GB950089A - Photographic silver halide emulsions of increased sensitivity - Google Patents

Abstract

7,13-Dithianonadecan -1, 19-diol is prepared by three different methods. The first is by the reaction of 1,5-dibromopentane on 6-thiol-1-hexanol in sodium and methanol, the second is by the reaction of hexamethylene chlorohydrin on 1,5-pentane-dithiol in sodium and methanol, and the third is by the action of ultra-violet light on a mixture of 1,4-pentadiene and 6-mercapto -1- hexanol. These three methods are generally applicable to the preparation of compounds of the general formula: <FORM:0950089/C2/1> wherein m and n are integers from 2 to 10. It is stated that, in a similar manner, compounds of the general formula HO-R (-S-R1)d-S-R-OH may be made, wherein R and R1 are alkylene groups of 2-10 carbon atoms and d is 1, 2 or 3. R and R1 may be branched chain alkylene groups such as methyl-substituted trimethylene and ethyl-substituted tetramethylene. Reference is made to the preparation of 7, 10, 13-trithia-1, 19-nonadecane-diol from the disodium salt of 3-thiapentane-1, 6-dithiol and 7-chloro-n-hexanol. Specifications 235,211, 541,589, 545,448, 627,814, 636,140, 649,660, 660,012, 680,488, 711,488, 736,922, 739,913, 791,219, 800,108, 873,198, 874,080, 886,722, and 942,932, are referred to.