Grignard Lab

1052 Words Jul 1st, 2013 5 Pages
A Grignard-Like Organic Reaction
The Synthesis of 1-phenyl-3-buten-1-ol

Introduction
The Grignard reaction is an important synthetic process by which a new carbon to carbon bond is formed. Magnesium metal is first reacted with an organic halide forming the Grignard reagent. The Grignard reaction is the addition of an organomagnesium halide (Grignard reagent) to a ketone or aldehyde, to form a tertiary or secondary alcohol, respectively. For example, the reaction with formaldehyde leads to a primary alcohol. Grignard Reagents are also used in the following important reactions: The addition of an excess of a Grignard reagent to an ester or lactone gives a tertiary alcohol in which two alkyl groups are the same, and the addition of a
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The reaction is carried out in saturated aqueous ammonium chloride solution. Thus no special drying of solvents, reagents, or glassware is required. The reaction mechanism for this experiment can be seen below (Fig. 2)

DATA | | | | | | Obtained Values | | | | | | Weight of Zinc powder | 0.165 g | | | | | Volume of NH4Cl (aq) | 1.0 mL | | | | | Volume of Benzaldehyde | 0.105 mL | | | | | Volume of THF | 0.5 mL | | | | | Volume of Allyl Bromide | 0.205 mL | | | | | Weight of Final Product | 0.0514 g | | | | | | | | | | | Percent Yield * | | | | | | Compound | Expected | Actual | % | | | 1-phenyl-3-buten-1-ol | 0.153 g | 0.0514 g | 33.60% | | | | | | | | | TLC | | | | | | solvent system: 30% ether-hexane | | | | | Compound | Rf Value | | | | | Benzaldehyde | 0.75 | | | | | 1-phenyl-3-buten-1-ol | 0.25 | | | | | | | | | | | * Please see calculation section Fig. 3 for further details. | | | | | | | | | | | | | | | Density (g/cm3) ++ | | | Formula Weight (g/mol) ++ | Compound | | | Zinc | 65.38 | | Benzaldehyde | 1.04 | | Benzaldehyde | 106.12 | | 1-phenyl-3-buten-1-ol | 0.992 | | Allyl Bromide | 120.99 | | NH4Cl (aq) | 1.53 | | 1-phenyl-3-buten-1-ol | 148.2 | | THF | 0.8892 | | Allyl Zinc Bromide | 186.37 | | Allyl Bromide | 1.40 | | | | | Diethyl Ether | 0.7134 | |

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