The results of our study of the caffeine maleic acid system have been mixed. We have failed to rediscover polymorph II of maleic acid or to grow a single crystal of the 2:1 cocrystal. On the positive side, however, we have mapped out a consistent preparative route to the 1:1 cocrystal. Study of this system has been complicated by problems brought about largely by the physical characteristics of the starting components- disparity in solubility characteristics of the pure
components and thermal decomposition of maleic acid