Without more information about the synthesis process and the specific substances used, it's difficult to say exactly what the solid or oil that was not soluble in hexanes might be. However, there are a few possibilities to consider.
One possibility is that the solid or oil is an impurity that was introduced during the synthesis process. For example, it could be a side product or a reactant that did not fully react with the adipoyl chloride. In this case, the substance may not be soluble in hexanes because it has different chemical properties than the desired product.
Another possibility is that the substance is a byproduct of the reaction between the adipoyl chloride and another substance, such as a solvent or a catalyst. In this case, the substance may not be soluble in hexanes because it has a different chemical structure than the desired product and is not compatible with hexanes.
Alternatively, it's possible that the solid or oil is a form of the adipoyl chloride itself. For example, if the adipoyl chloride was not fully purified or if it was synthesized using impure starting materials, it could contain other compounds that are not soluble in hexanes.
Overall, without more information about the synthesis process and the specific substances used, it's difficult to determine the exact nature of the solid or oil that was not soluble in hexanes. Further analysis, such as chromatography or spectroscopy, may be necessary to identify the substance and determine its origin.