Question

Preparation of Triphenylmethanol Using the Grignard Reaction.

RH ROOH CO TO R-R MgBr 1.ether 2.11-SO/10 Icther Grignard reagents are highly reactive and can undergo undesirable RCOH TH₂O side reactions if impurities such as water, carbon dioxide, or oxygen are present. If the organohalogen is added to the R-Mg-X magnesium too quickly, undesired coupling reactions can also occur. In this experiment, you will use 0.015 moles of either benzophenone or ethyl benzoate as the recipient of the phenylmagnesium bromide and this will be the limiting reagent. I recommend that you form your Grignard reagent using a 25% excess of bromobenzene and a 35% excess of magnesium. So, for each mole of benzophenone, you will need 1.25 moles bromobenzene and 1.35 moles of magnesium. For each mole of ethyl benzoate, you will need twice this amount of bromobenzene and magnesium. This lab has a prelab (below). Notebook checks will include the title, purpose, resources, chemical equation, reagent/product table, procedure and reagent table (7 pts). Pre-lab Questions (2 pts ea) 1. Please answer these questions about how water will affect your reaction. a. How many moles of phenylmagnesium bromide are you synthesizing? b. How much water would you have to add (mL) to convert all of your phenylmagnesium bromide into benzene + MgBr(OH)? 2.H SOHO