Further investigations into the formation of imide linkages during the amidation of mono‐ and difunctional aroxyacetyl chlorides

Abstract

AbstractThis paper further investigates imide formation in amidation reactions involving Bischloride A2 and suitably selected mono‐ and difunctional analogues on the one hand, and primary aromatic mono‐ and diamines on the other. It also investigates the reaction of these acid chlorides with secondary mono‐ and diamines. If, say, N,N′ dimethyl p‐phenylene diamine and hydroquinone dioxyacetyl chloride or bischloride A2 were to react quantitatively, then a linear unbranched polyamide would be expected to be the result which, in the absence of any hydrogen remaining at the amide link, would no longer present a site for further electrophilic attack on the part of the exceptionally reactive aroxyacetyl chloride. There also arises the possibility that a monoamine such as aniline could conceivably act as a difunctional reagent in the presence of aroxyacetyl chlorides. In the event of this reaction proceeding quantitatively one would expect to obtain a linear polyimide in which each imide–nitrogen atom carries a phenyl group. In carrying out the experimental preparative work which is required to elucidate these points we used both monofunctional reactants as model compounds and difunctional reactants in order to assess the polymeric resultants. The products were characterized by means of 1H‐NMR, 13C‐NMR, IR spectroscopy, TLC, and Tg determinations. The conclusions drawn on the basis of the experimental work provided a satisfactory interpretation of the complex reactions which occur during the polyamidation of bischloride A2. They also point to interesting possibilities for the use of difunctional aroxyacetyl chlorides as modifying comonomers in minor amounts in the preparation of copolyaramides with reduced crystallinity. Such copolyaramides would be expected to have better solubility in common solvents and to be more easily processable than the rather specialized and extremely high‐melting polyaramides currently commercially available and could therefore extend the range of useful applications for this class of polymers.The experimental section is preceded by an introduction which briefly reviews the “state of the art,” especially as far as bischloride A2‐based polyamidation reactions are concerned. It is followed by a discussion of the results, by the conclusions, and a brief summary.