Did a grignard experiment where we were supposed to form triphenylmethanol but something went wrong. When we heated up the mixture with the petroleum ether, it didn't solidify, it turned dark and oily. What went wrong?

Based on the information you've provided, it seems like the Grignard reaction did not proceed as expected. The formation of triphenylmethanol typically involves the reaction of a Grignard reagent (such as phenylmagnesium bromide) with a carbonyl compound (such as benzophenone). The reaction is usually conducted in anhydrous conditions, using an ether solvent like diethyl ether or tetrahydrofuran (THF).

There are a few possible reasons why your reaction did not yield the desired product and instead resulted in a dark, oily mixture. Here are a few factors to consider:

1. Moisture: Grignard reagents are highly sensitive to moisture, and even traces of water can quench the reactivity of the reagent. It is crucial to ensure that all glassware and reagents are completely dry before starting the reaction. Check if there was any moisture contamination during the setup or reaction process.

2. Solvent choice: You mentioned using petroleum ether as the solvent, which is not commonly used in Grignard reactions. Typically, diethyl ether or THF is preferred due to their low boiling points and better solubility of the Grignard reagent. Petroleum ether may not have provided the necessary conditions for the reaction to proceed efficiently.

3. Temperature: The temperature during the reaction plays a critical role. Grignard reactions are usually carried out at low temperatures, typically around 0-10 degrees Celsius, unless stated otherwise in the procedure. Excessive heating may result in side reactions or decomposition of the reagent.

4. Carbonyl compound quality: The purity and reactivity of the carbonyl compound (benzophenone, in this case) can also impact the reaction outcome. Ensure that the chosen compound is of good quality and has been properly stored.

To troubleshoot and improve the outcome of your Grignard reaction, consider the following steps:

1. Dry glassware and reagents thoroughly, using techniques like oven-drying, desiccators, or inert gas (such as nitrogen) purging.

2. Select an appropriate solvent, like diethyl ether or THF, and ensure it is anhydrous. Solvents can be prepared by refluxing over drying agents like sodium or potassium metal or using commercial grades of solvents.

3. Optimize the reaction temperature. Follow the literature or the given procedure to determine the recommended temperature range for your specific Grignard reaction.

4. Verify the quality and purity of your starting materials, particularly the carbonyl compound, to rule out any potential issues.

It is also important to consult your lab instructor or mentor for specific guidance regarding the Grignard reaction you performed, as they may have additional insights into the possible sources of error and troubleshooting steps.