Grignard reagent Normal 0 false false false EN-IE X-NONE AR-SA /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-st

Grignard reagent

Normal 0 false false false EN-IE X-NONE AR-SA /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:8.0pt; mso-para-margin-left:0cm; line-height:107%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri",sans-serif; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:Arial; mso-bidi-theme-font:minor-bidi; mso-ansi-language:EN-IE; mso-fareast-language:EN-US;}

Preparation of Grignard Reagent:-

add 3.5 g magnesium to 250ml round-bottomed flask and fit the flask with a water reflux condenser and procure a (CaCl) drying tube which can be attached to the top of the condenser.

Add enough anhydrous ether to cover the Mg (12 ml).

Heat the flask and add 2.5 ml of bromobenzene in 80 ml of dry ether through the condenser.

NOTES:-

In the procedure, scale and base quantities on the use of 5g of benzophenone used

The Grignard solution in this lab is premade and purchased.

 Determine from Grignard its molarity the correct amount to use. Show calculations.

After Grignard reagent is premade :

Using a syringe transfer the amount that is calculated of phenylmagnesium bromide from the septum a bottle of the purchased premade solution then add to the dry 3-necked flask.

Prepare a solution of benzophenone (21.5g) in dry ether (70ml). Place this solution by using the dropper funnel and add it steadily to the Grignard solution.

During the addition, you have to swirl the flask and then cool the flask solution to lab temp.

When it cools carefully add the concentrated HCl acid until the aqueous solution is acid to litmus.

The solids should be dissolved, maybe you will need to add more ether and water to see two distinct layers.

Separate the ether and aqueous layers using a separating funnel and extract the aqueous layer with ether (1 x 25ml).

Combine and dry the two ether layers and evaporate the off ether gently using a rotary evaporator.

Obtain the weight of the crude product recovered.

Recrystallize the product from petroleum ether (bp 60C - 80C).

Report the yield, % yield, and the mpt.