PVC bearing primary aliphatic or aromatic amine groups

The preparation of PVC compounds bearing primary aliphatic and/or aromatic amine groups exhibit several challenges which have been faced in this work. On the one hand, this polymer has never before been modified with aliphatic amine groups in a controlled manner or with a tailored degree of substitution. In this work we present a way to obtain, for the first time in a very selective way and with high degrees of substitution, PVC bearing aliphatic primary amine groups by chemical modification of the polymer. The modifier used for this purpose is 4-aminomethylthiophenol that has been synthesized starting from inexpensive benzyl chloride that is reacted with potassium phthalimide yielding a protected amine functionality. The aromatic thiol functionality, required for the introduction of the modifier molecule by nucleophilic substitution of PVC chlorine atoms is achieved by chlorosulfonation in para-position of the aromatic ring and reduction of the chlorosulfonyl group using sodium borhydride. This compound is used to modify PVC bearing a protected primary amine. The free amine is obtained after deprotection of the phthalimide moiety using hydrazine. On the other hand, the synthesis of primary aromatic amines has been described in the past using expensive precursors. In this work, 2-aminothiophenol or 3-aminothiophenol are used in order to modify the polymer with primary aromatic amine groups using inexpensive starting material.