DE2101436A1 - Process for making material with dye images - Google Patents

Description

phone: 555 476 8000 MUNICH 15, 13 January 1971

TELEGRAMS: KARPATENT NUSSBAUMSTRASSE 10

W. 40311/71 7 / de

IXford Limited Ilford, Essex (England)

Process for making material with dye images

The invention relates to the treatment or processing of photographic material, the silver halide emulsion layers to obtain material having dye images.

When handling usual color photographic Material becomes a developable silver salt image with a developing agent having an aromatic primary Amine of the paraphenylenediamine type (a so-called "color developer") in the presence of a compound (a so-called. "Color coupler") developed, which deals with the oxidation

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products of the color developer combined and an azomethine or Forms quinoneimine dye. The dye is thus formed in situ with the developed silver image. Thereafter, the product must be mixed with a bleach and a fixer or a combined bleach-fixer treated to thereby silver and any residual silver halide or other silver salt to remove, whereby only the color image remains in the product.

In the silver dye bleaching process of color photography, the photographic material comprises at least one silver halide emulsion layer which includes, in the form of a dispersion, an organic dye of the type which can be destroyed (or bleached) by finely divided silver in a suitable treatment bath. The organic dye is usually an azo dye. Usually there are three such silver halide emulsion layers? , lden, each of which is sensitive to a different region of the visible spectrum and each of which contains a different azo dye. The usual sequence of treatments to produce a dye image in the material is that, after imagewise exposure, the material is developed in a black and white developer. The development is then stopped or interrupted and the unexposed silver halide is fixed out. Then after washing the material is treated in a dye-bleach bath which oxidizes the silver image and at the same time the dye in the area

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of the silver image reduced ("bleaches"). The silver salts and any remaining silver must then be removed. This is usually achieved by washing the material after it has been treated in the dye-bleach bath and then washing it in a bleach bath which is followed by a fixer treatment or a combined bleach-fixer treatment treated. The photographic material then contains only one dye image; this dye image usually consists of a direct positive rendition of the original.

In the case of a commercially available silver dye, the amount of residual material is bleaching material Silver left after the dye bleaching step, not to be neglected because this material requires such a treatment that the dye bleaching step is ended before all of the image silver is used up for the reduction of the dye. at It is essential to the treatment of this silver dye bleaching material that there be an effective silver bleaching step follows the dye bleaching stage to ensure that the remaining silver is removed from the material as much as possible.

Both in the treatment of common color photographic Material as well as in the treatment of silver-dye-bleaching material will be the use of a Combined bleach-fix bath preferred as this is too a reduction in the treatment time and the Reduced effort for the required treatment facility. Usually a bleach-fix bath comprises one

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mild oxidizing agent, ζ. B. an iron (III) chelate complex, a copper (II) complex, a salt or a cobalt (III) complex, together with a solvent for silver halides or a fixative, ζ. Β. a water-soluble thiosulfate or a water-soluble shiocyanate. Strong oxidizing agents cannot be used as they tend to use the silver halide solvent to oxidize.

Stable bleach-fix solutions, the 'iron (III) chelate complexes and sodium thiosulfate can be obtained However, due to the weak oxidizing effect of the iron (III) chelate complexes, such lead-fixing baths can be used

only

commercially ^{v be used} for the treatment of photographic materials with a fairly low silver content.

It has been suggested to use selenium urea, certain N-alkyl substituted selenium ureas and certain substituted ones Selenium semicarbazide to use as a bleach-fix accelerator in the bleach-fix stage involved in the treatment of coloring photographers material with one relatively high silver content, e.g., color negative material and color reversal material, can be used. However, it has been found that certain metal complexes of these compounds act as bleach-fix accelerators in place of the compounds can be used.

According to the invention is in the treatment of color photographic A material comprising a silver halide emulsion layer to give a material having a dye image provided a bleach-fix stage which the treatment of the photographic material with a

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includes stable bleach-fix bath, which is an aqueous Solution of a mild oxidizing agent and a silver halide solvent which is a water-soluble thiosulfate or a water-soluble ihiocyanate, in the presence of a bleach-fix accelerator comprising one water-soluble complex, which consists of iron, cobalt, nickel, copper, zinc, palladium, silver, cadmium, indium, Tin, antiomon, platinum, gold, mercury, lead or bismuth and

a) selenium urea,

b) an N-alkyl-substituted selenium urea of the general formula

H>

- C - N ((I)

Il

Rj Se

in which R 1, R ₂ and R, are hydrogen atoms or alkyl groups, at least one of these symbols consisting of a hydrogen atom, or

c) a selenium semicarbazide of the general formula

Red 23

t η

-HCN ^ (II) R ₂ ^

in which one of the symbols R ₂₁ and R ₂₂ ^{consists of} a hydrogen atom or an alkyl, aralkyl or aryl group

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and the other of the symbols R ₂ -J and R ₂₂ is a hydrogen atom or an alkyl group, R ₂ * is a hydrogen atom or an alkyl, aralkyl or aryl group, one of the symbols R ₂ * and R ₂ c is a hydrogen atom or an alkyl, aralkyl or aryl group and the other of the symbols R ₂ ^ and R ₂ ^ is a hydrogen atom or an alkyl group, but at least one of the symbols ^{R g ^ t ^ 24 ° ^ er} ^? 5 ^{consisting of a} ^ ^nem If there is a hydrogen atom and there is no more than one aryl or aralkyl group in the compound, there is

Under "stable bleach-fix bath, which is an aqueous Solution of a mild oxidizer and a silver shark solvent "is a bleach-fix bath to understand in which the oxidizer is strong enough to bleach the silver but not strong enough, the silver halide solvent, e.g. B. the thiocyanate or thiosulfate, to an appreciable extent.

The preferred mild oxidizing agents used in the present invention are iron (III) chelate coraplexes or diaquotetramine cobalt (III) complexes.

Under "iron (III) chelate complex" is a coordination compound an iron (III) ion and a compound containing nitrogen and / or oxygen contains coordinative groups, understand. The main coordinative groups are amine, heterocyclic Nitrogen, carboxyl and carbonyl groups.

The preferred ferric chelate complex found in the Bleach-fix step is used in the present invention

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an iron (III) ethylenediamiutetraacetic acid complex. These Compound can be used as such in making a bleach-fix bath, or it can be used in in situ in a bleaching-elixir bath by mixing ethylenediaminetetraacetic acid with an iron (III) salt, z. B. iron (III) chloride, converts. In the following example 1 the iron (III) ethylenediaminetetraacetic acid complex formed in situ.

Other iron (III) chelate coraplexes according to the invention can be used are z. B. pyridine-2,6-dicarboxylate ferrate (III) complexes, Iminodiacetate ferrate (III) complexes and nitrile triacetate ferrate (III) complexes,

It is believed that the selenium urea metal complexes used as the bleach-fix accelerator in the present invention are used, which have the general formula III:

β R ₁ R ₂ R ₃ HN ₂ C Se) ₂ Mg Sy (III)

in which R ^, R ₂ and R, are hydrogen atoms or alkyl groups, where at least one of these groups is a hydrogen atom, M is one of the metals indicated above, Z is an anion, ζ is the valence of the anion and y is the valence of the complex cation.

It is believed that the metal complexes of the selenium semicarbazide of the general formula II, which are used according to the invention as bleach-fix accelerators, who have general IOrmel IV:

» ^R 23» ^R 24 » ^R 25» ^N 3 »° ^Se > i ^ ^Zy

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in which M, Z, y and ζ have the meanings given above, η is 1 or 2 and R ₂ 1 ^ is ^ 25 have the meanings given ^{in formula l.}

The production of the metal complex salts from selenium urea and silver, copper, mercury, lead and cadmium ions was described by MA Yerneuil in Annales de Chimie et de Physique, Ser. 6, 9, 289 (1886), by H. Schmidt in Med. Chem. Abhandl. med-chim. Forschungsstätten, IG Farbenid., 3, 418 (1936) and by NN Po Proskina, SM Chul'skaya, Gi ¹ . Volodina, AV Ablov, Shur. Structure Khim, 9, 1095 (1968).

The selenium semicarbazides of Formula III above are known compounds as exemplified by those below indicated references is shown.

The following general formula V denotes the nitrogen atom to which reference is made in the references is taken:

NH ₂ (D.

NH
(2)

■ Se

It

• C

- NH ₂ (4)

(V)

4-phenyl selenium semicarbazide 2-phenylselene seraicarbazLd

Manufacture described by

Jensen & Frederiksen, Z. anorg in general Chem 2JO _; 31-3 (1936)

Mautner & Kumler, J. Araer. Chem. Soc. 97-101 (1956)

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4-ethyl selenium semicarbazide 4-propyl selenium semicarbazide

1-phenyl selenium semicarbazide and 1- (p-tolyl) selenium semicarbazide

Manufacture described by

Hüls & Renson, Bull soc chim Beige 6 £ 684-95 (1956)

M. Colland-Charon, Hüls * Renson, Bull soc chim Beiges H 541-53 (1962)

Colland-Charon, JuIs & Renson, Bull soc chim, Beiges 71 554-62 (1962) ~ "

2-methyl selenium semicarbazide, 4-methyl selenium semicarbazide, 1,1-dimethyl selenium semicarbazide, ¹ 1,2-dimethyl selenium semicarbazide, '\ 1,4-dimethyl selenium semicarbazide r and' j

1,2,4-triraethyl selenium semicarbazide 3 J

2-methyl-4-phenylselenium semicarbazide,

4- (p-chlorophenyl) selenium seraicarbazide and

4- (p-methoxyphenyl) selenium

semicarbazid /

Jensen, Felbert, Peder-

-81 (1966)

BuIka, ühlens & Tucek Chem. Ber. 100 (4) 1373-8 (1967)

The bleach-fix accelerators used in the present invention are preferably added to the bleach-pixie bath, but they may also be adsorbed on or in the color photographic material during the bleach-fix treatment be absorbed. In the treatment of common color photographic material, e.g. B. Parb negative or Color reversal material, the bleaching pixel accelerator, which are used in the present invention can be present in any treatment bath or wash bath used in the color development process between the development stage and the white fixation stage is used. Examples of such baths are interruption baths and interruption fixing baths. However, the bleach-fix accelerators should not be used in

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be present in the developing solution as they interfere with the development of the color material. For the same reason should the soft-fixing accelerators used according to the invention not present in the photographic material from the start.

When treating silver dye bleach material can use the bleach-fix accelerators in the washing bath following the dye bleach treatment bath and the bleach-fix bath preceded, but the bleach-fix accelerators should not be used during the dye-bleaching treatment be present as they can interfere with this stage of treatment. The bleach-fix accelerator should that is, not present in the silver dye-bleach photographic material from the start.

A number of the above-mentioned bleach-fix accelerators used in the present invention are Not soluble in water if water is not a thiosulphate contains. Therefore, the bleach-fix accelerators used in the present invention are preferred added to a bleach-fix bath which is a thiosulfate or added to an interrupt fixer containing a thiosulfate.

According to another embodiment of the invention, a stable bleach-fix bath is provided, the one aqueous solution of a mild oxidizing agent as indicated above, a water-soluble thiosulfate and a bleach-fix accelerator, either a selenium semicarbzide metal complex as indicated above or a is as indicated above selenium urea metal complex.

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In this regard, that is used according to the invention mild oxidizing agent, preferably an iron (III) chelate complex or a diaquotetramine cobalt (III) complex.

The concentration of the selenium semicarbzide metal complex or the selenium urea metal complex, which is contained in the bleach-fix bath should preferably be greater than 1 mg / l bleach-fix bath. In particular, is the preferred Quantity 150 mg bleach-fix accelerator per liter of bleach-fix bath.

The concentration of the selenium semicarbazide metal complex or selenium urea metal complex that is present in the interruption fixer, Interrupt bath or in the wash bath, is preferably greater than 1 mg / l solution.

The selenium urea metal complexes which are used according to the invention are more resistant to air oxidation and photochemical decomposition than the selenium ureas from which they are produced. The metal complex compounds can be stored and packaged dry under normal conditions with little risk that the compounds will spoil. On the other hand, the selenium ureas stored or dry-packed under normal conditions soon turn first pink and then black, probably due to the decomposition of the compounds to form elemental selenium. For example, a sample of pure selenium urea obtained by recrystallization from methanol in the dark and stored in a sealed glass bottle under normal laboratory conditions turned black and showed a decomposition of about 15 % after 20 days.

to the
In contrast, samples of / C selenurea) _P -Ag Cl-

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complex, (selenium urea) p-Sb Cl-z complex, (selenium urea) ₂ -Sn Cl ₂ complex and (selenium urea) ₂ -Bi Cl * complex, which were stored under the same conditions for the same time, no analytically detectable decomposition .

Selenium semicarbazide metal complexes offer similar advantages

The production of a selenium urea-silver-thiosulphate coraplex described below Illustrates the general procedure for preparing the metal complexes useful in the present invention as bleach-fix accelerators be used.

Manufacturing

It was a solution containing 22.5 g boric acid, 12.5 g borax, 95.0 g sodium thiosulfate pentahydrate and water to one liter, prepared (solution A) · The pH of this solution was 7.04.

Silver nitrate (0.0060 mol) was dissolved in 10 ml of water. 1.0 g of sodium hydrogen carbonate was added to this solution. There was evolution of carbon dioxide, and it a yellow precipitate was obtained. 25 ml of the solution A was added to the suspension, and the resulting mixture was again a clear solution (solution B).

Selenium urea (0.0060 mol) was dissolved in 50 ml of solution A and the resulting solution became solution B admitted. The white precipitate obtained was filtered off, washed with water and then with methanol and dried under reduced pressure. The analytical

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Results gave a composition of the following formula:

H ₈ lfy O ₂ Se ₂ Ag ₂ S ₂ O ^

The selenium urea metal complexes can be prepared as described below: A specific volume of a 0.1 molar solution of the metal salt is prepared by dissolving the required amount of the metal salt in water or in a relatively rigid acidic solution (an acidic solution is necessary if salts of easily hydrolyzable metal ions are used, e.g. bismuth and > fot iraon) · This solution of the metal salt is added to a volume of a 0.3 molar solution of the selenium urea in a 2 normal acid. The volume of the selenium urea solution used is selected so that the molar ratio between selenium urea and the metal ion is slightly greater than 2. This addition is carried out at 40 ° C and, in the case of easily oxidizable metals, the entire preparation should be carried out under nitrogen. The complex salt precipitates out soon or after a few minutes after cooling.

The Selenseraicarbazid metal complexes, that is complexes formed between the above-mentioned metals and the compound of general formula II can be similarly prepared with the exception that may be the molar ratio between the Selensemicarbazid and the metal ion is greater than 1 .

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21 01Λ 3

The following example serves to illustrate the use of a selenium urea metal complex as a Bleach-fix accelerator.

example 1

Samples of a saturation of a negative tripack color

materials of the color coupler noun style, which is 73.6 mg

2
Silver containing per dm as silver iodobromide emulsion were fogged and treated at 24 ° C.

Below are details of the wasted ! Color film made:

Layer sequence and silver coating ₂

Sensitivity Weight in mg (Ag / dm)

without stress -

blue sensitive 13.4

colloidal silver filler layer

green sensitive
Upper class 13.1 Intermediate layer - green sensitive
Lower class 16.0 Intermediate layer - red sensitive
Upper class 17.5 red sensitive
Lower class 13.6 Cellulose carrier
triacetate -

TOTAL 73.6

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In this film, the "blue-sensitive layer" contained a yellow color coupler of the following Formula:

COCH ₂ COM

COOH

the green-sensitive layers contained a magenta dye coupler of the formula:

so.

N-H \ «

^C 17 ^H 35

the red-sensitive layers contained a cyan dye coupler the formula:

COM

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- 16 The treatment sequence was as follows:

Color development: 6 min

Sodium metaborate 53 »3 g

Sodium hydroxide 2.0 g

Sodium sulfite, anhydrous 3.9 g

Potassium bromide 0.70 g

Hydroxylamine sulfate 2.34 g

Sodium sulfate, anhydrous 7.8 g

4-amine-N-ethyl-N- (4-3iydr oxy-

■ butyl) aniline sulfate 6.0 g

Water to 1 liter

pH value: 10.5

Interrupt fixing treatment: 4 min

Sodium thiosulfate pentahydrate 171.0 g

Sodium acetate, anhydrous 31.4 g

Sodium sulfite, anhydrous 4.3 g

Glacial acetic acid 35 ml

Potassium alum 17.0 g

Ammonium chloride 43, og

Water to 1 liter pH value: 4.3

Washing: 4 min

Bleach-3x treatment: 6 min

Disodium tetraborate decahydrate 12.5 g

Boric acid 22.5 g

Sodium hydroxide 10.0 g

Ethylenediaminetetraacetic acid 16.2 g

Disodium salt of ethylenedi-

amine tetraacetic acid dinydrates 3.5 g

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0 , 50 g 4th , 5 g 10 ml 1 , 7 ml 1 . liter

- 17 -

Iron (III) chloride 15 ml

(60 # wt. AoI. Solution)

Sodium thiosulfate pentahydrate 95> O g

Sodium sulfite, anhydrous 4.0 g

Magnesium sulfate 12.5 g

Water to 1 liter pH: 7.0

Washing: 4 min
Conditioning: 4 min

Dinatriura salt of ethylenediarainetetraesoetic acid dihydrate

Sodium carbonate, anhydrous formaldehyde ($ 40 w / v solution)

Lissapol N (8 $ solution) water up

pH value: 10.7
Washing: 4 min

After the treatment, the obtained samples became analyzed and found to contain 13.84 mg of metallic silver per dm. Other samples of the same Negative material was masked and treated as described above, but bleach-fixed for 12 minutes. To the treatment was found to contain 9.81 mg of metallic

2
These results were used as a control for a series of experiments in which samples of the same negative material were fogged and treated as indicated above except that selenium urea-silver chloride complex was added to the interrupt fixer in row A and in row B, selenium urea-silver halide complex was added to the bleaching fixer.

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The effect of adding these bleach-fix accelerators to the bleach-fix bath and the break-fix bath is shown in Table I below, in which the amount of metallic silver remaining in the Negative material after treatment is indicated · The values refer to bleach-fix times of 6 and 12 min.

labile I

used accelerator

Bath, whose soles, was admitted

Conc.aes

Soles.

(mg / 1)

remaining syllable (mg / dm ^) after bleach-fix treatment from 6 min ι 12 min

Control - - 13.84

Row A (selenium urea) p-

Ag Cl interruption fix. 400 0.81 bath

Row B (selenium urine

substance) o-Ag Cl bleach 150 0.86 Fix.Bad

9.81 0.54

0.36

There was a large reduction in the amount of silver retained in samples treated with a bleach-fix bath, containing a bleach-fix accelerator (series B) were obtained. Even with the rehearsals of series A, which is made in the presence of the bleach-fix accelerator were bleach-fixed, there was a large reduction the amount of silver remaining. In this case the accelerators were absorbed in the film material and were from the interrupt fixer to which they were added.

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- 19 Example 2

A positive tripack color material that is used for the Silver dye bleaching system was provided, and silver halide emulsions containing bleachable azo dyes ("Cibachrom", manufactured by Oiba Geigy A.G., Switzerland) contain, was subjected to a gray wedge exposure and treated. The treatment was as follows:

Development: 10 min

p-methyl amine phenol sulfate. 1 g

Sodium sulfite, anhydrous 20 g Hydroquinone 4 g

Sodium carbonate, anhydrous 10 g Potassium bromide 2 g

Water to 1 liter

Interrupt fixing treatment: 4 min

Sodium thiosulfate pentahydrate 200 g sodium sulfite, anhydrous 20 g Water to 1 liter

Washing: 8 min. Color bleaching: 20 min

Sulfuric acid, 96 j6 27 _t 5 ml

Potassium iodide 10 g

Solution of 0.3 g of 2,3-dimethyl

6-aminquinoxaline in 50 ml

Ethanol 15 ml

Water to 1 liter

Washing: 4 min

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- 20 bleach-fix treatment: 6 min

Disodium tetraborate decahydrate 12.5 g

Boric acid 22.5 g

Sodium hydroxide 10.0 g

Ethylenediaminetetraacetic acid 16.2 g

Ethylenediaminetetraacetic acid dihydrate disodium salt 3.5 g iron (III) chloride (60 pounds wt /

Solution by volume) 15 ml

Sodium thiosulfate pentahydrate 95, Og

Sodium sulfite, anhydrous 4.0 g

(Selenium urea) ₂ Ag Cl 150 mg

Water .. to 1 liter

To wash; 8 min
dry

The treated material was satisfactory and essentially no residual silver remained in the material. not even in the high exposure areas. Similar silver dye bleach materials were exposed and treated using the same solutions given above with the exception that the bleach-fix solution did not contain a selenium urea silver complex. Even when the material has been treated in the bleach-fix bath for 25 minutes it was unsatisfactory as it had a high minimum density due to the incomplete removal of the residual silver in the high exposure areas.

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Claims (2)

2101 ^ 36-21 claims 1. Process for the production of material with dye images from color photographic material, which comprises silver halide emulsion layers, characterized in that in a bleach-fix step the photographic material with a stable bleach-fix bath, which is an aqueous solution of a mild oxidizing agent and a solvent for silver halide genid, which consists of either a water-soluble ™ thiosulfate or a water-soluble thiocyanate, in the presence of a solution of a bleach-fix accelerator treated, which is a complex compound of iron, cobalt, nickel, copper, zinc, palladium, Silver, cadmium, indium, tin, antimony, platinum, gold, Mercury, lead or bismuth and a) selenium urea, b) an N-alkyl substituted selenium urea the general formula (D - C - N <
Se in which R ₁ , R ₂ and R ^ are hydrogen atoms or alkyl groups , at least one of these symbols consisting of a hydrogen atom, or 109829/1688 2101 ^ 36 - 22 c) a selenium semicarbazide of the general formula Ro 4 Ro-z Se '24 - -NC- ^R 22 ^{> R} 25 in which one of the symbols R ₂₁ and R ₂₂ consists of a hydrogen atom or an alkyl, aralkyl or aryl group and the other of the symbols R ₂₁ and R _{22 is} a hydrogen atom or an alkyl group, R _{23 is} a hydrogen atom or an alkyl, Aralkyl or aryl group, one of the symbols R ₂ ^ and R ₂₅ consists of a hydrogen atom or an alkyl, aralkyl or aryl group and the other of the symbols R ₂ * and R ₂ ^ is a hydrogen atom or an alkyl group, but at least one of the symbols R ₂₃ , R ₂ * or R ₂₅ consists of a hydrogen atom and no more than one aryl or aralkyl group is present in the compound. 2. Stable bleach-fix bath containing an aqueous solution of a mild oxidizing agent and a thiosulfate comprises, characterized in that it comprises a complex compound as a bleach-fix accelerator in solution contains that of iron, cobalt, nickel, copper, zinc, palladium, silver, cadmium, indium, tin, antimony, Platinum, gold, mercury, lead and bismuth and a) selenium urea, b) an N-alkyl substituted selenium urea of the general formula (D > N - C - 1Ü9829 / 1688 2101 * 136 in which R ₁ , R ₂ and R, are hydrogen atoms or alkyl groups, at least one of these symbols consisting of a hydrogen atom, or c) a selenium semicarbazide of the general formula (II) R ₂ , Se I Il -N-C R ₂₂ R ₂₅ in which one of the symbols R ₂₁ and R ₂₂ consists of a hydrogen atom or an alkyl, aralkyl or aryl group and the other of the symbols R ₂₁ and R _{22 is} a hydrogen atom or an alkyl group, R _{23 is} a hydrogen atom or an alkyl group , Aralkyl or aryl group, one of the symbols R ₂ ^ and R ₂₅ consists of a hydrogen atom or an alkyl, aralkyl or aryl group and the other of the symbols R ₂ / and R _{25 is} a hydrogen atom or an alkyl group, but at least one of the symbols R ₂ ^, R ₂ / or R ₂₅ consists of a hydrogen atom and no more than one aryl or aralkyl group is present in the compound. "3 x interrupter fixer, comprising an aqueous solution of a thiosulphate, characterized in that it in solution contains a complex compound consisting of iron, cobalt, nickel, copper, zinc. Palladium, silver, cadmium, Indium, tin, antimony, platinum, gold, mercury, lead 109829/1688 2 10 i4 or Wisbut and a) SeI urea, b) an N-alkyl substituted selenium urea the general formula } Ή - G - N <(I) R _x Se in which R ₁ , R2 and R * are hydrogen atoms or alkyl groups, v / obei at least one of these symbols consists of a what s first off atom ", or c) a selenium seraicarbazide of the general formula ^R 21 T? Sp
ι ^ -> ti c - nC (ii) ^R 22 in which one of the symbols Ik ^ ^{un <} * ^ 22 ^{oua consists of} an oxygen atom or an alkyl, aralkyl or aryl group and the other of the symbols Rp ₁ and R ₀ - is a water off atom or an alkyl group, R _? - ^ means a hydrogen atom or an alkyl, Ara.llcyl- or aryl group, one of the symbols R _{O /} . and R ^, - consists of a hydrogen atom or an alkyl, alicyl or aryl group and the other of the symbols R ₂ ^ and Ro ^ '{ü y 8? 9 I 1 \\ B 8 2101 ^ 36 a hydrogen atom or an alkyl group, but at least one of the symbols & 23 » ^R 24 ° ^ ^er ^ 2 consists of a hydrogen atom and no more than one aryl or aralkyl group is present in the compound. '1U9829 / 1R88