GB942933A - Photographic silver halide emulsions of increased sensitivity - Google Patents

Abstract

The Specification describes linear polyamides of molecular weight at least 350 being free from disulphide linkages or mercapto substituents and having recurring units of the general formula -(S-R)p-CO-NH-X-NH-CO-R1- wherein R and R1 are alkylene groups, p is 1 or 2 and X is an alkylene group of 2 to 10 carbon atoms or such an alkylene group wherein the carbon chain is interrupted by an oxygen or sulphur atom or by the group -NR2- (where R2 is hydrogen or C1-4 alkyl). The polymers wherein R and R1 are identical may be prepared by condensing an acid of the formula HS-R-CO-OH (III) with a diamine of the formula H2N-X-NH2 (IV), preferably in the presence of an acid condensing agent such as benzene- or toluene sulphonic acid. Alternatively, an acid of the formula HO-CO-R-S-R1-CO-OH(V) may be condensed with the diamine of formula IV. Examples are given of the preparation of polyamides derived from units of formula I wherein R and R1 are (CH2) or (CH2)2, p is 1 and X is (CH2)6, (CH2)10, (CH2)2-S-(CH2)2, (CH2)3-O-(CH2)3, (CH2)3-O-(CH2)2-O-(CH2)3 or (CH2)3-NCH3- (CH2)3. The Specification also refers to polyamides having recurring units of the general formula II: (R)m-CO-NH-(R1-S)d-R3-NH-CO- wherein R, R1 and R3 are alkylene groups, d is 1, 2 or 3 and m is 0 or 1. These polymers may be prepared by condensing a dibasic acid of the formula HO-CO-R-CO-OH(VI) with a diamine of the formula H2N-R1-S-R3-NH2. An example is given of the condensation of glutaric acid with 3-thia-1;5-diaminopentane in the presence of p-toluene sulphonic acid. The thiopolyamides may have some or all of their thioether groups converted to ternary sulphonium salt groups by reaction with dimethyl sulphate, diethyl sulphate, methyl benzene sulphonate or methyl p-toluene sulphonate. Specifications 235,211, 541,589, 636,140, 719,920, 791,219, 942,932, 942,934 and U.S.A. Specification 2,948,614 are referred to.ALSO:The Specification describes linear polyamides of molecular weight at least 350 being free from disulphide linkages or mercapto substituents and having recurring units of the general formula I:-(S-R)p-CO-NH-X-NH-CO-R1-wherein R and R1 are alkylene groups, pis 1 or 2, and X is an alkylene group of 2 to 10 carbon atoms or such an alkylene group wherein the carbon chain is interrupted by an oxygen or sulphur atom or by the group -NR2- (where R2 is hydrogen or C1-4 alkyl), The polymers wherein R and R1 are identical may be prepared by condensing an acid of the formula HS-R-COOH (III) with a diamine of the formula H2N-XNH2 (IV), preferably in the presence of an acid condensing agent such as benzene- or toluene sulphonic acid. Alternatively, an acid of the formula HO-CO-R-S-R1-CO-OH (V) may be condensed with the diamine of formula IV. Examples are given of the preparation of polyamides derived from units of formula I wherein R and R1 are (CH2) or (CH2)2, pis 1 and X is (CH2)6, (CH2)10, (CH2)2-S-(CH2)2, (CH2)3O-(CH2)3, (CH2)2-O-(CH2)3 or (CH2)3-NCH3(CH2)3. The Specification also refers to polyamides having recurring units of the general formula II; -(R)m-CO-NH-(R1-S)d-R3-NH-CO- wherein R, R1 and R3 are alkylene groups, d is 1, 2 or 3 and m is 0 or 1. These polymers may be prepared by condensing a dibasic acid of the formula HO-CO-R-CO-OH (VI) with a diamine of the formula H2NR1-S-R3-NH2. An example is given of the condensation of glutaric acid with 3-thia-1;5-diaminopentane in the presence of p-toluene sulphonic acid. The thiopolyamides may have some or all of their thioether groups converted to ternary sulphonium salt groups by reaction with dimethyl sulphate, diethyl sulphate, methyl benzene sulphonate or methyl p-toluene sulphonate. Specifications 235,211, 541,589, 636,140, 719,920, 791,219, 942,932, 942,934, and U.S.A. Specification 2,948,614 are referred to.