I prepared triphenylmethanol by a grignard reaction. At the end you add petroleum ether to the mixture and heat it up. It stayed a liquid and got dark and oily but never solidified. What went wrong?
The fact that your triphenylmethanol did not solidify after adding petroleum ether and heating it could be attributed to a few possible issues. Let's go through these potential reasons:
1. Insufficient reaction completion: The grignard reaction involves the addition of a metal organometallic compound (such as an organomagnesium halide, commonly known as a grignard reagent) to a carbonyl compound like benzophenone. If the reaction did not proceed to completion or the grignard reagent was not fully consumed, this could lead to the formation of impurities or side products, preventing the triphenylmethanol from crystallizing.
Solution: Ensure that the reaction between the grignard reagent and benzophenone is carried out thoroughly and given ample reaction time, including the use of an appropriate catalyst if required.
2. Presence of impurities: If the reactants or solvents used are impure, it can hinder the formation of pure triphenylmethanol crystals. Contaminants or side products might prevent proper crystallization.
Solution: Use high-quality starting materials and ensure the purity of the solvents and reagents used. Purify the reactants if necessary through techniques such as distillation or recrystallization.
3. Suboptimal solvent choice: The choice of solvent, in this case, petroleum ether, might not be appropriate for crystallizing triphenylmethanol. Different compounds have different solubilities in various solvents, and if the solubility of triphenylmethanol is high in petroleum ether, it may remain a liquid even after cooling down.
Solution: Consider using other solvents with better solubility characteristics for triphenylmethanol, such as hexanes or diethyl ether, to promote crystallization.
4. Insufficient cooling time: In some cases, even if the reaction mixture is placed in a suitable solvent and cooled down, allowing sufficient time for crystallization is essential. If the mixture is not given enough time to cool, crystals may not form.
Solution: Ensure that the reaction mixture is thoroughly cooled and left undisturbed for an adequate period to achieve crystallization.
By troubleshooting these potential issues, you should be able to identify the problem and take appropriate steps to remedy it.