The Grignard Synthesis of 3-methyl-3-heptanol
In this experiment, an example of an organometallic compound which has a carbon magnesium bond will be utilized to form a tertiary alcohol. Grignard reagents have been extremely useful in the synthesis of a large number of classes of organic functional groups. Although Grignard reagents are unstable and decompose in air and moisture, they can be prepared and used immediately with moderate difficulty in the undergraduate organic chemistry laboratory. Care will need to be exercised and the equipment must be thoroughly dried before use to insure success. No water may enter the reaction mixture until the final product has been synthesized. The classical Grignard mechanism that this reaction will allow is as follows:
The objective of this lab is to become familiar with working with moisture sensitive chemicals and to create a Grignard reagent that will in turn, form a tertiary alcohol.
Table of Physical Constants
|Name |MW |mL/g used |Moles used |Density |M.P. |B.P. | |n-butyl bromide |137.02 g/mol | | |1.2686 g/cm3 |-112.4 C |101.6 C | |Anhydrous ether |74.12 g/mol | | |0.7134 g/cm3 |-116.3 C |34.6 C | |Methyl ethyl ketone |72.11 g/mol | | |0.8050 g/cm3 |-86 C |79.64 C | |Acetic acid |60.05 g/mol | | |1.049 g/cm3 |16.5 C |118.1 C |
After a reflux apparatus was copnstructed, 2.0g of Mg was put into a 100 ml reaction RB flask. A crystal of Iodine was added into this and stirred a with magnetic stirring bar. Then 7.90 mL of n-bromobutane was dissolved into this and then 20.0 mL of anhydrous ether was added. 5 mL of the n-bromobutane solution was ran...
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