, 5.5.

fl-DIMETHYLD1THIOCARBAMATOMETHYL-N-METHYL- PYRIDINIUM p-TOLUENESULFONATE (COMPOUND 2) This compound was prepared in 87 percentyield as described for Compound 5 and melted at 161-1625 after recrystallization from methanol-acetone.

Analysis.-Calcd. for C17H22N2O3S3: C, 51.3; H, 5.6; N, 7.0. Found: C, 51.1; H, 5.9; N, 6.7.

Compound 3 g 3- -PYRIDYL) PROPYL DIETHYLDITHIOCARBAMATE This compound was prepared in 71 percent yield from 'y-3-chloropropyl-pyridine and sodium diethyldithiocarbamate. It is a yellow oil, B. 177, which was further purified by chromatography using alumina.

Analysis.--Calcd. for C H N S C, 58.1; H, 7.5; N, 10.4. Found: C,-58.2; H, 7.2; N, 10.0. 'y-[3-(DIETHYLDITHIOCARBAMATO)PROPYL]-N-METH- YLPYRIDINIUM PERCHLORATE (COMPOUND 3) The p-toluenesulfonate salt, prepared in the usual manner, was so hygroscopic that a water solution of it was treated with an excess of sodium perchlorate in water. The non-hydroscopic perchlorate salt (73 percent yield) was filtered and recrystallized three times from acetone- 7 water solvent pair to afford a puresample of the title compound which melted at l01-2.

Analysis.Calcd. for C H ClN O S N, 7.3; S,

Found: N, 7.2; S, 16.6.

Compound 4 3-fi-PYRIDYLPROPYL DIMETHYLDITHIOCARBAMATE fl-3-Chloropropylpyridine was prepared from 3-pyridine-propanol by the method described for Compound 5. The p-3-chloropropylpyridine was then reacted with dimethylammonium dimethyldithiocarbamate as described for Compound 5. However, the product did not crystallize but was isolated as an oil. This brown oil was further purified by chromatography using alumina as the adsorbent and ether as the solvent. A light yellow oil resulted.

Analysis.-Calcd. for CnHmNgSgZ (2, 55.0; H, 6.7- Found: C, 55.0; H, 7.1.

s [3 (DIMETHYLDITHIOCARBAMATO)PROPYL] N METHYLPYRIDINIUM PERCHLORATE (COMPOUND 4) The p-toluenesulfonate salt, obtained by heating methyl p-toluenesulfonate and 3-}9-pyridylpropyl dimethyldithiocarbamate together in ether, was treated with a water solution of sodium perchlorate. was filtered and recrystallized, from acetone-water solvent pair and then from acetone giving the title compound,

melting at 75-76.5 in 50 percent yield.

Analysis.Calcd. for C H ClN S O N, 7.9; S, 18.0 Found: N, 7.7; S, 18.3.

The sensitivity increase produced'by the quaternary dithiocarbamates is unexpected for a number of reasons. In the first place, they contain the thiocarbonyl group =C=S which is usually an active source of desensitiza- The resulting white solid tion. Furthermore, they are of relatively low molecular weight compared to many of the prior sensitizers. Without the quaternary nitrogen atom, these compounds would be incapable of increasing the sensitivity of an already fully chemically sensitized emulsion. Both sulfur atoms in the compound are necessary for activity, and the reversal of the i gg in the chain destroystheir activity.

The chemical sensitizing agents and other addenda which we have described may be used in various kinds of photographic emulsions. In addition to being useful in non-optically sensitized emulsions they may also be used inorthochromatic, panchromatic and X-ray emulsions. They may be added to the emulsion before or after any sensitizing dyes which are used. Various silver salts may be used as the sensitive salt such as silver bromide, silver iodide, silver chloride or mixed silver'halides such as silver chlorobromide orsilver bromoiodide. The agents may be used in emulsions intended for color photography, for example, emulsions containing color-forming couplers or emulsions to be developed by solutions containing couplers.

The dispersing agent for the silver halide may be gelatin or other colloidal material such as collodion, albumin, cellulose derivatives or synthetic resins.

It will be understood that we contemplate as included within our invention all modifications and equivalents falling within. the scope of the appended claims.

I What we claim is:

1. A light-sensitive silver halide emulsion sensitized with a quaternary dithiocarbamate having the following composition:

in which R is selected from the class consisting of lower alkyl, hydroxy lower alkyl andcarboxy lower alkyl groups, R' represents a lower alkyl group, J: is an integer from 1 to 3, and X'represents an anion.

2. A light-sensitive silver halide emulsion sensitized with a quaternary dithiocarbamate having the following composition:

in which .1; is an integer from 1 to 3, and X is selected from the group consisting of perchlorate and p-toluene sulf onate.

3. A light-sensitive silver halide emulsion sensitized with a quaternary dithiocarbamate having the following composition:

in which 1: is an integer from 1 to 3, and X is selected from the group consisting of perchlorate and p-toluene sulfonate.

4. A light-sensitive silver halide emulsion sensitized with a quaternary dithiocarbamate having the following composition:

' i s V anti? -(orn).siiN(cH,)|

References Cited in the file of this patent FOREIGN PATENTS 494,604 Canada July 21, 1953

Claims (1)

1. A LIGHT-SENSITIVE SILVER HALIDE EMULSION SENSITIZED WITH A QUATERNARY DITHIOCARBAMATE HAVING THE FOLLOWING COMPOSITION: