After the solution had cooled to room temperature hexane 20 mL was added to complete precipitation. Continually the stretches at A Nujol bubbler was added to the end of the condenser to indicate evolution of carbon monoxide gas CO produced by carbonyl substitution.
Additionally, while cooling our yellow compound, we flushed the flask with N2 only enough to keep the bubbler from sucking Nujol back up through the tube, as cooling created a negative pressure in the reaction flask.
The condenser was not cooled with water to allow the mesitylene vapors to reflux.
The most troubling result is that the NMR spectrum of the methylbenzoate complex doesnt display shifts around 7. From this we can conclude that methylbenzoate is more electron withdrawing than both mesitylene and 2-methylanisole, which have similar if not identical electron withdrawing properties.
This can be explained by Cr possessing less electron density being a smaller metal than Mo, and thus has less to backbond to the carbonyl ligands. This was remedied in the methyl benzoate syntheses, however, there was most likely a leak in the 10 molybdenum apparatus or run at too high a tempwhich is why it turned black and gave no characterizable product.