Chemical modification of the surface of wool
The reactions of hypophosphorous acid ( H3P02 ) and phosphorous acid ( H3P03 ) with disuiphide compounds, particularly those of the cystine residues in wool, are investigated. The observed differences between the reactions of both acids are highlighted. Some of the products of the reaction of H3P02 and wool cystine are identified. These include the gases hydrogen suiphide H2S ) and sulphur dioxide ( S02 ) and the reduced form of cystine, the thiol cysteine. Quantification of the amounts of these products formed under given reaction conditions, is achieved by use of H2S and 502 sensitive meters, and a colorimetric reaction of 2- vinylpyridine with cysteine. The dyeing properties of wool pretreated with both phosphorus acids alone and a mixture of formaldehyde and both acids are investigated. The H3P02/formaldehyde mixture displays different dyeing properties to the other pretreatments. A series of novel aromatic and aliphatic aminoanthryl phosphonous acids are synthesised and their use as fluorescent whitening agents determined. The solution photolysis of some of the compounds of the series is also studied. Different compounds, namely two commercially available polysuiphides, acetic anhydride, diethylpyrocarbonate, isocyanates and their water soluble bisuiphite adducts, acid and acid/formaldehyde solutions are applied to the surface of wool. The effects of these compounds on therate and extent of photoyellowing of wool and on the fluorescence emission and excitation spectra of wool are noted. Acetic anhydride has the most profound effect on both properties. The possible identity of the compound(s) that contribute to the fluorescence emission spectrum of wool at 450 nm are investigated. A series of alLiphatic and aromatic pyruvamides are synthesised and their solution fluorescence emission maxima compared to that of wool. Finally, the reaction between cysteine and o-phthalaldehyde in the presence of excess primary amine is investigated. An unstable highly fluorescent species may be produced, which though unidentified is most probably an isoindole. Highly coloured products of side reactions also result. The production of the fluorescent species on the surface of wool is undertaken using tributyiphosphine and H3P02 reduced wool as the thiol function in the reaction.