Grignard Lab Homework Gilbert and Martin

Grignard Lab Homework

1, 3, 5, 8, 9, 10, 17, 31, 32

1. a. The dipole between the carbon and magnesium atoms in a Grignard is pointing towards the carbon because it has a partial negative charge.

b. The carbon atom in a Grignard is nucleophilic.

c. The conjugate acid of a Grignard is an alkane. Grignard reagents are strong bases because they are capable of accepting protons and are the conjugate bases of weak acids.

3. Glassware should not be flame dried in the vicinity of diethyl ether because it is extremely flammable and volatile.

5. The acidic hydrogen atom of ethanol would likely be abstracted as the Grignard formed, thus destroying it.

8. It is important to add the ethereal solution of the halide slowly to the turnings because the reaction is exothermic and the resulting heat drives the reflux. Adding to quickly may cause the gases to pass the condenser and escape.

9. The more expensive anhydrous form must be used to prepare the Grignard because it has no water which destroys the Grignard as it forms. I cannot find the work-up procedure so I do not know why this reaction does not require the anhydrous form.

10. The undesired coupling product octane is produced as a result of the reaction between the Grignard with the organic halide. It can be minimized by using dilute solutions, stirring and by slowly adding the halide.

32.c. There are eight peaks in the C-13 spectrum because there are eight carbons with different spins due to location and interactions with other atoms.

31.a.

b.

c.

32.a.

b.