The extent of reduction of disulphide groups in Merino wool by dilute solutions of thiols in aqueous alcohols at 20 �C has been studied by carboxymethylation of the reduced wool and estimation of the residual disulphide in the product. The wool fibres remain intact throughout the process. Under these conditions toluene-ω-thiol was the most effective agent giving 93% reduction in 2 days, and more than 99% reduction by repeated reduction-carboxymethylation cycles. With Lincoln wool 100% reduction was achieved.

Reduction of the disulphide groups in wool keratin by various substituted phosphines has been studied. Tri(hydroxymethyl)phosphine and tri(diethylaminomethyl)phosphine effect considerable reduction but with these reagents side reactions also occur, probably due to the formation of formaldehyde, as they hydrolyse in aqueous solution. With tri-n-butylphosphine the reduction is apparently specific and nearly quantitative. Only a slight excess of this reductant is required.

When tri-n-butylphosphine is used to reduce the disulphide groups in wool keratin, several different methods can be used for the subsequent alkylation of the thiol groups formed. A novel feature is that in some oases reduction and alkylation can be effected using tri-n- butylphosphine and the alkylating agent acting simultaneously. S-Alkyl kerateines have been prepared using 11 alkylating agents of various chemical types. By means of such a technique a quantitative and apparently specific conversion of cystinyl residues in wool keratin to S.(2-aminoethyl)cysteinyl residues has been achieved.

Aliphatic isocyanates react rapidly and quantitatively with aqueous bisulphite solutions to form stable water-soluble adducts which are salts of N-alkylcarbamyl sulphonio acids. Phenyl isocyanate gives lower yields of the corresponding adduct which is less stable in water. The rate of reaction of n-butyl isocyanate with bisulphite increases with increasing p H and is proportional to [OH-] over the pH range from 5 to 8. The rate of decomposition of the butyl isocyanatebisulphite adduct increases with increasing temperature and pH. A plot of the logarithm of the initial first-order rate constant for the decomposition of the adduct against pH is linear over the pH range from 2 to 7 and has a slope of 0.57&0.05. Water-insoluble polymers with aliphatic isocyanate groups do not form bisulphite adducts under the conditions which are suitable for simple isocyanates. However, the addition of water-soluble organic solvents such as dioxan and the lower alcohols enables the preparation of water-soluble bisulphite adducts which are indefinitely stable a t room temperature and low pH. The relative quantity of the organic solvent must be kept within specific limits which depend on the nature of the prepolymer, the solids content of the final product, and the nature of the organic cosolvent.Polymers with isocyanate groups are used extensively to produce polyurethane coatings, elastomers, adhesives, and foams.la This use of polyisocyanates results from the ease with which condensation polymers form from the reactions of the isocyanates with nucleophiles (e.g. with alcohols to give polyurethanes). Hence isocyanates react readily with water (Scheme 1). This reaction with water can be RNCO + H 2 0 -RSHC02H -RSH2 + C02 RNHz + RSCO -RNHCONHR Scheme 1

In the alkaline saponification at room temperature of six N-benzyloxycarbonyl peptide esters (I) different products were obtained depending on the amount of alkali employed. When 1 mole of alkali was used, all the esters gave the corresponding acids, although with benzyloxycarbonylglycyl-S-benzyl-L-cysteine ethyl ester some racemization occurred. With 2 moles of alkali, benzyl alcohol was eliminated from the benzyloxycarbonyl group in all esters where a glycine residue was next to the N-terminal residue, thereby forming either the corresponding urea derivative (III) or the hydantoin-3-acetic acid derivative (II). Excess alkali caused no similar rearrangement in other sequences under these conditions. The need for special care in saponifying certain N-benzyloxycarbonyl peptide sequences is indicated. An improvement in the tetraethyl pyrophosphite procedure for the synthesis of peptides is described.