CA1050990A - Cyanine dyes and their use as spectral sensitizers in direct positive photographic materials of the spectrally sensitized type - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE.
The present invention provides cyanine dyes derived from di-halogen benzoxazole or di-halogen benzothiazole, corresponding to one of the following general formula:

[I]

[II]

[III]

[IV]

wherein:
Y represents an oxygen or sulfur atom;
n represents a positive integer equal to 2,3,4;
m, p represent a positive integer of 1 or 2;
q represents a positive integer from 1 to 3;
R, R1, equal or different, each represent a halogen ato?;
R2 represents a hydrogen atoms, an alkyl group having from 1 to 4 carbon atoms;
R3 represents an acyclic hydrocarbon substituent, an alkyl-aryl substituent or an aryl substituent;
R4 represents a hydrogen atom or an alkyl group having from 1 to 3 carbon atoms;
R5, R6, equal or different, each represent an alkyl group having from 1 to 6 carbon atoms;
X" represents an acid anion;
Z represents the atoms selected from only carbon, oxygen, sulfur, nitrogen and selenium required to complete a heterocyclic nucleus containing from 5 to 6 atoms in the heterocyclic ring;
Q represents the atoms selected from only carbon, oxygen, sulfur, nitrogen and selenium required to complete a heterocyclic ketomethylene nucleus con-taining from 5 to 6 atoms in the heterocyclic ring.
New cyanine dyes derived form di-halogen benzoxazoles and benzothiazoles are desensitizers for silver halide negative emulsions and useful electron acceptor spectral sensitizers for direct positive silver halide emulsions.

Description

The present lnvention re~ers to a new class o~
cyanine dye~ and thelr use as ~pectral sensitizer~ in direct positive photographic materials of the spectrally sensitized type.
The new class o~ cyanine dyes of the present invention comprises at least one heterocyclic nucleus com-prislng a 5 or 6-membered ring Jolned by a methine lin~age to a second heterocyclic nucleus of a para~amino phenyl group J the first of sald heterocycllc nuclel being a nucleus o~ the benzoxazole or benzothiazole series having at least

2 halogen atoms as substituents in the phenyl group thereor, Joined to-the methine linkage in the 2-position o~ said :
nuclei; the second nucleus is a nucleus suitable to complete a oyanine dye. The second nucleus convenienkly contains a heterooycllc nitrogen atom or para-amino phenyl group and the me~hlne chain consists of a polyenic chain, containin~
an equal number of alternating single and double bonds, one termlnal carbon atom o~ which ls the carbon atom in the 2-po~ition Or a nucleus of the benzoxazole or benzoth:Lazole Z0 series, characterized in that it has at least 2 halogen atoms as substituen~ in the phenyl gr~up, the other termlnal ., ~
oarbon atom of the chain being comprised by the ~eoond nitrogen oontainin~ heterocyclic nucleus. Prererably, the second nucleus of these dyes is a desan~itizing nucleus ,, .
(known ~1 the prior art~ for example, a~ in U.S. Patent , .

3,431,111S col. 1, llne 60 - col. 2, llne 6, and F. M Hamer~

" he ~ ne Dyes and Related~Compo~nds" pp. F28-F2~, Interscience Pub~ hers, 1964) ~ . :

: ` In ano~her embodiment, the present invent.Lon re~érs to merocyanlne~ dyes oomprising two nuclei ~oined together by - ~ :
, ' ' . ' a methlne chain containing an equal number of alternating single and double bonds; the rirst of ~aid nuclei being a nucleus of the benæoxazole or benzothiazole serles, having at least 2 halogen atoms as substituents in the phenyl group, ~oined to the methine chain through ~ts carbon atom in the 2 positlon; and the other nucleus being a nitrogen containing ketomethylenic nucleus 7 having therefore a methylene group acti~ated by a carbonyl group being comprised in the eyclic ring.
In a further embodiment, the present invention relates to styryl dyes comprising a nucleus derived from di-halogen-benzoxazoles or di-halogen-benzothiazoles, ~oined khrough a methine chaln having a~ equal number of alternating ~ingle and double bonds, one terminal atom of the chain being the carbon atom in the 2-position of sald di~halogenated benzo-azole nuclei, the other terminal carbon atom being in the benzene ring, substituted in the para-po~ition with a dialkylamino group.
In still another eJnbodlment, the present invention refers to dyes containin~ 2 nuclei of the di-halo~en sub-~tltuted benzoxazole or benæothiazole series Joined together by a ~hain having an equal number o~ alternat~n~ single and double bond~ through the carbon atom~ in th~ 2-position of the heterocyclic nucleus. The methine chain ~oining the two nuclel pre~erably consi~ts of 3 methine groups~
The ne~ dyes according to the present invention derived from benzoxazoles and benzothiazoIes having two halogen atoms as substituents in the phenyl group, can be represented b~ the following ~eneral formulas:

.

~L~5~
R R

Rl~ Y~ ~R4 / X~ R /~:L 7 R

Rl~ /\C=CH-(CH=CH)n 1 C(-C~I-CH)m l_N_R3 ~ Z 7 2 3 X~
.
R

Rl~ \C-(CI~=CH)p~3 N/ 5 / 3 7 R
y ,-Q~~ : -Rl~ C=(CH~CH)q 1 -C--C=O / 4 7 R2 3 ~ .

wherein:
Y is oxygen or sulfur;
n Ls a posltive integer equal ko 2,3,4;
m a~d p are pos~tive lntegers o~ 1 or 2;
n is 1 or 2;
q is a positive integer o~ from 1 to 3, R and Rl, equal or dif~erent, represent two halogen atoms, such as chlorine, bromine, f`luorine and iodine;
R2 is a hydrogen atom or an alkyl group having ~rom 1 to 4 carbon a~oms;

~,:

91~
R3 represents an alky, cycloalkyl or substituted alkyl group, ~uch as for instance methyl$ ekhyl, propyl 3 isopropylg butyl, hexyl, cyclohexyl9 clecyl, or dodecyl;
an alkoxy-alkyl group, ~uch as for instance ~ -methoxy-ethyl or ~-buthoxy-butyl; an hydroxy alkyl group, such as for instance ~ -hydroxyethyl or ~l -hydroxybutyl; a carbo~y-alkyl ~roup, such as ~or instance carboxy-methyl3 -car~oxyethyl, ~ -carboxypropyl, ~ -carboxybutyl;
a sulfoalkyl group, such as Por instance ~ -sulroethyl, ~ -sulfopropyl, ~ -sulfobutyl, ~ -sul~obutyl, etc.;
a alkoxy-carbonyl-alkyl group, such as Por ins~ance ~ me~hoxycarbonyl-ethyl or ~ -methoxy-carbonyl-butyl;
an alkenyl Kroup, such as for lnstance alkyl, l-propènyl, 2_butenyl~ etc., an ar-yl group, such a~ ~or instance phenyl, tolyl, xilyl, chlorophenyl, methoxyphenyl, naphthyl, etc.;
R4 represents a hydro~en atom or an alkyl group having ~rom 1 to 3 carbon atom~, such as for instance methyl, ethyl~
propyl;
R5 and R6~ equal or different, each represent an alkyl group containing from 1 to 6 carbon atoms;
X represents an acid anion, such as ~or instance ohloride, bromide, iodide, sulPamate, perehlorate~ p-toluensulPonate, methyl-sul~ate, etc.;
z represents the non-metallic atoms regu1red ~ comple~e a sensitiz~ng or desensitizing heterocyclic nucleus conta~ning ~rom 5 to 6 atoms in the heterocycllc nucleusg whlch may aI~o include more than a hetero-ato~, such as ~or instance oxygen~ sul~ur~ selenium or nitrogen, for lnstance th~
3 follow1ng nuclei:

~LO~g90 a nucleu~ of the serles of the thlaæole 9 ~or instance thiazole, 4-methyl-5-phenyl-thiazole, 5-methyl-thlazole, 5-phenyl-thlazole, 4,5-dimethyl-thlazole" 4 9 5-diphenyl-thiazole, 4-~Z-thienyl)-thiazole or 4-nitro~thiazole;
o~ the benzothiazole (e.g. benzothiazole" 4-chloro-benzothiazole, 5-n~tro-benzothiazole, 5-chloro-benzothla-zole, 6-ni~ro-benzothiaæole, 5,6-dinltro--benzothia~ole~
6-chloro-benzothiazole, 7-chloro~benzothlazole, 4-methyl-benzothiazole, 5-methyl-benzothiazole, 6-~methyl-benzothia-zole, ~-bromo-benzothiazole, 6-bromo-benæothiazole, 5-phenyl-benzothiaæole, 6-phenyl-benzothiazole, l-metho~y-benzothiaæole, 5-methoxy-benzothlazole, 6-methoxy-benzo-thlazole, 5-bromo-benæot~llazole, 5-lodo-benzokhi~zole, 6-lodo-benzothlazole~ 4-et}loxy-benzothlazole, 5-ethoxy-benzothlazole, ~etrahydro-benzothiazole, 5~6-dimethoxy-benzothiaæole, 5~6-dloxymethglene~benzothiazole~ 5-hydraxy-benzothlazole, 6-hydroxy-benzothlazole); o~ the naph~ho-thiazole (e.g. a-naphthothiazole, ~-naphthothlazole, 5-methoxy-~-naphthothiazole, 5 ethoxy-~-naphthothiazole, 8-methoxy-a~naphthothiazole, 7-methoxy-a-naphthothiazole);
of the naphthothiazoles having a nitro-substltuent; of' the oxazole (e.~0 4-me~hyl-oKazole 9 4-nltro-oxazole, 5-methyl-oxazole, 4-pnenyl-oxazQle, 4,5-dlphenyl-oxazoleg

4-ethyl-oxazole, 4,5-dimethyl oxazole, ~-phenyl-oxazole);
of the benzoxazole ~e.g, be~zoxazole, 5-chloro-benzoxaæole~

5-nitro-~enzoxazole~ 5-methyl-benzoxazQle 3 5-phenyl~
~enzoxazole 7 6-nitro-benzoxazole~ 6-methyl-benzoxazQle, 5,6-dinitro-benzoxazole, 5,h-dlmethyl-benzoxazole, l~ 9 6-dimethyl-benzoxaæole, 5-met~loxy-benzoxazole, 5-e'Ghoxy~
3 benzoxazole 7 5-chloro-benzoxazole, 5-bromo-benzoxazole, .

.... .... ~ . .

g~
5-iodo-benzoxazole, 6-methoxy-benzoxazole, 5-hydroxy-benzoxazole, 6 hydroxy-benzoxa~ole)~ of the naphthoxa?ole (e.g. a-naphthoxazole, ~-naphthoxazole); o~ the naphthoxa-zoles substituted with a nitro - group; Or the selenazole (e.g. 3elenazole, 4-methyl-selenazole, 4-phenyl-selenazole);
o~ the benzoselenazole (e.g. benzoselenazole, 4-nitro benzoselenazole, 6-nitro-benzoselenazole, 5-chloro-benæoselenazole, 5-methoxy-benzoselenazole, 5-hydroxy--benzoselenazole, 5~nitro-benzoselenazole, tetrahydro-benzoselenazole); of the naphtho-selenazole (e.g. a-naphtho-~elenazole, ~-naphtho-selenazole~; o~ the naphtho-selena-zoles substitued with a nltro-group; of ~he thiazoline (e.g. thiazollne, 4-rnethyl-t~liazoline, 4-nltro-thiazoline, etc~); o~ the pyri~lne (e.g. pyrldine, 2-pyridine, 5-methyl-2-pyrldine, Il-pyri~lne, 3-methyl-4-pyridlne);
pyrldine substituted with a nitro~group; of the qulnoline (e.g. quinolinej 2-quinoline, 3-methyl-quinoline, 5~ethyl-quinollne, 6-chloro-qulnoline, 8-chloro-quinollne, 6-met~oxy-quinoline,8-ethoxy-quinoline, 8-hydroxy-quinoline);
o~ the 4-qulnollne (e.g. 6-methoxy-4-tluinollne, l-methoxy-4-qulnoline, 7-methyl-4-quinoline, 8-chloro-4-quinollne~;
of the l-i~oqulnoline ~e.~. 3,ll-dihydro~ oqulnoline);
3-lsoqulnoline; quinolines having a nitro~substituent; o~
the l,l-dialkyl-lndolenine te.g. l,l-dimethyl-5 or o-cyano indolenlne, 1,1-dimethyl-5 or 6-nitro-inaolenine~
131-dlmethyl-5-chloro-indolenine), o~ the imidazole (e.g.
imidazole, l-alkyl-lm~dazoIe~ l-alkyl-4-phenyl-imldazole, l-alk~1-4~5-dimethyl-lmidaæole); of the benzlmidazole ~(e.B. l-alkyl-benælmidazole, l-aryl-5,6-dichl~ro-benzim~da-zole8), o~ the naphthlmidazole te.~O l-alkyl--naphtllo--.. . . .

imidazole, l-aryl-~-naPhtho-imi~azole~ l-alkyl-5-methoxy a-naphtho-imidazole~.
The nuclei, wherein Z represents the atoms require~ to make a nitro-substituted heterocyclic nucleus, give desensitizing dyes particularly useful to make direct positive emulsions and materials using such emulslons, accordlng to the present invention. Particularly, the preferred nuclel are selected from the ~roup~ formed by nltro-benzothiazoles (e.g. 5-nitro-benzothiazole, 6~nitro-benzothiazole J 5-chloro-6-nitro-benzothiazole); or from the group~ formed by the homologous derivatives obtained by ~ub~tituting sulfur with oxygen or selenium~ or from the group~ formed by imidazo~4,5-b]qulnoxallne~ te.g~
imidazo~ll,5-b~quinoxallne, 1,3~dialkyl-lmldazo[4,5~b]
quinoxaline, 1,3-diethyl-imidazo~4,5-b]~ulnoxaline~ 6-chloro-1,3-diethyl-lmidazo~4,5-b]quinoxaline, 1,3-dialksnyl-lmidazo~4,5-b~qulnoxaline, 1,3-diallyl-lm$dazo ~4~-b]quinoxallne, 6,7-dichloro-1,3-dlallyl-imldazo ~4,5-b]qulnoxaline~ 1~3 diaryl-imidazo[4,5-bJquinoxaline 1,3-diphenyl--lmidazo[4,5-b~quinoxaline, ~-chloro 1,3-diphenyl-imidazoC4,5-b]quinoxaline); or from ~he groups formed by 311 pyrroloC2,3-b~pyridine (e.~ 3~3-d~alkyl-3H-pyrrolo~2,3-b]pyri~ine, 3,3-diethyl or 3~3-dlmethyl-3H-pyrrolo~2,3-b]pyridlne); or from the groups ~ormed by 3H-nitro-indoles (e.g. 3,3-dialkyl-3H-nitro-indole,~ 3,3-, dimethyl or 3,3-d~ethyl-5-nitro-3H-indole); from the group~ ~ormed by thiazole[4,5-~]quinollne or forme~ by nitro-quinollne (e.~. 5-nitro-quinoline, 6~nltro-quinoline; ~tc~).

. . ~ , . . . . ..

Q represent~ the non-metallic atoms required to complets a 5 to 6-membered heterocycl~c nucleus~ such as for instance a 2~pyrazolin-5-one nucleus (e.g. 3-methyl-l-phenyl-2-pyrazolin-5-one, 1-phenyl-2-pyrazolln-5-one, 1-(2-benzothiazolyl)-3-methyl-2-pyrazolin-5-one, etc.); an i30xazolone nucleus (e.~. 3-phenyl-5(4H~-isoxazolone, 3-methyl-5(4H~-isoxazolone~ etc.); an oxindole nucleus (e.g. l-alkyl-2,3-dlhyclro-2-oxindole~, etc.)~ a 2,4~6-trlketohexahydro-pyrimldine nucleus (e.g. barbituric acid or 2-thio-barbituric acid and their l~alkyl derivatives~ such as for instance l-methyl ?
l-ethyl, l-propyl, etc.; 1,3-dialkyl derivatives, such as for instance 1,3-dimethyl~ 1,3-diethyl, 1,3-dipropylg etc.; 1,3-dlaryl derivatives, such a~ for instance 1,3-diphenyl, 1,3-di(p-chlorophenyl), etc.; l-aryl deriva-tlves, sùch as for in~tance l-phenyl~ l-p-chlorophenyl;
l-alkyl-3-arylderivatives, such as ~or lnstance l-e~hyl-3-phenyl, 1-n-heptyl-3-phenyl, etc.~; a 2-thlo-2,4-thiazolidine-dione nucleus trhodanine) (e.~. rhodanine 3-alkyl-rhodanlne~ ~uch as for instance 3-methyl-rhodanine, 3-ethyl-rhodanine, 3~allyl-rhodanine; 3-carboxy-alkyl-rhodanines, such as ~or instance 3-~carboxy-ethyl~rhodanlne, 3-carboxy-methyl-rhodanine, eta.; 3-sulfo alkyl-rhodanine~, such as for in~tance 3-~sulfo-ethyl-rho~anlne, 3-~ sulfo-propyl-rhodanine~
etc; 3-aryl-rhodanine~, such as ~or instance 3-phenyl-rhodanlne, 3-p-slllfo-phenyl-rhodanine, etc.); a 2-thlo-2,4-oxaæolidine~dion~ nucleus te.g. 3-ethyl-2~thlo~-2,4-oxazolidln-dione, 3-p-sul~o-ethyl-2-thio-2,4-oxaæo~idine~
d~on~, 3~p-sul~o-ethyl-2-thio-2,4-oxazolidine_dione~

1~99~ :
3-~-sulfo-butyl-2-thio-2,4-oxazolidine-dione, 3-~-carboxy-propyl-2-thio-2,4-oxazolidin-dione, etc.); a thianaphthenone nucleus (e.g. 3-(2H)-thlanaphthenone, etc~); a 2-thio-2,5-thiazolidine-dione nucleus (e.g.
2-thlo-2,5-(3H,4H)-3-ethyl-thiazolldln-dione, etc.);
a 2-4-thiazolidlne-dione nucleus (e.g. 3~-ethyl-2~
thiazolldlne-dione, 3-phenyl-2,4-thiazolidine-dione, 3--naphthyl-2,4-thiazolldlne-dione, etc~); a thia-zolidinone nucleus (e.g. 4-thiazolidinone, 3-ethyl-4-thlazolidinone, 3-phenyl-4-thiaæolidinone, 3-~-naphthyl-4-thiazolidinone, etc.); a 2-thlazolln-4-one nucleus te.g. 2-ethyl-mercapto-2-thiazolin-4-one, 2-alkylphenyl-amino-?-thiazolin-4-one~ 2-diphenylamino-2-thiazolin-4-one, etc.); a 2-imino-4-oxazolidinone (i.e. pseuclo-hydantoin) nucleus; a Z,4-imidazolidlne-dione (hydantoin) nucleus (e.g. 2,4-imidazolldine-dione, 3-ethyl-2~4-imidazolidine-dione, 3-phenyl-2~4-imldazolidine-dione, 3-a-naphthyl-2,4-imidazolidlne-dlone, 1,3-diethyl-2,4-imidazolidine-dlone, l-ethyl-3-phenyl-2,4-imidazolidine-dlone, 1-ethyl-3-a-naphthyl-2,4-imldazolidine-dlone, 1,3-dlphenyl-2~4-imidazolldine-dione, eto.); a 2-thio-2,4-imldazolldlne-dione (i.è. 2-thio-hydantoin) nucleus (e.~. 2-thio-2,4-imidazolidine-dione, 3-ethyl-2-thio-2,4-imidazolidine-dione, 3-~-sulfobutyl-2-thlo-2,4-imidazolidin~-dione, 3-B-carboxyethyl-2-thio-2,4-lmldazolidine-dione, 3-phenyl-2-thlo-2,4-imidaæolidlne-dione, 3-a-naphthyl~2-thio-2,4-imida~olldine-dlone, l-ethyl-3-phenyl-2-thio-2,4-lmidazolldine-dione, l-ethyl-3-a-naphthyl-2-thio-2~4-imidazolldlne-dione, 1,3-diphenyl-2-thio-2,4-imldazolidine-dioneg ete.).
Pre~erably Q represents the atoms selected only Prom carbon, oxygen, sul~ur, nitrogen and selenium to complete a 5 to 6 membered heterocyclic ketomethylene nucleus~

~_9_ ':

9~0 The present invention ~urther relates to light sensitive direct positive silver halide emulsions characterized in that they contain a sensit~zing amount of cyanine d~e as described above.
The present invention also further relates to cyanine dyes and light-sensitive direct positive silver halide emulsions characterized in that they contain a sensi-tizing amount of said cyanine dyes, characterized ln that the moiety:
z _ _ _ _ _ _, -C~CH - CH~m_lN-R

represents a desensitizing heterocyclic nucleus.

-9a-- . , .

1~990 , ~
Ex¢ept where already limited in the above descrlptions of` dependent groups, such dependent groups as R3, X, an~ the second nucleus (heterocyclic or para-amino phenyl) do not substantially e~ect the per~ormance of the types by even extreme varlation in size. The rollowing limitations are derived mainly ~rom economic considerations in the selection of size limit for dependent ~roups.
Group R3 is generally preferred to have no more than 1~ carbon atoms, more preferred to have no more than 12 carbon atoms an~ most pre~erred to have no more than 4 carbon atoms. It is generally pre~erred to have no more than 8 non-metallic heteroatorns and more prererably no more than 5 æuch heteroatoms.
The secon~ nucleus la ~enerally prererred to have no more than 50 carbon atoms~ more pre~erably no more than 30, and moæt preferably no more than 20 aarbon atoms. It is generally preferred to have no more than 10 heteroatoms in the second nucleus, with no more than 5 he~e~oatoms in the heterocycllc rln~.
.
~ Aocordln~ to the present, lnvention, ~ne dyes repr~ented by general rormulas [1~, ~2], ~3~ ~4] can ; .
be oonvenlently prepared by u~ln~ new compounds o~ ~ormula:

R~ ~ -CH5 wherein:~
R~ B1J R2~ R3 and X have thc above mentloned meanlngs.

: , : , , ;
`

-3~la3~9~
The new compounds of ~ormula [5] can be advantageously prepared by cyclization of su~table intermedlates accordinr to whether Y i8 oxygen or sulfur.
The symmetrical carbocyanines having general formula Cl] can be conveniently prepared by reacting 2 moles of a cornpound selected among those represented by general formula [5~ with l mole, or with l mole +100% in excess, of ethylformate of diethoxymethylacetate to prepare carbocyanines (n=2) wherein R4 is hydrogen; with l mole, or wlth l rnole ~ lO0~ excess~ of triethylortho-acetate to prepare carbocyan~nes (n~2) wherein 1~4 is a methyl rroup; with l mole, or wlth l mole + lO0~ excess, of triethylorthopropionate to pre~ar-e carbocyanine~ (n=2) wherein R4 ls an ethyl group; wlth trimethoxypropene or acroleyn~ldehy~e dianylhydrochlor~de to give dlcarbo-cyanlnes (n~3), etc.
To prepare the unsymrnetrical cyanines of general formual t2], wherein n ~ 2, 3~ 4, a compound selected among those repre~ented by teneral formula ~5~ i9 reacted with a compound selected amon~ those represented by ~eneral forMula:

Z ~ ~
R7-N-(cll-c~)n-l C(=C}I-CH)m_l3 N 3 ~6}

wherein: .
na R3, ~ and X have the above mentioned meanlngs;
R7 ls an aryl group (such as for instance phenyl~ tolyl, etc.), and R~ is an alkyl ~roup having frorn l to 18 carbon atom~, ~ 11 --' ' . "

9~0 The reaction ls carried out ln an inert solY~nt in ~he presence of a baslc catalyst.
ParticularlyJ the unsymmetr~cal cyanines repre~ented by general for~ula [3], wherein n=2~ can be prepared by reacting a compound represented by general ~ormula [5] with a compound selected among those repre3ented by general formula:
_______z_____, OHC-CH~ CH~H)m~ 3 wherein:
R3, Z and m have the above-mentloned meaning~.
The aondensatlons are con~enlently carried out ln a¢etic aaid or acetlc anhydride; the dye separated by coollng 1~ puri~ied by one or more crystallization~ rrom a ~ulta~le ~olven~.
Styryl dyes havlng general ~ormula t3] can ~e pre-pared by heating a mixtura o~ a compound selecbed among tho3e represented by general formula C5] with a ~uitable N,N-dl-sub~tituted-p-amino-benzaldehyde or N~N-di-substieuted-p-amino-cinnam~ldehyde 5 pr*ferably in a sultable solvent and in the presence ~ a ba~ic cataly~:t.
The merocyanlnes represented by general formula t4~ can be prepared by reactlng a compou~d of gener~l formula C53 wikh a compound o~ general ~ormula:
~5 ,~Q~
Rg-N- ( cHccH 3 q l3d ~ o ~ ~3 ]
CORl o ~hereln~
Rg rQp~e~ent3 an aryl graup ~such a~ for lnstance phenyl, 3~ to~yl, ~t~
Rlo repr~sents an alkyl group having ~rom 1 to 1~ carbon ' , ~s~9g~
atom~0 The reactlon~ are eonvenlently carried out in an inert solvent and ln the pre~ence o~ a ba~lc catalysk.

::

~0S~99(1 The following ex~mples will better illustrate the pre~ent invention ln its di~ferent aspect~ 7 VlZ.
preparation of intermediate~, dyes as well a3 the~r uae in light~sensitive emul~ions.

_XAMPLE 1 Br Br ~ NUCOCH3 A mixture of 89 g. o~ 2-nitro-4,6-dibromo-phenol, 270 ml.
of methyl alcohol, 50 ml. of 30% NaOH aqueous ~olu~ion and 2,400 ml. of deminerallzed water was heated up to 50-55C., obtalning a yellow solutlon. To this ~olutlon, 178 g. Or Na2~203 were added in small portions, by keeping the tempera-ture at 50C. The reaction mlxture was then stirred for 30 mlnutes by keeping the temperature at 65C. and rinally for 30 minute~ at room temperature. By cooli~g, 44.2 g. o~
2-amlno-4,6-dibromo-phenol were obtained, having a mel~ing po1nt equal to 89-92C.
44.2 g. of 2-amino-4,6-dibromo-phenol were pro-cessed wlth 85.5 ml. of acetio anhydride keepln~ the temperature under 50C. ~y cooling, the 2-acetylamino-4,6-d~bromo-phenol separated; it ~as collected on a ~llt~r and crystalllzed ~rom ethyl alcohol. 30 g. of pure produ~t were obtalned. M.P~ = 175-176C.
Percent analy~ls: C% cal~ulated 31.10 found 3~
H~ " 2 . 28 " 2 . 29 Ng " 4. 53 " 4. 54 , ' ~ :

.

.
:

3t9~
X~MPL~ 2 -2-meth~ 5~_dibromo~-ben~oxazole Br Br ~ \ C-CH3 A mixture o~ 40 g. of 2-acetylamlno-4~6-dlbromo-phenol ~nd 1.5 g. of anhydrous sodium acetate was heated at 180C. ~or same minute~, obtalning a llquid ~lurry which was 1~ dlstilled under vacuum, by colle¢tion the fractlon pa~ed ~rom 1:50C. to 155C. at 1.6 mm. Hg. The distllled oil by standing became a solld which was crystallized ~rom ligroin, obtaining 25 g. of 2-methyl-5,7-dibrom~-ben~oxa~ole.
M.P. 5 122-124C.
15 Percent analy~ls: C% calculated 33.02 round 33.14 ~% " 1.73 " 1.70 N~ " 4.81 " 4.52 2-aceCyl.aml~ _thyl-4,6-dlc 2a al H3C ~ OH
Cl NHC~CH
:To a mixture of 68.4 g. o~ 2-a~ino-5~methyl-4,6-di hloro-ph~nol hydrochlorlde and 96 ml. o~ N~N~diethyl- :
an~ e in 750 ml~ o~ acekone, 23.4 ml. o~ ac~tyl chloride ! ' were add~d:~lowly b~ keepln~ the temperature under 20C. ~t ~the end~ the reactlon mixture was heated to reflux for an ~ :
hou~. A~er aooling, the ~olutlon was poured ~nt~ wllter;

.
: ~ - 15 -s~9~

the solid product, thus ~btained, was collected on a buckner, washed with water untll the washings were neutral and dried in a desicator at 50~C. The raw product obtained was purifled by crystallization from e~hyl alcohol~ ylelding 44 g. o~ a pure product with M.P. = 175-176.5C.

-2 6-dimethyl-5,7-dichloro-benzoxazole .

Cl H3C ~ ~C-CH3 A mixture of 79 g. of 2-acetylamlno-5-methyl-li,6-di-chloro-phenol and 3.6 g. o~ anhydrous sodlum acetate wa~
heated a~ 180C. for some mlnutes. The liquld obtalned was ~istilled under vacuum~collectlng the fractlon pas~ed rrom 140C. to 145C. at 1.2 mm. HK. The dlstilléd oil became a mas~ of crystalswhich was purified by crystallization from li~roln. 36 g. of pure base were ob~alned. M.P~ ~ 80-82C~
Percent analysis: C,0 calculated 50.05 found 50.02 H% " 3.27 " 3.16 N~ ll 6.49 ll 6~55 EXAMYL~ 5 ? ~ 3-dlmeth~1-5~7-dibromo-benzoxazole methyl-sulfate ~ ~C-CH

.. . .
1 .

., ' . ' ' ~

99~
A m~xture o~ 2.9 gO of 2-methyl-5,7-dibromo-benzoxazole and 2.5 ml. of dimethyl-~ul~ate were heated at 150C. ~or 5 minutes. By cooling, a solld ¢ake was obtained. It was then ground in a mortar by wa~h~ng re-peatedly with ethyl ether. The product was employed without~urther purification ~or the dye ~ynthesis.

2-m~thyl-3-ethyl-5~7-dibromo~benzoxazole ethyl-~ul~ate Br ~ ~ C-CH3 C2H5 C2H5So4~3 The compound wa~ prepared a3 de~cribed in Example 5 using dlethylsul~ate ln~tead of methy~sul~ater EXAMP~E 7 dimethyl-3-eth~_-5,7-dichloro-benzoxazole ethyl~sul:~ate Cl H3C ~ + C- CH
Cl ~ N~ 3 C2H5 C2H5S04~

~he compound wa3 prepared as des¢ribed in Exampl~ 5 uslng 2,6-dlmethyl-5,7-dl~hloro benzoxazole and diethyl- :~
sul~ate.

~XAM

2 6-dimet~ 1~3~ethyl-5 7-dichloro-ben~oxazole p-toluen~
~ .
sul~onate .

- . . ~

99~
Cl ClG~ ~ C-CH3 ~2H5 CH ~SO3~
A mi~ture of 2 .1 g. of 2, 6-dimet;hyl-5, 7-dichloro-benzoxaz~le and 2 g. of ethyl-p-toluene-sulfonate wa~ heated at 150C. f'or 30 minutes. ~y cooling, a plck cake was ob~ained. I~ was then ground in a mortar by washing 10 repeatedly w1 th ethyl ether . The product, thus obtal ned, wa~ dried and ~sed without further purif'icatlon for the synthesis of dyes.

Anhydro-2; 6-di~nethyl-3-y-sul~o-propyl-5, 7-dlchloro-benz,oxazole 1$ h~qroxid~ . ,_, , H3C~ ;~,C - CH3 ~C~2)3s03~3 A mlxture Or 4.32 gO of 2,6-dimethyl-597-dichloro-ben20xazole and 3.66 g./o~ 1,3-propane~sulfone was heated at .:.
150C. ~or 15 mlnute~. ,The pick cake, obtained by cooli~g, was ~ound in a mortar by wa~hing repeatedly with ethyl ether.
The hygr~c~pic ~olid, thus obtained, was drled under vacuum and u~ed lmmediately wlthout any further purlfieatlon for the dye synthe~ls.

:. .

~ 09~ ;

2-methyl-5~6~dlchlorobenzothiazole C1 ~ C - CH3 A mixture of 66 g. of 2,4,~-trich1.oro-1-nitro-ben~ene and 120 ml. o~ ethyl alcohol was poured lnto a 750 ml. flask equ~pped with reflux condenser~ mechanical stlrrer and dropping funnel and heated to reflux. Through the funnel, a sodium disulfide aqueous solutlon, obtalned by dissolving 72 g. of Na2S H20 and 9.6 ~. of sulfur in 45 ml. of boiling water, was dropped into. At the end, the reaction mixture was heated to rerlux under stirrtng 1Por half an hour. By c~oling, a gum ~eparated which became solid on ~tandlng o~ernlght and by washing with hot water.
61.8 g. o~ 2,2'-dinitro-4,5-4',5' tetrachloro-dlphenyl-disul~lde was obtained and poured ~mmediately into a 1,500 ml. keller equlpped wlth mechanical stirrer~ thermo-meter and reflux condenser, containlng 3~4 ml. o~ acetic aci~
and moun~ed on a sand bath~ To this mixtu~eS heated up to 90a.j 112 g. of Zn-powder was added ln ~mall portions. At the end the heating was contlnued for two hour~ and a hal then 45 ml. o~ acetic anhyd~ide were added and the re~lux heatln~ contlnued for 2 hours. 'rhe ho~ mlxture was hot filtered on a buckner, wash~ng the solid with hot acetic acid and then ~ :
oooled and made ba~lc with ammonia. The gum obtained on ~tan~in~ became solid.. It was then ground in a mortar by washlng ~ith ammonia ~queous solution and then alr dried~ : .
m e solld was dlstilled under reduced pressure collecting the~ ~racblon from l90~C. to 200C. ~t 2 mm. Hg. The dl~tilled oll, on~tandln~, became a mass o~ whlte cry~tals which were _ lg ~

` ' . . ......
.

~a~99~
puri~ied by crystallizat$on ~rom ligroin. 20 gO o~ pure base were obtained~ havlng a melting point equal ~o 165-170C.

Percent analysis: N% calculated 6.4 found 6.o.

_ 3,3'-diethyl-5,7-5' 3 7'-tetrabromo-oxacarbocyanine perchlorate Br Br ,~ ~C=CH-CX=CH-C +~
Br N~ ~ r C2~5 ~2H5 ClOlF ~
A mlxture of 2.91 g. o~ 2-methyl-597-dibromo-benzoxazole and 2.6 g. of ethyl~p-toluene-sul~onate wa~
heated to 140C. for 4 hours. The pick cake obtained by coolln~ was ground in a mortar by washing repeatedly wlth ethyl ether. 'llhe resulting ~olid was dlssolved in 15 ml.
15 of anhydrous pyridine and 2.5 ml. Or triethylorthorormiat~ ::
and the solution wa~ heated to re~lux for 15 minutes. By eoolin~, the dye æeparated as gum which wa~ dissolved 1~
a mlnimum q~antity af ethyl alcohol. An ammonlum perchlorate aqueous solution waB adde~ to the dye solution. By standing, the raw dye 3eparated; it wa~ collected on a ~'ilter, washed and cry~talli~ed ~rom ethyl alcohol. 0.85 g. o~ pure dye were obtained having an M.P. ~ 283-6C.
maX. = 4g5 nm. (ethyl ~lcohol).

~5 3,3 t -diethyl-5~7-5',7'-tetrabramo-ax~earbocyanine lodld ~ 20 -: . , . , ;, , ~5Q~
Br Br C~CH-CH~CH-C ~
~r N~ ~\~ Br ~2H5 C2H~

The dye was prepared as de~cribed :in Example ll, u~ng potassium iodide instead of ammonium p~erchlorate.
After crystallizatlon from ethyl alcohol ~ a pure dye was obtained, having an M.P. = 278-281C.
A max. 3 495 nm. (ethyl alcohol).

3,3'-dimethyl-5,7-5',7'-tetrabromo~9-ethyl-oxacarbocyanin~
~erchlorate ~r ~ H ~r ~ C=CH-C~CH-C ~
Br Nt ~ r GH3 C~3 Cl04 ;
A mixture o~ 4.17 g. o~ 2~3-dime~hyl-5,7-dlbromo-ben~oxazole methyl-~ulfate in 15 ml. o~ pyridine and 2.5 mi.
o~ triethyl-or~ho-propionate was heated to re~lux ~or an hour.
Aft~r cooling, the reaction mixture W~ poure~ lnto ethyl ethar. The yellow separated, was washed with ethyl ether ~nd dis~olved in a minimum quantity o~ hot ethyl ~lcohol. ~o thi~ solution, an ammonlum perchlorate a~ueou~ 801ution was addsd. The dye, ~eparated by coolingg wa~ c~l}ected on a buc~ner, dried und~r ~acuum and crystallized ~r~m dimethyl :~
fo~m~micl~ 0.1 g. o~ pure dye was obt~insd having an M.P. - -330C. . ~. .
A max. ~ 500 nm. (ethyl alcohol - dlmethylformamide~, `.....
.

. - 21 _ . .

99~

3,3',9-trlethyl-5,7~5',7l-tetrabromo-oxacarbocyanine per-chlorate . . .
Br C H Br ~ 0 \ ,2 5 / 0 ~
Br N ~ Br C2H5 ~2H5 C104~

The dye wa~ prepared as reported in Example 12 using trlethylorthoproplonate as condensing agent, lnsteacl o~ triethylorthorormiate. The raw dye was purlfied by cry~talliæation from ethyl alcohol. M.P. - 281-4C, max. ~ 499 nm. (ethyl alcohol).

E-xAMpLE 15 3-ethyl-3~-methyl-5,7-dibromo-5',6'-dimethyl-oxacarbo-15 ~yanlne iodide _ Br ~ C=CH-CH=GH-C + ~ CH3 Br N ~ ~N CH3 CH3 C2H5 I ~

A mix~ure o~ 4.17 ~. Or 2,3-dlmethyl-5,7-dlbromo~
benzoxazole methyl-~ulfate and 4.62 g. of 2-~-aoetanllido-vinyl-3-~thyl-5,6-dim~thyl-benzoxazole in 20 ml. Or ~nhydrou~
pyridin~ and 2 ml. o~ trlethylamine, was heated to reflux ~or 2~0 ml~ute~ The reaction s~lution wa~ chilled 1nto ethyl ~ ether: the separated dye wa~ colleot~d on a ~ilter, drled and ~rystàllized from ethyl alcohol. 1.2 g. of pure dye were obeained. M.P. - 256-25~C. ~
m~x. ~495 nm. ~e~hyl alcoho-).
. ~

.

99~

(3-methyl-5,7-dibromo-benzoxazole-2)-(3-ethyl-thiazolidine-2)-trlmethine-cyanine iodide _ _ .
Br 5~ ~C~CH-CH=CH-C + ¦ 2 Br N/ ~ N - CH2 CH3 C2~5 I ~
A mixture of 2.08 g. of 2,3-dimethlyl-5,7-dlbromo-~enzoxazole methyl sulfate and 2.01 g. of 2-~-acetanilldo-vlnyl-3-ethyl-thiazoline iodide in 15 ml. o~ anhydrous pyrldine and 1 ml. of triethylamine was heated to rerlux ~or 20 mlnutes. The raw dye, ~eparated from the reaction mixture by adding ethyl ether, was collected on a buclcner and washed repeatedly with ethyl ether. Arter arystallization rrom a mixture of ethyl alcohol ethyl ether 9 the pure dye was obtained havlng an M.P. ~ 165-173C.
max. ~ 465 nm. (ethyl alcohol).

EXAMP~E 17 .
(3-methyl-5,7~dibromo benzoxazole-2)-(3-ethyl-6-nitro-benzothiazole-?)-trimethi~ecyanine meth~ sul~t~ .

~ ~C~CH-CH~C~-C~ ~ ~ N2 .
Br N / ~ N

A m~xbure of 2. o8 g. 0~ 2,3-d~me~hyl-5~7-dibromo-benzoxazQle and 1~.25 ~. o~ 2-formyl-methylene-3 ethvl-6-nltro-benzothiazoline in 30 ml. o:~ acetic anh~drlde, was . .
hea~ed to rerlux for 6 minutes. After cooling, t~e crude : dye was aollected on a buckner, wa~hed with ac~tic anhydride . . .

' '" ' 23 ~ ! , . I .

~s~v ethyl ether and ethyl alcohol and purified by repeatedly boillng wlth acetic acid. 1.9 g. of pure dye were o~ta~ned having an M~P. = 297-299~5C.
1 max. - 539 nm. (ethyl alcohol-dlmethylrormamide), ~XAMPLE 18 3,3' diethyl-5,7-5',7'-tetrachloro-6,6'-dimethyl-oxa-c~rbo,c~_n~ne ethyl ~ulfate Cl ~1 H3C ~ ~ / ~ C 3 I 1I C=CH GH~CH-C l Cl '~ N / ~ N~ ~ `Cl , C2H5 C2HS C2H5S04~

A ~olution o~ 3.6 g. Or 2,6-dimethyl-3-ethyl-5,7-di-ohloro-benzoxaæole ethyl-sulrate ln 20 ml. of an-hydrou~ pyridine and 3 ml. o~ triethyl-ortho-formlate was boile~ for 6 mlnute~ and a~ter cooling poured into ethyl etXer. The crude dye was collected on a buckner, wa~hed repeatedly with ethyl ether ànd then boiled ~th ethyl aloohol. A~ter recry~tallization, 1.0 g. o~ pure dy~ wa~
obtalned having an M.P. - 263-270C.
1 max. ~ 497 nm. (ethyl alcohol-dlmethylformamide3.
, ~ ~XAMP~E 19 Anhy~ro~ -sul~o3-propyl-5,7-$'~7'-tetrach~oro-6,6~- :
dimethyl-oxacarbocyan~ne hydroxide :, ': Cl Cl . H3C ~ 0 ~ 0 ~ CH3 1 Il C8~H-CH3aH-C
~1 J~ ~ Cl , ~ ~CH2)3so3H ~C 2)3So3 . , `, ;',:

` - 24 ~
, g~
A mixture Or 3.38 g. of anhydro-2y6-dimethyl-3~
~-sulfo-propyl-~,7-dichlorO-benzoxazole-hydroxlde in 25 ml.
of nitrobenzene and 5 ml. of triethylorthoformlate was heated to reflux for 15 minutes. A~ter cooling, the ~olutlon was poured into ethyl ether and acetone, the crude dye was collected and bolled with water. After crystallization from a 3:1 mlxture o~ ethyl alcohol and dlmethylformamide, 0.8 g.
of pure dye was obtalned. M.P. 299-303C.
A max. - 499 nm. (ethyl alcohol-dimethylformamide~.

~XAMPLE 20 (3 ethyl-5,7-dichloro-6-methyl benzoxazole-2~-(3-~thyl-6-nitro-benzothlazole-?)-trimethinecyanine ethyl-sul~ate _ H3C ~ ~ / S N2 I l C~CH-CH~CH-C
Cl ~ ~ N / ~ N~`~

C2H5 C2~5 C2H5S ~

A mlxture of 3.6 8~ O~ 2,6-dlmethyl-3-ethyl-5,7-di-chloro-benzoxaæole ethyl ~ul~ate and 2.5 g. of ~-formyl-mskhyl~ne-3-ethyl~6-n~tro-benzothiazoline $n 15 ml. o~ acetiG
anhydride and 7 ml. Or acetlc acid, was bolled ~or 6 minutes.
A~ter ¢oolingJ the reaction mixture was poured into ethyl ether:
the dye separated a~ gum~ It wa3 then boiled with ab~oluta ethyl alcohol untll a dark-green powder was obtained.
The crude dye was puri~ied by boillng lt repea~edly Wit~ ab~olu~e ethyl alc~hol and the pure dye collect~d on a buckner and wa~hed with ethyl sther. 1.7 g. of pure dye dye were o~kain&d. M.P. ~ 194-197C.
A ma~. 3 541 nm. (ethyl alcohol-dime~hyl~ormamide~.

: ' . :
~ ~ ' .

:........... ,: . ., ;, . . . , , . .. ,. .:

~S~

3-ethyl-5-C(3-ethyl-5,7-dichloro-6-methyl~benzoxazoline-2-~lidene3-ethylidene~-rhodanine _ _ _ Cl H3C ~ C-CH-CH-C - S

4.44 g. of 2,6-dimethyl-3-ethyl-5~7-dichluro-benzoxazole ethyl sul~ate and 2.16 g. of 3-ethyl~5-~
acetanilido-methylene-rhodanlne were dissolved in a mixture of 25 ml. o~ pyridine and 2.5 ml. o~ triethylam~ne and the solution hèated to r~rlux for 45 mlnutes. After coollng overnight, the crude dye was collectQd on a buckner, washed with ethyl alcohol and crystallized from d~methylrormamide.
1.5 g. of pure dye were obtained. M.P. = 154-5C.
max. - 489 nm. ~ethyl alcohol-d~methylformamide~.

EXAMPL~ 22 .

2 p-diethyl-amlno-styryl-3-ethyl-5,7 dichloro-6-me~hyI-benzoxazole ethyl-sulfate Cl H C ~ ~ fi~~~ ~C2H5 3 11 C-CH~CH~ N
Cl ~ ~N J/ ~ \C2H5 C H C2H5S04~

A mixture of 3.6 g. o~ 2,6-dimethyl-3-ethyl-5,7-dichloro-benzoxaæole ethyl ulfa~e and 1~77 ~. of p-diethyl- .
aminokenzaldehyde in 10 ml. of acetic anhydrlde a~d 5 ml.
o~ aC~tic aold wa~ boiled ~or 10 nlnutes.

j: ' w 26 --- : . .- .. .. : : , :

1~5~9~
After cooling, the rsaction mixture wa~ poured into ethyl ether; ~he pick cake, thus obtained~ wa~ ~round in a mortar by washing wl~h ethyl e~her, collecked on a buckner and dried. The raw dye was purified by washing it repeatedly with ethyl alcohol~ 3.5 g. of pure dye were obtained with ethyl alcohol.
max. = 525 nm. ~ ethyl alcohol ) .

3,3'-diethyl-5,6-5',6'-tetrachloro-thlacarbocyanine ethyl-~ulr~te .

Cl ~S~ f S~ Cl l C-CH-CH-CH-C ~ l Cl ~ ;~V ~N / ~ N~ ~ ` Cl c2f~5 C2H5 C2H~S040 A mixture of 2.2 g. o~ 2-methyl-5,6-dichloro-benzothiazole and 2 ml. o~ dlethylsulrate was heated at 120C. ~or 20 minute~. After cooling, the pick cake was ground in a mortar by washing with ethyl ether and dried.
The ~olid product, khu~ obtalned, was disæolved in 15 ml.
of anhydrous pyridine and 1~8 ml. of triethylorthoformiate and the solution heated to reflux ~or 40 minutes. Arter coollng, the crude dye was precipltated wlth a lar~ quantity o~ ethyl ether, collected on a fllker and dried in a desicator.
A~t~r bolling repeatedly with ethyl alcohol and ethyl ether~ :
0.8 g. o~ pure dye was obtained. M.P. - 260-~70C~
A max. 3 578 nm. (ethyl alcohol).

.
' ~

''.

: ~ , . . .
, , . ~ . , . : .

~5~9 EXAMI?LE~ 24 3,3'-diethy1-5,6-5'-6'-tetrachloro-thia~arbo~yanirle bromide ~

Cl ~ /C-CH-CH=CH-C ~ Cl C2H5 C2H5 Br The dye wa~ prepared as reported in Example 23, pre~pitatlng ~he dye w1th a potassium bromide aqueou~
~olution. M.P. = 233-238C.
~ax, - 568 nm. (ethyl alcohol).

EXAMPL~ 25 3,3',9~krlethyl-5,6-5',6'-tetrachloro-thiaoarbocyanine ethyl-~ulfate __ Cl ~5~S \ ' ~ S ~ y~Cl l ll C=CH-G-CH-C
Cl ~i~N / ~ N ~ Cl C2H5 C2H5 C2H5SollQ

A mlxture o~ 2.2 g. o~ 2-methyl-5,6-~ichloro-be~zothiazole and 2 ml. o~ die~hylsulfate ~a3 heated at 120~C. ror 20 minute~; the pick caks, obtained by cooling, ~as ground in ~ mortar by wa~hing with ether and drled.
The ~olid, thu~ obtained, was di~so1ved in 20 ml. o~ :
anhydrou~ pyridine and 2 ml. o~ triethylorthopr~pionate and ~he olution bolled ~or 40 m1nute~. A~ter cooling, the react~on mixture wa~ poured into ~thyl ether, the crude dy~ wa~ p~r~fled by boiling r~peat~dly wlth wate/. 0.5 g.

.
.

~ 2~ -5Dg~
of pure dye was obtained. M.P. ~ 134-139C.
max. - 577 nm. (ethyl alcohol).

EXAMPLE ? 6 3~3l 3 9-triethyl-5,6-5',6'-tetrachloro-thiacarbocyanlne p-toluene-sulfonate C H
Cl ~ S \ ,2 5 /S ~ y~Cl I ll C=cH-c-cH-c t l l Cl ~ N ' ~ Cl c2~ C2H5 CH3 ~ -S03 The dye was prepared as reported in Example 25 9 by using ethyl-p~toluene-sulfonate, in~tead Or diethyl-~ulfate, as ~uaternary a~ent. M.P. ~ 129-133C.
A max. - 589 nm.(ethyl alcohol).

323' diethyl-5,7-5',7'-tetrachloro~carbo~yanlne iodide Cl Cl - ~ C~CH-CH~CH-C ~ ~
Cl ~ N ~ ~ N'~ Cl C2H~; C2H5 I~3 The dye was prepared a~ de~¢ribed ln ~xample 23, using Z-methyl-5,7~dichloro-benzothiazolè in~teAd o~ 2-methyl-5,6-methyl-dichloro-benzothiazole and employing pota~sium iodlde as precipitating agent of the dye. M.P. ~
- 234-Z40VC. . ;
~ max. - 569 n~. ~ethyl alcohol).
:

: ' : - 2g ~

~: ~ ~ " ,'' .: '' 3 3' 9-trlethyl-5,7-5t,7'-tetrachloro-carbocyanine ~odlde ,, Cl C H
~ S ,2 5S ~
Cl N / ~ N~ Cl C2H5 C2H5 I ~

The dye was prepared as described in Ex~mple 25, using 2-methyl-5,7-dichloro-~enzothiazole~ instead of 2-methyl-5,6-d~chloro-benzothiazole and precipitating the crude dye with an aqueous solution o~ potassium iodide. M.P. - 225-230C.
A max. - 561 nm. ~ethyl alcohol).

.

` - .

. ~ . .
3 ~

~ - , 9~
The dyes Or the present invention are powerful desen~ltlzer3 for light-sensitive sllver halide emul~ion~
and therefore can be used ln tho~e photographlc element~
wherein de~en~itization is required, such a3 for instance in the manu~acture of emulslons used ~or the prod~ction o~
direct po~itive lmages, a~ described by Kend~ll and col.
in U. S~ Pat. No. 2,541,472 or in U. S. Pat. No. 2966~,515 and by Hlllson and col. in U. S. Pat. No. 3~962,651, eto.
The cyanine dye~ of this invention, such a~ ~or ln~tance those represented by examples 11, 12, 13~ 14 3 18 24, 27, 23 are uae~ul electron acceptor ~pectral ~en3i~1zer~
~or d~ect posltive ~mulsions, since the dlrect po~it~ve emulsions, which cont~in them, have an improved E~ensitivity.
To prepare photographic emulsion~, the dyes acaording to the present inventlon are conYenlently incorporat0d into the ~inished emulsions and o~ cour~e unirormly distrlbuted throu~hout the em~l~iDn. The method~ o~ incorporating the dyes into the 2mul~ion~ are qulte ea~y and well known to those ~kllled ~n the art. It i~ convenient to add the dy~s~
e.g., under the ~orm of ~olutlons in an appropriate ~301v~nt selected among tho~e havlng no harmful e~eot upon the fini~hed emulsion. Methanol, ethanol 3 ~opropyl alçohol, pyridine, etc., alone or ln comblnation, are use~u`l ~olvents to dis~olve the dyes according to th~ present invenblon.
~he emul~ion~ t~ be used wlth the n2w dyas o~ thl~ . -in~entlon c~n be all tho~e prepared u~lng natural hy~rophl~ic c~llo~d~ a3 silver halide dispersln~ medla, ~uch as gelatln3 a~bumin, agar-a~ar, arabio gùm, ~ynthetic alginla aclds, such as ror lnsta~ce polyv~nyl alcohol, polyvinyl pyrrolld~ne, ~ellulo~e ~ters 9 p~rtially hydrolized cellulo~e ac~tate~ ~tc.

~5~
The concentration of the new dye~ in the emulslon may largely vary: ~rom 10 to 1000 mg. per mol~ of ~ er halide. The speclfic concentration wi:ll vary according to the type of the emulsion to be used and according to the required e~fects~
The most convenient conc~ntration of the dye ~or each glven emul3ion can be e slly determlned by maXing con-centration series and relative measurement~ and examination~
which are well-known to tho~e skllled :ln the art. The 10 emulsion containlng the dyes according to thi~ invention can be convenlently coated on any support material u~ed ~or the pro~uction o~ photographic materials~ such as paper, gla~9 oellulose acetate, cellulose nitrate, rl~m~forming ~ynthet$c resin~, polyester~, polyamide~, polystyroles, eto.
To prepare a ~ilver hallde emul~ion desen~itlzed with one o~ our dyes, we proceeded in the rollowing way:
a numb~r o~ dyes according to the present in~ention was ~epara~èly inoorporated in an emu1gion ln a ratio Or 12 or 24 or 36 mg. o~ dye per Kg. oP ~lnl~hed emu1slon. The dye~
2Q were added under the rorm of solutlons and u~l~ormly incor-pora~ed throu~hout the emul~isn under 3tlrrlng. Sometlmes h~her or lower conoentrations m~y be neoe~sary to en~ure the d~sired degree o~ desen~itizatlon.
Our inventlon i8 further illu~trated by the ~ollowing Table I which r2ports the relatlve ~ensitl~1~y data ~desen~i-tlæat10n) expre~sed in log It ~*~ produoed in si1~er ha1ide e~ul~ions of the ~romo-iod~de and bromo~c~loride ~yp@ ~y the ~dyes ~ the pre~ent invent~on, added to the emulsion in the above ~entloned way.
: ~ :
~ ~ lower ~en~tivity.
', , ' ~ .

. .

`' 9~
After digestlon at 50C. for lO', the emulslons were coated on a cellulose acetate film support. A compari-son te~ coatlng was made of each emul~ion con~aining no desensitlxing dye. A ~ample of each coating was exposed to a sensitometer and ln a spectrograph and then developed in the Ferrania R6 developer, ~or 6 minutes at 20C., having the ~ollowlng composition:

Me~ol~.................................... 1 g.
Sodium sulfite, anhydrous................ 25 g.
Hydroquinone............................ 3.5 g.
Sodium carbonate, anhydrous.............. 25 g.
Potasslum bromide....................... 0.7 g.
Wa~er to make........................ l,000 ml.

(when the emul~ion was of the bromo-chloride type) and with the Ferrania Rl8 developer, for 12 mlnutes at 20C., havlng the ~ollowing composltion:

Mé~.,................................... 2 g.
Sodium sulfite, anhydrous............... lO0 g.
Hydro~uinone.............................. 5 g.
~orax..................................... 2 g.
~ater to make......~................. 1,000 ml.
(when the emulsion was of the bromo-lodide ~ype).

* TRADE MARK

~,' .

9~9 ~ABI~ I

Dye Dye ~elatlve ~xampleConcentrationEmul~on Sen~ltlvlby ~o.mg~Kg. em. Type E~pre~ed ln lo~: _It without any dye - bronl~o-lodide TE5T
addlt ion 13 24 " - 0.37 lr 24 " - 1.18 18 24 " - C.25 24 " - 1.66 22 24 " _ 0.03 :':, without any dye _ bromo-chloride TES~
addibion 17 24 " - 0.68 24 " - 0.85 22 ~4 " ~ 3 . . _ . ,,~ .. _ .

:
_ :

. .' ': . , :~
~,. . .

. ".,,~.

The u~ed bromo-lodide emul~ion contalned 96%
bromide and 4~ iodide and the bromo~cllloride one 9 8g~ 2%
bromlde and lQ~ 8g chloride. From the data of Table I z we can ~ee that some rapresentative dye~ o~ this invention 5 ca~e a desensltization of more than 80,~ in the emulsion~
containing such dyes. We can give evtdence in the same way tha'c also the other dyes of the pre~ent ln~ention are ~llver hal~de emulslon desensitizers. Though both emul~ions selected for our tests are made o~ silver hal~de and gelatin~ lt should be understood tha~ the desensltizers of the pre~ent invention can be used tc advanta~e in emulsions whereln gelati:n ~ :
su~stituted with hydrophilic colloid~, o~ the type ~ent~oned above a3 po~sible or partial substltutes o~ gelakin.
The dyes acoording to the pre~ent lnvention aro uge~ul eleotron aoceptor spectral ~en8itizers and u3e~ul halogen acceptor sensltlzers which can be u,c~ed in all types o~ direct posit1ve emul~lons.
Aacordlng to the present inventlon,~improved direct po~itlve emul~ions ¢an be obtalned by introduelng one or morè
c~anine dyes o~ this invention ~nto a suitable ~ogged ~ilver hallde emul~lon. The emulsion ¢an be ~og~ed in any way kno~n to tho8e skilled ln th~ art, sucn as for lnstance by mean~ o~
llg~t~ or o~ chemical ~ogg1ng agents, ~ucb a8 ~or lnstance ~tannous chlorldeg ~ormaldehyde, thiourea dioxldQ 9 and th~
llke. ~he emulsions can~be ~o~ged also by addltlon of a ~educing agent, such as those de~crib~d above, and o~ æ m~tal m~re electr~positive tharl 8i}Y~r9 such aæ a gold saI~, ~or ~:
~nstan¢e, potasslum chloro-aurate, as deserilbed ~n the Brlti~h Pat. No. 723,dlg~
The dge~ ~ this in~er~tion can be lnco:rp;orated ~: al~o 1~ direc~ positive emulslon3 o~ the type wher~in the : ' .

~s~ 9~
sllver halide grain~ have a sllver salt central core in~oluble in water and an outer shell consisting of a f'ogged ~ilver salt insoluble in water which can be developed to metallic ~llver without any exposure. The dyes according to the present inventlon are prererably incorporated lnto the fogged outer shell. These emulsions can be prepared in se~eral ways, such as ror instance as described in U~ S. Patent NoO 3,367~778.
The dye6 according to the present invention are electron acceptor spectral sensitizers which can be used also in high-sensitivity direct positive emulsions, such as those described ln U. S. Patent No. 3,501,307.
The silver halide~ used ror the preparation o~ the direct positive photographic emulsions, according to this invention, comprise any type of ~ilver halides, sucq as f'or ins~ance ~ilver bromide, silver iodlde, silver chloride, silver chloro~iodide, silver bromo-iodide, silver bromo-chloride, and the llke.
The silver halide grains may be regular and of every crystalline shape, such as cubical or octahedral shape, as described in U. S. Patent No. 3,501,306. Such grains advantageously have a narrow distribution curve, aæ described ln U. S. Patent 3,501,305. It is further known that emulsions having si.lver halide gralns with an avera~e diameter lower than 1 ~ ~ preferably 0.5 ~ , are particularly use~ul. The dyes o~ the present lnventlon can be used to advantage in the direct positive emulsionæ deæcribed in Can~dian paten~
appllcation S.N. 222~,603, filed on March 20 3 1975 .
The merocyanine dyes of the present invention (such as ~or instance example 21) can be used in the direct poæltive .
30 emulsions o~ the above-mentloned type as halogen accep~ors 19~
i.e., as dyes preferably ha-ving a hal~-~ave polarographic cathodic potential lower t~an -Q.9 V., ~ile the difference between the cathodic and the anodic half-wave polarographic potentials is higher than 1.5 V in absolute value.
The types of emulsions wherein our dyes can increase the sensitivity by means of their halogen accepting power are those described for instance in: U.S. Patents Nos. 3,501,307; 3,531,290 and 3,537,858, and in the French Patents 1,518,09~ and 1,520,822 and in Canadian patent application serial No. 222,603, filed on March 20, 1975.
The direct positive emulsions sensitized with the dyes according to the present invention may also contain color-for~ers dissolved in the layer in an appropriate solvent or added as dispersions in a crystal~
loid solvent, such as or instance di-n-butylphthalate, tricresylphosphate, etc. Examples of direct positive emulsions containing sensitizers of this invention and color couplers are described in Canadian patent application Serial No. 222,603, filed on March 20, 1975.
A certain number of dyes of the present invention were photographically tested as electron acceptors and spectral sensitizers for fogged direct positive emulsions by adding the sensitizers dissolved in an appropriate solvent in the concentration reported in Table II of mg.
of the dye per mole of Ag. to an emulsion o the type described in Example lb o Canadian patent application Serial No. 222,603, filed on March 20, 1975. The final emulsion, ready to be coated, had a p~l - 6 and a pAg - 10.5.
After having been coated, a sample of each coating was exposed in a sensitometer and in a spectrograph using a tungsten lamp, developed at 20C for 3 minutes with the Kodak D-19b developer having the following composition:

.

.

,.~

~ ~ 50 9 9 ~

Me~ol*.............................. 2.2 g.
Sodium sulflte, anhydrous........... 72 g.
Hydroquinone........................ 8.8 g.
Sodlum carbonate, anhydrous......... 48 g.
potassium bromide.. ~.......... 4 g.
Water to make...... -............ - 15 ~00 ml.
then ~ixed, washed and dried. The results thereof are reported in Table II. The same emulsion containing the same quantity of yellow-pinacryptole as electron acceptor was taken as a re~erence test. The sensltivity is therefore expressed in log It relative to the yellow-pinacryptole containing coating whlch is taken as reference. A mlnus sign means lower sensitivity and a plus sign means higher sen itivity.

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The polarographic anodic and cathodlc potential v~lues, repor~ed ln Table II are referred to the ab~olute potential scale.
As described by Tani and Kikuchi in Phot. Sci. Engng. ll (3) 129 (1967) ~or s~mmetrical cyanine dyes and by Shiba an~ Kubodera in "Preprlnt ~NB 12~" of I.C.P.S. - 1970, Moscow3 for merocyanine dye~, the polarographic potentlal value~ are strictly re~erred to their electronlc energy level~ and therefore to the~r photographic behavior~
The measurement~ can be carrled oug following the methods reported in P. Delahay, "New instrumen~al method~ ln Electrochemistry", Interscience Publ. Inc., New York, 1954 and those reported in I. M. Kolto~f and J. J. Llngane~
"Polarography", 2nd edition, Intersclence Publ. ~nc., New York and in R. N. Adams, "~lectrocheml3try at ~olid electrode", Marcel Dekker, Inc., New York, 1969.
The cathodic hal~-wave polarographlc potential value (E red) ls the value ln ~olts corre~pondlng to the more posltive cathodic wave Thi~ value is obtained by u~ing 4 a d~opping mercury ele¢trode (DM~) in a solution o~ l.lO
lO- M a~ the electron a¢ceptor in a ~ultable solvent~ as m~yl alcohol oontainlng llth~um chloride (0.05 M) at 20C.
The anodic hal~-peak voltammetric Potential value ~E ox~
i~ the value ln volts corresponding to ~he more negatlve anodic wave.
Thia value i~ determined b~ using a Garpon paste electrode in an aqueou~ ~olvent solution o~ l.lO- ~ 1.10-~ M o~ the electron acceptor or the halogen acceptor~ ~or example a 50~ methanoiic solutio~, containlng ~odium acetata ~0.05 M) and ace~ic acid ~0.005 M). The re~erence electrode is ~n Ag.AgCl - KCl (~) in water at 20C.
The electron acceptor~ u~eful aocordi~g to th~ :Lnvention have an anodlc (E Ox) and a cathodic (E red) polaro~raphlc half-wave potentlal, the ~um o~ whlch ls a positIve number.
Pre~erably, the halogen aacep~or a¢aord~n~ to our lnv~ntlon is ~ dye whose cathodic hal~-wav~ polarographic potential i~ more negatlve than -0.9 V, while the di*ference between the ~athodlc and the an~dic hal~-~av~ polaro~raphic potentials is hlgher than 1.5 V ln ab~olut~ value. (potent~al :
value3 ar- r~erred to the ab301ute potential ~cale).

. .

.

.

~ .

.. . . ` .
. , .,. . . , , . . , ~, . . .

~L~S0990 The dyes of the present invention can be us~d a~
~ilter dye use~ul in photography. For instance, ~olutions of dyes of Example nos. 13, 18, 19 and 22 are bleached by R6 developer solutions havin~ the above-reported composltlon.
Fig. 1 show~ the Jarrel-Ash spectra of some electron acceptor spectral se~itizers and Fig. 2, the Zeisæ ~pectra of same other electron acceptor spectral sensitizers, all tested in the above-descr~bed experimental conditlons who~e data are reported in Table II.

_ 41 -. .

Claims (12)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. Cyanine dyes derived from di-halogen benzoxazole or di-halogen benzothiazole, corresponding to one of the following general formulas:

[I]

[II]

[III]

[IV]

wherein:
Y represents an oxygen or sulfur atom;
n represents a positive integer equal to 2,3,4;
m, p represent a positive integer of 1 or 2;
q represents a positive integer of from 1 to 3;
R, R1, equal or different, each represent a halogen atom;
R2 represents a hydrogen atom, an alkyl group having from 1 to 4 carbon atoms;
R3 represents an acyclic hydrocarbon substituent, an alkyl-aryl substituent or an aryl substituent;
R4 represents a hydrogen atom or an alkyl group having from 1 to 3 carbon atoms;
R5, R6, equal or different, each represent an alkyl group having from 1 to 6 carbon atoms;
X- represents an acid anion;
Z represents the atoms selected from only carbon, oxygen, sulfur, nitrogen and selenium required to complete a heterocyclic nucleus containing from 5 to 6 atoms in the heterocyclic ring;
Q represents the atoms selected from only carbon, oxygen, sulfur, nitrogen and selenium required to complete a heterocyclic ketomethylene nucleus con-taining from 5 to 6 atoms in the heterocyclic ring.

2. Cyanine dyes of claim 1, characterized in that the moiety:

+ X-represents a desensitizing heterocyclic nucleus.

3. Light-sensitive direct positive silver halide emulsions, charac-terized in that they contain a sensitizing amount of a cyanine dye correspond-ing to one of the following general formulas:

[I]

[II]

[III]

[IV]

wherein:
Y is an oxygen or sulfur atom;
n is a positive integer equal to 2,3,4;
m, p are a positive integer equal to 1 or 2;
q is a positive integer of from 1 to 3;

R, R1, equal or different, each represent a halogen atom;
R2 is a hydrogen atom or an alkyl group having from 1 to 4 carbon atoms;
R3 represents an acyclic hydrocarbon substituent, an alkyl aryl substituent or an aryl substituent;
R4 represents a hydrogen atom or an alkyl group having from 1 to 3 carbon atoms;
R5, R6, equal or different, each represent an alkyl group having from 1 to 6 carbon atoms;
X represents an acid anion;
Z represents the atoms selected from only carbon, oxygen, sulfur, nitrogen and selenium required to complete a heterocyclic nucleus containing from 5 to 6 atoms in the desensitizing heterocyclic ring;
Q represents the atoms selected from only carbon, oxygen, sulfur, nitrogen and selenium required to complete a ketomethylenic heterocyclic nucleus con-taining from 5 to 6 atoms in the heterocyclic ring.

4. Light-sensitive direct positive silver halide emulsions, charater-ized in that they contain a sensitizing amount of 3,3'-diethyl-5,7-5',7'-tetrabromo-oxacarbocyanine perchlorate.

5. Light-sensitive direct positive silver halide emulsions, charac-terized in that they contain a sensitizing amount of 3,3'-dimethyl-5,7-5', 7'-tetrabromo-9-ethyl-oxacarbocyanine perchlorate.

6. Ligth-sensitive direct positive silver halide emulsions, charac-terized in that they contain a sensitizing amount of 3,3'-diethyl-5,7-5', 7'-tetrachloro-6,6'-dimethyloxacarbocyanine ethylsulfate.

7. Light-sensitive direct positive silver halide emulsions, charac-terized in that they contain a sensitizing amount of 3,3'-diethyl-5,6-5', 6'-tetrachloro-thiacarbocyanine bromide.

8. Light-sensitive direct positive silver halide emulsions, characterized in that they contain a sensitizing amount of 3,3'-diethyl-5, 7-5',7'-tetrachloro-thiocarbocyanine iodide.

9. Light-sensitive direct positive silver halide emulsions, characterized in that they contain a sensitizing amount of 3,3',9-triethyl-5,7-5',7'-tetrachloro-thiocarbocyanine iodide.

10. Light-sensitive silver halide emulsions characterized in that they contain a cyanine dye selected among those represented by formulas I
to IV of claim 1.

11. Light-sensitive direct positive silver halide emulsion of claim 3 also containing a color former.

12. Direct positive photographic elements characterized in that they contain at least one layer of light-sensitive emulsion of claim 3.