Abstract: Squarylium compounds of the formula: wherein Q1 and Q2 are each independently a pyrylium, thiopyrylium, selenopyrylium, benzpyrylium, benzthiopyrylium or benzselenopyrylium nucleus, and R1 and R2 are each independently an aliphatic or cycloaliphatic group, can be prepared by reacting a squaric acid derivative of the formula: with a compound of the formula Q2CH2R2 in the presence of a base. The derivatives of Formula II may be prepared by condensing a 2,3,4,4-tetrahalocyclobut-2-en-1-one with a compound of the formula Q1CH2R1 in the presence of a base to produce a compound of the formula: wherein Q1 and R1 are as defined above, and X represents chlorine or bromine, and hydrolyzing the compound of Formula III.

Abstract: Dyes comprising an inner salt of a compound of the formula:Q.sup.1 =Z-Q.sup.2wherein:Q.sup.1 is a 4-(benz[b]-4H-pyrylium)methylidene, 4-(benz[b]-4H-thiopyrylium)methylidene or 4-(benz[b]-4H-selenopyrylium)methylidene grouping;Z is a 1,3-(2-hydroxy-4-oxo-2-cyclobutylidene) hydroxide or 1,3-(2-hydroxy-4,5-dioxo-2-cyclopentylidene) hydroxide ring; andQ.sup.2 is a 4-(benz[b]-4H-pyran-4-ylidene)methyl, 4-(benz[b]-4H-thiopyran-4-ylidene)methyl or 4-(benz[b]-4H-selenopyran-4-ylidene)methyl grouping;wherein at least one of the groupings Q.sup.1 and Q.sup.

Abstract: Squarylium compounds of the formula: ##STR1## wherein Q.sup.1 and Q.sup.2 are each independently a pyrylium, thiopyrylium, selenopyrylium, benzpyrylium, benzthiopyrylium or benzselenopyrylium nucleus, and R.sup.1 and R.sup.2 are each independently an aliphatic or cycloaliphatic group, can be prepared by reacting a squaric acid derivative of the formula: ##STR2## with a compound of the formula Q.sup.2 CH.sub.2 R.sup.2 in the presence of a base.

Abstract: Certain squaric acid derivatives are useful for the thermochemical generation of acid. The squaric acid derivatives may be used in imaging media in conjunction with acid-sensitive materials which undergo a color change when contacted by the acid generated from the squaric acid derivatives. Preferably, the acid-sensitive materials undergo an irreversible color change, so that the image can be fixed by neutralizing all the acid generated with excess base, thereby preventing further color change in the image during long term storage.

Abstract: Dyes comprising an inner salt of a compound of the formula:Q.sup.1 =Z-Q.sup.2wherein:Q.sup.1 is a 4-(benz[b]-4H-pyrylium)methylidene, 4-(benz[b]-4H-thiopyrylium)methylidene or 4-(benz[b]-4H-selenopyrylium)methylidene grouping;Z is a 1,3-(2-hydroxy-4-oxo-2-cyclobutylidene) hydroxide or 1,3-(2-hydroxy-4,5-dioxo-2-cyclopentylidene) hydroxide ring; andQ.sup.2 is a 4-(benz[b]-4H-pyran-4-ylidene)methyl, 4-(benz[b]-4H-thiopyran-4-ylidene)methyl or 4-(benz[b]-4H-selenopyran-4-ylidene)methyl grouping;wherein at least one of the groupings Q.sup.1 and Q.sup.

Abstract: Acid can be generated by exposing a mixture of a superacid precursor and a dye to actinic radiation of a first wavelength which does not, in the absence of the dye, cause decomposition of the superacid precursor to form the corresponding superacid, thereby causing absorption of the actinic radiation and decomposition of part of the superacid precursor, with formation of a protonated product derived from the dye, then irradiating the mixture with actinic radiation of a second wavelength, thereby causing decomposition of part of the remaining superacid precursor, with formation of unbuffered superacid. Preferably, following these irradiations, the imaging medium is heated while the superacid is admixed with a secondary acid generator capable of being thermally decomposed to form a second acid, the thermal decomposition of the secondary acid generator being catalyzed by the presence of the superacid.

Abstract: Acid can be generated by exposing a superacid precursor to actinic radiation effective to generate superacid from the superacid precursor and heating the superacid in admixture with a secondary acid generator capable of undergoing thermal decomposition to produce a secondary acid. The superacid catalyzes decomposition of the secondary acid generator, thus increasing the quantity of strong acid present in the medium. The resultant secondary acid can be used to effect a color change in an acid-sensitive material, so providing an imaging process.

Abstract: Certain squaric acid derivatives are useful for the thermochemical generation of acid. The squaric acid derivatives may be used in imaging media in conjunction with acid-sensitive materials which undergo a color change when contacted by the acid generated from the squaric acid derivatives. Preferably, the acid-sensitive materials undergo an irreversible color change, so that the image can be fixed by neutralizing all the acid generated with excess base, thereby preventing further color change in the image during long term storage.

Abstract: Acid can be generated by exposing a mixture of a superacid precursor and a dye to actinic radiation of a first wavelength which does not, in the absence of the dye, cause decomposition of the superacid precursor to form the corresponding superacid, thereby causing absorption of the actinic radiation and decomposition of part of the superacid precursor, with formation of a protonated product derived from the dye, then irradiating the mixture with actinic radiation of a second wavelength, thereby causing decomposition of part of the remaining superacid precursor, with formation of unbuffered superacid. Preferably, following these irradiations, the imaging medium is heated while the superacid is admixed with a secondary acid generator capable of being thermally decomposed to form a second acid, the thermal decomposition of the secondary acid generator being catalyzed by the presence of the superacid.

Abstract: Acid can be generated by exposing a superacid precursor to actinic radiation effective to generate superacid from the superacid precursor and heating the superacid in admixture with a secondary acid generator capable of undergoing thermal decomposition to produce a secondary acid. The superacid catalyzes decomposition of the secondary acid generator, thus increasing the quantity of strong acid present in the medium. The resultant secondary acid can be used to effect a color change in an acid-sensitive material, so providing an imaging process.

Abstract: Dyes comprising an inner salt of a compound of the formula:Q.sup.1 =Z-Q.sup.2wherein:Q.sup.1 is a 4-(benz[b]-4H-pyrylium)methylidene, 4-(benz[b]-4H-thiopyrylium)methylidene or 4-(benz[b]-4H-selenopyrylium)methylidene grouping;Z is a 1,3-(2-hydroxy-4-oxo-2-cyclobutylidene) hydroxide or 1,3-(2-hydroxy-4,5-dioxo-2-cyclopentylidene) hydroxide ring; andQ.sup.2 is a 4-(benz[b]-4H-pyran-4-ylidene)methyl, 4-(benz[b]-4H-thiopyran-4-ylidene)methyl or 4-(benz[b]-4H-selenopyran-4-ylidene)methyl grouping;wherein at least one of the groupings Q.sup.1 and Q.sup.

Abstract: Certain squaric acid derivatives are useful for the thermochemical generation of acid. The squaric acid derivatives may be used in imaging media in conjunction with acid-sensitive materials which undergo a color change when contacted by the acid generated from the squaric acid derivatives. Preferably, the acid-sensitive materials undergo an irreversible color change, so that the image can be fixed by neutralizing all the acid generated with excess base, thereby preventing further color change in the image during long term storage.

Abstract: Acid can be generated by exposing a superacid precursor to actinic radiation effective to generate superacid from the superacid precursor and heating the superacid in admixture with a secondary acid generator capable of undergoing thermal decomposition to produce a secondary acid. The superacid catalyzes decomposition of the secondary acid generator, thus increasing the quantity of strong acid present in the medium. The resultant secondary acid can be used to effect a color change in an acid-sensitive material, so providing an imaging process.

Abstract: Certain squaric acid derivatives are useful for the thermochemical generation of acid. The squaric acid derivatives may be used in imaging media in conjunction with acid-sensitive materials which undergo a color change when contacted by the acid generated from the squaric acid derivatives. Preferably, the acid-sensitive materials undergo an irreversible color change, so that the image can be fixed by neutralizing all the acid generated with excess base, thereby preventing further color change in the image during long term storage.

Abstract: There are described novel photographic products and processes which utilize compounds which release a photographic reagent in the presence of alkali. The compounds include an imidazole blocking group and cleave in alkali to release the photographic reagent. Also described are novel compounds.

Abstract: Compounds which include a quaternary group connected to a pyrimidine residue through a linkage are disclosed. These compounds are useful as silver halide solvents in photographic products, processes and compositions.

Abstract: Novel compounds which release thio- or selenourea moieties or derivatives thereof upon contact with aqueous alkaline compositions and are therefore useful in photographic applications. The compounds include, in addition to the thio- or selenourea moiety, a uracil blocking moiety and an anion.

Abstract: There are described novel photographic products and processes which utilize compounds which release a photographic reagent in the presence of alkali. The compounds include an imidazole blocking group and cleave in alkali to release the photographic reagent. Also described are novel compounds.

Abstract: There are described novel compounds which are represented by the formula ##STR1## wherein R is ##STR2## A is sulfur or selenium; X represents the nonmetallic atoms necessary to form a nucleus which completes a five or six membered heterocyclic moiety; R.sub.1 is H or lower alkyl; R.sub.2 is H or a hydrolyzable group; and R.sub.3 is H, alkyl or a hydrolyzable group. The compounds are useful in photographic applications and provide controlled release of a photographically useful material during processing of photographic elements with an aqueous alkaline processing composition.

Abstract: There are described novel compounds which are represented by the formula ##STR1## wherein R is ##STR2## A is sulfur or selenium; X represents the nonmetallic atoms necessary to form a nucleus which completes a five or six membered heterocyclic moiety; R.sub.1 is H or lower alkyl; R.sub.2 is H or a hydrolyzable group; and R.sub.3 is H, alkyl or a hydrolyzable group. The compounds are useful in photographic applications and provide controlled release of a photographically useful material during processing of photographic elements with an aqueous alkaline processing composition.