Ciba-Geigy Ag

Ilford Limited

Geoffrey E Ficken

Rolf Steiger

Aaron David Ezekiel

Jean-Francois Reber

Victor W Dolden

William E Long

Rainer Kitzing

Clive W Mowforth

Trevor J Maternaghan

Andrew W Yates

Douglas J Edwards

Michael E Dale

David Rowland

Compounds of the formula ##STR1## where A represents the atoms necessary to complete a benzoxazole or naphthoxazole ring which is optionally substituted, R.sub.1 and R.sub.2 are each alkyl, hydroxyalkyl or alkoxy alkyl groups wherein the alkyl moiety comprises 1 to 4 carbon atoms, R.sub.3, R.sub.4, R.sub.5 and R.sub.6 are each hydrogen atoms or alkyl groups having 1 to 4 carbon atoms or phenyl groups, and X is an anion.

Monomethine compounds

Dyes of the formula ##STR1## wherein Y completes a benzothiazole or benzoselenazole nucleus, R.sub.1 is alkyl, R.sub.2 and R.sub.3 are hydrogen, alkyl or phenyl and Z is alkylene, are suitable for sensitizing fine grain silver halide emulsions.

Optical sensitizing dyes

Tetra-aza indene compounds of the formula ##STR1## wherein R.sub.1 is alkyl or a ring system and R.sub.2 and R.sub.3 are hydrogen or alkyl. These compounds are of use as image toners in photographic materials.

Tetra-aza indene compounds

Sulphoalkyl quaternary salts of the formula ##STR1## wherein X is --O--, --Se--, --S--, --NR-- or --CR(R)--, R is hydrogen or alkyl, R.sub.1 is hydrogen, methyl or ethyl, R.sub.2 and R.sub.3 are each hydrogen or substituents or together represent the atoms necessary to complete an optionally substituted benzene ring, R.sub.4 is optionally substituted alkylene of 3 or 4 carbon atoms and n is 1 or 0, except that when n is 1, R.sub.1 cannot be hydrogen, are prepared by heating at a temperature above 80.degree. C. a heterocyclic base of the formula ##STR2## wherein X, R.sub.1, R.sub.2, R.sub.3 and n have the indicated meanings with a hydroxysulphonic acid of the formula HOR.sub.4 SO.sub.3 H.

Preparation of sulphoalkyl quaternary salts

The present invention relates to light-sensitive photographic material with a light-sensitive heavy metal compound, e.g. a silver halide, and a spectral sensitizer. The spectral sensitizer is a compound in which the radicals of a sensitizing dyestuff are covalently bonded to amino, imino, hydroxyl, mercapto, carboxylic acid or carboxylic acid amide groups of a natural hydrophilic colloid, preferably gelatin. The invention also relates to new sensitizing dyes which are dinuclear cyanine dyes or merocyanine dyes which have attached either to a heterocyclic nucleus of the dye or to its methine chain a group which is reactive with a hydrophilic colloid.

Spectral sensitization of photographic material and new spectral

Spectral sensitization of photographic material with natural colloids

Growing community of inventors

Wilmslow, United Kingdom

Geoffrey E Ficken