Essay on Grignard Reaction

1130 Words Nov 5th, 2011 5 Pages
Lab #5: Grignard Reaction – Synthesis of Triphenylmethanol
John Kang
Chem 152L
Performed: 7/20/04
Date submitted: ________________
Lab Partners: Sang Lee, Vicky Lai
TA: John Stanko

Abstract:

This experiment explored the synthesis of triphenylmethanol through the use of Grignard reagents. The percent yield of the product was 10% on a relatively humid day. The melting point was calculate to be 127.2oC with a literature value of 162oC. An IR spectrum of the product was taken and used for positive identification of the product. The mechanism of the formation of triphenylmethanol was explored. Byproducts were also considered and their mechanisms duly noted.

Introduction:

This experiment explores the use of
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The reaction is a carbonyl addition reaction and is detailed below as Figure 3.
[pic]
Fig. 3: Phenylmagnesium bromide carbonyl addition to benzophenone to form triphenylmethanol There are some safety issues to consider. Bromobenzene may be toxic if inhaled and should be worked with under the hood. Diethyl ether and magnesium are very flammable and should be kept away from heat. This report will detail the percent yield and melting point of the synthesized triphenylmethanol and their implications. An IR spectrum of the product is also included and analyzed. The mechanism of triphenylmethanol formation will be discussed, along with any byproducts that were formed in the reaction.

Experimental:

The lab procedure was followed closely.1 The experiments were formed at standard conditions: 25oC and 1 atmosphere.

Results:

The mass of triphenylmethanol synthesized was 0.103g. From Figure 3, the molar mass of triphenylmethanol can be calculated to be 260g/mol. The moles of product formed can be calculated as [pic]. To calculate the percent yield, the expected yield must first be calculated. The mass of benzophenone used was 0.7g. From Figure 3, the mass of benzophenone can be calculated to be 158g/mol. Thus the expected molar yield can be calculated to be [pic]. The percent yield can be calculated as [pic]. It should be noted that if the limiting reagent is

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