Final answer:
The precipitation of an amorphous oily precipitate instead of a cocrystal in the presence of L-thyroxine and isonicotinamide in DMF may be due to improper solvent choice, reactant compatibility.
Step-by-step explanation:
The formation of an amorphous oily precipitate instead of a cocrystal during an experiment involving L-thyroxine and isonicotinamide in DMF can be attributed to several factors.
In the realm of cocrystal formation, factors such as solvent choice, reactant compatibility, and reaction conditions play significant roles. The choice of solvents like DMF, water, and methanol may have implications on the solubility and crystal formation.
As every solvent can interact differently with the reactants. In this case, the solubility of L-thyroxine or its compatibility with the co-former could have been suboptimal in the selected solvents.
Furthermore, the amorphous nature of the precipitate indicates that the conditions might not have been favorable for orderly crystal lattice formation, which is essential for successful powder X-ray diffraction (PXRD) analysis.
Other potential issues could include impurities in the reactants or inadequacies in the experimental procedure, such as temperature control, concentration of solutions, or timing of the experiment.
It might be beneficial to revise the solvent system, reaction parameters, or even the choice of co-former to achieve a more structured crystal suitable for PXRD.